source: MondoRescue/branches/stable/mindi-busybox/libbb/loop.c @ 821

Last change on this file since 821 was 821, checked in by Bruno Cornec, 14 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)

File size: 3.9 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
4 *
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 *
7 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
8 */
9
10
11#include <features.h>
12#include <stdio.h>
13#include <errno.h>
14#include <fcntl.h>
15#include <string.h>
16#include <unistd.h>
17#include <sys/ioctl.h>
18#include "libbb.h"
19
20/* For 2.6, use the cleaned up header to get the 64 bit API. */
21#include <linux/version.h>
22#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
23#include <linux/loop.h>
24typedef 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/* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
29#else
30/* Stuff stolen from linux/loop.h for 2.4 and earlier kernels*/
31#include <linux/posix_types.h>
32#define LO_NAME_SIZE        64
33#define LO_KEY_SIZE         32
34#define LOOP_SET_FD         0x4C00
35#define LOOP_CLR_FD         0x4C01
36#define BB_LOOP_SET_STATUS  0x4C02
37#define BB_LOOP_GET_STATUS  0x4C03
38typedef struct {
39    int                lo_number;
40    __kernel_dev_t     lo_device;
41    unsigned long      lo_inode;
42    __kernel_dev_t     lo_rdevice;
43    int                lo_offset;
44    int                lo_encrypt_type;
45    int                lo_encrypt_key_size;
46    int                lo_flags;
47    char               lo_file_name[LO_NAME_SIZE];
48    unsigned char      lo_encrypt_key[LO_KEY_SIZE];
49    unsigned long      lo_init[2];
50    char               reserved[4];
51} bb_loop_info;
52#endif
53
54char *query_loop(const char *device)
55{
56    int fd;
57    bb_loop_info loopinfo;
58    char *dev=0;
59
60    if ((fd = open(device, O_RDONLY)) < 0) return 0;
61    if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo))
62        dev=bb_xasprintf("%ld %s", (long) loopinfo.lo_offset,
63                (char *)loopinfo.lo_file_name);
64    close(fd);
65
66    return dev;
67}
68
69
70int del_loop(const char *device)
71{
72    int fd, rc;
73
74    if ((fd = open(device, O_RDONLY)) < 0) return 1;
75    rc=ioctl(fd, LOOP_CLR_FD, 0);
76    close(fd);
77
78    return rc;
79}
80
81/* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
82   *device is loop device to use, or if *device==NULL finds a loop device to
83   mount it on and sets *device to a strdup of that loop device name.  This
84   search will re-use an existing loop device already bound to that
85   file/offset if it finds one.
86 */
87int set_loop(char **device, const char *file, int offset)
88{
89    char dev[20], *try;
90    bb_loop_info loopinfo;
91    struct stat statbuf;
92    int i, dfd, ffd, mode, rc=-1;
93   
94    /* Open the file.  Barf if this doesn't work.  */
95    if((ffd = open(file, mode=O_RDWR))<0 && (ffd = open(file,mode=O_RDONLY))<0)
96        return -errno;
97
98    /* Find a loop device.  */
99    try=*device ? : dev;
100    for(i=0;rc;i++) {
101        sprintf(dev, LOOP_FORMAT, i);
102
103        /* Ran out of block devices, return failure.  */
104        if(stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) {
105            rc=-ENOENT;
106            break;
107        }
108        /* Open the sucker and check its loopiness.  */
109        if((dfd=open(try, mode))<0 && errno==EROFS)
110            dfd=open(try, mode = O_RDONLY);
111        if(dfd<0) goto try_again;
112
113        rc=ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
114
115        /* If device free, claim it.  */
116        if(rc && errno==ENXIO) {
117            memset(&loopinfo, 0, sizeof(loopinfo));
118            safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
119            loopinfo.lo_offset = offset;
120            /* Associate free loop device with file.  */
121            if(!ioctl(dfd, LOOP_SET_FD, ffd)) {
122                if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo)) rc=0;
123                else ioctl(dfd, LOOP_CLR_FD, 0);
124            }
125
126        /* If this block device already set up right, re-use it.
127           (Yes this is racy, but associating two loop devices with the same
128           file isn't pretty either.  In general, mounting the same file twice
129           without using losetup manually is problematic.)
130         */
131        } else if(strcmp(file,(char *)loopinfo.lo_file_name)
132                    || offset!=loopinfo.lo_offset) rc=-1;
133        close(dfd);
134try_again:
135        if(*device) break;
136    }
137    close(ffd);
138    if(!rc) {
139        if(!*device) *device=strdup(dev);
140        return mode==O_RDONLY ? 1 : 0;
141    } else return rc;
142}
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