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#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//# this function will generate the fmt specifier for appendsnprintf, should only be used for this use case
char *genfmt(char *buf, char *fmt){
int len = strlen(buf) + strlen(fmt) + 1;
char *out = malloc(len);
int j = 0, i = 0;
while (buf[i] != '\0'){
out[i] = buf[i];
i++;
}
while (fmt[j] != '\0'){
out[i] = fmt[j];
i++;
j++;
}
out[i] = '\0';
return out;
}
//# this function will append size number of bytes, onto the end of buf, a format string in the form of vaargs
char *appendsnprintf(char *buf, int size, char *format, ...){
va_list ap;
char *outputbuf = malloc(size);
va_start(ap, format);
char *fmt = genfmt(buf, format);
vsnprintf(outputbuf, size, fmt, ap);
free(fmt);
buf = realloc(outputbuf, strlen(outputbuf) + 1);
va_end(ap);
return buf;
}
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