#include <string.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]){
char *str = malloc(sizeof(char)*5);
str = strcpy(str, "test");
printf("%s\n", str);
free(str);
return 0;
}
Khi tôi sử dụng Valgrind trên máy Mac của tôi (OS X, 10.9.5) tôi nhận được thông báo sau:Valgrind cho thấy rò rỉ bộ nhớ cho printf và khối không sử dụng
==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)
Liệu printf
phân bổ bộ nhớ bằng cách riêng của mình? Nếu tôi loại bỏ các printf
tôi chỉ nhận được như sau:
==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)
Trường hợp không 373 khối đến từ đâu?
Trên hệ thống Linux amd64 của tôi, nó nói rằng không có rò rỉ nào cả. – Jay