check_fopen.c

#pragma once
#ifndef CHECK_FOPEN_INCLUDED
#define CHECK_FOPEN_INCLUDED

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

FILE *
check_fopen( const char *path, const char *mode )
{
    FILE *fp;

    fp = fopen( path, mode );

    if( NULL == fp ) {
        char *msg;
        size_t len;

        len = strlen( path ) + strlen( mode ) + 40;
        msg = ( char * ) malloc( len * sizeof( char ) );

        if( NULL == msg ) {
            fprintf( stderr, "ERROR: cannot allocate a string of %zd elements\n", len );
            exit( EXIT_FAILURE );
        }

        snprintf( msg, len, "could not open '%s' (mode %s)", path, mode );
        if( 0 == errno ) {
            fprintf( stderr, "ERROR: %s\n", msg );
        } else {
            perror( msg );
        }

        free( msg );
        exit( EXIT_FAILURE );
    }

    return fp;
}

#endif