mirror of
https://github.com/topjohnwu/ndk-busybox.git
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76 lines
1.7 KiB
C
76 lines
1.7 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Utility routines.
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*
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* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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/* Find block device /dev/XXX which contains specified file
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* We handle /dev/dir/dir/dir too, at a cost of ~80 more bytes code */
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/* Do not reallocate all this stuff on each recursion */
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enum { DEVNAME_MAX = 256 };
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struct arena {
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struct stat st;
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dev_t dev;
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/* Was PATH_MAX, but we recurse _/dev_. We can assume
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* people are not crazy enough to have mega-deep tree there */
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char devpath[DEVNAME_MAX];
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};
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static char *find_block_device_in_dir(struct arena *ap)
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{
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DIR *dir;
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struct dirent *entry;
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char *retpath = NULL;
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int len, rem;
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len = strlen(ap->devpath);
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rem = DEVNAME_MAX-2 - len;
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if (rem <= 0)
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return NULL;
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dir = opendir(ap->devpath);
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if (!dir)
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return NULL;
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ap->devpath[len++] = '/';
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while ((entry = readdir(dir)) != NULL) {
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safe_strncpy(ap->devpath + len, entry->d_name, rem);
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/* lstat: do not follow links */
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if (lstat(ap->devpath, &ap->st) != 0)
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continue;
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if (S_ISBLK(ap->st.st_mode) && ap->st.st_rdev == ap->dev) {
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retpath = xstrdup(ap->devpath);
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break;
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}
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if (S_ISDIR(ap->st.st_mode)) {
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/* Do not recurse for '.' and '..' */
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if (DOT_OR_DOTDOT(entry->d_name))
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continue;
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retpath = find_block_device_in_dir(ap);
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if (retpath)
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break;
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}
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}
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closedir(dir);
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return retpath;
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}
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char* FAST_FUNC find_block_device(const char *path)
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{
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struct arena a;
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if (stat(path, &a.st) != 0)
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return NULL;
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a.dev = S_ISBLK(a.st.st_mode) ? a.st.st_rdev : a.st.st_dev;
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strcpy(a.devpath, "/dev");
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return find_block_device_in_dir(&a);
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}
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