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    Contents of /trunk/mkinitrd-magellan/busybox/libbb/loop.c

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    Revision 984 - (show annotations) (download)
    Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
    File MIME type: text/plain
    File size: 4428 byte(s) 
    -updated to busybox-1.16.1 and enabled blkid/uuid support in default config
    1 /* vi: set sw=4 ts=4: */
    2 /*
    3 * Utility routines.
    4 *
    5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
    6 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
    7 *
    8 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
    9 */
    10 #include "libbb.h"
    11 #include <linux/version.h>
    12
    13 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
    14
    15 /* For 2.6, use the cleaned up header to get the 64 bit API. */
    16 /* linux/loop.h relies on __u64. Make sure we have that as a proper type
    17 * until userspace is widely fixed. */
    18 # if (defined __INTEL_COMPILER && !defined __GNUC__) \
    19 || (defined __GNUC__ && defined __STRICT_ANSI__)
    20 __extension__ typedef long long __s64;
    21 __extension__ typedef unsigned long long __u64;
    22 # endif
    23 # include <linux/loop.h>
    24 typedef struct loop_info64 bb_loop_info;
    25 # define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
    26 # define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
    27
    28 #else
    29
    30 /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
    31 /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */
    32 # include <linux/posix_types.h>
    33 # define LO_NAME_SIZE 64
    34 # define LO_KEY_SIZE 32
    35 # define LOOP_SET_FD 0x4C00
    36 # define LOOP_CLR_FD 0x4C01
    37 # define BB_LOOP_SET_STATUS 0x4C02
    38 # define BB_LOOP_GET_STATUS 0x4C03
    39 typedef struct {
    40 int lo_number;
    41 __kernel_dev_t lo_device;
    42 unsigned long lo_inode;
    43 __kernel_dev_t lo_rdevice;
    44 int lo_offset;
    45 int lo_encrypt_type;
    46 int lo_encrypt_key_size;
    47 int lo_flags;
    48 char lo_file_name[LO_NAME_SIZE];
    49 unsigned char lo_encrypt_key[LO_KEY_SIZE];
    50 unsigned long lo_init[2];
    51 char reserved[4];
    52 } bb_loop_info;
    53 #endif
    54
    55 char* FAST_FUNC query_loop(const char *device)
    56 {
    57 int fd;
    58 bb_loop_info loopinfo;
    59 char *dev = 0;
    60
    61 fd = open(device, O_RDONLY);
    62 if (fd < 0) return 0;
    63 if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo))
    64 dev = xasprintf("%ld %s", (long) loopinfo.lo_offset,
    65 (char *)loopinfo.lo_file_name);
    66 close(fd);
    67
    68 return dev;
    69 }
    70
    71 int FAST_FUNC del_loop(const char *device)
    72 {
    73 int fd, rc;
    74
    75 fd = open(device, O_RDONLY);
    76 if (fd < 0) return 1;
    77 rc = ioctl(fd, LOOP_CLR_FD, 0);
    78 close(fd);
    79
    80 return rc;
    81 }
    82
    83 /* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
    84 *device is loop device to use, or if *device==NULL finds a loop device to
    85 mount it on and sets *device to a strdup of that loop device name. This
    86 search will re-use an existing loop device already bound to that
    87 file/offset if it finds one.
    88 */
    89 int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset)
    90 {
    91 char dev[LOOP_NAMESIZE];
    92 char *try;
    93 bb_loop_info loopinfo;
    94 struct stat statbuf;
    95 int i, dfd, ffd, mode, rc = -1;
    96
    97 /* Open the file. Barf if this doesn't work. */
    98 mode = O_RDWR;
    99 ffd = open(file, mode);
    100 if (ffd < 0) {
    101 mode = O_RDONLY;
    102 ffd = open(file, mode);
    103 if (ffd < 0)
    104 return -errno;
    105 }
    106
    107 /* Find a loop device. */
    108 try = *device ? *device : dev;
    109 for (i = 0; rc; i++) {
    110 sprintf(dev, LOOP_FORMAT, i);
    111
    112 /* Ran out of block devices, return failure. */
    113 if (stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) {
    114 rc = -ENOENT;
    115 break;
    116 }
    117 /* Open the sucker and check its loopiness. */
    118 dfd = open(try, mode);
    119 if (dfd < 0 && errno == EROFS) {
    120 mode = O_RDONLY;
    121 dfd = open(try, mode);
    122 }
    123 if (dfd < 0)
    124 goto try_again;
    125
    126 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
    127
    128 /* If device is free, claim it. */
    129 if (rc && errno == ENXIO) {
    130 memset(&loopinfo, 0, sizeof(loopinfo));
    131 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
    132 loopinfo.lo_offset = offset;
    133 /* Associate free loop device with file. */
    134 if (!ioctl(dfd, LOOP_SET_FD, ffd)) {
    135 if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo))
    136 rc = 0;
    137 else
    138 ioctl(dfd, LOOP_CLR_FD, 0);
    139 }
    140
    141 /* If this block device already set up right, re-use it.
    142 (Yes this is racy, but associating two loop devices with the same
    143 file isn't pretty either. In general, mounting the same file twice
    144 without using losetup manually is problematic.)
    145 */
    146 } else if (strcmp(file, (char *)loopinfo.lo_file_name) != 0
    147 || offset != loopinfo.lo_offset) {
    148 rc = -1;
    149 }
    150 close(dfd);
    151 try_again:
    152 if (*device) break;
    153 }
    154 close(ffd);
    155 if (!rc) {
    156 if (!*device)
    157 *device = xstrdup(dev);
    158 return (mode == O_RDONLY); /* 1:ro, 0:rw */
    159 }
    160 return rc;
    161 }