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authorLennart Poettering <lennart@poettering.net>2015-11-01 20:28:55 +0100
committerLennart Poettering <lennart@poettering.net>2015-11-02 23:07:20 +0100
commit9fe4ea21bec739bfe0ebac5565f0539b0e25b317 (patch)
tree4147053da096c3dacbef1a976b29c9add5c39c95 /src/basic/string-util.h
parent5732a7dbb0efa79cc36c6864a4af2e98685b53d6 (diff)
string-util: rework memory_erase() so that it cannot be optimized away
memory_erase() so far just called memset(), which the compiler might optimize away under certain conditions if it feels there's benefit in it. C11 knows a new memset_s() call that is like memset(), but may not be optimized away. Ideally, we'd just use that call, but glibc currently does not support it. Hence, implement our own simplistic version of it. We use a GCC pragma to turn off optimization for this call, and also use the "volatile" keyword on the pointers to ensure that gcc will use the pointers as-is. According to a variety of internet sources, either one does the trick. However, there are also reports that at least the volatile thing isn't fully correct, hence let's add some snake oil and employ both techniques. https://news.ycombinator.com/item?id=4711346
Diffstat (limited to 'src/basic/string-util.h')
-rw-r--r--src/basic/string-util.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/src/basic/string-util.h b/src/basic/string-util.h
index 297b8f8232..15244b8184 100644
--- a/src/basic/string-util.h
+++ b/src/basic/string-util.h
@@ -162,8 +162,8 @@ static inline void *memmem_safe(const void *haystack, size_t haystacklen, const
return memmem(haystack, haystacklen, needle, needlelen);
}
-#define memory_erase(p, l) memset((p), 'x', (l))
-void string_erase(char *x);
+void* memory_erase(void *p, size_t l);
+char *string_erase(char *x);
char *string_free_erase(char *s);
DEFINE_TRIVIAL_CLEANUP_FUNC(char *, string_free_erase);