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authorAndreas Schneider <asn@cryptomilk.org>2013-07-22 10:18:33 +0200
committerAndreas Schneider <asn@cryptomilk.org>2013-07-23 10:44:39 +0200
commit1829e9981bb5b3269c1bc005f30c4fc41b5724e7 (patch)
treed08b7dfd163bc6b7e959406511ccf3bbdf667aa4 /include
parent5145daba69e462ddd69d961b0d940db3aebafa11 (diff)
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cmake: Check for HAVE_GCC_VOLATILE_MEMORY_PROTECTION.
This ensures that the memset call is not optimized out by the compiler (works works with gcc and clang).
Diffstat (limited to 'include')
-rw-r--r--include/libssh/priv.h37
1 files changed, 35 insertions, 2 deletions
diff --git a/include/libssh/priv.h b/include/libssh/priv.h
index abf307ad..44806ab6 100644
--- a/include/libssh/priv.h
+++ b/include/libssh/priv.h
@@ -137,6 +137,17 @@ int gettimeofday(struct timeval *__p, void *__t);
# define LIBSSH_THREAD
#endif
+/*
+ * This makes sure that the compiler doesn't optimize out the code
+ *
+ * Use it in a macro where the provided variable is 'x'.
+ */
+#if defined(HAVE_GCC_VOLATILE_MEMORY_PROTECTION)
+# define LIBSSH_MEM_PROTECTION __asm__ volatile("" : : "r"(&(x)) : "memory")
+#else
+# define LIBSSH_MEM_PROTECTION
+#endif
+
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
@@ -226,11 +237,33 @@ int match_hostname(const char *host, const char *pattern, unsigned int len);
/** Get the size of an array */
#define ARRAY_SIZE(a) (sizeof(a)/sizeof(a[0]))
+/*
+ * See http://llvm.org/bugs/show_bug.cgi?id=15495
+ */
+#if defined(HAVE_GCC_VOLATILE_MEMORY_PROTECTION)
+/** Overwrite a string with '\0' */
+# define BURN_STRING(x) do { \
+ if ((x) != NULL) \
+ memset((x), '\0', strlen((x))); __asm__ volatile("" : : "r"(&(x)) : "memory"); \
+ } while(0)
+
+/** Overwrite the buffer with '\0' */
+# define BURN_BUFFER(x, size) do { \
+ if ((x) != NULL) \
+ memset((x), '\0', (size))); __asm__ volatile("" : : "r"(&(x)) : "memory"); \
+ } while(0)
+#else /* HAVE_GCC_VOLATILE_MEMORY_PROTECTION */
/** Overwrite a string with '\0' */
-#define BURN_STRING(x) do { if ((x) != NULL) memset((x), '\0', strlen((x))); __asm__ volatile ("" : : : "memory"); } while(0)
+# define BURN_STRING(x) do { \
+ if ((x) != NULL) memset((x), '\0', strlen((x))); \
+ } while(0)
/** Overwrite the buffer with '\0' */
-#define BURN_BUFFER(x, size) do { if ((x) != NULL) memset((x), '\0', (size))); __asm__ volatile ("") : : : "memory"; } while(0)
+# define BURN_BUFFER(x, size) do { \
+ if ((x) != NULL) \
+ memset((x), '\0', (size))); __asm__ volatile("" : : "r"(&(x)) : "memory"); \
+ } while(0)
+#endif /* HAVE_GCC_VOLATILE_MEMORY_PROTECTION */
/**
* This is a hack to fix warnings. The idea is to use this everywhere that we