| /* 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 source tree. |
| */ |
| |
| #include "libbb.h" |
| |
| /* #define DEBUGGING 1 */ |
| |
| #ifdef DEBUGGING |
| #define debug(...) do { printf(__VA_ARGS__); } while (0) |
| #else |
| #define debug(...) ((void)0) |
| #endif |
| |
| |
| /* 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; |
| |
| len = strlen(ap->devpath); |
| rem = DEVNAME_MAX-2 - len; |
| if (rem <= 0) |
| return NULL; |
| |
| dir = opendir(ap->devpath); |
| if (!dir) |
| 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; |
| } |
| |
| #define PROC_MOUNTINFO "/proc/self/mountinfo" |
| /* A major of zero indicates a non-device mount. Use the kernel's show_mountinfo(), |
| * exposed through /proc/self/mountinfo to lookup the device reference. */ |
| static char *find_device_in_mountinfo(struct arena *ap) |
| { |
| char line[1024]; |
| char *linePtr; |
| char *retpath = NULL; |
| |
| FILE *fp = fopen_for_read(PROC_MOUNTINFO); |
| if (!fp) |
| return NULL; |
| |
| debug("Looking for device %u:%u\n", major(ap->dev), minor(ap->dev)); |
| while (fgets(line, sizeof(line), fp)) { |
| int mnt_id, parent_mnt_id; |
| unsigned int major, minor; |
| char mnt_typename[1024], mnt_devname[1024]; |
| |
| linePtr = line; |
| if (sscanf(linePtr, "%i %i %u:%u", &mnt_id, &parent_mnt_id, &major, &minor) != 4) { |
| debug("Couldn't parse line: '%s'\n", line); |
| } else if ((linePtr = strstr(linePtr, " - ")) == NULL) { |
| debug("Couldn't find ' - ': '%s'\n", line); |
| } else if (sscanf(linePtr, " - %s %s ", mnt_typename, mnt_devname) != 2) { |
| debug("Couldn't parse line: '%s'\n", line); |
| } else if ((major(ap->dev) != major) || (minor(ap->dev) != minor)) { |
| debug("Non-matching device %u:%u --> %s\n", major, minor, mnt_devname); |
| } else { |
| debug("Found a match %u:%u --> %s\n", major, minor, mnt_devname); |
| retpath = xstrdup(mnt_devname); |
| break; |
| } |
| } |
| |
| fclose(fp); |
| |
| 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; |
| if (major(a.dev) != 0) { |
| strcpy(a.devpath, "/dev"); |
| return find_block_device_in_dir(&a); |
| } else { |
| return find_device_in_mountinfo(&a); |
| } |
| } |