[英]C solving memory leaks using Valgrind
所以我有一个php,ruby和python背景,并开始使用C。我正在使用Valgrind检查我的程序是否没有做愚蠢的事情,但是我经常得到这种输出:
14072== <...VALGRIND HEADER & COPYRIGHT...>
14158== HEAP SUMMARY:
14158== in use at exit: 137,084 bytes in 196 blocks
14158== total heap usage: 247 allocs, 51 frees, 149,496 bytes allocated
14158==
14158== 7 bytes in 1 blocks are definitely lost in loss record 3 of 74 at
14158== 0x4C2745D: malloc in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so
14158== by 0x50F3369: strdup in /usr/lib64/libc-2.18.so
14158== by 0x4E51B34: readline in /usr/lib64/libedit.so.0.0.43
14158== by 0x40083C: main in /home/<program location>/
14158==
14158== LEAK SUMMARY:
14158== definitely lost: 7 bytes in 1 blocks
14158== indirectly lost: 0 bytes in 0 blocks
14158== possibly lost: 0 bytes in 0 blocks
14158== still reachable: 137,077 bytes in 195 blocks
14158== suppressed: 0 bytes in 0 blocks
14158== Reachable blocks (those to which a pointer was found) are not shown.
14158== To see them, rerun with: --leak-check=full --show-leak-kinds=all
14158==
14158== For counts of detected and suppressed errors, rerun with: -v
14158== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
此valgrind调试输出是来自此快速REPL的,它只是在屏幕上大喊用户输入或在输入等于:exit
:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <editline/readline.h>
static char prompt[5] = "repl>";
static char* cmd_exit = ":exit";
int main(int argc, char** argv) {
puts("Press Ctrl+c to Exit\n");
while(1) {
char* input = readline(prompt);
add_history(input);
if(strcmp(input,cmd_exit) == 0) {
puts("Bye!");
return 0;
}
printf("%s\n", input);
free(input);
}
return 0;
}
根据Valgrind,我已经尝试在函数main返回值之前释放prompt
和cmd_exit
变量,但泄漏仍然存在。
...
free(prompt);
free(cmd_exit);
return 0;
}
一些问题:
欢迎任何好的建议或材料。
你只需要free
的东西,你malloc
版,这样你就不会需要释放的静态变量。
由于您的readline函数似乎使用了strdup并且使用了malloc / calloc,因此您需要释放input
。 您可以在循环中执行此操作,但这很好,但是退出循环时却错过了它:
if(strcmp(input,cmd_exit) == 0) {
puts("Bye!");
free(input);
return 0;
}
顺便说说:
static char prompt[6] = "repl>";
文本“ repl>”具有6个字符,即r,e,p,l,>和一个nul字节,用于标记字符串的结尾。
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