下面的C程序应该分配一个列表，然后重新分配它并同时打印其内容：
#include <stdlib.h>
#include <stdio.h>
typedef struct {
struct chain *next;
int contents; } chain;
int main() {
int index;
chain *list;
chain *p;
chain *pointer;
list = malloc(sizeof(chain));
p = list;
for(index=0;index<10;index++) {
(*p).contents = index;
(*p).next = malloc(sizeof(chain));
p = (*p).next;
} ;
p = pointer = list;
index = 0;
while (index < 9) {
printf("cell # %d: %d\n",index,(*p).contents);
p = (*p).next;
free(pointer);
pointer = p;
index++;
} ;
printf("First cell: %d\n",(*list).contents);
return 0;
}
当我运行Valgrind进行完全泄漏检查时，我得到以下指示2个错误/内存泄漏的日志：
--13792-- REDIR: 0x401f2f0 (ld-linux-x86-64.so.2:strlen) redirected to 0x580608c1 (???)
--13792-- REDIR: 0x401f0d0 (ld-linux-x86-64.so.2:index) redirected to 0x580608db (???)
--13792-- Reading syms from /usr/lib/valgrind/vgpreload_core-amd64-linux.so
--13792-- Considering /usr/lib/valgrind/vgpreload_core-amd64-linux.so ..
--13792-- .. CRC mismatch (computed 50df1b30 wanted 4800a4cf)
--13792-- object doesn't have a symbol table
--13792-- Reading syms from /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so
--13792-- Considering /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so ..
--13792-- .. CRC mismatch (computed f893b962 wanted 95ee359e)
--13792-- object doesn't have a symbol table
==13792== WARNING: new redirection conflicts with existing -- ignoring it
--13792-- old: 0x0401f2f0 (strlen ) R-> (0000.0) 0x580608c1 ???
--13792-- new: 0x0401f2f0 (strlen ) R-> (2007.0) 0x04c32db0 strlen
--13792-- REDIR: 0x401d360 (ld-linux-x86-64.so.2:strcmp) redirected to 0x4c33ee0 (strcmp)
--13792-- REDIR: 0x401f830 (ld-linux-x86-64.so.2:mempcpy) redirected to 0x4c374f0 (mempcpy)
--13792-- Reading syms from /lib/x86_64-linux-gnu/libc-2.27.so
--13792-- Considering /lib/x86_64-linux-gnu/libc-2.27.so ..
--13792-- .. CRC mismatch (computed b1c74187 wanted 042cc048)
--13792-- Considering /usr/lib/debug/lib/x86_64-linux-gnu/libc-2.27.so ..
--13792-- .. CRC is valid
--13792-- REDIR: 0x4edac70 (libc.so.6:memmove) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9d40 (libc.so.6:strncpy) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edaf50 (libc.so.6:strcasecmp) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9790 (libc.so.6:strcat) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9d70 (libc.so.6:rindex) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edc7c0 (libc.so.6:rawmemchr) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edade0 (libc.so.6:mempcpy) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edac10 (libc.so.6:bcmp) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9d00 (libc.so.6:strncmp) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9800 (libc.so.6:strcmp) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edad40 (libc.so.6:memset) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ef80f0 (libc.so.6:wcschr) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9ca0 (libc.so.6:strnlen) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9870 (libc.so.6:strcspn) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edafa0 (libc.so.6:strncasecmp) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9840 (libc.so.6:strcpy) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edb0e0 (libc.so.6:memcpy@@GLIBC_2.14) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9da0 (libc.so.6:strpbrk) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed97c0 (libc.so.6:index) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ed9c70 (libc.so.6:strlen) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ee46c0 (libc.so.6:memrchr) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edaff0 (libc.so.6:strcasecmp_l) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edabe0 (libc.so.6:memchr) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4ef8eb0 (libc.so.6:wcslen) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4eda050 (libc.so.6:strspn) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edaf20 (libc.so.6:stpncpy) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edaef0 (libc.so.6:stpcpy) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edc7f0 (libc.so.6:strchrnul) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4edb040 (libc.so.6:strncasecmp_l) redirected to 0x4a2a6e0 (_vgnU_ifunc_wrapper)
--13792-- REDIR: 0x4fca3c0 (libc.so.6:__strrchr_avx2) redirected to 0x4c32730 (rindex)
--13792-- REDIR: 0x4ed3070 (libc.so.6:malloc) redirected to 0x4c2faa0 (malloc)
--13792-- REDIR: 0x4fca1d0 (libc.so.6:__strchrnul_avx2) redirected to 0x4c37020 (strchrnul)
--13792-- REDIR: 0x4fcaab0 (libc.so.6:__mempcpy_avx_unaligned_erms) redirected to 0x4c37130 (mempcpy)
cell # 0: 0
--13792-- REDIR: 0x4ed3950 (libc.so.6:free) redirected to 0x4c30cd0 (free)
cell # 1: 1
cell # 2: 2
cell # 3: 3
cell # 4: 4
cell # 5: 5
cell # 6: 6
cell # 7: 7
cell # 8: 8
cell # 9: 9
==13792== Invalid read of size 4
==13792== at 0x108797: main (dynmem.c:31)
==13792== Address 0x522d048 is 8 bytes inside a block of size 16 free'd
==13792== at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==13792== by 0x108780: main (dynmem.c:27)
==13792== Block was alloc'd at
==13792== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==13792== by 0x1086EB: main (dynmem.c:15)
==13792==
First cell: 0
==13792==
==13792== HEAP SUMMARY:
==13792== in use at exit: 16 bytes in 1 blocks
==13792== total heap usage: 12 allocs, 11 frees, 1,200 bytes allocated
==13792==
==13792== Searching for pointers to 1 not-freed blocks
==13792== Checked 70,200 bytes
==13792==
==13792== 16 bytes in 1 blocks are definitely lost in loss record 1 of 1
==13792== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==13792== by 0x108714: main (dynmem.c:19)
==13792==
==13792== LEAK SUMMARY:
==13792== definitely lost: 16 bytes in 1 blocks
==13792== indirectly lost: 0 bytes in 0 blocks
==13792== possibly lost: 0 bytes in 0 blocks
==13792== still reachable: 0 bytes in 0 blocks
==13792== suppressed: 0 bytes in 0 blocks
==13792==
==13792== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)
==13792==
==13792== 1 errors in context 1 of 2:
==13792== Invalid read of size 4
==13792== at 0x108797: main (dynmem.c:31)
==13792== Address 0x522d048 is 8 bytes inside a block of size 16 free'd
==13792== at 0x4C30D3B: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==13792== by 0x108780: main (dynmem.c:27)
==13792== Block was alloc'd at
==13792== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==13792== by 0x1086EB: main (dynmem.c:15)
==13792==
==13792== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)
我是一名完全的C新手，无法解决这些泄漏的来源以及纠正这些泄漏所需要采取的措施。帮助非常感谢。