devnum-util: define helper macros for formatting devnum major/minor pairs

And port some parts over.

8 files changed, 50 insertions, 25 deletions

diff --git a/src/basic/devnum-util.c b/src/basic/devnum-util.c
index d13a87d6d1..e0ecf54883 100644
--- a/src/basic/devnum-util.c
+++ b/src/basic/devnum-util.c
@@ -49,7 +49,7 @@ int device_path_make_major_minor(mode_t mode, dev_t devnum, char **ret) {
         else
                 return -ENODEV;
 
-        if (asprintf(ret, "/dev/%s/%u:%u", t, major(devnum), minor(devnum)) < 0)
+        if (asprintf(ret, "/dev/%s/" DEVNUM_FORMAT_STR, t, DEVNUM_FORMAT_VAL(devnum)) < 0)
                 return -ENOMEM;
 
         return 0;
diff --git a/src/basic/devnum-util.h b/src/basic/devnum-util.h
index 9632e992bb..3f1894b2fd 100644
--- a/src/basic/devnum-util.h
+++ b/src/basic/devnum-util.h
@@ -5,6 +5,8 @@
 #include <stdbool.h>
 #include <sys/types.h>
 
+#include "stdio-util.h"
+
 int parse_devnum(const char *s, dev_t *ret);
 
 /* glibc and the Linux kernel have different ideas about the major/minor size. These calls will check whether the
@@ -35,3 +37,15 @@ static inline bool devnum_set_and_equal(dev_t a, dev_t b) {
          * know" and we'll return false */
         return a == b && a != 0;
 }
+
+/* Maximum string length for a major:minor string. (Note that DECIMAL_STR_MAX includes space for a trailing NUL) */
+#define DEVNUM_STR_MAX (DECIMAL_STR_MAX(dev_t)-1+1+DECIMAL_STR_MAX(dev_t))
+
+#define DEVNUM_FORMAT_STR "%u:%u"
+#define DEVNUM_FORMAT_VAL(d) major(d), minor(d)
+
+static inline char *format_devnum(dev_t d, char buf[static DEVNUM_STR_MAX]) {
+        return ASSERT_PTR(snprintf_ok(buf, DEVNUM_STR_MAX, DEVNUM_FORMAT_STR, DEVNUM_FORMAT_VAL(d)));
+}
+
+#define FORMAT_DEVNUM(d) format_devnum((d), (char[DEVNUM_STR_MAX]) {})
diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index d3b617dc1a..9282b1ff20 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -1084,7 +1084,7 @@ static int set_bfq_weight(Unit *u, const char *controller, dev_t dev, uint64_t i
         bfq_weight = BFQ_WEIGHT(io_weight);
 
         if (major(dev) > 0)
-                xsprintf(buf, "%u:%u %" PRIu64 "\n", major(dev), minor(dev), bfq_weight);
+                xsprintf(buf, DEVNUM_FORMAT_STR " %" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), bfq_weight);
         else
                 xsprintf(buf, "%" PRIu64 "\n", bfq_weight);
 
@@ -1117,7 +1117,7 @@ static void cgroup_apply_io_device_weight(Unit *u, const char *dev_path, uint64_
 
         r1 = set_bfq_weight(u, "io", dev, io_weight);
 
-        xsprintf(buf, "%u:%u %" PRIu64 "\n", major(dev), minor(dev), io_weight);
+        xsprintf(buf, DEVNUM_FORMAT_STR " %" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), io_weight);
         r2 = cg_set_attribute("io", u->cgroup_path, "io.weight", buf);
 
         /* Look at the configured device, when both fail, prefer io.weight errno. */
@@ -1138,7 +1138,7 @@ static void cgroup_apply_blkio_device_weight(Unit *u, const char *dev_path, uint
         if (r < 0)
                 return;
 
-        xsprintf(buf, "%u:%u %" PRIu64 "\n", major(dev), minor(dev), blkio_weight);
+        xsprintf(buf, DEVNUM_FORMAT_STR " %" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), blkio_weight);
         (void) set_attribute_and_warn(u, "blkio", "blkio.weight_device", buf);
 }
 
@@ -1152,9 +1152,9 @@ static void cgroup_apply_io_device_latency(Unit *u, const char *dev_path, usec_t
                 return;
 
         if (target != USEC_INFINITY)
-                xsprintf(buf, "%u:%u target=%" PRIu64 "\n", major(dev), minor(dev), target);
+                xsprintf(buf, DEVNUM_FORMAT_STR " target=%" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), target);
         else
-                xsprintf(buf, "%u:%u target=max\n", major(dev), minor(dev));
+                xsprintf(buf, DEVNUM_FORMAT_STR " target=max\n", DEVNUM_FORMAT_VAL(dev));
 
         (void) set_attribute_and_warn(u, "io", "io.latency", buf);
 }
@@ -1173,7 +1173,7 @@ static void cgroup_apply_io_device_limit(Unit *u, const char *dev_path, uint64_t
                 else
                         xsprintf(limit_bufs[type], "%s", limits[type] == CGROUP_LIMIT_MAX ? "max" : "0");
 
-        xsprintf(buf, "%u:%u rbps=%s wbps=%s riops=%s wiops=%s\n", major(dev), minor(dev),
+        xsprintf(buf, DEVNUM_FORMAT_STR " rbps=%s wbps=%s riops=%s wiops=%s\n", DEVNUM_FORMAT_VAL(dev),
                  limit_bufs[CGROUP_IO_RBPS_MAX], limit_bufs[CGROUP_IO_WBPS_MAX],
                  limit_bufs[CGROUP_IO_RIOPS_MAX], limit_bufs[CGROUP_IO_WIOPS_MAX]);
         (void) set_attribute_and_warn(u, "io", "io.max", buf);
@@ -1186,10 +1186,10 @@ static void cgroup_apply_blkio_device_limit(Unit *u, const char *dev_path, uint6
         if (lookup_block_device(dev_path, &dev) < 0)
                 return;
 
-        sprintf(buf, "%u:%u %" PRIu64 "\n", major(dev), minor(dev), rbps);
+        sprintf(buf, DEVNUM_FORMAT_STR " %" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), rbps);
         (void) set_attribute_and_warn(u, "blkio", "blkio.throttle.read_bps_device", buf);
 
-        sprintf(buf, "%u:%u %" PRIu64 "\n", major(dev), minor(dev), wbps);
+        sprintf(buf, DEVNUM_FORMAT_STR " %" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), wbps);
         (void) set_attribute_and_warn(u, "blkio", "blkio.throttle.write_bps_device", buf);
 }
 
diff --git a/src/core/namespace.c b/src/core/namespace.c
index 5fa7a59bc5..926aa96174 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -12,6 +12,7 @@
 #include "base-filesystem.h"
 #include "chase-symlinks.h"
 #include "dev-setup.h"
+#include "devnum-util.h"
 #include "env-util.h"
 #include "escape.h"
 #include "extension-release.h"
@@ -885,10 +886,10 @@ add_symlink:
                 return 0;
 
         /* Create symlinks like /dev/char/1:9 → ../urandom */
-        if (asprintf(&sl, "%s/dev/%s/%u:%u",
+        if (asprintf(&sl, "%s/dev/%s/" DEVNUM_FORMAT_STR,
                      temporary_mount,
                      S_ISCHR(st.st_mode) ? "char" : "block",
-                     major(st.st_rdev), minor(st.st_rdev)) < 0)
+                     DEVNUM_FORMAT_VAL(st.st_rdev)) < 0)
                 return log_oom();
 
         (void) mkdir_parents(sl, 0755);
diff --git a/src/gpt-auto-generator/gpt-auto-generator.c b/src/gpt-auto-generator/gpt-auto-generator.c
index 8b35b2364d..cd4b05c52d 100644
--- a/src/gpt-auto-generator/gpt-auto-generator.c
+++ b/src/gpt-auto-generator/gpt-auto-generator.c
@@ -58,8 +58,8 @@ static int open_parent_block_device(dev_t devnum, int *ret_fd) {
         if (sd_device_get_devname(d, &name) < 0) {
                 r = sd_device_get_syspath(d, &name);
                 if (r < 0) {
-                        log_device_debug_errno(d, r, "Device %u:%u does not have a name, ignoring: %m",
-                                               major(devnum), minor(devnum));
+                        log_device_debug_errno(d, r, "Device " DEVNUM_FORMAT_STR " does not have a name, ignoring: %m",
+                                               DEVNUM_FORMAT_VAL(devnum));
                         return 0;
                 }
         }
diff --git a/src/hibernate-resume/hibernate-resume.c b/src/hibernate-resume/hibernate-resume.c
index 58e35e403e..1c7d9179d8 100644
--- a/src/hibernate-resume/hibernate-resume.c
+++ b/src/hibernate-resume/hibernate-resume.c
@@ -5,6 +5,7 @@
 #include <sys/stat.h>
 
 #include "alloc-util.h"
+#include "devnum-util.h"
 #include "fileio.h"
 #include "log.h"
 #include "util.h"
@@ -12,7 +13,6 @@
 int main(int argc, char *argv[]) {
         struct stat st;
         const char *device;
-        _cleanup_free_ char *major_minor = NULL;
         int r;
 
         if (argc != 2) {
@@ -40,14 +40,9 @@ int main(int argc, char *argv[]) {
                 return EXIT_FAILURE;
         }
 
-        if (asprintf(&major_minor, "%d:%d", major(st.st_rdev), minor(st.st_rdev)) < 0) {
-                log_oom();
-                return EXIT_FAILURE;
-        }
-
-        r = write_string_file("/sys/power/resume", major_minor, WRITE_STRING_FILE_DISABLE_BUFFER);
+        r = write_string_file("/sys/power/resume", FORMAT_DEVNUM(st.st_rdev), WRITE_STRING_FILE_DISABLE_BUFFER);
         if (r < 0) {
-                log_error_errno(r, "Failed to write '%s' to /sys/power/resume: %m", major_minor);
+                log_error_errno(r, "Failed to write '" DEVNUM_FORMAT_STR "' to /sys/power/resume: %m", DEVNUM_FORMAT_VAL(st.st_rdev));
                 return EXIT_FAILURE;
         }
 
@@ -58,6 +53,6 @@ int main(int argc, char *argv[]) {
          * no hibernation image).
          */
 
-        log_info("Could not resume from '%s' (%s).", device, major_minor);
+        log_info("Could not resume from '%s' (" DEVNUM_FORMAT_STR ").", device, DEVNUM_FORMAT_VAL(st.st_rdev));
         return EXIT_SUCCESS;
 }
diff --git a/src/home/homework-luks.c b/src/home/homework-luks.c
index 9cfb0e7ae6..17c2f4f4e2 100644
--- a/src/home/homework-luks.c
+++ b/src/home/homework-luks.c
@@ -1301,7 +1301,7 @@ int home_setup_luks(
                                 return log_error_errno(r, "Failed to stat block device %s: %m", n);
                         assert(S_ISBLK(st.st_mode));
 
-                        if (asprintf(&sysfs, "/sys/dev/block/%u:%u/partition", major(st.st_rdev), minor(st.st_rdev)) < 0)
+                        if (asprintf(&sysfs, "/sys/dev/block/" DEVNUM_FORMAT_STR "/partition", DEVNUM_FORMAT_VAL(st.st_rdev)) < 0)
                                 return log_oom();
 
                         if (access(sysfs, F_OK) < 0) {
@@ -1312,7 +1312,7 @@ int home_setup_luks(
                         } else {
                                 _cleanup_free_ char *buffer = NULL;
 
-                                if (asprintf(&sysfs, "/sys/dev/block/%u:%u/start", major(st.st_rdev), minor(st.st_rdev)) < 0)
+                                if (asprintf(&sysfs, "/sys/dev/block/" DEVNUM_FORMAT_STR "/start", DEVNUM_FORMAT_VAL(st.st_rdev)) < 0)
                                         return log_oom();
 
                                 r = read_one_line_file(sysfs, &buffer);
@@ -2205,7 +2205,7 @@ int home_create_luks(
                 if (!S_ISBLK(st.st_mode))
                         return log_error_errno(SYNTHETIC_ERRNO(ENOTBLK), "Device is not a block device, refusing.");
 
-                if (asprintf(&sysfs, "/sys/dev/block/%u:%u/partition", major(st.st_rdev), minor(st.st_rdev)) < 0)
+                if (asprintf(&sysfs, "/sys/dev/block/" DEVNUM_FORMAT_STR "/partition", DEVNUM_FORMAT_VAL(st.st_rdev)) < 0)
                         return log_oom();
                 if (access(sysfs, F_OK) < 0) {
                         if (errno != ENOENT)
diff --git a/src/test/test-devnum-util.c b/src/test/test-devnum-util.c
index 9cb9a8ea76..66f4ac9149 100644
--- a/src/test/test-devnum-util.c
+++ b/src/test/test-devnum-util.c
@@ -106,4 +106,19 @@ TEST(device_path_make_canonical) {
         }
 }
 
+static void test_devnum_format_str_one(dev_t devnum, const char *s) {
+        dev_t x;
+
+        assert_se(streq(FORMAT_DEVNUM(devnum), s));
+        assert_se(parse_devnum(s, &x) >= 0);
+        assert_se(x == devnum);
+}
+
+TEST(devnum_format_str) {
+        test_devnum_format_str_one(makedev(0, 0), "0:0");
+        test_devnum_format_str_one(makedev(1, 2), "1:2");
+        test_devnum_format_str_one(makedev(99, 100), "99:100");
+        test_devnum_format_str_one(makedev(4095, 1048575), "4095:1048575");
+}
+
 DEFINE_TEST_MAIN(LOG_INFO);