lib/safe_file_ops.c

/*
 * Copyright (C) 2012 Cyril Hrubis chrubis@suse.cz
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdarg.h>
#include <stdio.h>

#include "safe_file_ops.h"

/*
 * Count number of expected assigned conversions. Any conversion starts with '%'.
 * The '%%' matches % and no assigment is done. The %*x matches as x would do but
 * the assigment is supressed.
 *
 * NOTE: This is not 100% correct for complex scanf strings, but will do for
 *       all of our intended usage.
 */
static int count_scanf_conversions(const char *fmt)
{
	unsigned int cnt = 0;
	int flag = 0;

	while (*fmt) {
		switch (*fmt) {
		case '%':
			if (flag) {
				cnt--;
				flag = 0;
			} else {
				flag = 1;
				cnt++;
			}
		break;
		case '*':
			if (flag) {
				cnt--;
				flag = 0;
			}
		break;
		default:
			flag = 0;
		}
	
		fmt++;
	}

	return cnt;
}

void safe_file_scanf(const char *file, const int lineno,
                     void (*cleanup_fn)(void),
		     const char *path, const char *fmt, ...)
{
	va_list va;
	FILE *f;
	int exp_convs, ret;

	f = fopen(path, "r");

	if (f == NULL) {
		tst_brkm(TBROK | TERRNO, cleanup_fn,
		         "Failed to open FILE '%s' for reading at %s:%d",
		         path, file, lineno);
	}
	
	exp_convs = count_scanf_conversions(fmt);

	va_start(va, fmt);
	ret = vfscanf(f, fmt, va);
	va_end(va);
		
	if (ret == EOF) {
		tst_brkm(TBROK, cleanup_fn,
		         "The FILE '%s' ended prematurely at %s:%d",
		         path, file, lineno);
	}

	if (ret != exp_convs) {
		tst_brkm(TBROK, cleanup_fn,
		         "Expected %i conversions got %i FILE '%s' at %s:%d",
		         exp_convs, ret, path, file, lineno);
	}

}


void safe_file_printf(const char *file, const int lineno,
                      void (*cleanup_fn)(void),
                      const char *path, const char *fmt, ...)
{
	va_list va;
	FILE *f;

	f = fopen(path, "w");

	if (f == NULL) {
		tst_brkm(TBROK | TERRNO, cleanup_fn,
		         "Failed to open FILE '%s' for writing at %s:%d",
		         path, file, lineno);
	}

	va_start(va, fmt);

	if (vfprintf(f, fmt, va) < 0) {
		tst_brkm(TBROK, cleanup_fn,
		         "Failed to print to FILE '%s' at %s:%d",
		         path, file, lineno);
	}

	va_end(va);

	if (fclose(f)) {
		tst_brkm(TBROK | TERRNO, cleanup_fn,
		         "Failed to close FILE '%s' at %s:%d",
		         path, file, lineno);
	}
}

//TODO: C implementation? better error condition reporting?
void safe_cp(const char *file, const int lineno,
             void (*cleanup_fn)(void),
	     const char *src, const char *dst)
{
	size_t len = strlen(src) + strlen(dst) + 16;
	char buf[len];
	int ret;

	snprintf(buf, sizeof(buf), "cp \"%s\" \"%s\"", src, dst);

	ret = system(buf);

	if (ret) {
		tst_brkm(TBROK, cleanup_fn,
		         "Failed to copy '%s' to '%s' at %s:%d",
		         src, dst, file, lineno);
	}
}