diff options
Diffstat (limited to 'libbb/find_root_device.c')
-rw-r--r-- | libbb/find_root_device.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/libbb/find_root_device.c b/libbb/find_root_device.c new file mode 100644 index 0000000..ca46bf5 --- /dev/null +++ b/libbb/find_root_device.c @@ -0,0 +1,74 @@ +/* vi: set sw=4 ts=4: */ +/* + * Utility routines. + * + * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org> + * + * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. + */ + +#include "libbb.h" + +/* Find block device /dev/XXX which contains specified file + * We handle /dev/dir/dir/dir too, at a cost of ~80 more bytes code */ + +/* Do not reallocate all this stuff on each recursion */ +enum { DEVNAME_MAX = 256 }; +struct arena { + struct stat st; + dev_t dev; + /* Was PATH_MAX, but we recurse _/dev_. We can assume + * people are not crazy enough to have mega-deep tree there */ + char devpath[DEVNAME_MAX]; +}; + +static char *find_block_device_in_dir(struct arena *ap) +{ + DIR *dir; + struct dirent *entry; + char *retpath = NULL; + int len, rem; + + dir = opendir(ap->devpath); + if (!dir) + return NULL; + + len = strlen(ap->devpath); + rem = DEVNAME_MAX-2 - len; + if (rem <= 0) + return NULL; + ap->devpath[len++] = '/'; + + while ((entry = readdir(dir)) != NULL) { + safe_strncpy(ap->devpath + len, entry->d_name, rem); + /* lstat: do not follow links */ + if (lstat(ap->devpath, &ap->st) != 0) + continue; + if (S_ISBLK(ap->st.st_mode) && ap->st.st_rdev == ap->dev) { + retpath = xstrdup(ap->devpath); + break; + } + if (S_ISDIR(ap->st.st_mode)) { + /* Do not recurse for '.' and '..' */ + if (DOT_OR_DOTDOT(entry->d_name)) + continue; + retpath = find_block_device_in_dir(ap); + if (retpath) + break; + } + } + closedir(dir); + + return retpath; +} + +char* FAST_FUNC find_block_device(const char *path) +{ + struct arena a; + + if (stat(path, &a.st) != 0) + return NULL; + a.dev = S_ISBLK(a.st.st_mode) ? a.st.st_rdev : a.st.st_dev; + strcpy(a.devpath, "/dev"); + return find_block_device_in_dir(&a); +} |