source: trunk/mindi-busybox/util-linux/umount.c @ 956

Last change on this file since 956 was 904, checked in by bruno, 13 years ago

merge -r890:902 $SVN_M/branches/stable

File size: 4.2 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * Mini umount implementation for busybox
4 *
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
7 *
8 * This program is licensed under the GNU General Public license (GPL)
9 * version 2 or later, see http://www.fsf.org/licensing/licenses/gpl.html
10 * or the file "LICENSE" in the busybox source tarball for the full text.
11 *
12 */
13
14#include "busybox.h"
15#include <mntent.h>
16#include <errno.h>
17#include <getopt.h>
18
19#define OPTION_STRING       "flDnravd"
20#define OPT_FORCE           1
21#define OPT_LAZY            2
22#define OPT_DONTFREELOOP    4
23#define OPT_NO_MTAB         8
24#define OPT_REMOUNT         16
25#define OPT_ALL             (ENABLE_FEATURE_UMOUNT_ALL ? 32 : 0)
26
27int umount_main(int argc, char **argv)
28{
29    int doForce;
30    char path[2*PATH_MAX];
31    struct mntent me;
32    FILE *fp;
33    int status = EXIT_SUCCESS;
34    unsigned long opt;
35    struct mtab_list {
36        char *dir;
37        char *device;
38        struct mtab_list *next;
39    } *mtl, *m;
40
41    /* Parse any options */
42
43    opt = bb_getopt_ulflags(argc, argv, OPTION_STRING);
44
45    argc -= optind;
46    argv += optind;
47
48    doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
49
50    /* Get a list of mount points from mtab.  We read them all in now mostly
51     * for umount -a (so we don't have to worry about the list changing while
52     * we iterate over it, or about getting stuck in a loop on the same failing
53     * entry.  Notice that this also naturally reverses the list so that -a
54     * umounts the most recent entries first. */
55
56    m = mtl = 0;
57
58    /* If we're umounting all, then m points to the start of the list and
59     * the argument list should be empty (which will match all). */
60
61    if (!(fp = setmntent(bb_path_mtab_file, "r"))) {
62        if (opt & OPT_ALL)
63            bb_error_msg_and_die("Cannot open %s", bb_path_mtab_file);
64    } else while (getmntent_r(fp,&me,path,sizeof(path))) {
65        m = xmalloc(sizeof(struct mtab_list));
66        m->next = mtl;
67        m->device = bb_xstrdup(me.mnt_fsname);
68        m->dir = bb_xstrdup(me.mnt_dir);
69        mtl = m;
70    }
71    endmntent(fp);
72
73    /* If we're not mounting all, we need at least one argument. */
74    if (!(opt & OPT_ALL)) {
75        m = 0;
76        if (!argc) bb_show_usage();
77    }
78   
79    // Loop through everything we're supposed to umount, and do so.
80    for (;;) {
81        int curstat;
82        char *zapit = *argv;
83
84        // Do we already know what to umount this time through the loop?
85        if (m) safe_strncpy(path, m->dir, PATH_MAX);
86        // For umount -a, end of mtab means time to exit.
87        else if (opt & OPT_ALL) break;
88        // Get next command line argument (and look it up in mtab list)
89        else if (!argc--) break;
90        else {
91            argv++;
92            realpath(zapit, path);
93            for (m = mtl; m; m = m->next)
94                if (!strcmp(path, m->dir) || !strcmp(path, m->device))
95                    break;
96        }
97        // If we couldn't find this sucker in /etc/mtab, punt by passing our
98        // command line argument straight to the umount syscall.  Otherwise,
99        // umount the directory even if we were given the block device.
100        if (m) zapit = m->dir;
101
102        // Let's ask the thing nicely to unmount.
103        curstat = umount(zapit);
104
105        // Force the unmount, if necessary.
106        if (curstat && doForce) {
107            curstat = umount2(zapit, doForce);
108            if (curstat)
109                bb_error_msg_and_die("forced umount of %s failed!", zapit);
110        }
111
112        // If still can't umount, maybe remount read-only?
113        if (curstat && (opt & OPT_REMOUNT) && errno == EBUSY && m) {
114            curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
115            bb_error_msg(curstat ? "Cannot remount %s read-only" :
116                         "%s busy - remounted read-only", m->device);
117        }
118
119        if (curstat) {
120            status = EXIT_FAILURE;
121            bb_perror_msg("Couldn't umount %s", zapit);
122        } else {
123            /* De-allocate the loop device.  This ioctl should be ignored on
124             * any non-loop block devices. */
125            if (ENABLE_FEATURE_MOUNT_LOOP && !(opt & OPT_DONTFREELOOP) && m)
126                del_loop(m->device);
127            if (ENABLE_FEATURE_MTAB_SUPPORT && !(opt & OPT_NO_MTAB) && m)
128                erase_mtab(m->dir);
129        }
130
131        // Find next matching mtab entry for -a or umount /dev
132        // Note this means that "umount /dev/blah" will unmount all instances
133        // of /dev/blah, not just the most recent.
134        while (m && (m = m->next))
135            if ((opt & OPT_ALL) || !strcmp(path,m->device))
136                break;
137    }
138
139    // Free mtab list if necessary
140
141    if (ENABLE_FEATURE_CLEAN_UP) {
142        while (mtl) {
143            m = mtl->next;
144            free(mtl->device);
145            free(mtl->dir);
146            free(mtl);
147            mtl=m;
148        }
149    }
150
151    return status;
152}
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