# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID c519ab0f70f3be3128b1940027a4ad3774df4c58
# Parent a4d1f99e5a534d31501ecad91ae1de53d391b4a1
[LIBXC] Make strerror() thread-safe by protecting it with a mutex.
Using strerror_r() is made difficult by the different GNU definition,
and different distros variously choose the POSIX or GNU prototype.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
tools/libxc/Makefile | 4 ++--
tools/libxc/xc_private.c | 22 ++++++++++++++--------
2 files changed, 16 insertions(+), 10 deletions(-)
diff -r a4d1f99e5a53 -r c519ab0f70f3 tools/libxc/Makefile
--- a/tools/libxc/Makefile Fri Dec 08 13:31:21 2006 +0000
+++ b/tools/libxc/Makefile Fri Dec 08 15:59:30 2006 +0000
@@ -119,7 +119,7 @@ libxenctrl.so.$(MAJOR): libxenctrl.so.$(
ln -sf $< $@
libxenctrl.so.$(MAJOR).$(MINOR): $(CTRL_PIC_OBJS)
- $(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG)
-Wl,libxenctrl.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $^
+ $(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG)
-Wl,libxenctrl.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $^ -lpthread
# libxenguest
@@ -132,7 +132,7 @@ libxenguest.so.$(MAJOR): libxenguest.so.
ln -sf $< $@
libxenguest.so.$(MAJOR).$(MINOR): $(GUEST_PIC_OBJS) libxenctrl.so
- $(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG)
-Wl,libxenguest.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $(GUEST_PIC_OBJS) -lz
-lxenctrl
+ $(CC) $(CFLAGS) $(LDFLAGS) -Wl,$(SONAME_LDFLAG)
-Wl,libxenguest.so.$(MAJOR) $(SHLIB_CFLAGS) -o $@ $(GUEST_PIC_OBJS) -lz
-lxenctrl -lpthread
-include $(DEPS)
diff -r a4d1f99e5a53 -r c519ab0f70f3 tools/libxc/xc_private.c
--- a/tools/libxc/xc_private.c Fri Dec 08 13:31:21 2006 +0000
+++ b/tools/libxc/xc_private.c Fri Dec 08 15:59:30 2006 +0000
@@ -7,8 +7,8 @@
#include <inttypes.h>
#include "xc_private.h"
#include "xg_private.h"
-
#include <stdarg.h>
+#include <pthread.h>
static __thread xc_error last_error = { XC_ERROR_NONE, ""};
#if DEBUG
@@ -486,14 +486,20 @@ char *safe_strerror(int errcode)
char *safe_strerror(int errcode)
{
static __thread char errbuf[32];
-#ifdef __GLIBC__
- /* Broken GNU definition of strerror_r may not use our supplied buffer. */
- return strerror_r(errcode, errbuf, sizeof(errbuf));
-#else
- /* Assume we have the POSIX definition of strerror_r. */
- strerror_r(errcode, errbuf, sizeof(errbuf));
+ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+ char *strerror_str;
+
+ /*
+ * Thread-unsafe strerror() is protected by a local mutex. We copy
+ * the string to a thread-private buffer before releasing the mutex.
+ */
+ pthread_mutex_lock(&mutex);
+ strerror_str = strerror(errcode);
+ strncpy(errbuf, strerror_str, sizeof(errbuf));
+ errbuf[sizeof(errbuf)-1] = '\0';
+ pthread_mutex_unlock(&mutex);
+
return errbuf;
-#endif
}
/*
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