Project

General

Profile

Download (1.26 KB)

Review #751 » memccpy_poc.c

PoC for bip_strcat_fit() and bip_strcatf_fit() - Loïc Gomez, 2022-01-05 17:29

 
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

#define MAX_LEN 45

char *bip_strcat_fit(size_t *remaining, char *str, char *str2)
{
char *res;

if (!remaining || !str || !str2)
return NULL;

res = memccpy(str, str2, '\0', *remaining);
if (!res)
return NULL;

res--;
if (res < str)
return NULL;
(*remaining) -= (size_t)(res - str);
return res;
}

char *bip_strcatf_fit(size_t *remaining, char *str, char *fmt, ...)
{
va_list ap;
char str2[MAX_LEN];
int written;
char *res = NULL;

if (!remaining || !str || !fmt)
return NULL;

va_start(ap, fmt);
written = vsnprintf(str2, *remaining, fmt, ap);
if (written < 0)
goto end;

if ((size_t)written >= *remaining)
goto end;

res = memccpy(str, str2, '\0', *remaining);
if (!res)
goto end;

res--;
if (res < str)
return NULL;
(*remaining) -= (size_t)(res - str);

end:
va_end(ap);
return res;
}

int main(void)
{
size_t remaining = MAX_LEN;
char buf[MAX_LEN+1];
char *bufpos = buf;

for (int i=0; i<30; i++) {
if (i == 0)
bufpos = bip_strcat_fit(&remaining, bufpos, "test");
else
bufpos = bip_strcatf_fit(&remaining, bufpos, " %d", i);
if (!bufpos) {
printf("buf is full: %lu/%d\n", strlen(buf), MAX_LEN);
break;
}
}
printf("%s\n", buf);
return 0;
}
(1-1/4)