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/* Formatted fopen()
*
* Copyright (c) 2021 Joachim Wiberg <troglobit@gmail.com>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/**
* @file fopenf.c
* @author Joachim Wiberg
* @date 2021
* @copyright ISC License
*/
#include <errno.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
/**
* Similar to fopenf() except it takes a @a va_list argument
* @param mode An fopen() mode string, e.g. "w+".
* @param fmt Formatted string to be composed into a pathname.
* @param ap List of variable arguemnts from va_start().
*
* See fopenf() for details.
*
* @returns a FILE pointer, or @c NULL on error.
*/
FILE *vfopenf(const char *mode, const char *fmt, va_list ap)
{
va_list apc;
char *file;
int len;
va_copy(apc, ap);
len = vsnprintf(NULL, 0, fmt, apc);
va_end(apc);
file = alloca(len + 1);
if (!file) {
errno = ENOMEM;
return NULL;
}
va_copy(apc, ap);
vsnprintf(file, len + 1, fmt, apc);
va_end(apc);
return fopen(file, mode);
}
/**
* Open a file based on the formatted string and optional arguments
* @param mode An fopen() mode string, e.g. "w+".
* @param fmt Formatted string to be composed into a pathname.
*
* This function is an extension to the fopen() family, lessening the burden
* of first having to compose the filename from parts in a seprate buffer.
*
* @returns Upon successful completion, fopenf() returns a FILE pointer.
* Otherwise, @c NULL is returned and @a errno is set to indicate the
* error.
*/
FILE *fopenf(const char *mode, const char *fmt, ...)
{
va_list ap;
FILE *fp;
va_start(ap, fmt);
fp = vfopenf(mode, fmt, ap);
va_end(ap);
if (!fp)
return NULL;
return fp;
}
/**
* Local Variables:
* indent-tabs-mode: t
* c-file-style: "linux"
* End:
*/
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