Valgrind显示printf和未使用的块的内存泄漏

#include  #include  #include  int main(int argc, char *argv[]){ char *str = malloc(sizeof(char)*5); str = strcpy(str, "test"); printf("%s\n", str); free(str); return 0; } 

当我在Mac上使用Valgrind（OS X，10.9.5）时，我收到以下消息：

 ==77215== HEAP SUMMARY: ==77215== in use at exit: 29,211 bytes in 374 blocks ==77215== total heap usage: 451 allocs, 77 frees, 35,160 bytes allocated ==77215== ==77215== 4,096 bytes in 1 blocks are still reachable in loss record 76 of 76 ==77215== at 0x66CB: malloc (in /usr/local/Cellar/valgrind/3.10.0/lib/valgrind/vgpreload_memcheck-amd64-darwin.so) ==77215== by 0x182855: __smakebuf (in /usr/lib/system/libsystem_c.dylib) ==77215== by 0x197217: __swsetup (in /usr/lib/system/libsystem_c.dylib) ==77215== by 0x1B0158: __v2printf (in /usr/lib/system/libsystem_c.dylib) ==77215== by 0x1B06AF: __xvprintf (in /usr/lib/system/libsystem_c.dylib) ==77215== by 0x187B29: vfprintf_l (in /usr/lib/system/libsystem_c.dylib) ==77215== by 0x18596F: printf (in /usr/lib/system/libsystem_c.dylib) ==77215== by 0x100000F2B: main (test.c:8) ==77215== ==77215== LEAK SUMMARY: ==77215== definitely lost: 0 bytes in 0 blocks ==77215== indirectly lost: 0 bytes in 0 blocks ==77215== possibly lost: 0 bytes in 0 blocks ==77215== still reachable: 4,096 bytes in 1 blocks ==77215== suppressed: 25,115 bytes in 373 blocks ==77215== ==77215== For counts of detected and suppressed errors, rerun with: -v ==77215== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 15 from 15) 

printf自己分配内存吗？ 如果我删除printf我只得到以下内容：

 ==77237== HEAP SUMMARY: ==77237== in use at exit: 25,115 bytes in 373 blocks ==77237== total heap usage: 450 allocs, 77 frees, 31,064 bytes allocated ==77237== ==77237== LEAK SUMMARY: ==77237== definitely lost: 0 bytes in 0 blocks ==77237== indirectly lost: 0 bytes in 0 blocks ==77237== possibly lost: 0 bytes in 0 blocks ==77237== still reachable: 0 bytes in 0 blocks ==77237== suppressed: 25,115 bytes in 373 blocks ==77237== ==77237== For counts of detected and suppressed errors, rerun with: -v ==77237== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 15 from 15) 

373块来自哪里？

Answer 1

在Valgrind团队优先考虑OS X之前，您可以放心地假设它不会在运行OS X版本高于10.7的Apple系统上提供正确的结果。

在我的小牛队（10.9.5）机器上，我仍然收到Valgrind（3.9.0）的以下警告

 WARNING: Support on MacOS 10.8/10.9 is experimental and mostly broken. WARNING: Expect incorrect results, assertions and crashes. WARNING: In particular, Memcheck on 32-bit programs will fail to WARNING: detect any errors associated with heap-allocated data. 

对于它的价值，Valgrind 3.10.0显示我的Debian Jessie安装没有泄漏。

Answer 2

它没有告诉你有泄漏：

 ==77215== LEAK SUMMARY: ==77215== definitely lost: 0 bytes in 0 blocks ==77215== indirectly lost: 0 bytes in 0 blocks ==77215== possibly lost: 0 bytes in 0 blocks ==77215== still reachable: 4,096 bytes in 1 blocks ==77215== suppressed: 25,115 bytes in 373 blocks 

它告诉你有一个块仍然可以到达; 是否存在泄漏取决于您对“泄漏”的定义。 它的意思是在某处有一个指向块的指针。

有关详细信息，请参阅Valgrind检测到的仍然可达到的泄漏 。