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authorZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2016-02-01 21:57:41 -0500
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2016-02-11 13:07:02 -0500
commit75f32f047cc380bdb648faf3ee277f7dc3cdd007 (patch)
tree62f5383768643896e2dfe2788c2bcd0933c19ab4 /src/basic
parent8cd095cc2724dac7523eda400522bbda41219d43 (diff)
Add memcpy_safe
ISO/IEC 9899:1999 §7.21.1/2 says: Where an argument declared as size_t n specifies the length of the array for a function, n can have the value zero on a call to that function. Unless explicitly stated otherwise in the description of a particular function in this subclause, pointer arguments on such a call shall still have valid values, as described in 7.1.4. In base64_append_width memcpy was called as memcpy(x, NULL, 0). GCC 4.9 started making use of this and assumes This worked fine under -O0, but does something strange under -O3. This patch fixes a bug in base64_append_width(), fixes a possible bug in journal_file_append_entry_internal(), and makes use of the new function to simplify the code in other places.
Diffstat (limited to 'src/basic')
-rw-r--r--src/basic/hexdecoct.c3
-rw-r--r--src/basic/util.h10
2 files changed, 12 insertions, 1 deletions
diff --git a/src/basic/hexdecoct.c b/src/basic/hexdecoct.c
index f30e028f45..cbd97a1b69 100644
--- a/src/basic/hexdecoct.c
+++ b/src/basic/hexdecoct.c
@@ -27,6 +27,7 @@
#include "alloc-util.h"
#include "hexdecoct.h"
#include "macro.h"
+#include "util.h"
char octchar(int x) {
return '0' + (x & 7);
@@ -574,7 +575,7 @@ static int base64_append_width(char **prefix, int plen,
if (!t)
return -ENOMEM;
- memcpy(t + plen, sep, slen);
+ memcpy_safe(t + plen, sep, slen);
for (line = 0, s = t + plen + slen, avail = len; line < lines; line++) {
int act = MIN(width, avail);
diff --git a/src/basic/util.h b/src/basic/util.h
index 76a06822b7..b7bad76212 100644
--- a/src/basic/util.h
+++ b/src/basic/util.h
@@ -104,6 +104,16 @@ static inline void qsort_safe(void *base, size_t nmemb, size_t size, comparison_
qsort(base, nmemb, size, compar);
}
+/**
+ * Normal memcpy requires src to be nonnull. We do nothing if n is 0.
+ */
+static inline void memcpy_safe(void *dst, const void *src, size_t n) {
+ if (n == 0)
+ return;
+ assert(src);
+ memcpy(dst, src, n);
+}
+
int on_ac_power(void);
#define memzero(x,l) (memset((x), 0, (l)))