file.c

来自「linux下自动mount各种即插即用设备的一个小程序源码 文件包含内容： 」· C语言 代码 · 共 129 行

/*
 * file.c
 * Data source for files and block devices.
 *
 * Copyright (c) 2003 Christoph Pfisterer
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. 
 */

#include "file.h"

#define USE_BINARY_SEARCH 0
#define DEBUG_SIZE 0

#ifdef USE_IOCTL_LINUX
#include <sys/ioctl.h>
#include <linux/fs.h>
#endif

#ifdef USE_IOCTL_FREEBSD
#include <sys/disklabel.h>
#endif

#ifdef USE_IOCTL_DARWIN
#include <sys/ioctl.h>
#include <sys/disk.h>
#endif

/*
 * special handling hook: devices may have out-of-band structure
 */

int analyze_file(SOURCE *s, DT_Info* info) {
	if(s->source_open == 0) return 0;
	
	if (analyze_cdaccess(s->fd, s, 0))
		return 1;

	return 0;
}

/*
 * raw read
 */

U64 read_file(SOURCE *s, U64 pos, U64 len, void *buf) {
	off_t result_seek;
	ssize_t result_read;
	char *p;
	U64 got;
	int fd = s->fd;
	
	if(s->source_open == 0) return 0;

	/* seek to the requested position */
	result_seek = lseek(fd, pos, SEEK_SET);
	if (result_seek != pos) {
		errore("Seek to %llu failed", pos);
		return 0;
	}

	/* read from there */
	p = (char *)buf;
	got = 0;
	while (len > 0) {
		result_read = read(fd, p, len);
		if (result_read < 0) {
			if (errno == EINTR || errno == EAGAIN)
				continue;
			errore("Data read failed at position %llu", pos + got);
			break;
		} else if (result_read == 0) {
			/* simple EOF, no message */
			break;
		} else {
			len -= result_read;
			got += result_read;
			p += result_read;
		}
	}

	return got;
}

/*
 * dispose of everything
 */

void close_file(SOURCE *s) {
	DBG("closing source");
	if(s->source_open != 0)
		close(s->fd);
}

int open_file(SOURCE *s, char* filename) {
	if(s->source_open != 0) {
		error("Internal malfunction! SOURCE already opened!");
		return 0;
	} else {
		s->fd = open(filename, O_RDONLY);
		if(s->fd < 0) {
			errore("Can't open %.300s for reading (detect)", filename);
			return 0;
		}
		s->source_open = 1;
	}
	return 1;
}

/* EOF */