githubmirror/efivar

src/util.h
210 строк5 KB
Peter Jones
Add some more utility functions for reading sysfs crap.
01 май 2015, 18:05
01 май 2015, 18:05f9524f1
/*
 * Copyright 2011-2014 Red Hat, Inc.
 * All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Author(s): Peter Jones <pjones@redhat.com>
 */
#ifndef EFIVAR_UTIL_H
#define EFIVAR_UTIL_H 1

#include <errno.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <unistd.h>

static inline int
__attribute__((unused))
read_file(int fd, uint8_t **buf, size_t *bufsize)
{
	uint8_t *p;
	size_t size = 4096;
	size_t filesize = 0;
	ssize_t s = 0;

	uint8_t *newbuf;
	if (!(newbuf = calloc(size, sizeof (uint8_t))))
		return -1;
	*buf = newbuf;

	do {
		p = *buf + filesize;
		/* size - filesize shouldn't exceed SSIZE_MAX because we're
		 * only allocating 4096 bytes at a time and we're checking that
		 * before doing so. */
		s = read(fd, p, size - filesize);
		if (s < 0 && errno == EAGAIN) {
			continue;
		} else if (s < 0) {
			int saved_errno = errno;
			free(*buf);
			*buf = NULL;
			*bufsize = 0;
			errno = saved_errno;
			return -1;
		}
		filesize += s;
		/* only exit for empty reads */
		if (s == 0)
			break;
		if (filesize >= size) {
			/* See if we're going to overrun and return an error
			 * instead. */
			if (size > (size_t)-1 - 4096) {
				free(*buf);
				*buf = NULL;
				*bufsize = 0;
				errno = ENOMEM;
				return -1;
			}
			newbuf = realloc(*buf, size + 4096);
			if (newbuf == NULL) {
				int saved_errno = errno;
				free(*buf);
				*buf = NULL;
				*bufsize = 0;
				errno = saved_errno;
				return -1;
			}
			*buf = newbuf;
			memset(*buf + size, '\0', 4096);
			size += 4096;
		}
	} while (1);

	newbuf = realloc(*buf, filesize+1);
	if (!newbuf) {
		free(*buf);
		*buf = NULL;
		return -1;
	}
	newbuf[filesize] = '\0';
	*buf = newbuf;
	*bufsize = filesize+1;
	return 0;
}

static inline uint64_t
__attribute__((unused))
lcm(uint64_t x, uint64_t y)
{
	uint64_t m = x, n = y, o;
	while ((o = m % n)) {
		m = n;
		n = o;
	}
	return (x / n) * y;
}

/************************************************************
 * get_sector_size
 * Requires:
 *  - filedes is an open file descriptor, suitable for reading
 * Modifies: nothing
 * Returns:
 *  sector size, or 512.
 ************************************************************/
static inline int
__attribute__((unused))
get_sector_size(int filedes)
{
	int rc, sector_size = 512;

	rc = ioctl(filedes, BLKSSZGET, &sector_size);
	if (rc)
		sector_size = 512;
	return sector_size;
}

#define asprintfa(str, fmt, args...)					\
	({								\
		char *_tmp = NULL;					\
		int _rc;						\
		*(str) = NULL;						\
		_rc = asprintf((str), (fmt), ## args);			\
		if (_rc > 0) {						\
			_tmp = strdupa(*(str));				\
			if (!_tmp) {					\
				_rc = -1;				\
			} else {					\
				free(*(str));				\
				*(str) = _tmp;				\
			}						\
		} else {						\
			_rc = -1;					\
		}							\
		_rc;							\
	})

#define read_sysfs_file(buf, fmt, args...)				\
	({								\
		int _rc=-1;						\
		char *_pathname;					\
		uint8_t *_buf=NULL;					\
		size_t _bufsize=-1;					\
		int _saved_errno;					\
									\
		*(buf) = NULL;						\
		_rc = asprintfa(&_pathname, (fmt), ## args);		\
		if (_rc >= 0) {						\
			int _fd;					\
			_fd = open(_pathname, O_RDONLY);		\
			_saved_errno = errno;				\
			_rc = -1;					\
			if (_fd >= 0) {					\
				_rc = read_file(_fd, &_buf, &_bufsize);	\
				_saved_errno = errno;			\
				close(_fd);				\
				errno = _saved_errno;			\
			}						\
		}							\
		if (_rc >= 0) {						\
			uint8_t *_buf2 = alloca(_bufsize);		\
			_saved_errno = errno;				\
			if (_buf2) {					\
				memcpy(_buf2, _buf, _bufsize);		\
				_rc = _bufsize;				\
			}						\
			free(_buf);					\
			*((uint8_t **)buf) = _buf2;			\
			errno = _saved_errno;				\
		}							\
		_rc;							\
	})

#define sysfs_readlink(linkbuf, fmt, args...)				\
	({								\
		char *_lb = alloca(PATH_MAX+1);				\
		char *_pn;						\
		int _rc;						\
									\
		*(linkbuf) = NULL;					\
		_rc = asprintfa(&_pn, fmt, ## args);			\
		if (_rc >= 0) {						\
			ssize_t _linksz;				\
			_linksz = readlink(_pn, _lb, PATH_MAX);		\
			_rc = _linksz;					\
			if (_linksz >= 0)				\
				_lb[_linksz] = '\0';			\
			*(linkbuf) = _lb;				\
		}							\
		_rc;							\
	})

#endif /* EFIVAR_UTIL_H */