volume identification: abolish /proc/partitions and /proc/cdroms

scanning. It does not catch volume managers and such.
Adding even more cruft is bad, so I decided to simply
scan /dev/* for any block devices. See how much better
it finds devices now:

# ./busybox_old blkid
/dev/sda1: LABEL="/boot" UUID="7931e231-dcb4-4b6d-9301-f7354ae24061"
/dev/dm-0: LABEL="Fedora-9-Live-x8" UUID="bb491e1e-1145-4f5b-b0ab-cbd2baf4f15a"
/dev/dm-1: UUID="edc2a920-ef83-437e-ba64-d3b6dc851267"
/dev/sdb1: UUID="6F84-ED0F"

# ./busybox blkid
/dev/sdb1: UUID="6F84-ED0F"
/dev/root: LABEL="Fedora-9-Live-x8" UUID="bb491e1e-1145-4f5b-b0ab-cbd2baf4f15a"
/dev/dm-1: UUID="edc2a920-ef83-437e-ba64-d3b6dc851267"
/dev/dm-0: LABEL="Fedora-9-Live-x8" UUID="bb491e1e-1145-4f5b-b0ab-cbd2baf4f15a"
/dev/sda1: LABEL="/boot" UUID="7931e231-dcb4-4b6d-9301-f7354ae24061"
/dev/mapper/VolGroup00-LogVol01: UUID="edc2a920-ef83-437e-ba64-d3b6dc851267"
/dev/mapper/VolGroup00-LogVol00: LABEL="Fedora-9-Live-x8" UUID="bb491e1e-1145-4f5b-b0ab-cbd2baf4f15a"

function                                             old     new   delta
static.drive_name_string                              12       -     -12
append_mount_options                                 205     190     -15
volume_id_open_node                                   37      18     -19
uuidcache_check_device                               485     257    -228
uuidcache_init                                       637      36    -601
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 0/4 up/down: 0/-875)           Total: -875 bytes
   text    data     bss     dec     hex filename
 792218     592    6648  799458   c32e2 busybox_old
 791260     592    6648  798500   c2f24 busybox_unstripped

3 files changed, 33 insertions, 225 deletions

diff --git a/util-linux/volume_id/get_devname.c b/util-linux/volume_id/get_devname.c
index 83c085650..e99c15b02 100644
--- a/util-linux/volume_id/get_devname.c
+++ b/util-linux/volume_id/get_devname.c
@@ -22,38 +22,23 @@ static struct uuidCache_s {
 
 /* Returns !0 on error.
  * Otherwise, returns malloc'ed strings for label and uuid
- * (and they can't be NULL, although they can be "") */
-#if !ENABLE_FEATURE_VOLUMEID_ISO9660
-#define get_label_uuid(device, label, uuid, iso_only) \
-        get_label_uuid(device, label, uuid)
-#endif
+ * (and they can't be NULL, although they can be "").
+ * NB: closes fd. */
 static int
-get_label_uuid(const char *device, char **label, char **uuid, int iso_only)
+get_label_uuid(int fd, char **label, char **uuid)
 {
         int rv = 1;
         uint64_t size;
         struct volume_id *vid;
 
-        vid = volume_id_open_node(device);
-        if (!vid)
-                return rv;
+        /* fd is owned by vid now */
+        vid = volume_id_open_node(fd);
 
-        if (ioctl(vid->fd, BLKGETSIZE64, &size) != 0)
+        if (ioctl(/*vid->*/fd, BLKGETSIZE64, &size) != 0)
                 size = 0;
 
-#if ENABLE_FEATURE_VOLUMEID_ISO9660
-        if ((iso_only ?
-             volume_id_probe_iso9660(vid, 0) :
-             volume_id_probe_all(vid, 0, size)
-            ) != 0
-        ) {
-                goto ret;
-        }
-#else
-        if (volume_id_probe_all(vid, 0, size) != 0) {
+        if (volume_id_probe_all(vid, 0, size) != 0)
                 goto ret;
-        }
-#endif
 
         if (vid->label[0] != '\0' || vid->uuid[0] != '\0') {
                 *label = xstrndup(vid->label, sizeof(vid->label));
@@ -62,7 +47,7 @@ get_label_uuid(const char *device, char **label, char **uuid, int iso_only)
                 rv = 0;
         }
  ret:
-        free_volume_id(vid);
+        free_volume_id(vid); /* also closes fd */
         return rv;
 }
 
@@ -91,204 +76,29 @@ uuidcache_addentry(char *device, /*int major, int minor,*/ char *label, char *uu
 /* If get_label_uuid() on device_name returns success,
  * add a cache entry for this device.
  * If device node does not exist, it will be temporarily created. */
-#if !ENABLE_FEATURE_VOLUMEID_ISO9660
-#define uuidcache_check_device(device_name, ma, mi, iso_only) \
-        uuidcache_check_device(device_name, ma, mi)
-#endif
-static void
-uuidcache_check_device(const char *device_name, int ma, int mi, int iso_only)
+static int FAST_FUNC
+uuidcache_check_device(const char *device,
+                struct stat *statbuf,
+                void *userData UNUSED_PARAM,
+                int depth UNUSED_PARAM)
 {
-        char *device, *last_slash;
-        char *uuid, *label;
-        char *ptr;
-        int must_remove = 0;
-        int added = 0;
-
-        last_slash = NULL;
-        device = xasprintf("/dev/%s", device_name);
-        if (access(device, F_OK) != 0) {
-                /* device does not exist, temporarily create */
-                int slash_cnt = 0;
-
-                if ((ma | mi) < 0)
-                        goto ret; /* we don't know major:minor! */
-
-                ptr = device;
-                while (*ptr)
-                        if (*ptr++ == '/')
-                                slash_cnt++;
-                if (slash_cnt > 2) {
-// BUG: handles only slash_cnt == 3 case
-                        last_slash = strrchr(device, '/');
-                        *last_slash = '\0';
-                        if (mkdir(device, 0644)) {
-                                bb_perror_msg("can't create directory %s", device);
-                                *last_slash = '/';
-                                last_slash = NULL; /* prevents rmdir */
-                        } else {
-                                *last_slash = '/';
-                        }
-                }
-                mknod(device, S_IFBLK | 0600, makedev(ma, mi));
-                must_remove = 1;
-        }
+        char *uuid = uuid; /* for compiler */
+        char *label = label;
+        int fd;
 
-        uuid = NULL;
-        label = NULL;
-        if (get_label_uuid(device, &label, &uuid, iso_only) == 0) {
-                uuidcache_addentry(device, /*ma, mi,*/ label, uuid);
-                /* "device" is owned by cache now, don't free */
-                added = 1;
-        }
+        if (!S_ISBLK(statbuf->st_mode))
+                return TRUE;
 
-        if (must_remove)
-                unlink(device);
-        if (last_slash) {
-                *last_slash = '\0';
-                rmdir(device);
-        }
- ret:
-        if (!added)
-                free(device);
-}
+        fd = open(device, O_RDONLY);
+        if (fd < 0)
+                return TRUE;
 
-/* Run uuidcache_check_device() for every device mentioned
- * in /proc/partitions */
-static void
-uuidcache_init_partitions(void)
-{
-        char line[100];
-        int ma, mi;
-        unsigned long long sz;
-        FILE *procpt;
-        int firstPass;
-        int handleOnFirst;
-        char *chptr;
-
-        procpt = xfopen_for_read("/proc/partitions");
-/*
-# cat /proc/partitions
-major minor  #blocks  name
-
-   8     0  293036184 sda
-   8     1    6835626 sda1
-   8     2          1 sda2
-   8     5     979933 sda5
-   8     6   15623181 sda6
-   8     7   97659103 sda7
-   8     8  171935631 sda8
-*/
-        for (firstPass = 1; firstPass >= 0; firstPass--) {
-                fseek(procpt, 0, SEEK_SET);
-
-                while (fgets(line, sizeof(line), procpt)) {
-                        /* The original version of this code used sscanf, but
-                           diet's sscanf is quite limited */
-                        chptr = line;
-                        if (*chptr != ' ') continue;
-                        chptr = skip_whitespace(chptr);
-
-                        ma = bb_strtou(chptr, &chptr, 0);
-                        if (ma < 0) continue;
-                        chptr = skip_whitespace(chptr);
-
-                        mi = bb_strtou(chptr, &chptr, 0);
-                        if (mi < 0) continue;
-                        chptr = skip_whitespace(chptr);
-
-                        sz = bb_strtoull(chptr, &chptr, 0);
-                        if ((long long)sz == -1LL) continue;
-                        chptr = skip_whitespace(chptr);
-
-                        /* skip extended partitions (heuristic: size 1) */
-                        if (sz == 1)
-                                continue;
-
-                        *strchrnul(chptr, '\n') = '\0';
-                        /* now chptr => device name */
-                        dbg("/proc/partitions: maj:%d min:%d sz:%llu name:'%s'",
-                                                ma, mi, sz, chptr);
-                        if (!chptr[0])
-                                continue;
-
-                        /* look only at md devices on first pass */
-                        handleOnFirst = (chptr[0] == 'm' && chptr[1] == 'd');
-                        if (firstPass != handleOnFirst)
-                                continue;
-
-                        /* heuristic: partition name ends in a digit */
-                        if (isdigit(chptr[strlen(chptr) - 1])) {
-                                uuidcache_check_device(chptr, ma, mi, 0);
-                        }
-                }
+        /* get_label_uuid() closes fd in all cases (success & failure) */
+        if (get_label_uuid(fd, &label, &uuid) == 0) {
+                /* uuidcache_addentry() takes ownership of all three params */
+                uuidcache_addentry(xstrdup(device), /*ma, mi,*/ label, uuid);
         }
-
-        fclose(procpt);
-}
-
-static void
-dev_get_major_minor(char *device_name, int *major, int *minor)
-{
-        char dev[16];
-        char *dev_path;
-        char *colon;
-        int sz;
-
-        dev_path = xasprintf("/sys/block/%s/dev", device_name);
-        sz = open_read_close(dev_path, dev, sizeof(dev) - 1);
-        if (sz < 0)
-                goto ret;
-        dev[sz] = '\0';
-
-        colon = strchr(dev, ':');
-        if (!colon)
-                goto ret;
-        *major = bb_strtou(dev, NULL, 10);
-        *minor = bb_strtou(colon + 1, NULL, 10);
-
- ret:
-        free(dev_path);
-        return;
-}
-
-static void
-uuidcache_init_cdroms(void)
-{
-#define PROC_CDROMS "/proc/sys/dev/cdrom/info"
-        char line[100];
-        int ma, mi;
-        FILE *proccd;
-
-        proccd = fopen_for_read(PROC_CDROMS);
-        if (!proccd) {
-//              static smallint warn = 0;
-//              if (!warn) {
-//                      warn = 1;
-//                      bb_error_msg("can't open %s, UUID and LABEL "
-//                              "conversion cannot be done for CD-Roms",
-//                              PROC_CDROMS);
-//              }
-                return;
-        }
-
-        while (fgets(line, sizeof(line), proccd)) {
-                static const char drive_name_string[] ALIGN1 = "drive name:";
-
-                if (strncmp(line, drive_name_string, sizeof(drive_name_string) - 1) == 0) {
-                        char *device_name;
-
-                        device_name = strtok(skip_whitespace(line + sizeof(drive_name_string) - 1), " \t\n");
-                        while (device_name && device_name[0]) {
-                                ma = mi = -1;
-                                dev_get_major_minor(device_name, &ma, &mi);
-                                uuidcache_check_device(device_name, ma, mi, 1);
-                                device_name = strtok(NULL, " \t\n");
-                        }
-                        break;
-                }
-        }
-
-        fclose(proccd);
+        return TRUE;
 }
 
 static void
@@ -297,8 +107,11 @@ uuidcache_init(void)
         if (uuidCache)
                 return;
 
-        uuidcache_init_partitions();
-        uuidcache_init_cdroms();
+        recursive_action("/dev", ACTION_RECURSE,
+                uuidcache_check_device, /* file_action */
+                NULL, /* dir_action */
+                NULL, /* userData */
+                0 /* depth */);
 }
 
 #define UUID   1
diff --git a/util-linux/volume_id/volume_id.c b/util-linux/volume_id/volume_id.c
index d81f3f94c..6852a8203 100644
--- a/util-linux/volume_id/volume_id.c
+++ b/util-linux/volume_id/volume_id.c
@@ -190,19 +190,14 @@ int volume_id_probe_all(struct volume_id *id, uint64_t off, uint64_t size)
 }
 
 /* open volume by device node */
-struct volume_id *volume_id_open_node(const char *path)
+struct volume_id *volume_id_open_node(int fd)
 {
         struct volume_id *id;
-        int fd;
 
-        fd = open(path, O_RDONLY);
-        if (fd < 0)
-                return NULL;
         id = xzalloc(sizeof(struct volume_id));
         id->fd = fd;
         ///* close fd on device close */
         //id->fd_close = 1;
-
         return id;
 }
 
diff --git a/util-linux/volume_id/volume_id_internal.h b/util-linux/volume_id/volume_id_internal.h
index 6619d2c6e..075ddb344 100644
--- a/util-linux/volume_id/volume_id_internal.h
+++ b/util-linux/volume_id/volume_id_internal.h
@@ -87,7 +87,7 @@ struct volume_id {
 //      int             fd_close:1;
 };
 
-struct volume_id *volume_id_open_node(const char *path);
+struct volume_id *volume_id_open_node(int fd);
 int volume_id_probe_all(struct volume_id *id, uint64_t off, uint64_t size);
 void free_volume_id(struct volume_id *id);