我一直在使用valgrind和gdb，但我无法确定问题出在哪里。在gdb中，跟踪它的过程太复杂了，而在valgrind中，我又没有足够的信息。下面是我的makeargv函数，它将strtok()函数输出的字符串放入数组中，makeargv函数被下面的parse函数调用。我不知道哪里出错了。如果能得到帮助，我会非常感激。
顺便提一句，我对malloc函数很陌生，也不太理解这个概念。我不确定具体什么时候需要malloc。我感觉由于我主要设置常量值，因此不需要使用malloc，但我想知道为什么它不起作用。
makeargv函数：
int makeargv(const char *string, char **argvp) {
int i = 0;
int numtokens = 0;
const char *copy;
char *buffer = malloc(160*sizeof(char));
if ((string == NULL) || (delims == NULL) || (argvp == NULL)) {
return -1;
}
argvp = NULL;
copy = string + strspn(string, delims);
if ((buffer = malloc(strlen(copy) + 1)) == NULL) {
return -1;
}
strcpy(buffer, copy);
numtokens = 0;
if (strtok(buffer, delims) != NULL) {
for (numtokens = 1; strtok(NULL, delims) != NULL; numtokens++);
}
if ((argvp = malloc((numtokens + 2)*sizeof(int))) == NULL) {
free(buffer);
return -1;
}
if (numtokens == 0) {
free(buffer);
}
else {
strcpy(buffer, copy);
*argvp = malloc(16);
*argvp = strtok(buffer, delims);
for (i = 2; i < (numtokens*2); i += 2) {
*(argvp + i) = strtok(NULL, delims);
//printf("%s\n", strtok(NULL, delims)); /*When I run this the tokens come out
correctly so I know it isn't a problem with strtok */
}
}
// *((argvp) + numtokens) = NULL;
free(buffer);
return numtokens;
}
解析函数
void parse_file(char* filename) {
char* line = malloc(160*sizeof(char));
FILE* fp = file_open(filename);
int i = 0;
while((line = file_getline(line, fp)) != NULL) {
char** results = malloc(16*10*sizeof(char));
if (strlen(line) == 1){
continue;
}
if ((i = makeargv(line, results)) == -1){
printf("ERROR SOMEWHERE IN MAKEARGV");
continue;
}
}
fclose(fp);
free(line);
}
Valgrind输出
==7309== Memcheck, a memory error detector
==7309== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==7309== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==7309== Command: ./custmake
==7309==
==7309== Invalid write of size 8
==7309== at 0x400C23: makeargv (main.c:62)
==7309== by 0x400CD4: parse_file (main.c:120)
==7309== by 0x400DFF: main (main.c:172)
==7309== Address 0x51f25c0 is 16 bytes inside a block of size 20 alloc'd
==7309== at 0x4C2B6CD: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7309== by 0x400B76: makeargv (main.c:49)
==7309== by 0x400CD4: parse_file (main.c:120)
==7309== by 0x400DFF: main (main.c:172)
==7309==
==7309== Use of uninitialised value of size 8
==7309== at 0x4C2BFC2: __GI_strlen (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7309== by 0x4EA2CEB: puts (ioputs.c:37)
==7309== by 0x400D09: parse_file (main.c:128)
==7309== by 0x400DFF: main (main.c:172)
==7309==
==7309== Invalid read of size 1
==7309== at 0x4C2BFC2: __GI_strlen (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7309== by 0x4EA2CEB: puts (ioputs.c:37)
==7309== by 0x400D09: parse_file (main.c:128)
==7309== by 0x400DFF: main (main.c:172)
==7309== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==7309==
==7309==
==7309== Process terminating with default action of signal 11 (SIGSEGV)
==7309== Access not within mapped region at address 0x0
==7309== at 0x4C2BFC2: __GI_strlen (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7309== by 0x4EA2CEB: puts (ioputs.c:37)
==7309== by 0x400D09: parse_file (main.c:128)
==7309== by 0x400DFF: main (main.c:172)
==7309== If you believe this happened as a result of a stack
==7309== overflow in your program's main thread (unlikely but
==7309== possible), you can try to increase the size of the
==7309== main thread stack using the --main-stacksize= flag.
==7309== The main thread stack size used in this run was 8388608.
==7309==
==7309== HEAP SUMMARY:
==7309== in use at exit: 1,084 bytes in 6 blocks
==7309== total heap usage: 7 allocs, 1 frees, 1,100 bytes allocated
==7309==
==7309== 16 bytes in 1 blocks are definitely lost in loss record 1 of 6
==7309== at 0x4C2B6CD: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7309== by 0x400BCB: makeargv (main.c:59)
==7309== by 0x400CD4: parse_file (main.c:120)
==7309== by 0x400DFF: main (main.c:172)
==7309==
==7309== 20 bytes in 1 blocks are definitely lost in loss record 2 of 6
==7309== at 0x4C2B6CD: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7309== by 0x400B76: makeargv (main.c:49)
==7309== by 0x400CD4: parse_file (main.c:120)
==7309== by 0x400DFF: main (main.c:172)
==7309==
==7309== 160 bytes in 1 blocks are definitely lost in loss record 5 of 6
==7309== at 0x4C2B6CD: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7309== by 0x400A6E: makeargv (main.c:32)
==7309== by 0x400CD4: parse_file (main.c:120)
==7309== by 0x400DFF: main (main.c:172)
==7309==
==7309== LEAK SUMMARY:
==7309== definitely lost: 196 bytes in 3 blocks
==7309== indirectly lost: 0 bytes in 0 blocks
==7309== possibly lost: 0 bytes in 0 blocks
==7309== still reachable: 888 bytes in 3 blocks
==7309== suppressed: 0 bytes in 0 blocks
==7309== Reachable blocks (those to which a pointer was found) are not shown.
==7309== To see them, rerun with: --leak-check=full --show-reachable=yes
==7309==
==7309== For counts of detected and suppressed errors, rerun with: -v
==7309== Use --track-origins=yes to see where uninitialised values come from
==7309== ERROR SUMMARY: 7 errors from 6 contexts (suppressed: 2 from 2)
Segmentation fault (core dumped)