lib: New data structure - smap.

A smap is a string to string hash map.  It has a cleaner interface
than shash's which were traditionally used for the same purpose.
This patch implements the data structure, and changes netdev and
its providers to use it.

Signed-off-by: Ethan Jackson <ethan@nicira.com>

13 files changed, 558 insertions, 287 deletions

diff --git a/lib/automake.mk b/lib/automake.mk
index 1d404c2c2..6d3667cca 100644
--- a/lib/automake.mk
+++ b/lib/automake.mk
@@ -141,6 +141,8 @@ lib_libopenvswitch_a_SOURCES = \
 	lib/simap.h \
 	lib/signals.c \
 	lib/signals.h \
+	lib/smap.c \
+	lib/smap.h \
 	lib/socket-util.c \
 	lib/socket-util.h \
 	lib/sort.c \
diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index 4d2f3ac09..61363c638 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -181,7 +181,7 @@ struct tc_ops {
      *
      * (This function is null for tc_ops_other, which cannot be installed.  For
      * other TC classes it should always be nonnull.) */
-    int (*tc_install)(struct netdev *netdev, const struct shash *details);
+    int (*tc_install)(struct netdev *netdev, const struct smap *details);
 
     /* Called when the netdev code determines (through a Netlink query) that
      * this TC class's qdisc is installed on 'netdev', but we didn't install
@@ -221,7 +221,7 @@ struct tc_ops {
      *
      * This function may be null if 'tc' is not configurable.
      */
-    int (*qdisc_get)(const struct netdev *netdev, struct shash *details);
+    int (*qdisc_get)(const struct netdev *netdev, struct smap *details);
 
     /* Reconfigures 'netdev->tc' according to 'details', performing any
      * required Netlink calls to complete the reconfiguration.
@@ -232,7 +232,7 @@ struct tc_ops {
      *
      * This function may be null if 'tc' is not configurable.
      */
-    int (*qdisc_set)(struct netdev *, const struct shash *details);
+    int (*qdisc_set)(struct netdev *, const struct smap *details);
 
     /* Retrieves details of 'queue' on 'netdev->tc' into 'details'.  'queue' is
      * one of the 'struct tc_queue's within 'netdev->tc->queues'.
@@ -248,7 +248,7 @@ struct tc_ops {
      * This function may be null if 'tc' does not have queues ('n_queues' is
      * 0). */
     int (*class_get)(const struct netdev *netdev, const struct tc_queue *queue,
-                     struct shash *details);
+                     struct smap *details);
 
     /* Configures or reconfigures 'queue_id' on 'netdev->tc' according to
      * 'details', perfoming any required Netlink calls to complete the
@@ -262,7 +262,7 @@ struct tc_ops {
      * This function may be null if 'tc' does not have queues or its queues are
      * not configurable. */
     int (*class_set)(struct netdev *, unsigned int queue_id,
-                     const struct shash *details);
+                     const struct smap *details);
 
     /* Deletes 'queue' from 'netdev->tc'.  'queue' is one of the 'struct
      * tc_queue's within 'netdev->tc->queues'.
@@ -1845,7 +1845,7 @@ netdev_linux_get_qos_capabilities(const struct netdev *netdev OVS_UNUSED,
 
 static int
 netdev_linux_get_qos(const struct netdev *netdev,
-                     const char **typep, struct shash *details)
+                     const char **typep, struct smap *details)
 {
     struct netdev_dev_linux *netdev_dev =
                                 netdev_dev_linux_cast(netdev_get_dev(netdev));
@@ -1864,7 +1864,7 @@ netdev_linux_get_qos(const struct netdev *netdev,
 
 static int
 netdev_linux_set_qos(struct netdev *netdev,
-                     const char *type, const struct shash *details)
+                     const char *type, const struct smap *details)
 {
     struct netdev_dev_linux *netdev_dev =
                                 netdev_dev_linux_cast(netdev_get_dev(netdev));
@@ -1901,7 +1901,7 @@ netdev_linux_set_qos(struct netdev *netdev,
 
 static int
 netdev_linux_get_queue(const struct netdev *netdev,
-                       unsigned int queue_id, struct shash *details)
+                       unsigned int queue_id, struct smap *details)
 {
     struct netdev_dev_linux *netdev_dev =
                                 netdev_dev_linux_cast(netdev_get_dev(netdev));
@@ -1920,7 +1920,7 @@ netdev_linux_get_queue(const struct netdev *netdev,
 
 static int
 netdev_linux_set_queue(struct netdev *netdev,
-                       unsigned int queue_id, const struct shash *details)
+                       unsigned int queue_id, const struct smap *details)
 {
     struct netdev_dev_linux *netdev_dev =
                                 netdev_dev_linux_cast(netdev_get_dev(netdev));
@@ -2002,7 +2002,7 @@ netdev_linux_dump_queues(const struct netdev *netdev,
     struct netdev_dev_linux *netdev_dev =
                                 netdev_dev_linux_cast(netdev_get_dev(netdev));
     struct tc_queue *queue, *next_queue;
-    struct shash details;
+    struct smap details;
     int last_error;
     int error;
 
@@ -2014,10 +2014,10 @@ netdev_linux_dump_queues(const struct netdev *netdev,
     }
 
     last_error = 0;
-    shash_init(&details);
+    smap_init(&details);
     HMAP_FOR_EACH_SAFE (queue, next_queue, hmap_node,
                         &netdev_dev->tc->queues) {
-        shash_clear(&details);
+        smap_clear(&details);
 
         error = netdev_dev->tc->ops->class_get(netdev, queue, &details);
         if (!error) {
@@ -2026,7 +2026,7 @@ netdev_linux_dump_queues(const struct netdev *netdev,
             last_error = error;
         }
     }
-    shash_destroy(&details);
+    smap_destroy(&details);
 
     return last_error;
 }
@@ -2271,7 +2271,7 @@ netdev_linux_get_next_hop(const struct in_addr *host, struct in_addr *next_hop,
 }
 
 static int
-netdev_linux_get_drv_info(const struct netdev *netdev, struct shash *sh)
+netdev_linux_get_drv_info(const struct netdev *netdev, struct smap *smap)
 {
     int error;
     struct netdev_dev_linux *netdev_dev =
@@ -2279,17 +2279,18 @@ netdev_linux_get_drv_info(const struct netdev *netdev, struct shash *sh)
 
     error = netdev_linux_get_drvinfo(netdev_dev);
     if (!error) {
-        shash_add(sh, "driver_name", xstrdup(netdev_dev->drvinfo.driver));
-        shash_add(sh, "driver_version", xstrdup(netdev_dev->drvinfo.version));
-        shash_add(sh, "firmware_version", xstrdup(netdev_dev->drvinfo.fw_version));
+        smap_add(smap, "driver_name", netdev_dev->drvinfo.driver);
+        smap_add(smap, "driver_version", netdev_dev->drvinfo.version);
+        smap_add(smap, "firmware_version", netdev_dev->drvinfo.fw_version);
     }
     return error;
 }
 
 static int
-netdev_internal_get_drv_info(const struct netdev *netdev OVS_UNUSED, struct shash *sh)
+netdev_internal_get_drv_info(const struct netdev *netdev OVS_UNUSED,
+                             struct smap *smap)
 {
-    shash_add(sh, "driver_name", xstrdup("openvswitch"));
+    smap_add(smap, "driver_name", "openvswitch");
     return 0;
 }
 
@@ -2651,11 +2652,11 @@ htb_parse_tcmsg__(struct ofpbuf *tcmsg, unsigned int *queue_id,
 
 static void
 htb_parse_qdisc_details__(struct netdev *netdev,
-                          const struct shash *details, struct htb_class *hc)
+                          const struct smap *details, struct htb_class *hc)
 {
     const char *max_rate_s;
 
-    max_rate_s = shash_find_data(details, "max-rate");
+    max_rate_s = smap_get(details, "max-rate");
     hc->max_rate = max_rate_s ? strtoull(max_rate_s, NULL, 10) / 8 : 0;
     if (!hc->max_rate) {
         enum netdev_features current;
@@ -2670,13 +2671,13 @@ htb_parse_qdisc_details__(struct netdev *netdev,
 
 static int
 htb_parse_class_details__(struct netdev *netdev,
-                          const struct shash *details, struct htb_class *hc)
+                          const struct smap *details, struct htb_class *hc)
 {
     const struct htb *htb = htb_get__(netdev);
-    const char *min_rate_s = shash_find_data(details, "min-rate");
-    const char *max_rate_s = shash_find_data(details, "max-rate");
-    const char *burst_s = shash_find_data(details, "burst");
-    const char *priority_s = shash_find_data(details, "priority");
+    const char *min_rate_s = smap_get(details, "min-rate");
+    const char *max_rate_s = smap_get(details, "max-rate");
+    const char *burst_s = smap_get(details, "burst");
+    const char *priority_s = smap_get(details, "priority");
     int mtu, error;
 
     error = netdev_get_mtu(netdev, &mtu);
@@ -2734,7 +2735,7 @@ htb_query_class__(const struct netdev *netdev, unsigned int handle,
 }
 
 static int
-htb_tc_install(struct netdev *netdev, const struct shash *details)
+htb_tc_install(struct netdev *netdev, const struct smap *details)
 {
     int error;
 
@@ -2826,15 +2827,15 @@ htb_tc_destroy(struct tc *tc)
 }
 
 static int
-htb_qdisc_get(const struct netdev *netdev, struct shash *details)
+htb_qdisc_get(const struct netdev *netdev, struct smap *details)
 {
     const struct htb *htb = htb_get__(netdev);
-    shash_add(details, "max-rate", xasprintf("%llu", 8ULL * htb->max_rate));
+    smap_add_format(details, "max-rate", "%llu", 8ULL * htb->max_rate);
     return 0;
 }
 
 static int
-htb_qdisc_set(struct netdev *netdev, const struct shash *details)
+htb_qdisc_set(struct netdev *netdev, const struct smap *details)
 {
     struct htb_class hc;
     int error;
@@ -2850,24 +2851,24 @@ htb_qdisc_set(struct netdev *netdev, const struct shash *details)
 
 static int
 htb_class_get(const struct netdev *netdev OVS_UNUSED,
-              const struct tc_queue *queue, struct shash *details)
+              const struct tc_queue *queue, struct smap *details)
 {
     const struct htb_class *hc = htb_class_cast__(queue);
 
-    shash_add(details, "min-rate", xasprintf("%llu", 8ULL * hc->min_rate));
+    smap_add_format(details, "min-rate", "%llu", 8ULL * hc->min_rate);
     if (hc->min_rate != hc->max_rate) {
-        shash_add(details, "max-rate", xasprintf("%llu", 8ULL * hc->max_rate));
+        smap_add_format(details, "max-rate", "%llu", 8ULL * hc->max_rate);
     }
-    shash_add(details, "burst", xasprintf("%llu", 8ULL * hc->burst));
+    smap_add_format(details, "burst", "%llu", 8ULL * hc->burst);
     if (hc->priority) {
-        shash_add(details, "priority", xasprintf("%u", hc->priority));
+        smap_add_format(details, "priority", "%u", hc->priority);
     }
     return 0;
 }
 
 static int
 htb_class_set(struct netdev *netdev, unsigned int queue_id,
-              const struct shash *details)
+              const struct smap *details)
 {
     struct htb_class hc;
     int error;
@@ -3127,13 +3128,13 @@ hfsc_query_class__(const struct netdev *netdev, unsigned int handle,
 }
 
 static void
-hfsc_parse_qdisc_details__(struct netdev *netdev, const struct shash *details,
+hfsc_parse_qdisc_details__(struct netdev *netdev, const struct smap *details,
                            struct hfsc_class *class)
 {
     uint32_t max_rate;
     const char *max_rate_s;
 
-    max_rate_s = shash_find_data(details, "max-rate");
+    max_rate_s = smap_get(details, "max-rate");
     max_rate   = max_rate_s ? strtoull(max_rate_s, NULL, 10) / 8 : 0;
 
     if (!max_rate) {
@@ -3149,7 +3150,7 @@ hfsc_parse_qdisc_details__(struct netdev *netdev, const struct shash *details,
 
 static int
 hfsc_parse_class_details__(struct netdev *netdev,
-                           const struct shash *details,
+                           const struct smap *details,
                            struct hfsc_class * class)
 {
     const struct hfsc *hfsc;
@@ -3157,8 +3158,8 @@ hfsc_parse_class_details__(struct netdev *netdev,
     const char *min_rate_s, *max_rate_s;
 
     hfsc       = hfsc_get__(netdev);
-    min_rate_s = shash_find_data(details, "min-rate");
-    max_rate_s = shash_find_data(details, "max-rate");
+    min_rate_s = smap_get(details, "min-rate");
+    max_rate_s = smap_get(details, "max-rate");
 
     min_rate = min_rate_s ? strtoull(min_rate_s, NULL, 10) / 8 : 0;
     min_rate = MAX(min_rate, 1);
@@ -3259,7 +3260,7 @@ hfsc_setup_class__(struct netdev *netdev, unsigned int handle,
 }
 
 static int
-hfsc_tc_install(struct netdev *netdev, const struct shash *details)
+hfsc_tc_install(struct netdev *netdev, const struct smap *details)
 {
     int error;
     struct hfsc_class class;
@@ -3327,16 +3328,16 @@ hfsc_tc_destroy(struct tc *tc)
 }
 
 static int
-hfsc_qdisc_get(const struct netdev *netdev, struct shash *details)
+hfsc_qdisc_get(const struct netdev *netdev, struct smap *details)
 {
     const struct hfsc *hfsc;
     hfsc = hfsc_get__(netdev);
-    shash_add(details, "max-rate", xasprintf("%llu", 8ULL * hfsc->max_rate));
+    smap_add_format(details, "max-rate", "%llu", 8ULL * hfsc->max_rate);
     return 0;
 }
 
 static int
-hfsc_qdisc_set(struct netdev *netdev, const struct shash *details)
+hfsc_qdisc_set(struct netdev *netdev, const struct smap *details)
 {
     int error;
     struct hfsc_class class;
@@ -3354,21 +3355,21 @@ hfsc_qdisc_set(struct netdev *netdev, const struct shash *details)
 
 static int
 hfsc_class_get(const struct netdev *netdev OVS_UNUSED,
-              const struct tc_queue *queue, struct shash *details)
+              const struct tc_queue *queue, struct smap *details)
 {
     const struct hfsc_class *hc;
 
     hc = hfsc_class_cast__(queue);
-    shash_add(details, "min-rate", xasprintf("%llu", 8ULL * hc->min_rate));
+    smap_add_format(details, "min-rate", "%llu", 8ULL * hc->min_rate);
     if (hc->min_rate != hc->max_rate) {
-        shash_add(details, "max-rate", xasprintf("%llu", 8ULL * hc->max_rate));
+        smap_add_format(details, "max-rate", "%llu", 8ULL * hc->max_rate);
     }
     return 0;
 }
 
 static int
 hfsc_class_set(struct netdev *netdev, unsigned int queue_id,
-               const struct shash *details)
+               const struct smap *details)
 {
     int error;
     struct hfsc_class class;
@@ -3473,7 +3474,7 @@ default_install__(struct netdev *netdev)
 
 static int
 default_tc_install(struct netdev *netdev,
-                   const struct shash *details OVS_UNUSED)
+                   const struct smap *details OVS_UNUSED)
 {
     default_install__(netdev);
     return 0;
diff --git a/lib/netdev-provider.h b/lib/netdev-provider.h
index 080b76a68..5fb1bbf23 100644
--- a/lib/netdev-provider.h
+++ b/lib/netdev-provider.h
@@ -24,6 +24,7 @@
 #include "netdev.h"
 #include "list.h"
 #include "shash.h"
+#include "smap.h"
 
 #ifdef  __cplusplus
 extern "C" {
@@ -126,17 +127,17 @@ struct netdev_class {
     void (*destroy)(struct netdev_dev *netdev_dev);
 
     /* Fetches the device 'netdev_dev''s configuration, storing it in 'args'.
-     * The caller owns 'args' and pre-initializes it to an empty shash.
+     * The caller owns 'args' and pre-initializes it to an empty smap.
      *
      * If this netdev class does not have any configuration options, this may
      * be a null pointer. */
-    int (*get_config)(struct netdev_dev *netdev_dev, struct shash *args);
+    int (*get_config)(struct netdev_dev *netdev_dev, struct smap *args);
 
     /* Changes the device 'netdev_dev''s configuration to 'args'.
      *
      * If this netdev class does not support configuration, this may be a null
      * pointer. */
-    int (*set_config)(struct netdev_dev *netdev_dev, const struct shash *args);
+    int (*set_config)(struct netdev_dev *netdev_dev, const struct smap *args);
 
     /* Attempts to open a network device.  On success, sets 'netdevp'
      * to the new network device. */
@@ -381,7 +382,7 @@ struct netdev_class {
      *
      * May be NULL if 'netdev' does not support QoS at all. */
     int (*get_qos)(const struct netdev *netdev,
-                   const char **typep, struct shash *details);
+                   const char **typep, struct smap *details);
 
     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
      * 'type' with details of configuration from 'details'.
@@ -401,7 +402,7 @@ struct netdev_class {
      *
      * May be NULL if 'netdev' does not support QoS at all. */
     int (*set_qos)(struct netdev *netdev,
-                   const char *type, const struct shash *details);
+                   const char *type, const struct smap *details);
 
     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
      * If successful, adds that information as string key-value pairs to
@@ -420,7 +421,7 @@ struct netdev_class {
      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
      */
     int (*get_queue)(const struct netdev *netdev,
-                     unsigned int queue_id, struct shash *details);
+                     unsigned int queue_id, struct smap *details);
 
     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
      * string pairs in 'details'.  The contents of 'details' should be
@@ -440,7 +441,7 @@ struct netdev_class {
      *
      * May be NULL if 'netdev' does not support QoS at all. */
     int (*set_queue)(struct netdev *netdev,
-                     unsigned int queue_id, const struct shash *details);
+                     unsigned int queue_id, const struct smap *details);
 
     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
      *
@@ -475,7 +476,7 @@ struct netdev_class {
      */
     int (*dump_queues)(const struct netdev *netdev,
                        void (*cb)(unsigned int queue_id,
-                                  const struct shash *details,
+                                  const struct smap *details,
                                   void *aux),
                        void *aux);
 
@@ -550,12 +551,11 @@ struct netdev_class {
      * representing netdev type specific information.  For more information see
      * ovs-vswitchd.conf.db(5).
      *
-     * The data of 'sh' are heap allocated strings which the caller is
-     * responsible for deallocating.
+     * The caller is responsible for destroying 'smap' and its data.
      *
      * This function may be set to null if it would always return EOPNOTSUPP
      * anyhow. */
-    int (*get_drv_info)(const struct netdev *netdev, struct shash *sh);
+    int (*get_drv_info)(const struct netdev *netdev, struct smap *smap);
 
     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
diff --git a/lib/netdev-vport.c b/lib/netdev-vport.c
index a9eb3eb14..7fe169e36 100644
--- a/lib/netdev-vport.c
+++ b/lib/netdev-vport.c
@@ -65,10 +65,10 @@ struct vport_class {
     enum ovs_vport_type type;
     struct netdev_class netdev_class;
     int (*parse_config)(const char *name, const char *type,
-                        const struct shash *args, struct ofpbuf *options);
+                        const struct smap *args, struct ofpbuf *options);
     int (*unparse_config)(const char *name, const char *type,
                           const struct nlattr *options, size_t options_len,
-                          struct shash *args);
+                          struct smap *args);
 };
 
 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
@@ -223,7 +223,7 @@ netdev_vport_close(struct netdev *netdev_)
 }
 
 static int
-netdev_vport_get_config(struct netdev_dev *dev_, struct shash *args)
+netdev_vport_get_config(struct netdev_dev *dev_, struct smap *args)
 {
     const struct netdev_class *netdev_class = netdev_dev_get_class(dev_);
     const struct vport_class *vport_class = vport_class_cast(netdev_class);
@@ -260,7 +260,7 @@ netdev_vport_get_config(struct netdev_dev *dev_, struct shash *args)
 }
 
 static int
-netdev_vport_set_config(struct netdev_dev *dev_, const struct shash *args)
+netdev_vport_set_config(struct netdev_dev *dev_, const struct smap *args)
 {
     const struct netdev_class *netdev_class = netdev_dev_get_class(dev_);
     const struct vport_class *vport_class = vport_class_cast(netdev_class);
@@ -459,19 +459,18 @@ netdev_vport_set_stats(struct netdev *netdev, const struct netdev_stats *stats)
 }
 
 static int
-netdev_vport_get_drv_info(const struct netdev *netdev, struct shash *sh)
+netdev_vport_get_drv_info(const struct netdev *netdev, struct smap *smap)
 {
     const char *iface = netdev_vport_get_tnl_iface(netdev);
 
     if (iface) {
         struct netdev *egress_netdev;
 
-        shash_add(sh, "tunnel_egress_iface", xstrdup(iface));
+        smap_add(smap, "tunnel_egress_iface", iface);
 
         if (!netdev_open(iface, "system", &egress_netdev)) {
-            shash_add(sh, "tunnel_egress_iface_carrier",
-                      xstrdup(netdev_get_carrier(egress_netdev)
-                              ? "up" : "down"));
+            smap_add(smap, "tunnel_egress_iface_carrier",
+                     netdev_get_carrier(egress_netdev) ? "up" : "down");
             netdev_close(egress_netdev);
         }
     }
@@ -551,14 +550,14 @@ netdev_vport_poll_notify(const struct netdev *netdev)
 /* Code specific to individual vport types. */
 
 static void
-set_key(const struct shash *args, const char *name, uint16_t type,
+set_key(const struct smap *args, const char *name, uint16_t type,
         struct ofpbuf *options)
 {
     const char *s;
 
-    s = shash_find_data(args, name);
+    s = smap_get(args, name);
     if (!s) {
-        s = shash_find_data(args, "key");
+        s = smap_get(args, "key");
         if (!s) {
             s = "0";
         }
@@ -573,11 +572,11 @@ set_key(const struct shash *args, const char *name, uint16_t type,
 
 static int
 parse_tunnel_config(const char *name, const char *type,
-                    const struct shash *args, struct ofpbuf *options)
+                    const struct smap *args, struct ofpbuf *options)
 {
     bool is_gre = false;
     bool is_ipsec = false;
-    struct shash_node *node;
+    struct smap_node *node;
     bool ipsec_mech_set = false;
     ovs_be32 daddr = htonl(0);
     ovs_be32 saddr = htonl(0);
@@ -593,60 +592,60 @@ parse_tunnel_config(const char *name, const char *type,
         flags &= ~TNL_F_HDR_CACHE;
     }
 
-    SHASH_FOR_EACH (node, args) {
-        if (!strcmp(node->name, "remote_ip")) {
+    SMAP_FOR_EACH (node, args) {
+        if (!strcmp(node->key, "remote_ip")) {
             struct in_addr in_addr;
-            if (lookup_ip(node->data, &in_addr)) {
+            if (lookup_ip(node->value, &in_addr)) {
                 VLOG_WARN("%s: bad %s 'remote_ip'", name, type);
             } else {
                 daddr = in_addr.s_addr;
             }
-        } else if (!strcmp(node->name, "local_ip")) {
+        } else if (!strcmp(node->key, "local_ip")) {
             struct in_addr in_addr;
-            if (lookup_ip(node->data, &in_addr)) {
+            if (lookup_ip(node->value, &in_addr)) {
                 VLOG_WARN("%s: bad %s 'local_ip'", name, type);
             } else {
                 saddr = in_addr.s_addr;
             }
-        } else if (!strcmp(node->name, "tos")) {
-            if (!strcmp(node->data, "inherit")) {
+        } else if (!strcmp(node->key, "tos")) {
+            if (!strcmp(node->value, "inherit")) {
                 flags |= TNL_F_TOS_INHERIT;
             } else {
                 char *endptr;
                 int tos;
-                tos = strtol(node->data, &endptr, 0);
+                tos = strtol(node->value, &endptr, 0);
                 if (*endptr == '\0') {
                     nl_msg_put_u8(options, OVS_TUNNEL_ATTR_TOS, tos);
                 }
             }
-        } else if (!strcmp(node->name, "ttl")) {
-            if (!strcmp(node->data, "inherit")) {
+        } else if (!strcmp(node->key, "ttl")) {
+            if (!strcmp(node->value, "inherit")) {
                 flags |= TNL_F_TTL_INHERIT;
             } else {
-                nl_msg_put_u8(options, OVS_TUNNEL_ATTR_TTL, atoi(node->data));
+                nl_msg_put_u8(options, OVS_TUNNEL_ATTR_TTL, atoi(node->value));
             }
-        } else if (!strcmp(node->name, "csum") && is_gre) {
-            if (!strcmp(node->data, "true")) {
+        } else if (!strcmp(node->key, "csum") && is_gre) {
+            if (!strcmp(node->value, "true")) {
                 flags |= TNL_F_CSUM;
             }
-        } else if (!strcmp(node->name, "df_inherit")) {
-            if (!strcmp(node->data, "true")) {
+        } else if (!strcmp(node->key, "df_inherit")) {
+            if (!strcmp(node->value, "true")) {
                 flags |= TNL_F_DF_INHERIT;
             }
-        } else if (!strcmp(node->name, "df_default")) {
-            if (!strcmp(node->data, "false")) {
+        } else if (!strcmp(node->key, "df_default")) {
+            if (!strcmp(node->value, "false")) {
                 flags &= ~TNL_F_DF_DEFAULT;
             }
-        } else if (!strcmp(node->name, "pmtud")) {
-            if (!strcmp(node->data, "false")) {
+        } else if (!strcmp(node->key, "pmtud")) {
+            if (!strcmp(node->value, "false")) {
                 flags &= ~TNL_F_PMTUD;
             }
-        } else if (!strcmp(node->name, "header_cache")) {
-            if (!strcmp(node->data, "false")) {
+        } else if (!strcmp(node->key, "header_cache")) {
+            if (!strcmp(node->value, "false")) {
                 flags &= ~TNL_F_HDR_CACHE;
             }
-        } else if (!strcmp(node->name, "peer_cert") && is_ipsec) {
-            if (shash_find(args, "certificate")) {
+        } else if (!strcmp(node->key, "peer_cert") && is_ipsec) {
+            if (smap_get(args, "certificate")) {
                 ipsec_mech_set = true;
             } else {
                 const char *use_ssl_cert;
@@ -657,7 +656,7 @@ parse_tunnel_config(const char *name, const char *type,
                  * will like be removed when multiple SSL configurations
                  * are supported by OVS.
                  */
-                use_ssl_cert = shash_find_data(args, "use_ssl_cert");
+                use_ssl_cert = smap_get(args, "use_ssl_cert");
                 if (!use_ssl_cert || strcmp(use_ssl_cert, "true")) {
                     VLOG_ERR("%s: 'peer_cert' requires 'certificate' argument",
                              name);
@@ -665,19 +664,19 @@ parse_tunnel_config(const char *name, const char *type,
                 }
                 ipsec_mech_set = true;
             }
-        } else if (!strcmp(node->name, "psk") && is_ipsec) {
+        } else if (!strcmp(node->key, "psk") && is_ipsec) {
             ipsec_mech_set = true;
         } else if (is_ipsec
-                && (!strcmp(node->name, "certificate")
-                    || !strcmp(node->name, "private_key")
-                    || !strcmp(node->name, "use_ssl_cert"))) {
+                && (!strcmp(node->key, "certificate")
+                    || !strcmp(node->key, "private_key")
+                    || !strcmp(node->key, "use_ssl_cert"))) {
             /* Ignore options not used by the netdev. */
-        } else if (!strcmp(node->name, "key") ||
-                   !strcmp(node->name, "in_key") ||
-                   !strcmp(node->name, "out_key")) {
+        } else if (!strcmp(node->key, "key") ||
+                   !strcmp(node->key, "in_key") ||
+                   !strcmp(node->key, "out_key")) {
             /* Handled separately below. */
         } else {
-            VLOG_WARN("%s: unknown %s argument '%s'", name, type, node->name);
+            VLOG_WARN("%s: unknown %s argument '%s'", name, type, node->key);
         }
     }
 
@@ -692,7 +691,7 @@ parse_tunnel_config(const char *name, const char *type,
             return EINVAL;
         }
 
-        if (shash_find(args, "peer_cert") && shash_find(args, "psk")) {
+        if (smap_get(args, "peer_cert") && smap_get(args, "psk")) {
             VLOG_ERR("%s: cannot define both 'peer_cert' and 'psk'", name);
             return EINVAL;
         }
@@ -759,7 +758,7 @@ get_be64_or_zero(const struct nlattr *a)
 static int
 unparse_tunnel_config(const char *name OVS_UNUSED, const char *type OVS_UNUSED,
                       const struct nlattr *options, size_t options_len,
-                      struct shash *args)
+                      struct smap *args)
 {
     struct nlattr *a[OVS_TUNNEL_ATTR_MAX + 1];
     ovs_be32 daddr;
@@ -778,11 +777,11 @@ unparse_tunnel_config(const char *name OVS_UNUSED, const char *type OVS_UNUSED,
     }
 
     daddr = nl_attr_get_be32(a[OVS_TUNNEL_ATTR_DST_IPV4]);
-    shash_add(args, "remote_ip", xasprintf(IP_FMT, IP_ARGS(&daddr)));
+    smap_add_format(args, "remote_ip", IP_FMT, IP_ARGS(&daddr));
 
     if (a[OVS_TUNNEL_ATTR_SRC_IPV4]) {
         ovs_be32 saddr = nl_attr_get_be32(a[OVS_TUNNEL_ATTR_SRC_IPV4]);
-        shash_add(args, "local_ip", xasprintf(IP_FMT, IP_ARGS(&saddr)));
+        smap_add_format(args, "local_ip", IP_FMT, IP_ARGS(&saddr));
     }
 
     if (!a[OVS_TUNNEL_ATTR_IN_KEY] && !a[OVS_TUNNEL_ATTR_OUT_KEY]) {
@@ -792,18 +791,18 @@ unparse_tunnel_config(const char *name OVS_UNUSED, const char *type OVS_UNUSED,
         uint64_t out_key = get_be64_or_zero(a[OVS_TUNNEL_ATTR_OUT_KEY]);
 
         if (in_key && in_key == out_key) {
-            shash_add(args, "key", xasprintf("%"PRIu64, in_key));
+            smap_add_format(args, "key", "%"PRIu64, in_key);
         } else {
             if (!a[OVS_TUNNEL_ATTR_IN_KEY]) {
                 smap_add(args, "in_key", "flow");
             } else if (in_key) {
-                shash_add(args, "in_key", xasprintf("%"PRIu64, in_key));
+                smap_add_format(args, "in_key", "%"PRIu64, in_key);
             }
 
             if (!a[OVS_TUNNEL_ATTR_OUT_KEY]) {
                 smap_add(args, "out_key", "flow");
             } else if (out_key) {
-                shash_add(args, "out_key", xasprintf("%"PRIu64, out_key));
+                smap_add_format(args, "out_key", "%"PRIu64, out_key);
             }
         }
     }
@@ -812,14 +811,14 @@ unparse_tunnel_config(const char *name OVS_UNUSED, const char *type OVS_UNUSED,
         smap_add(args, "tos", "inherit");
     } else if (a[OVS_TUNNEL_ATTR_TTL]) {
         int ttl = nl_attr_get_u8(a[OVS_TUNNEL_ATTR_TTL]);
-        shash_add(args, "tos", xasprintf("%d", ttl));
+        smap_add_format(args, "tos", "%d", ttl);
     }
 
     if (flags & TNL_F_TOS_INHERIT) {
         smap_add(args, "tos", "inherit");
     } else if (a[OVS_TUNNEL_ATTR_TOS]) {
         int tos = nl_attr_get_u8(a[OVS_TUNNEL_ATTR_TOS]);
-        shash_add(args, "tos", xasprintf("0x%x", tos));
+        smap_add_format(args, "tos", "0x%x", tos);
     }
 
     if (flags & TNL_F_CSUM) {
@@ -840,17 +839,17 @@ unparse_tunnel_config(const char *name OVS_UNUSED, const char *type OVS_UNUSED,
 
 static int
 parse_patch_config(const char *name, const char *type OVS_UNUSED,
-                   const struct shash *args, struct ofpbuf *options)
+                   const struct smap *args, struct ofpbuf *options)
 {
     const char *peer;
 
-    peer = shash_find_data(args, "peer");
+    peer = smap_get(args, "peer");
     if (!peer) {
         VLOG_ERR("%s: patch type requires valid 'peer' argument", name);
         return EINVAL;
     }
 
-    if (shash_count(args) > 1) {
+    if (smap_count(args) > 1) {
         VLOG_ERR("%s: patch type takes only a 'peer' argument", name);
         return EINVAL;
     }
@@ -873,7 +872,7 @@ parse_patch_config(const char *name, const char *type OVS_UNUSED,
 static int
 unparse_patch_config(const char *name OVS_UNUSED, const char *type OVS_UNUSED,
                      const struct nlattr *options, size_t options_len,
-                     struct shash *args)
+                     struct smap *args)
 {
     static const struct nl_policy ovs_patch_policy[] = {
         [OVS_PATCH_ATTR_PEER] = { .type = NL_A_STRING,
diff --git a/lib/netdev.c b/lib/netdev.c
index e4e7ab132..1b76785ae 100644
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -37,6 +37,7 @@
 #include "packets.h"
 #include "poll-loop.h"
 #include "shash.h"
+#include "smap.h"
 #include "sset.h"
 #include "svec.h"
 #include "vlog.h"
@@ -243,15 +244,15 @@ netdev_open(const char *name, const char *type, struct netdev **netdevp)
 /* Reconfigures the device 'netdev' with 'args'.  'args' may be empty
  * or NULL if none are needed. */
 int
-netdev_set_config(struct netdev *netdev, const struct shash *args)
+netdev_set_config(struct netdev *netdev, const struct smap *args)
 {
     struct netdev_dev *netdev_dev = netdev_get_dev(netdev);
 
     if (netdev_dev->netdev_class->set_config) {
-        struct shash no_args = SHASH_INITIALIZER(&no_args);
+        struct smap no_args = SMAP_INITIALIZER(&no_args);
         return netdev_dev->netdev_class->set_config(netdev_dev,
                                                     args ? args : &no_args);
-    } else if (args && !shash_is_empty(args)) {
+    } else if (args && !smap_is_empty(args)) {
         VLOG_WARN("%s: arguments provided to device that is not configurable",
                   netdev_get_name(netdev));
     }
@@ -260,23 +261,23 @@ netdev_set_config(struct netdev *netdev, const struct shash *args)
 }
 
 /* Returns the current configuration for 'netdev' in 'args'.  The caller must
- * have already initialized 'args' with shash_init().  Returns 0 on success, in
+ * have already initialized 'args' with smap_init().  Returns 0 on success, in
  * which case 'args' will be filled with 'netdev''s configuration.  On failure
  * returns a positive errno value, in which case 'args' will be empty.
  *
  * The caller owns 'args' and its contents and must eventually free them with
- * shash_destroy_free_data(). */
+ * smap_destroy(). */
 int
-netdev_get_config(const struct netdev *netdev, struct shash *args)
+netdev_get_config(const struct netdev *netdev, struct smap *args)
 {
     struct netdev_dev *netdev_dev = netdev_get_dev(netdev);
     int error;
 
-    shash_clear_free_data(args);
+    smap_clear(args);
     if (netdev_dev->netdev_class->get_config) {
         error = netdev_dev->netdev_class->get_config(netdev_dev, args);
         if (error) {
-            shash_clear_free_data(args);
+            smap_clear(args);
         }
     } else {
         error = 0;
@@ -759,18 +760,18 @@ netdev_get_next_hop(const struct netdev *netdev,
     return error;
 }
 
-/* Populates 'sh' with status information.
+/* Populates 'smap' with status information.
  *
- * Populates 'sh' with 'netdev' specific status information.  This information
- * may be used to populate the status column of the Interface table as defined
- * in ovs-vswitchd.conf.db(5). */
+ * Populates 'smap' with 'netdev' specific status information.  This
+ * information may be used to populate the status column of the Interface table
+ * as defined in ovs-vswitchd.conf.db(5). */
 int
-netdev_get_drv_info(const struct netdev *netdev, struct shash *sh)
+netdev_get_drv_info(const struct netdev *netdev, struct smap *smap)
 {
     struct netdev_dev *dev = netdev_get_dev(netdev);
 
     return (dev->netdev_class->get_drv_info
-            ? dev->netdev_class->get_drv_info(netdev, sh)
+            ? dev->netdev_class->get_drv_info(netdev, smap)
             : EOPNOTSUPP);
 }
 
@@ -1065,10 +1066,9 @@ netdev_get_n_queues(const struct netdev *netdev,
  *
  * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
  *
- * The caller must initialize 'details' as an empty shash (e.g. with
- * shash_init()) before calling this function.  The caller must free 'details',
- * including 'data' members, when it is no longer needed (e.g. with
- * shash_destroy_free_data()).
+ * The caller must initialize 'details' as an empty smap (e.g. with
+ * smap_init()) before calling this function.  The caller must free 'details'
+ * when it is no longer needed (e.g. with smap_destroy()).
  *
  * The caller must not modify or free '*typep'.
  *
@@ -1078,7 +1078,7 @@ netdev_get_n_queues(const struct netdev *netdev,
  * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)). */
 int
 netdev_get_qos(const struct netdev *netdev,
-               const char **typep, struct shash *details)
+               const char **typep, struct smap *details)
 {
     const struct netdev_class *class = netdev_get_dev(netdev)->netdev_class;
     int retval;
@@ -1087,7 +1087,7 @@ netdev_get_qos(const struct netdev *netdev,
         retval = class->get_qos(netdev, typep, details);
         if (retval) {
             *typep = NULL;
-            shash_clear_free_data(details);
+            smap_clear(details);
         }
         return retval;
     } else {
@@ -1117,7 +1117,7 @@ netdev_get_qos(const struct netdev *netdev,
  * details. */
 int
 netdev_set_qos(struct netdev *netdev,
-               const char *type, const struct shash *details)
+               const char *type, const struct smap *details)
 {
     const struct netdev_class *class = netdev_get_dev(netdev)->netdev_class;
 
@@ -1127,7 +1127,7 @@ netdev_set_qos(struct netdev *netdev,
 
     if (class->set_qos) {
         if (!details) {
-            static struct shash empty = SHASH_INITIALIZER(&empty);
+            static struct smap empty = SMAP_INITIALIZER(&empty);
             details = ∅
         }
         return class->set_qos(netdev, type, details);
@@ -1147,12 +1147,12 @@ netdev_set_qos(struct netdev *netdev,
  * given 'type' in the "other_config" column in the "Queue" table in
  * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
  *
- * The caller must initialize 'details' (e.g. with shash_init()) before calling
- * this function.  The caller must free 'details', including 'data' members,
- * when it is no longer needed (e.g. with shash_destroy_free_data()). */
+ * The caller must initialize 'details' (e.g. with smap_init()) before calling
+ * this function.  The caller must free 'details' when it is no longer needed
+ * (e.g. with smap_destroy()). */
 int
 netdev_get_queue(const struct netdev *netdev,
-                 unsigned int queue_id, struct shash *details)
+                 unsigned int queue_id, struct smap *details)
 {
     const struct netdev_class *class = netdev_get_dev(netdev)->netdev_class;
     int retval;
@@ -1161,7 +1161,7 @@ netdev_get_queue(const struct netdev *netdev,
               ? class->get_queue(netdev, queue_id, details)
               : EOPNOTSUPP);
     if (retval) {
-        shash_clear_free_data(details);
+        smap_clear(details);
     }
     return retval;
 }
@@ -1180,7 +1180,7 @@ netdev_get_queue(const struct netdev *netdev,
  * it. */
 int
 netdev_set_queue(struct netdev *netdev,
-                 unsigned int queue_id, const struct shash *details)
+                 unsigned int queue_id, const struct smap *details)
 {
     const struct netdev_class *class = netdev_get_dev(netdev)->netdev_class;
     return (class->set_queue
diff --git a/lib/netdev.h b/lib/netdev.h
index 4b86c21ef..d2cc8b5d9 100644
--- a/lib/netdev.h
+++ b/lib/netdev.h
@@ -35,7 +35,7 @@ extern "C" {
 struct ofpbuf;
 struct in_addr;
 struct in6_addr;
-struct shash;
+struct smap;
 struct sset;
 
 enum netdev_flags {
@@ -93,8 +93,8 @@ bool netdev_is_open(const char *name);
 void netdev_parse_name(const char *netdev_name, char **name, char **type);
 
 /* Options. */
-int netdev_set_config(struct netdev *, const struct shash *args);
-int netdev_get_config(const struct netdev *, struct shash *);
+int netdev_set_config(struct netdev *, const struct smap *args);
+int netdev_get_config(const struct netdev *, struct smap *);
 
 /* Basic properties. */
 const char *netdev_get_name(const struct netdev *);
@@ -159,7 +159,7 @@ int netdev_get_in6(const struct netdev *, struct in6_addr *);
 int netdev_add_router(struct netdev *, struct in_addr router);
 int netdev_get_next_hop(const struct netdev *, const struct in_addr *host,
                         struct in_addr *next_hop, char **);
-int netdev_get_drv_info(const struct netdev *, struct shash *sh);
+int netdev_get_drv_info(const struct netdev *, struct smap *);
 int netdev_arp_lookup(const struct netdev *, ovs_be32 ip, uint8_t mac[6]);
 
 int netdev_get_flags(const struct netdev *, enum netdev_flags *);
@@ -195,20 +195,20 @@ int netdev_get_n_queues(const struct netdev *,
                         const char *type, unsigned int *n_queuesp);
 
 int netdev_get_qos(const struct netdev *,
-                   const char **typep, struct shash *details);
+                   const char **typep, struct smap *details);
 int netdev_set_qos(struct netdev *,
-                   const char *type, const struct shash *details);
+                   const char *type, const struct smap *details);
 
 int netdev_get_queue(const struct netdev *,
-                     unsigned int queue_id, struct shash *details);
+                     unsigned int queue_id, struct smap *details);
 int netdev_set_queue(struct netdev *,
-                     unsigned int queue_id, const struct shash *details);
+                     unsigned int queue_id, const struct smap *details);
 int netdev_delete_queue(struct netdev *, unsigned int queue_id);
 int netdev_get_queue_stats(const struct netdev *, unsigned int queue_id,
                            struct netdev_queue_stats *);
 
 typedef void netdev_dump_queues_cb(unsigned int queue_id,
-                                   const struct shash *details, void *aux);
+                                   const struct smap *details, void *aux);
 int netdev_dump_queues(const struct netdev *,
                        netdev_dump_queues_cb *, void *aux);
 
diff --git a/lib/shash.c b/lib/shash.c
index af917b33c..74801763e 100644
--- a/lib/shash.c
+++ b/lib/shash.c
@@ -313,58 +313,3 @@ shash_random_node(struct shash *sh)
 {
     return CONTAINER_OF(hmap_random_node(&sh->map), struct shash_node, node);
 }
-
-/* String-to-string maps (smaps). */
-
-/* Frees 'smap', including its keys and string values. */
-void
-smap_destroy(struct shash *smap)
-{
-    shash_destroy_free_data(smap);
-}
-
-/* Returns true if string-to-string maps 'a' and 'b' contain the same keys and
- * values, false otherwise. */
-bool
-smap_equal(const struct shash *a, const struct shash *b)
-{
-    struct shash_node *a_node;
-
-    if (shash_count(a) != shash_count(b)) {
-        return false;
-    }
-
-    SHASH_FOR_EACH (a_node, a) {
-        uint32_t hash = a_node->node.hash;
-        size_t len = strlen(a_node->name);
-        struct shash_node *b_node = shash_find__(b, a_node->name, len, hash);
-        if (!b_node || strcmp(a_node->data, b_node->data)) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
-/* Initializes 'dst' as a clone of 'src'. */
-void
-smap_clone(struct shash *dst, const struct shash *src)
-{
-    struct shash_node *node;
-
-    shash_init(dst);
-    SHASH_FOR_EACH (node, src) {
-        shash_add_nocopy__(dst, xstrdup(node->name), xstrdup(node->data),
-                           node->node.hash);
-    }
-}
-
-/* Adds 'key' with string 'value' to 'smap', making a copy of each.
- *
- * It is the caller's responsibility to avoid duplicate names, if that is
- * desirable. */
-void
-smap_add(struct shash *smap, const char *key, const char *value)
-{
-    shash_add(smap, key, xstrdup(value));
-}
diff --git a/lib/shash.h b/lib/shash.h
index decfcbc1f..97d36badd 100644
--- a/lib/shash.h
+++ b/lib/shash.h
@@ -67,12 +67,6 @@ const struct shash_node **shash_sort(const struct shash *);
 bool shash_equal_keys(const struct shash *, const struct shash *);
 struct shash_node *shash_random_node(struct shash *);
 
-/* Working with "smaps": shashes used as string-to-string maps. */
-void smap_destroy(struct shash *);
-bool smap_equal(const struct shash *, const struct shash *);
-void smap_clone(struct shash *, const struct shash *);
-void smap_add(struct shash *, const char *key, const char *value);
-
 #ifdef  __cplusplus
 }
 #endif
diff --git a/lib/smap.c b/lib/smap.c
new file mode 100644
index 000000000..642804ee5
--- /dev/null
+++ b/lib/smap.c
@@ -0,0 +1,269 @@
+/* Copyright (c) 2012 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License. */
+
+#include <config.h>
+#include "smap.h"
+
+#include <assert.h>
+
+#include "hash.h"
+
+static struct smap_node *smap_add__(struct smap *, char *, void *,
+                                    size_t hash);
+static struct smap_node *smap_find__(const struct smap *, const char *key,
+                                     size_t key_len, size_t hash);
+static int compare_nodes_by_key(const void *, const void *);
+
+/* Public Functions. */
+
+void
+smap_init(struct smap *smap)
+{
+    hmap_init(&smap->map);
+}
+
+void
+smap_destroy(struct smap *smap)
+{
+    if (smap) {
+        smap_clear(smap);
+        hmap_destroy(&smap->map);
+    }
+}
+
+/* Adds 'key' paired with 'value' to 'smap'.  It is the caller's responsibility
+ * to avoid duplicate keys if desirable. */
+struct smap_node *
+smap_add(struct smap *smap, const char *key, const char *value)
+{
+    size_t key_len = strlen(key);
+    return smap_add__(smap, xmemdup0(key, key_len), xstrdup(value),
+                      hash_bytes(key, key_len, 0));
+}
+
+/* Attempts to add 'key' to 'smap' associated with 'value'.  If 'key' already
+ * exists in 'smap', does nothing and returns false.  Otherwise, performs the
+ * addition and returns true. */
+bool
+smap_add_once(struct smap *smap, const char *key, const char *value)
+{
+    if (!smap_get(smap, key)) {
+        smap_add(smap, key, value);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+/* Adds 'key' paired with a value derived from 'format' (similar to printf).
+ * It is the caller's responsibility to avoid duplicate keys if desirable. */
+void
+smap_add_format(struct smap *smap, const char *key, const char *format, ...)
+{
+    size_t key_len;
+    va_list args;
+    char *value;
+
+    va_start(args, format);
+    value = xvasprintf(format, args);
+    va_end(args);
+
+    key_len = strlen(key);
+    smap_add__(smap, xmemdup0(key, key_len), value,
+               hash_bytes(key, key_len, 0));
+}
+
+/* Searches for 'key' in 'smap'.  If it does not already exists, adds it.
+ * Otherwise, changes its value to 'value'. */
+void
+smap_replace(struct smap *smap, const char *key, const char *value)
+{
+    size_t  key_len = strlen(key);
+    size_t hash = hash_bytes(key, key_len, 0);
+
+    struct smap_node *node;
+
+    node = smap_find__(smap, key, key_len, hash);
+    if (node) {
+        free(node->value);
+        node->value = xstrdup(value);
+    } else {
+        smap_add__(smap, xmemdup0(key, key_len), xstrdup(value), hash);
+    }
+}
+
+/* If 'key' is in 'smap', removes it.  Otherwise does nothing. */
+void
+smap_remove(struct smap *smap, const char *key)
+{
+    struct smap_node *node = smap_get_node(smap, key);
+
+    if (node) {
+        smap_remove_node(smap, node);
+    }
+}
+
+/* Removes 'node' from 'smap'. */
+void
+smap_remove_node(struct smap *smap, struct smap_node *node)
+{
+    hmap_remove(&smap->map, &node->node);
+    free(node->key);
+    free(node->value);
+    free(node);
+}
+
+/* Removes all key-value pairs from 'smap'. */
+void
+smap_clear(struct smap *smap)
+{
+    struct smap_node *node, *next;
+
+    SMAP_FOR_EACH_SAFE (node, next, smap) {
+        smap_remove_node(smap, node);
+    }
+}
+
+/* Returns the value associated with 'key' in 'smap', or NULL. */
+const char *
+smap_get(const struct smap *smap, const char *key)
+{
+    struct smap_node *node = smap_get_node(smap, key);
+    return node ? node->value : NULL;
+}
+
+/* Returns the node associated with 'key' in 'smap', or NULL. */
+struct smap_node *
+smap_get_node(const struct smap *smap, const char *key)
+{
+    size_t key_len = strlen(key);
+    return smap_find__(smap, key, key_len, hash_bytes(key, key_len, 0));
+}
+
+/* Gets the value associated with 'key' in 'smap' and converts it to a boolean.
+ * If 'key' is not in 'smap', or its value is neither "true" nor "false",
+ * returns 'def'. */
+bool
+smap_get_bool(const struct smap *smap, const char *key, bool def)
+{
+    const char *value = smap_get(smap, key);
+
+    if (!value) {
+        return def;
+    }
+
+    if (def) {
+        return strcasecmp("false", value) != 0;
+    } else {
+        return !strcasecmp("true", value);
+    }
+}
+
+/* Gets the value associated with 'key' in 'smap' and converts it to an int
+ * using atoi().  If 'key' is not in 'smap', returns 'def'. */
+int
+smap_get_int(const struct smap *smap, const char *key, int def)
+{
+    const char *value = smap_get(smap, key);
+
+    return value ? atoi(value) : def;
+}
+
+/* Returns true of there are no elements in 'smap'. */
+bool
+smap_is_empty(const struct smap *smap)
+{
+    return hmap_is_empty(&smap->map);
+}
+
+/* Returns the number of elements in 'smap'. */
+size_t
+smap_count(const struct smap *smap)
+{
+    return hmap_count(&smap->map);
+}
+
+/* Initializes 'dst' as a clone of 'src. */
+void
+smap_clone(struct smap *dst, struct smap *src)
+{
+    struct smap_node *node;
+
+    smap_init(dst);
+    SMAP_FOR_EACH (node, src) {
+        smap_add__(dst, xstrdup(node->key), xstrdup(node->value),
+                   node->node.hash);
+    }
+}
+
+/* Returns an array of nodes sorted on key or NULL if 'smap' is empty.  The
+ * caller is responsible for freeing this array. */
+const struct smap_node **
+smap_sort(const struct smap *smap)
+{
+    if (smap_is_empty(smap)) {
+        return NULL;
+    } else {
+        const struct smap_node **nodes;
+        struct smap_node *node;
+        size_t i, n;
+
+        n = smap_count(smap);
+        nodes = xmalloc(n * sizeof *nodes);
+        i = 0;
+        SMAP_FOR_EACH (node, smap) {
+            nodes[i++] = node;
+        }
+        assert(i == n);
+
+        qsort(nodes, n, sizeof *nodes, compare_nodes_by_key);
+
+        return nodes;
+    }
+}
+
+/* Private Helpers. */
+
+static struct smap_node *
+smap_add__(struct smap *smap, char *key, void *value, size_t hash)
+{
+    struct smap_node *node = xmalloc(sizeof *node);
+    node->key = key;
+    node->value = value;
+    hmap_insert(&smap->map, &node->node, hash);
+    return node;
+}
+
+static struct smap_node *
+smap_find__(const struct smap *smap, const char *key, size_t key_len,
+            size_t hash)
+{
+    struct smap_node *node;
+
+    HMAP_FOR_EACH_WITH_HASH (node, node, hash, &smap->map) {
+        if (!strncmp(node->key, key, key_len) && !node->key[key_len]) {
+            return node;
+        }
+    }
+
+    return NULL;
+}
+
+static int
+compare_nodes_by_key(const void *a_, const void *b_)
+{
+    const struct smap_node *const *a = a_;
+    const struct smap_node *const *b = b_;
+    return strcmp((*a)->key, (*b)->key);
+}
diff --git a/lib/smap.h b/lib/smap.h
new file mode 100644
index 000000000..993d0b243
--- /dev/null
+++ b/lib/smap.h
@@ -0,0 +1,63 @@
+/* Copyright (c) 2012 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.  */
+
+#ifndef SMAP_H
+#define SMAP_H 1
+
+#include "hmap.h"
+
+/* A map from string to string. */
+struct smap {
+    struct hmap map;           /* Contains "struct smap_node"s. */
+};
+
+struct smap_node {
+    struct hmap_node node;     /* In struct smap's 'map' hmap. */
+    char *key;
+    char *value;
+};
+
+#define SMAP_INITIALIZER(SMAP) { HMAP_INITIALIZER(&(SMAP)->map) }
+
+#define SMAP_FOR_EACH(SMAP_NODE, SMAP) \
+    HMAP_FOR_EACH (SMAP_NODE, node, &(SMAP)->map)
+
+#define SMAP_FOR_EACH_SAFE(SMAP_NODE, NEXT, SMAP) \
+    HMAP_FOR_EACH_SAFE (SMAP_NODE, NEXT, node, &(SMAP)->map)
+
+void smap_init(struct smap *);
+void smap_destroy(struct smap *);
+
+struct smap_node *smap_add(struct smap *, const char *, const char *);
+bool smap_add_once(struct smap *, const char *, const char *);
+void smap_add_format(struct smap *, const char *key, const char *, ...)
+    PRINTF_FORMAT(3, 4);
+void smap_replace(struct smap *, const char *, const char *);
+
+void smap_remove(struct smap *, const char *);
+void smap_remove_node(struct smap *smap, struct smap_node *);
+void smap_clear(struct smap *);
+
+const char *smap_get(const struct smap *, const char *);
+struct smap_node *smap_get_node(const struct smap *, const char *);
+bool smap_get_bool(const struct smap *smap, const char *key, bool def);
+int smap_get_int(const struct smap *smap, const char *key, int def);
+
+bool smap_is_empty(const struct smap *);
+size_t smap_count(const struct smap *);
+
+void smap_clone(struct smap *dst, struct smap *src);
+const struct smap_node **smap_sort(const struct smap *);
+
+#endif /* smap.h */
diff --git a/utilities/ovs-dpctl.c b/utilities/ovs-dpctl.c
index 6cb05b887..950e8f417 100644
--- a/utilities/ovs-dpctl.c
+++ b/utilities/ovs-dpctl.c
@@ -44,6 +44,7 @@
 #include "packets.h"
 #include "shash.h"
 #include "simap.h"
+#include "smap.h"
 #include "sset.h"
 #include "timeval.h"
 #include "util.h"
@@ -246,7 +247,7 @@ do_add_if(int argc OVS_UNUSED, char *argv[])
         const char *name, *type;
         char *save_ptr = NULL;
         struct netdev *netdev = NULL;
-        struct shash args;
+        struct smap args;
         char *option;
         int error;
 
@@ -259,7 +260,7 @@ do_add_if(int argc OVS_UNUSED, char *argv[])
             continue;
         }
 
-        shash_init(&args);
+        smap_init(&args);
         while ((option = strtok_r(NULL, ",", &save_ptr)) != NULL) {
             char *save_ptr_2 = NULL;
             char *key, *value;
@@ -272,7 +273,7 @@ do_add_if(int argc OVS_UNUSED, char *argv[])
 
             if (!strcmp(key, "type")) {
                 type = value;
-            } else if (!shash_add_once(&args, key, value)) {
+            } else if (!smap_add_once(&args, key, value)) {
                 ovs_error(0, "duplicate \"%s\" option", key);
             }
         }
@@ -323,7 +324,7 @@ do_set_if(int argc, char *argv[])
         char *save_ptr = NULL;
         char *type = NULL;
         const char *name;
-        struct shash args;
+        struct smap args;
         char *option;
         int error;
 
@@ -350,7 +351,7 @@ do_set_if(int argc, char *argv[])
             goto next;
         }
 
-        shash_init(&args);
+        smap_init(&args);
         error = netdev_get_config(netdev, &args);
         if (error) {
             ovs_error(error, "%s: failed to fetch configuration", name);
@@ -375,9 +376,9 @@ do_set_if(int argc, char *argv[])
                     failure = true;
                 }
             } else if (value[0] == '\0') {
-                free(shash_find_and_delete(&args, key));
+                smap_remove(&args, key);
             } else {
-                free(shash_replace(&args, key, xstrdup(value)));
+                smap_replace(&args, key, value);
             }
         }
 
@@ -500,26 +501,26 @@ show_dpif(struct dpif *dpif)
 
             error = netdev_open(dpif_port.name, dpif_port.type, &netdev);
             if (!error) {
-                struct shash config;
+                struct smap config;
 
-                shash_init(&config);
+                smap_init(&config);
                 error = netdev_get_config(netdev, &config);
                 if (!error) {
-                    const struct shash_node **nodes;
+                    const struct smap_node **nodes;
                     size_t i;
 
-                    nodes = shash_sort(&config);
-                    for (i = 0; i < shash_count(&config); i++) {
-                        const struct shash_node *node = nodes[i];
-                        printf("%c %s=%s", i ? ',' : ':',
-                               node->name, (char *) node->data);
+                    nodes = smap_sort(&config);
+                    for (i = 0; i < smap_count(&config); i++) {
+                        const struct smap_node *node = nodes[i];
+                        printf("%c %s=%s", i ? ',' : ':', node->key,
+                               node->value);
                     }
                     free(nodes);
                 } else {
                     printf(", could not retrieve configuration (%s)",
                            strerror(error));
                 }
-                shash_destroy_free_data(&config);
+                smap_destroy(&config);
 
                 netdev_close(netdev);
             } else {
diff --git a/utilities/ovs-vsctl.c b/utilities/ovs-vsctl.c
index bd4725807..830132c37 100644
--- a/utilities/ovs-vsctl.c
+++ b/utilities/ovs-vsctl.c
@@ -3936,7 +3936,7 @@ do_vsctl(const char *args, struct vsctl_command *commands, size_t n_commands,
         table_destroy(c->table);
         free(c->table);
 
-        smap_destroy(&c->options);
+        shash_destroy_free_data(&c->options);
     }
     free(commands);
 
diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index fe92d6fb2..53454db44 100644
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -41,6 +41,7 @@
 #include "poll-loop.h"
 #include "sha1.h"
 #include "shash.h"
+#include "smap.h"
 #include "socket-util.h"
 #include "stream.h"
 #include "stream-ssl.h"
@@ -245,10 +246,10 @@ static void iface_refresh_cfm_stats(struct iface *);
 static void iface_refresh_stats(struct iface *);
 static void iface_refresh_status(struct iface *);
 static bool iface_is_synthetic(const struct iface *);
-static void shash_from_ovs_idl_map(char **keys, char **values, size_t n,
-                                   struct shash *);
-static void shash_to_ovs_idl_map(struct shash *,
-                                 char ***keys, char ***values, size_t *n);
+static void smap_from_ovs_idl_map(char **keys, char **values, size_t n,
+                                  struct smap *);
+static void smap_to_ovs_idl_map(struct smap *,
+                                char ***keys, char ***values, size_t *n);
 
 /* Linux VLAN device support (e.g. "eth0.10" for VLAN 10.)
  *
@@ -1150,15 +1151,15 @@ static int
 iface_set_netdev_config(const struct ovsrec_interface *iface_cfg,
                         struct netdev *netdev)
 {
-    struct shash args;
+    struct smap args;
     int error;
 
-    shash_init(&args);
-    shash_from_ovs_idl_map(iface_cfg->key_options,
-                           iface_cfg->value_options,
-                           iface_cfg->n_options, &args);
+    smap_init(&args);
+    smap_from_ovs_idl_map(iface_cfg->key_options,
+                          iface_cfg->value_options,
+                          iface_cfg->n_options, &args);
     error = netdev_set_config(netdev, &args);
-    shash_destroy(&args);
+    smap_destroy(&args);
 
     if (error) {
         VLOG_WARN("could not configure network device %s (%s)",
@@ -1650,7 +1651,7 @@ dpid_from_hash(const void *data, size_t n)
 static void
 iface_refresh_status(struct iface *iface)
 {
-    struct shash sh;
+    struct smap smap;
 
     enum netdev_features current;
     enum netdev_flags flags;
@@ -1663,13 +1664,13 @@ iface_refresh_status(struct iface *iface)
         return;
     }
 
-    shash_init(&sh);
+    smap_init(&smap);
 
-    if (!netdev_get_drv_info(iface->netdev, &sh)) {
+    if (!netdev_get_drv_info(iface->netdev, &smap)) {
         size_t n;
         char **keys, **values;
 
-        shash_to_ovs_idl_map(&sh, &keys, &values, &n);
+        smap_to_ovs_idl_map(&smap, &keys, &values, &n);
         ovsrec_interface_set_status(iface->cfg, keys, values, n);
 
         free(keys);
@@ -1678,7 +1679,7 @@ iface_refresh_status(struct iface *iface)
         ovsrec_interface_set_status(iface->cfg, NULL, NULL, 0);
     }
 
-    shash_destroy_free_data(&sh);
+    smap_destroy(&smap);
 
     error = netdev_get_flags(iface->netdev, &flags);
     if (!error) {
@@ -2250,14 +2251,14 @@ struct qos_unixctl_show_cbdata {
 
 static void
 qos_unixctl_show_cb(unsigned int queue_id,
-                    const struct shash *details,
+                    const struct smap *details,
                     void *aux)
 {
     struct qos_unixctl_show_cbdata *data = aux;
     struct ds *ds = data->ds;
     struct iface *iface = data->iface;
     struct netdev_queue_stats stats;
-    struct shash_node *node;
+    struct smap_node *node;
     int error;
 
     ds_put_cstr(ds, "\n");
@@ -2267,8 +2268,8 @@ qos_unixctl_show_cb(unsigned int queue_id,
         ds_put_cstr(ds, "Default:\n");
     }
 
-    SHASH_FOR_EACH (node, details) {
-        ds_put_format(ds, "\t%s: %s\n", node->name, (char *)node->data);
+    SMAP_FOR_EACH (node, details) {
+        ds_put_format(ds, "\t%s: %s\n", node->key, node->value);
     }
 
     error = netdev_get_queue_stats(iface->netdev, queue_id, &stats);
@@ -2295,10 +2296,10 @@ qos_unixctl_show(struct unixctl_conn *conn, int argc OVS_UNUSED,
                  const char *argv[], void *aux OVS_UNUSED)
 {
     struct ds ds = DS_EMPTY_INITIALIZER;
-    struct shash sh = SHASH_INITIALIZER(&sh);
+    struct smap smap = SMAP_INITIALIZER(&smap);
     struct iface *iface;
     const char *type;
-    struct shash_node *node;
+    struct smap_node *node;
     struct qos_unixctl_show_cbdata data;
     int error;
 
@@ -2308,13 +2309,13 @@ qos_unixctl_show(struct unixctl_conn *conn, int argc OVS_UNUSED,
         return;
     }
 
-    netdev_get_qos(iface->netdev, &type, &sh);
+    netdev_get_qos(iface->netdev, &type, &smap);
 
     if (*type != '\0') {
         ds_put_format(&ds, "QoS: %s %s\n", iface->name, type);
 
-        SHASH_FOR_EACH (node, &sh) {
-            ds_put_format(&ds, "%s: %s\n", node->name, (char *)node->data);
+        SMAP_FOR_EACH (node, &smap) {
+            ds_put_format(&ds, "%s: %s\n", node->key, node->value);
         }
 
         data.ds = &ds;
@@ -2330,7 +2331,7 @@ qos_unixctl_show(struct unixctl_conn *conn, int argc OVS_UNUSED,
         unixctl_command_reply_error(conn, ds_cstr(&ds));
     }
 
-    shash_destroy_free_data(&sh);
+    smap_destroy(&smap);
     ds_destroy(&ds);
 }
 
@@ -3273,46 +3274,42 @@ iface_clear_db_record(const struct ovsrec_interface *if_cfg)
     }
 }
 
-/* Adds the 'n' key-value pairs in 'keys' in 'values' to 'shash'.
- *
- * The value strings in '*shash' are taken directly from values[], not copied,
- * so the caller should not modify or free them. */
+/* Adds the 'n' key-value pairs in 'keys' in 'values' to 'shash'. */
 static void
-shash_from_ovs_idl_map(char **keys, char **values, size_t n,
-                       struct shash *shash)
+smap_from_ovs_idl_map(char **keys, char **values, size_t n, struct smap *smap)
 {
     size_t i;
 
-    shash_init(shash);
+    smap_init(smap);
     for (i = 0; i < n; i++) {
-        shash_add(shash, keys[i], values[i]);
+        smap_add(smap, keys[i], values[i]);
     }
 }
 
 /* Creates 'keys' and 'values' arrays from 'shash'.
  *
  * Sets 'keys' and 'values' to heap allocated arrays representing the key-value
- * pairs in 'shash'.  The caller takes ownership of 'keys' and 'values'.  They
+ * pairs in 'smap'.  The caller takes ownership of 'keys' and 'values'.  They
  * are populated with with strings taken directly from 'shash' and thus have
  * the same ownership of the key-value pairs in shash.
  */
 static void
-shash_to_ovs_idl_map(struct shash *shash,
-                     char ***keys, char ***values, size_t *n)
+smap_to_ovs_idl_map(struct smap *smap,
+                    char ***keys, char ***values, size_t *n)
 {
     size_t i, count;
     char **k, **v;
-    struct shash_node *sn;
+    struct smap_node *sn;
 
-    count = shash_count(shash);
+    count = smap_count(smap);
 
     k = xmalloc(count * sizeof *k);
     v = xmalloc(count * sizeof *v);
 
     i = 0;
-    SHASH_FOR_EACH(sn, shash) {
-        k[i] = sn->name;
-        v[i] = sn->data;
+    SMAP_FOR_EACH(sn, smap) {
+        k[i] = sn->key;
+        v[i] = sn->value;
         i++;
     }
 
@@ -3337,7 +3334,7 @@ queue_ids_include(const struct ovsdb_datum *queues, int64_t target)
 
 static void
 iface_delete_queues(unsigned int queue_id,
-                    const struct shash *details OVS_UNUSED, void *cbdata_)
+                    const struct smap *details OVS_UNUSED, void *cbdata_)
 {
     struct iface_delete_queues_cbdata *cbdata = cbdata_;
 
@@ -3357,15 +3354,15 @@ iface_configure_qos(struct iface *iface, const struct ovsrec_qos *qos)
         netdev_set_qos(iface->netdev, NULL, NULL);
     } else {
         struct iface_delete_queues_cbdata cbdata;
-        struct shash details;
+        struct smap details;
         bool queue_zero;
         size_t i;
 
         /* Configure top-level Qos for 'iface'. */
-        shash_from_ovs_idl_map(qos->key_other_config, qos->value_other_config,
-                               qos->n_other_config, &details);
+        smap_from_ovs_idl_map(qos->key_other_config, qos->value_other_config,
+                              qos->n_other_config, &details);
         netdev_set_qos(iface->netdev, qos->type, &details);
-        shash_destroy(&details);
+        smap_destroy(&details);
 
         /* Deconfigure queues that were deleted. */
         cbdata.netdev = iface->netdev;
@@ -3392,16 +3389,16 @@ iface_configure_qos(struct iface *iface, const struct ovsrec_qos *qos)
                 port_queue->dscp = queue->dscp[0];
             }
 
-            shash_from_ovs_idl_map(queue->key_other_config,
-                                   queue->value_other_config,
-                                   queue->n_other_config, &details);
+            smap_from_ovs_idl_map(queue->key_other_config,
+                                  queue->value_other_config,
+                                  queue->n_other_config, &details);
             netdev_set_queue(iface->netdev, queue_id, &details);
-            shash_destroy(&details);
+            smap_destroy(&details);
         }
         if (!queue_zero) {
-            shash_init(&details);
+            smap_init(&details);
             netdev_set_queue(iface->netdev, 0, &details);
-            shash_destroy(&details);
+            smap_destroy(&details);
         }
     }