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Diffstat (limited to 'e2fsprogs/blkid/devno.c')
| -rw-r--r-- | e2fsprogs/blkid/devno.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/e2fsprogs/blkid/devno.c b/e2fsprogs/blkid/devno.c new file mode 100644 index 0000000..31aa52b --- /dev/null +++ b/e2fsprogs/blkid/devno.c @@ -0,0 +1,233 @@ +/* + * 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 <stdio.h> +#include <string.h> +#if HAVE_UNISTD_H +#include <unistd.h> +#endif +#include <stdlib.h> +#include <string.h> +#if HAVE_SYS_TYPES_H +#include <sys/types.h> +#endif +#if HAVE_SYS_STAT_H +#include <sys/stat.h> +#endif +#include <dirent.h> +#if HAVE_ERRNO_H +#include <errno.h> +#endif +#if HAVE_SYS_MKDEV_H +#include <sys/mkdev.h> +#endif + +#include "blkidP.h" + +struct dir_list { + char *name; + struct dir_list *next; +}; + +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); +} + +/* + * This function adds an entry to the directory list + */ +static void add_to_dirlist(const char *name, struct dir_list **list) +{ + struct dir_list *dp; + + dp = malloc(sizeof(struct dir_list)); + if (!dp) + return; + dp->name = blkid_strdup(name); + 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; +} + +static void scan_dir(char *dir_name, dev_t devno, struct dir_list **list, + char **devname) +{ + DIR *dir; + struct dirent *dp; + char path[1024]; + int dirlen; + struct stat st; + + if ((dir = opendir(dir_name)) == NULL) + return; + dirlen = strlen(dir_name) + 2; + while ((dp = readdir(dir)) != 0) { + if (dirlen + strlen(dp->d_name) >= sizeof(path)) + continue; + + if (dp->d_name[0] == '.' && + ((dp->d_name[1] == 0) || + ((dp->d_name[1] == '.') && (dp->d_name[2] == 0)))) + continue; + + sprintf(path, "%s/%s", dir_name, dp->d_name); + if (stat(path, &st) < 0) + continue; + + if (S_ISDIR(st.st_mode)) + add_to_dirlist(path, list); + else if (S_ISBLK(st.st_mode) && st.st_rdev == devno) { + *devname = blkid_strdup(path); + DBG(DEBUG_DEVNO, + printf("found 0x%Lx at %s (%p)\n", devno, + path, *devname)); + break; + } + } + closedir(dir); + return; +} + +/* Directories where we will try to search for device numbers */ +const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL }; + +/* + * This function finds the pathname to a block device with a given + * device number. It 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 = blkid_devdirs; *dir; dir++) + add_to_dirlist(*dir, &list); + + while (list) { + struct dir_list *current = list; + + list = list->next; + DBG(DEBUG_DEVNO, printf("directory %s\n", current->name)); + 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%04Lx as %s\n", devno, devname)); + } + + + return devname; +} + +#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_debug_mask = 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%04Lx\n", devno); + devname = blkid_devno_to_devname(devno); + if (devname) + free(devname); + return 0; +} +#endif |