/* * devno.c - find a particular device by its device number (major/minor) * * Copyright (C) 2000, 2001, 2003 Theodore Ts'o * Copyright (C) 2001 Andreas Dilger * * %Begin-Header% * This file may be redistributed under the terms of the * GNU Lesser General Public License. * %End-Header% */ #include #include #if HAVE_UNISTD_H #include #endif #include #if HAVE_SYS_TYPES_H #include #endif #if HAVE_SYS_STAT_H #include #endif #include #if HAVE_ERRNO_H #include #endif #if HAVE_SYS_MKDEV_H #include #endif #include #include #include "blkidP.h" #include "pathnames.h" char *blkid_strndup(const char *s, int length) { char *ret; if (!s) return NULL; if (!length) length = strlen(s); ret = malloc(length + 1); if (ret) { strncpy(ret, s, length); ret[length] = '\0'; } return ret; } char *blkid_strdup(const char *s) { return blkid_strndup(s, 0); } char *blkid_strconcat(const char *a, const char *b, const char *c) { char *res, *p; size_t len, al, bl, cl; al = a ? strlen(a) : 0; bl = b ? strlen(b) : 0; cl = c ? strlen(c) : 0; len = al + bl + cl; if (!len) return NULL; p = res = malloc(len + 1); if (!res) return NULL; if (al) { memcpy(p, a, al); p += al; } if (bl) { memcpy(p, b, bl); p += bl; } if (cl) { memcpy(p, c, cl); p += cl; } *p = '\0'; return res; } int blkid_fstatat(DIR *dir, const char *dirname, const char *filename, struct stat *st, int nofollow) { #ifdef HAVE_FSTATAT return fstatat(dirfd(dir), filename, st, nofollow ? AT_SYMLINK_NOFOLLOW : 0); #else char path[PATH_MAX]; int len; len = snprintf(path, sizeof(path), "%s/%s", dirname, filename); if (len < 0 || len + 1 > sizeof(path)) return -1; return nofollow ? lstat(path, st) : stat(path, st); #endif } int blkid_openat(DIR *dir, const char *dirname, const char *filename, int flags) { #ifdef HAVE_FSTATAT return openat(dirfd(dir), filename, flags); #else char path[PATH_MAX]; int len; len = snprintf(path, sizeof(path), "%s/%s", dirname, filename); if (len < 0 || len + 1 > sizeof(path)) return -1; return open(path, flags); #endif } /* * This function adds an entry to the directory list */ static void add_to_dirlist(const char *dir, const char *subdir, struct dir_list **list) { struct dir_list *dp; dp = malloc(sizeof(struct dir_list)); if (!dp) return; dp->name = subdir ? blkid_strconcat(dir, "/", subdir) : blkid_strdup(dir); if (!dp->name) { free(dp); return; } dp->next = *list; *list = dp; } /* * This function frees a directory list */ static void free_dirlist(struct dir_list **list) { struct dir_list *dp, *next; for (dp = *list; dp; dp = next) { next = dp->next; free(dp->name); free(dp); } *list = NULL; } void blkid__scan_dir(char *dirname, dev_t devno, struct dir_list **list, char **devname) { DIR *dir; struct dirent *dp; struct stat st; if ((dir = opendir(dirname)) == NULL) return; while ((dp = readdir(dir)) != 0) { #ifdef _DIRENT_HAVE_D_TYPE if (dp->d_type != DT_UNKNOWN && dp->d_type != DT_BLK && dp->d_type != DT_LNK && dp->d_type != DT_DIR) continue; #endif if (dp->d_name[0] == '.' && ((dp->d_name[1] == 0) || ((dp->d_name[1] == '.') && (dp->d_name[2] == 0)))) continue; if (blkid_fstatat(dir, dirname, dp->d_name, &st, 0)) continue; if (S_ISBLK(st.st_mode) && st.st_rdev == devno) { *devname = blkid_strconcat(dirname, "/", dp->d_name); DBG(DEBUG_DEVNO, printf("found 0x%llx at %s\n", (long long)devno, *devname)); break; } if (!list || !S_ISDIR(st.st_mode)) continue; /* add subdirectory (but not symlink) to the list */ #ifdef _DIRENT_HAVE_D_TYPE if (dp->d_type == DT_LNK) continue; if (dp->d_type == DT_UNKNOWN) #endif { if (blkid_fstatat(dir, dirname, dp->d_name, &st, 1) || !S_ISDIR(st.st_mode)) continue; /* symlink or lstat() failed */ } if (strcmp(".udev", dp->d_name) == 0) /* udev private direcory is huge and uninteresting */ continue; add_to_dirlist(dirname, dp->d_name, list); } closedir(dir); return; } /* Directories where we will try to search for device numbers */ static const char *devdirs[] = { "/devices", "/devfs", "/dev", NULL }; /** * SECTION: misc * @title: Miscellaneous utils * @short_description: mix of various utils for low-level and high-level API */ /** * blkid_devno_to_devname: * @devno: device number * * This function finds the pathname to a block device with a given * device number. * * Returns: a pointer to allocated memory to the pathname on success, * and NULL on failure. */ char *blkid_devno_to_devname(dev_t devno) { struct dir_list *list = NULL, *new_list = NULL; char *devname = NULL; const char **dir; /* * Add the starting directories to search in reverse order of * importance, since we are using a stack... */ for (dir = devdirs; *dir; dir++) add_to_dirlist(*dir, NULL, &list); while (list) { struct dir_list *current = list; list = list->next; DBG(DEBUG_DEVNO, printf("directory %s\n", current->name)); blkid__scan_dir(current->name, devno, &new_list, &devname); free(current->name); free(current); if (devname) break; /* * If we're done checking at this level, descend to * the next level of subdirectories. (breadth-first) */ if (list == NULL) { list = new_list; new_list = NULL; } } free_dirlist(&list); free_dirlist(&new_list); if (!devname) { DBG(DEBUG_DEVNO, printf("blkid: couldn't find devno 0x%04lx\n", (unsigned long) devno)); } else { DBG(DEBUG_DEVNO, printf("found devno 0x%04llx as %s\n", (long long)devno, devname)); } return devname; } /* returns basename and keeps dirname in the @path */ static char *stripoff_last_component(char *path) { char *p = strrchr(path, '/'); if (!p) return NULL; *p = '\0'; return ++p; } /** * blkid_devno_to_wholedisk: * @dev: device number * @diskname: buffer to return diskname (or NULL) * @len: diskname buffer size (or 0) * @diskdevno: pointer to returns devno of entire disk (or NULL) * * This function uses sysfs to convert the @devno device number to the *name* * of the whole disk. The function DOES NOT return full device name. The @dev * argument could be partition or whole disk -- both is converted. * * For example: sda1, 0x0801 --> sda, 0x0800 * * For conversion to the full disk *path* use blkid_devno_to_devname(), for * example: * * * * * dev_t dev = 0x0801, disk; // sda1 = 8:1 * char *diskpath, diskname[32]; * * blkid_devno_to_wholedisk(dev, diskname, sizeof(diskname), &disk); * diskpath = blkid_devno_to_devname(disk); * * // print "0x0801: sda, /dev/sda, 8:0 * printf("0x%x: %s, %s, %d:%d\n", * dev, diskname, diskpath, major(disk), minor(disk)); * * free(diskpath); * * * * * Returns: 0 on success or -1 in case of error. */ int blkid_devno_to_wholedisk(dev_t dev, char *diskname, size_t len, dev_t *diskdevno) { char path[PATH_MAX]; char linkpath[PATH_MAX]; struct stat info; char *name; int rc, linklen; if (!dev) goto err; /* check if dev is a partition */ rc = snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/partition", major(dev), minor(dev)); if (rc < 0 || rc + 1 > sizeof(path)) goto err; rc = stat(path, &info); /* 'rc == 0' means partitioned dev */ /* aka dirname (remove "/partition" from the path*/ stripoff_last_component(path); /* * Unpartitioned device: * - readlink /sys/dev/block/8:0 = ../../block/sda * - basename ../../block/sda = sda * * Partitioned device: * - readlink /sys/dev/block/8:1 = ../../block/sda/sda1 * - dirname ../../block/sda/sda1 = ../../block/sda * - basename ../../block/sda = sda */ linklen = readlink(path, linkpath, sizeof(linkpath)); if (linklen < 0) goto err; linkpath[linklen] = '\0'; if (rc == 0) /* partitioned device */ stripoff_last_component(linkpath); /* dirname */ name = stripoff_last_component(linkpath); /* basename */ if (!name) goto err; if (diskname && len) { strncpy(diskname, name, len); diskname[len - 1] = '\0'; } if (diskdevno) { int maj, min; FILE *f; /* read wholedisk devno */ rc = snprintf(path, sizeof(path), "/sys/block/%s/dev", name); if (rc < 0 || rc + 1 > sizeof(path)) goto err; f = fopen(path, "r"); if (!f) goto err; rc = fscanf(f, "%d:%d", &maj, &min); fclose(f); if (rc != 2) goto err; *diskdevno = makedev(maj, min); } DBG(DEBUG_DEVNO, printf("found entire diskname for devno 0x%04llx as %s\n", (long long) dev, name)); return 0; err: DBG(DEBUG_DEVNO, printf("failed to convert 0x%04llx to wholedisk name, errno=%d\n", (long long) dev, errno)); return -1; } /* * Returns 1 if the @major number is associated with @drvname. */ int blkid_driver_has_major(const char *drvname, int major) { FILE *f; char buf[128]; int match = 0; f = fopen(_PATH_PROC_DEVICES, "r"); if (!f) return 0; while (fgets(buf, sizeof(buf), f)) { /* skip to block dev section */ if (strncmp("Block devices:\n", buf, sizeof(buf)) == 0) break; } while (fgets(buf, sizeof(buf), f)) { unsigned int maj; char name[64]; if (sscanf(buf, "%u %64[^\n ]", &maj, name) != 2) continue; if (maj == major && strcmp(name, drvname) == 0) { match = 1; break; } } fclose(f); DBG(DEBUG_DEVNO, printf("major %d %s associated with '%s' driver\n", major, match ? "is" : "is NOT", drvname)); return match; } static char *mk_devno_attribute_path(char *buf, size_t buflen, dev_t devno, const char *attr) { int len = snprintf(buf, buflen, "/sys/dev/block/%d:%d/%s", major(devno), minor(devno), attr); if (len < 0 || len + 1 > buflen) return NULL; return buf; } int blkid_devno_has_attribute(dev_t devno, const char *attribute) { char path[PATH_MAX]; struct stat info; if (!mk_devno_attribute_path(path, sizeof(path), devno, attribute)) return 0; if (stat(path, &info) == 0) return 1; return 0; } int blkid_devno_get_attribute(dev_t devno, const char *attribute, uint64_t *result) { FILE *f; char path[PATH_MAX]; int rc = 0; if (!mk_devno_attribute_path(path, sizeof(path), devno, attribute)) return -1; f = fopen(path, "r"); if (f) { rc = fscanf(f, "%" SCNu64, result); fclose(f); } return rc == 1 ? 0 : -1; } #ifdef TEST_PROGRAM int main(int argc, char** argv) { char *devname, *tmp; int major, minor; dev_t devno; const char *errmsg = "Couldn't parse %s: %s\n"; blkid_init_debug(DEBUG_ALL); if ((argc != 2) && (argc != 3)) { fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n" "Resolve a device number to a device name\n", argv[0], argv[0]); exit(1); } if (argc == 2) { devno = strtoul(argv[1], &tmp, 0); if (*tmp) { fprintf(stderr, errmsg, "device number", argv[1]); exit(1); } } else { major = strtoul(argv[1], &tmp, 0); if (*tmp) { fprintf(stderr, errmsg, "major number", argv[1]); exit(1); } minor = strtoul(argv[2], &tmp, 0); if (*tmp) { fprintf(stderr, errmsg, "minor number", argv[2]); exit(1); } devno = makedev(major, minor); } printf("Looking for device 0x%04llx\n", (long long)devno); devname = blkid_devno_to_devname(devno); free(devname); return 0; } #endif