Make some static variables thread-local.

This should make some functions thread-safe, even if it doesn't make
them fully-reentrant; at least some of them would requiree API changes
to full reentrancy.

This should fix #1174.

6 files changed, 90 insertions, 10 deletions

diff --git a/Makefile.in b/Makefile.in
index e4d14ea6..7421daa7 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -149,6 +149,7 @@ HDR = $(PUBHDR) \
 	sf-pcap.h \
 	sf-pcapng.h \
 	sunatmpos.h \
+	thread-local.h \
 	varattrs.h
 
 GENHDR = \
diff --git a/bpf_image.c b/bpf_image.c
index e48c76d5..febd07bb 100644
--- a/bpf_image.c
+++ b/bpf_image.c
@@ -44,6 +44,8 @@
 
 #include "pcap-int.h"
 
+#include "thread-local.h"
+
 #ifdef HAVE_OS_PROTO_H
 #include "os-proto.h"
 #endif
@@ -130,7 +132,7 @@ char *
 bpf_image(const struct bpf_insn *p, int n)
 {
 	const char *op;
-	static char image[256];
+	static thread_local char image[256];
 	char operand_buf[64];
 	const char *operand;
 
diff --git a/etherent.c b/etherent.c
index 69da9a54..e0e5023c 100644
--- a/etherent.c
+++ b/etherent.c
@@ -33,6 +33,8 @@
 
 #include <pcap/namedb.h>
 
+#include "thread-local.h"
+
 #ifdef HAVE_OS_PROTO_H
 #include "os-proto.h"
 #endif
@@ -87,7 +89,7 @@ pcap_next_etherent(FILE *fp)
 	u_char d;
 	char *bp;
 	size_t namesize;
-	static struct pcap_etherent e;
+	static thread_local struct pcap_etherent e;
 
 	memset((char *)&e, 0, sizeof(e));
 	for (;;) {
diff --git a/nametoaddr.c b/nametoaddr.c
index a746cb6d..6f1dafe9 100644
--- a/nametoaddr.c
+++ b/nametoaddr.c
@@ -135,6 +135,8 @@
 #include <pcap/namedb.h>
 #include "nametoaddr.h"
 
+#include "thread-local.h"
+
 #ifdef HAVE_OS_PROTO_H
 #include "os-proto.h"
 #endif
@@ -806,16 +808,18 @@ pcap_ether_aton(const char *s)
 #ifndef HAVE_ETHER_HOSTTON
 /*
  * Roll our own.
- * XXX - not thread-safe, because pcap_next_etherent() isn't thread-
- * safe!  Needs a mutex or a thread-safe pcap_next_etherent().
+ *
+ * This should be thread-safe, as we define the static variables
+ * we use to be thread-local, and as pcap_next_etherent() does so
+ * as well.
  */
 u_char *
 pcap_ether_hostton(const char *name)
 {
 	register struct pcap_etherent *ep;
 	register u_char *ap;
-	static FILE *fp = NULL;
-	static int init = 0;
+	static thread_local FILE *fp = NULL;
+	static thread_local int init = 0;
 
 	if (!init) {
 		fp = fopen(PCAP_ETHERS_FILE, "r");
diff --git a/pcap.c b/pcap.c
index 6e012da3..04aa7441 100644
--- a/pcap.c
+++ b/pcap.c
@@ -65,6 +65,8 @@ struct rtentry;		/* declarations in <net/if.h> */
 
 #include "diag-control.h"
 
+#include "thread-local.h"
+
 #ifdef HAVE_OS_PROTO_H
 #include "os-proto.h"
 #endif
@@ -3394,7 +3396,7 @@ pcap_datalink_val_to_description(int dlt)
 const char *
 pcap_datalink_val_to_description_or_dlt(int dlt)
 {
-        static char unkbuf[40];
+        static thread_local char unkbuf[40];
         const char *description;
 
         description = pcap_datalink_val_to_description(dlt);
@@ -3660,7 +3662,7 @@ pcap_setnonblock_fd(pcap_t *p, int nonblock)
 const char *
 pcap_statustostr(int errnum)
 {
-	static char ebuf[15+10+1];
+	static thread_local char ebuf[15+10+1];
 
 	switch (errnum) {
 
@@ -3721,7 +3723,7 @@ pcap_strerror(int errnum)
 {
 #ifdef HAVE_STRERROR
 #ifdef _WIN32
-	static char errbuf[PCAP_ERRBUF_SIZE];
+	static thread_local char errbuf[PCAP_ERRBUF_SIZE];
 	errno_t err = strerror_s(errbuf, PCAP_ERRBUF_SIZE, errnum);
 
 	if (err != 0) /* err = 0 if successful */
@@ -3733,7 +3735,7 @@ pcap_strerror(int errnum)
 #else
 	extern int sys_nerr;
 	extern const char *const sys_errlist[];
-	static char errbuf[PCAP_ERRBUF_SIZE];
+	static thread_local char errbuf[PCAP_ERRBUF_SIZE];
 
 	if ((unsigned int)errnum < sys_nerr)
 		return ((char *)sys_errlist[errnum]);
diff --git a/thread-local.h b/thread-local.h
new file mode 100644
index 00000000..61296e56
--- /dev/null
+++ b/thread-local.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 1994, 1995, 1996
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the Computer Systems
+ *	Engineering Group at Lawrence Berkeley Laboratory.
+ * 4. Neither the name of the University nor of the Laboratory may be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef thread_local_h
+#define	thread_local_h
+
+/*
+ * This defines thread_local to specify thread-local storage, if it
+ * is not already defined.
+ *
+ * C11, if __STDC_NO_THREADS__ is not defined to be 1, defines
+ * _Thread_local to indicate thread-local storage.  (You can also
+ * include <threads.h> to so define it, but we don't use any of
+ * the other stuff there.)
+ *
+ * Otherwise, we define it ourselves, based on the compiler.
+ *
+ * This is taken from https://stackoverflow.com/a/18298965/16139739.
+ */
+#ifndef thread_local
+  #if __STDC_VERSION__ >= 201112 && !defined __STDC_NO_THREADS__
+    #define thread_local _Thread_local
+  #elif defined _WIN32 && ( \
+         defined _MSC_VER || \
+         defined __ICL || \
+         defined __DMC__ || \
+         defined __BORLANDC__ )
+    #define thread_local __declspec(thread)
+  /* note that ICC (linux) and Clang are covered by __GNUC__ */
+  #elif defined __GNUC__ || \
+         defined __SUNPRO_C || \
+         defined __xlC__
+    #define thread_local __thread
+  #else
+    #error "Cannot define thread_local"
+  #endif
+#endif
+
+#endif