| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Utility routines.
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| 4 | *
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| 5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 8 | */
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| 9 |
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| 10 | #include "libbb.h"
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| 11 |
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| 12 | /* Find block device /dev/XXX which contains specified file
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| 13 | * We handle /dev/dir/dir/dir too, at a cost of ~80 more bytes code */
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| 14 |
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| 15 | /* Do not reallocate all this stuff on each recursion */
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| 16 | enum { DEVNAME_MAX = 256 };
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| 17 | struct arena {
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| 18 | struct stat st;
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| 19 | dev_t dev;
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| 20 | /* Was PATH_MAX, but we recurse _/dev_. We can assume
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| 21 | * people are not crazy enough to have mega-deep tree there */
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| 22 | char devpath[DEVNAME_MAX];
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| 23 | };
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| 24 |
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| 25 | static char *find_block_device_in_dir(struct arena *ap)
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| 26 | {
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| 27 | DIR *dir;
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| 28 | struct dirent *entry;
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| 29 | char *retpath = NULL;
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| 30 | int len, rem;
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| 31 |
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| 32 | dir = opendir(ap->devpath);
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| 33 | if (!dir)
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| 34 | return NULL;
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| 35 |
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| 36 | len = strlen(ap->devpath);
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| 37 | rem = DEVNAME_MAX-2 - len;
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| 38 | if (rem <= 0)
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| 39 | return NULL;
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| 40 | ap->devpath[len++] = '/';
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| 41 |
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| 42 | while ((entry = readdir(dir)) != NULL) {
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| 43 | safe_strncpy(ap->devpath + len, entry->d_name, rem);
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| 44 | /* lstat: do not follow links */
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| 45 | if (lstat(ap->devpath, &ap->st) != 0)
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| 46 | continue;
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| 47 | if (S_ISBLK(ap->st.st_mode) && ap->st.st_rdev == ap->dev) {
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| 48 | retpath = xstrdup(ap->devpath);
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| 49 | break;
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| 50 | }
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| 51 | if (S_ISDIR(ap->st.st_mode)) {
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| 52 | /* Do not recurse for '.' and '..' */
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| 53 | if (DOT_OR_DOTDOT(entry->d_name))
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| 54 | continue;
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| 55 | retpath = find_block_device_in_dir(ap);
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| 56 | if (retpath)
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| 57 | break;
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| 58 | }
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| 59 | }
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| 60 | closedir(dir);
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| 61 |
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| 62 | return retpath;
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| 63 | }
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| 64 |
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| 65 | char* FAST_FUNC find_block_device(const char *path)
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| 66 | {
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| 67 | struct arena a;
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| 68 |
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| 69 | if (stat(path, &a.st) != 0)
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| 70 | return NULL;
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| 71 | a.dev = S_ISBLK(a.st.st_mode) ? a.st.st_rdev : a.st.st_dev;
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| 72 | strcpy(a.devpath, "/dev");
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| 73 | return find_block_device_in_dir(&a);
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| 74 | }
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