c - Valgrind - 无法理解错误输出

Question

如果我最终做错了什么，我很抱歉。好的，我的问题如下:

我刚刚编写了一些非常简单的代码，但是当你查看 Valgrind 错误输出时，它让我感到困惑。

代码:

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
int num1 = 100;
double num2 = 1.2;

printf("Number 1 one is: %d.\n Number two is: %f.\n", num1, num2);

return 0;
}

Valgrind 错误报告:

$ valgrind --leak-check=full ./yaq
==50642== Memcheck, a memory error detector
==50642== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et       al.
==50642== Using Valgrind-3.11.0.SVN and LibVEX; rerun with -h for     copyright info
==50642== Command: ./yaq
==50642== 
--50642-- ./yaq:
--50642-- dSYM directory has wrong UUID; consider using --dsymutil=yes
==50642== Conditional jump or move depends on uninitialised value(s)
==50642==    at 0x1003FCC3F: _platform_memchr$VARIANT$Haswell (in     /usr/lib/system/libsystem_platform.dylib)
==50642==    by 0x1001F0B96: __sfvwrite (in    /usr/lib/system/libsystem_c.dylib)
==50642==    by 0x1001FAFE5: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==50642==    by 0x1002209AE: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==50642==    by 0x100220C80: __xvprintf (in /usr/lib/system/libsystem_c.dylib)
==50642==    by 0x1001F6B71: vfprintf_l (in /usr/lib/system/libsystem_c.dylib)
==50642==    by 0x1001F49D7: printf (in /usr/lib/system/libsystem_c.dylib)
==50642==    by 0x100000F32: main (in ./yaq)
==50642== 
Number 1 one is: 100.
 Number two is: 1.200000.
==50642== 
==50642== HEAP SUMMARY:
==50642==     in use at exit: 38,673 bytes in 427 blocks
==50642==   total heap usage: 510 allocs, 83 frees, 44,945 bytes.
==50642== To see them, rerun with: --leak-check=full --show-leak- kinds=all
==50642== 
==50642== For counts of detected and suppressed errors, rerun with: -v
==50642== Use --track-origins=yes to see where uninitialised values come from
==50642== ERROR SUMMARY: 3 errors from 1 contexts (suppressed: 17 from 17)

为什么显示 3 个错误？

提前致谢。最好的问候

Answer 1

如果您使用 --show-leak-kinds=all 运行，您也许能够看到它们:

==96034== Memcheck, a memory error detector
==96034== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==96034== Using Valgrind-3.11.0.SVN and LibVEX; rerun with -h for copyright info
==96034== Command: ./yaq
==96034==
--96034-- ./yaq:
--96034-- dSYM directory is missing; consider using --dsymutil=yes
==96034== Conditional jump or move depends on uninitialised value(s)
==96034==    by 0x10021FCA0: __xvprintf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001F5B91: vfprintf_l (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001F39F7: printf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x100000F32: main (in ./yaq)
==96034==
==96034== 80 bytes in 1 blocks are still reachable in loss record 48 of 85
==96034==    at 0x10000859B: malloc (in /usr/local/Cellar/valgrind/HEAD/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
==96034==    by 0x1001D1756: __Balloc_D2A (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001D2075: __d2b_D2A (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001CE88B: __dtoa (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001F6D72: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x10021F9CE: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x10021FCA0: __xvprintf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001F5B91: vfprintf_l (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001F39F7: printf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x100000F32: main (in ./yaq)
==96034==
==96034== 4,096 bytes in 1 blocks are still reachable in loss record 85 of 85
==96034==    at 0x10000859B: malloc (in /usr/local/Cellar/valgrind/HEAD/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
==96034==    by 0x1001F0856: __smakebuf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1002053A7: __swsetup (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x10021F77D: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x10021FCA0: __xvprintf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001F5B91: vfprintf_l (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x1001F39F7: printf (in /usr/lib/system/libsystem_c.dylib)
==96034==    by 0x100000F32: main (in ./yaq)
==96034==
==96034== LEAK SUMMARY:
==96034==    definitely lost: 0 bytes in 0 blocks
==96034==    indirectly lost: 0 bytes in 0 blocks
==96034==      possibly lost: 0 bytes in 0 blocks
==96034==    still reachable: 4,244 bytes in 4 blocks
==96034==         suppressed: 34,783 bytes in 425 blocks
==96034==
==96034== For counts of detected and suppressed errors, rerun with: -v
==96034== Use --track-origins=yes to see where uninitialised values come from
==96034== ERROR SUMMARY: 3 errors from 1 contexts (suppressed: 18 from 18)

这些是 OS X 系统库中的问题。我通过使用 valgrind --leak-check=yes --show-leak-kinds=all --gen-suppressions=yes ./yaq 生成 this suppressions file 来抑制它们。那么输出会更干净一些:

$ valgrind --leak-check=yes --show-leak-kinds=all --suppressions=yaq.supp ./yaq                            [7:47:49]
==96285== Memcheck, a memory error detector
==96285== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==96285== Using Valgrind-3.11.0.SVN and LibVEX; rerun with -h for copyright info
==96285== Command: ./yaq
==96285==
--96285-- ./yaq:
--96285-- dSYM directory is missing; consider using --dsymutil=yes
Number 1 one is: 100.
 Number two is: 1.200000.
==96285==
==96285== HEAP SUMMARY:
==96285==     in use at exit: 39,027 bytes in 429 blocks
==96285==   total heap usage: 510 allocs, 81 frees, 45,171 bytes allocated
==96285==
==96285== LEAK SUMMARY:
==96285==    definitely lost: 0 bytes in 0 blocks
==96285==    indirectly lost: 0 bytes in 0 blocks
==96285==      possibly lost: 0 bytes in 0 blocks
==96285==    still reachable: 0 bytes in 0 blocks
==96285==         suppressed: 39,027 bytes in 429 blocks
==96285==
==96285== For counts of detected and suppressed errors, rerun with: -v
==96285== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 21 from 19)