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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
* Copyright (C) 2005 by Rob Landley <rob@landley.net>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
#include "libbb.h"
#include <linux/version.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
/* For 2.6, use the cleaned up header to get the 64 bit API. */
// Commented out per Rob's request
//# include "fix_u32.h" /* some old toolchains need __u64 for linux/loop.h */
# include <linux/loop.h>
typedef struct loop_info64 bb_loop_info;
# define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
# define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
#else
/* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
/* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */
# include <linux/posix_types.h>
# define LO_NAME_SIZE 64
# define LO_KEY_SIZE 32
# define LOOP_SET_FD 0x4C00
# define LOOP_CLR_FD 0x4C01
# define BB_LOOP_SET_STATUS 0x4C02
# define BB_LOOP_GET_STATUS 0x4C03
typedef struct {
int lo_number;
__kernel_dev_t lo_device;
unsigned long lo_inode;
__kernel_dev_t lo_rdevice;
int lo_offset;
int lo_encrypt_type;
int lo_encrypt_key_size;
int lo_flags;
char lo_file_name[LO_NAME_SIZE];
unsigned char lo_encrypt_key[LO_KEY_SIZE];
unsigned long lo_init[2];
char reserved[4];
} bb_loop_info;
#endif
char* FAST_FUNC query_loop(const char *device)
{
int fd;
bb_loop_info loopinfo;
char *dev = NULL;
fd = open(device, O_RDONLY);
if (fd >= 0) {
if (ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo) == 0) {
dev = xasprintf("%"OFF_FMT"u %s", (off_t) loopinfo.lo_offset,
(char *)loopinfo.lo_file_name);
}
close(fd);
}
return dev;
}
int FAST_FUNC del_loop(const char *device)
{
int fd, rc;
fd = open(device, O_RDONLY);
if (fd < 0)
return 1;
rc = ioctl(fd, LOOP_CLR_FD, 0);
close(fd);
return rc;
}
/* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
*device is loop device to use, or if *device==NULL finds a loop device to
mount it on and sets *device to a strdup of that loop device name. This
search will re-use an existing loop device already bound to that
file/offset if it finds one.
*/
int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, int ro)
{
char dev[LOOP_NAMESIZE];
char *try;
bb_loop_info loopinfo;
struct stat statbuf;
int i, dfd, ffd, mode, rc = -1;
/* Open the file. Barf if this doesn't work. */
mode = ro ? O_RDONLY : O_RDWR;
open_ffd:
ffd = open(file, mode);
if (ffd < 0) {
if (mode != O_RDONLY) {
mode = O_RDONLY;
goto open_ffd;
}
return -errno;
}
/* Find a loop device. */
try = *device ? *device : dev;
/* 1048575 (0xfffff) is a max possible minor number in Linux circa 2010 */
for (i = 0; rc && i < 1048576; i++) {
sprintf(dev, LOOP_FORMAT, i);
IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
&& errno == ENOENT
&& try == dev
) {
/* Node doesn't exist, try to create it. */
if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
goto try_to_open;
}
/* Ran out of block devices, return failure. */
rc = -1;
break;
}
try_to_open:
/* Open the sucker and check its loopiness. */
dfd = open(try, mode);
if (dfd < 0 && errno == EROFS) {
mode = O_RDONLY;
dfd = open(try, mode);
}
if (dfd < 0) {
if (errno == ENXIO) {
/* Happens if loop module is not loaded */
rc = -1;
break;
}
goto try_again;
}
rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
/* If device is free, claim it. */
if (rc && errno == ENXIO) {
memset(&loopinfo, 0, sizeof(loopinfo));
safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
loopinfo.lo_offset = offset;
/* Associate free loop device with file. */
if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
if (ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo) == 0)
rc = 0;
else
ioctl(dfd, LOOP_CLR_FD, 0);
}
/* If this block device already set up right, re-use it.
* (Yes this is racy, but associating two loop devices with the same
* file isn't pretty either. In general, mounting the same file twice
* without using losetup manually is problematic.)
*/
} else
if (strcmp(file, (char *)loopinfo.lo_file_name) != 0
|| offset != loopinfo.lo_offset
) {
rc = -1;
}
close(dfd);
try_again:
if (*device) break;
}
close(ffd);
if (rc == 0) {
if (!*device)
*device = xstrdup(dev);
return (mode == O_RDONLY); /* 1:ro, 0:rw */
}
return rc;
}
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