Weird seg faults on consecutive calls to the same array - c

Question

I tried really hard to search for a solution to this but I can't think of good enough keywords.
Currently I'm having troubles grasping the concept behind makeargv and it's usage with triple pointers (I have no idea what ***foo means, it doesn't seem to be as easy of a concept as **foo or *foo). So I made my own:
const char **makeargv(char *string, int *numargs) {
string = string + strspn(string, delims);
char *copy = malloc(strlen(string) + 1);
int i;
strcpy(copy, string);
int numtokens;
if (strtok(copy, delims) != NULL) {
for (numtokens = 1; strtok(NULL, delims) != NULL; numtokens++) {}
}
strcpy(copy, string);
const char *results[numtokens+1];
results[0] = strtok(copy, delims);
for (i = 1; i < numtokens; i++) {
results[i] = strtok(NULL, delims);
}
results[numtokens+1] = NULL;
*numargs = numtokens;
return results;
}
Here's the part at where it breaks:
void parse_file(char* filename) {
char* line = malloc(160*sizeof(char));
FILE* fp = file_open(filename);
int i = 0;
int numargs = 0;
int *pointer = &numargs;
while((line = file_getline(line, fp)) != NULL) {
if (strlen(line) == 1){
continue;
}
const char **args = makeargv(line, pointer);
printf("%s\n", args[0]);
printf("%s\n", args[1]);
/* This prints out args[0], but then args[1] causes a seg fault. Even if I replace
the args[1] with another args[0] it still causes a seg fault */
}
fclose(fp);
free(line);
}
I have a working array of strings. However when I try to print out the strings in the array, I can only print 1 of my choice and then it seg faults for any subsequent calls. lets pretend my array of strings is argv[3] = {"Yes", "no", "maybe"}, if i call argv[0], it will let me call "Yes", but any other calls (even if i call argv[0] again) do not work and cause a segfault. I can call any of the elements in the array, but once i call one the rest cease to work causing segfaults.
Help please? D: This is in C.

Answer 1

const char *results[numtokens+1];
This array "results" is a local variable, it is only available inside of "makeargv".
You'd better use malloc:
results = malloc(numtokens+1)
And I believe there is memory leak in your code.
You will not be able to free the memory for "char *copy"
char *copy = malloc(strlen(string) + 1);

Answer 2

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char **makeargv(char *string, int *numargs) {
static const char *delims = " \t\n";
string = string + strspn(string, delims);
char *copy = malloc(strlen(string) + 1), *p = copy;
strcpy(copy, string);
int numtokens;
for (numtokens = 0; strtok(p, delims); ++numtokens, p = NULL);
char **results = malloc(sizeof(char*)*(numtokens+1));
strcpy(copy, string);
int i;
p = copy;
for (i = 0; i < numtokens; ++i, p = NULL)
results[i] = strtok(p, delims);
results[i] = NULL;
*numargs = numtokens;
return results;
}
FILE *file_open(char *filename){
FILE *fp = fopen(filename, "r");
if(!fp){
perror("file_open");
exit(1);
}
return fp;
}
void parse_file(char* filename) {
char* line = malloc(160*sizeof(char));
FILE* fp = file_open(filename);
int i = 0, numargs = 0;
while(fgets(line, 160, fp)){
if (*line == '\n')
continue;
char **args = makeargv(line, &numargs);
for(i = 0;i<numargs;++i)
printf("%s\n", args[i]);
printf("\n");
if(args[0])
free(args[0]);
free(args);
}
fclose(fp);
free(line);
}
int main(int argc, char *argv[]){
parse_file(argv[1]);
return 0;
}