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/* sprintf_alloc.c -- like sprintf with memory allocation
Carl D. Worth
Copyright (C) 2001 University of Southern California
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
*/
#include "ipkg.h"
#include <stdarg.h>
#include "sprintf_alloc.h"
int sprintf_alloc(char **str, const char *fmt, ...)
{
va_list ap;
char *new_str;
int n, size = 100;
if (!str) {
fprintf(stderr, "Null string pointer passed to sprintf_alloc\n");
return -1;
}
if (!fmt) {
fprintf(stderr, "Null fmt string passed to sprintf_alloc\n");
return -1;
}
/* On x86_64 systems, any strings over 100 were segfaulting.
It seems that the ap needs to be reinitalized before every
use of the v*printf() functions. I pulled the functionality out
of vsprintf_alloc and combined it all here instead.
*/
/* ripped more or less straight out of PRINTF(3) */
if ((new_str = malloc(size)) == NULL)
return -1;
*str = new_str;
while(1) {
va_start(ap, fmt);
n = vsnprintf (new_str, size, fmt, ap);
va_end(ap);
/* If that worked, return the size. */
if (n > -1 && n < size)
return n;
/* Else try again with more space. */
if (n > -1) /* glibc 2.1 */
size = n+1; /* precisely what is needed */
else /* glibc 2.0 */
size *= 2; /* twice the old size */
new_str = realloc(new_str, size);
if (new_str == NULL) {
free(new_str);
*str = NULL;
return -1;
}
*str = new_str;
}
return -1; /* Just to be correct - it probably won't get here */
}
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