ChangeLog, Makefile.in, ext2fs.h, finddev.c:

finddev.c, ext2fs.h, Makefile.in: Add new file, finddev.c, which
  	provides the function ext2fs_find_block_device().  This function
  	returns the pathname to a block device, given its device number.

lib/ext2fs/ChangeLog

@@ -1,3 +1,10 @@
+2000-08-19    <tytso@valinux.com>
+
+	* finddev.c, ext2fs.h, Makefile.in: Add new file, finddev.c, which
+		provides the function ext2fs_find_block_device().  This
+		function returns the pathname to a block device, given its
+		device number.
+
 2000-07-13    <tytso@valinux.com>
 
 	* Release of E2fsprogs 1.19

lib/ext2fs/Makefile.in

@@ -27,6 +27,7 @@ OBJS= ext2_err.o \
 	dupfs.o \
 	expanddir.o \
 	fileio.o \
+	finddev.o \
 	freefs.o \
 	get_pathname.o \
 	getsize.o \
@@ -75,6 +76,7 @@ SRCS= ext2_err.c \
 	$(srcdir)/dupfs.c \
 	$(srcdir)/expanddir.c \
 	$(srcdir)/fileio.c \
+	$(srcidr)/finddev.c \
 	$(srcdir)/freefs.c \
 	$(srcdir)/get_pathname.c \
 	$(srcdir)/getsize.c \

lib/ext2fs/ext2fs.h

@@ -708,6 +708,9 @@ extern errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
 extern ext2_off_t ext2fs_file_get_size(ext2_file_t file);
 extern errcode_t ext2fs_file_set_size(ext2_file_t file, ext2_off_t size);
 
+/* finddev.c */
+extern char *ext2fs_find_block_device(dev_t device);
+
 /* freefs.c */
 extern void ext2fs_free(ext2_filsys fs);
 extern void ext2fs_free_generic_bitmap(ext2fs_inode_bitmap bitmap);

lib/ext2fs/finddev.c

@@ -0,0 +1,209 @@
+/*
+ * finddev.c -- this routine attempts to find a particular device in
+ * 	/dev
+ * 
+ * Copyright (C) 2000 Theodore Ts'o.
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU 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
+
+struct dir_list {
+	char	*name;
+	struct dir_list *next;
+};
+
+#ifdef sun
+#define DEVDIR	"/devices"
+#else
+#define DEVDIR	"/dev"
+#endif
+
+/*
+ * This function adds an entry to the directory list
+ */
+static void add_to_dirlist(char *name, struct dir_list **list)
+{
+	struct dir_list *dp;
+
+	dp = malloc(sizeof(struct dir_list));
+	if (!dp)
+		return;
+	dp->name = malloc(strlen(name)+1);
+	if (!dp->name) {
+		free(dp);
+		return;
+	}
+	strcpy(dp->name, name);
+	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 = 0;
+}
+
+static int scan_dir(char *dirname, dev_t device, struct dir_list **list,
+		    char **ret_path)
+{
+	DIR	*dir;
+	struct dirent *dp;
+	char	path[1024], *cp;
+	int	dirlen;
+	struct stat st;
+
+	dirlen = strlen(dirname);
+	if ((dir = opendir(dirname)) == NULL)
+		return errno;
+	dp = readdir(dir);
+	while (dp) {
+		if (dirlen + strlen(dp->d_name) + 2 >= sizeof(path))
+			goto skip_to_next;
+		if (dp->d_name[0] == '.' &&
+		    ((dp->d_name[1] == 0) ||
+		     (dp->d_name[1] == '.') && (dp->d_name[2] == 0)))
+			goto skip_to_next;
+		sprintf(path, "%s/%s", dirname, dp->d_name);
+		if (stat(path, &st) < 0)
+			continue;
+		if (S_ISDIR(st.st_mode))
+			add_to_dirlist(path, list);
+		if (S_ISBLK(st.st_mode) && st.st_rdev == device) {
+			cp = malloc(strlen(path)+1);
+			if (!cp)
+				return ENOMEM;
+			strcpy(cp, path);
+			*ret_path = cp;
+			return 0;
+		}
+	skip_to_next:
+		dp = readdir(dir);
+	}
+	closedir(dir);
+	return 0;
+}
+
+/*
+ * 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 *ext2fs_find_block_device(dev_t device)
+{
+	struct dir_list *list = 0, *new_list = 0;
+	struct dir_list *current;
+	char	*ret_path = 0;
+
+	/*
+	 * Add the starting directories to search...
+	 */
+	add_to_dirlist("/devices", &list);
+	add_to_dirlist("/devfs", &list);
+	add_to_dirlist("/dev", &list);
+	
+	while (list) {
+		current = list;
+		list = list->next;
+#ifdef DEBUG
+		printf("Scanning directory %s\n", current->name);
+#endif
+		scan_dir(current->name, device, &new_list, &ret_path);
+		free(current->name);
+		free(current);
+		if (ret_path)
+			break;
+		/*
+		 * If we're done checking at this level, descend to
+		 * the next level of subdirectories. (breadth-first)
+		 */
+		if (list == 0) {
+			list = new_list;
+			new_list = 0;
+		}
+	}
+found_it:
+	free_dirlist(&list);
+	free_dirlist(&new_list);
+	return ret_path;
+}
+
+	
+#ifdef DEBUG
+int main(int argc, char** argv)
+{
+	char	*devname, *tmp;
+	int	major, minor;
+	dev_t	device;
+	const char *errmsg = "Couldn't parse %s: %s\n";
+
+	if ((argc != 2) && (argc != 3)) {
+		fprintf(stderr, "Usage: %s device_number\n", argv[0]);
+		fprintf(stderr, "\t: %s major minor\n", argv[0]);
+		exit(1);
+	}
+	if (argc == 2) {
+		device = 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);
+		}
+		device = makedev(major, minor);
+		printf("Looking for device 0x%04x (%d:%d)\n", device,
+		       major, minor);
+	}
+	devname = ext2fs_find_block_device(device);
+	if (devname) {
+		printf("Found device!  %s\n", devname);
+		free(devname);
+	} else {
+		printf("Couldn't find device.\n");
+	}
+	return 0;
+}
+	
+#endif