#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
/*
* mprintf, a sprintf clone that automaticly mallocs the string
* and new content to same string applys after that content.
*/
int mprintf (char ** p, const char *format, ...)
{
va_list arg; /* used for the variable lists */
int len = 0; /* will contain lent for current string */
int add_len = 0; /* This mutch more strings are we gonna alloc for */
/*printf("\n\nmprintf(%s);\n", format);*/
/* count old chars */
if(*p)
len = strlen(*p);
/*
* format contains the minimum needed chars that
* are gonna be used, so we set that value and try
* with that.
*/
add_len = strlen(format) + 1;
/*
* Now realloc the memoryspace containing the
* string so that the new apending string will
* have room.
* Also have a check that it succeds.
*/
/*printf("Changing size to %i\n", len + add_len);*/
if(!(*p=realloc(*p, ((len + add_len) * sizeof(char)))))
return(-1);
/* Ok, have a try until vsnprintf succeds */
while(1)
{
/* start filling the newly allocaded area */
va_start (arg, format);
int done = vsnprintf ((*p)+len, add_len, format, arg);
va_end (arg);
/* check if that was enouth */
if(done > -1 && done < add_len)
{
/*printf("GOOD: done : %i, len: %i\n", done, add_len);*/
/* Ok return happily */
return(done);
}
/*printf("BAD: done : %i, len: %i\n", done, add_len);*/
/* try increase it a bit. */
add_len = ( done < 0 ? add_len * 2 : done + 1);
/*printf("Changing size to %i\n", len + add_len);*/
if(!(*p=realloc(*p, ((len + add_len) * sizeof(char)))))
return(-1);
}
/* will never go here */
return(-1);
}
int main(int argc, char **argv)
{
char *test=NULL;
mprintf(&test, "Hello world\n");
mprintf(&test, "This is a funny test\n");
mprintf(&test, "Of an self reallocating function\n");
mprintf(&test, "that shud work with %s\n", "variables");
printf("This is test (%i): \n\"%s\"\n", strlen(test), test);
free(test);
exit(0);
}