1 files changed, 143 insertions, 0 deletions
diff --git a/mount/mount_by_label.c b/mount/mount_by_label.c
new file mode 100644
index 000000000..a48c9de19
--- /dev/null
+++ b/mount/mount_by_label.c
@@ -0,0 +1,143 @@
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "sundries.h"		/* for xstrdup */
+#include "linux_fs.h"
+#include "mount_by_label.h"
+
+#define PROC_PARTITIONS "/proc/partitions"
+#define DEVLABELDIR	"/dev"
+
+static FILE *procpt;
+
+static void
+procptclose(void) {
+    if (procpt)
+        fclose (procpt);
+    procpt = 0;
+}
+
+static int
+procptopen(void) {
+    return ((procpt = fopen(PROC_PARTITIONS, "r")) != NULL);
+}
+
+static char *
+procptnext(void) {
+   char line[100];
+   char *s;
+   int ma, mi, sz;
+   static char ptname[100];
+
+   while (fgets(line, sizeof(line), procpt)) {
+      if (sscanf (line, " %d %d %d %[^\n]\n", &ma, &mi, &sz, ptname) != 4)
+	      continue;
+
+      /* skip extended partitions (heuristic: size 1) */
+      if (sz == 1)
+	      continue;
+
+      /* skip entire disk (minor 0, 64, ... on ide; 0, 16, ... on sd) */
+      /* heuristic: partition name ends in a digit */
+      for(s = ptname; *s; s++);
+      if (isdigit(s[-1]))
+	      return ptname;
+   }
+   return 0;
+}
+
+#define UUID	1
+#define VOL	2
+
+/* for now, only ext2 is supported */
+static int
+has_right_label(const char *device, int n, const char *label) {
+
+	/* start with a test for ext2, taken from mount_guess_fstype */
+	/* should merge these later */
+	int fd;
+	char *s;
+	struct ext2_super_block e2sb;
+
+	fd = open(device, O_RDONLY);
+	if (fd < 0)
+		return 0;
+
+	if (lseek(fd, 1024, SEEK_SET) != 1024
+	    || read(fd, (char *) &e2sb, sizeof(e2sb)) != sizeof(e2sb)
+	    || (ext2magic(e2sb) != EXT2_SUPER_MAGIC)) {
+		close(fd);
+		return 0;
+	}
+
+	close(fd);
+
+	/* superblock is ext2 - now what is its label? */
+	s = ((n == UUID) ? e2sb.s_uuid : e2sb.s_volume_name);
+	return (strncmp(s, label, 16) == 0);
+}
+
+static char *
+get_spec_by_x(int n, const char *t) {
+	char *pt;
+	char device[110];
+
+	if(!procptopen())
+		return NULL;
+	while((pt = procptnext()) != NULL) {
+		/* Note: this is a heuristic only - there is no reason
+		   why these devices should live in /dev.
+		   Perhaps this directory should be specifiable by option.
+		   One might for example have /devlabel with links to /dev
+		   for the devices that may be accessed in this way.
+		   (This is useful, if the cdrom on /dev/hdc must not
+		   be accessed.)
+		*/
+		sprintf(device, "%s/%s", DEVLABELDIR, pt);
+		if (has_right_label(device, n, t)) {
+			procptclose();
+			return xstrdup(device);
+		}
+	}
+	procptclose();
+	return NULL;
+}
+
+static u_char
+fromhex(char c) {
+	if (isdigit(c))
+		return (c - '0');
+	else if (islower(c))
+		return (c - 'a' + 10);
+	else
+		return (c - 'A' + 10);
+}
+
+char *
+get_spec_by_uuid(const char *s) {
+	u_char uuid[16];
+	int i;
+
+	if (strlen(s) != 36 ||
+	    s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-')
+		goto bad_uuid;
+	for (i=0; i<16; i++) {
+	    if (*s == '-') s++;
+	    if (!isxdigit(s[0]) || !isxdigit(s[1]))
+		    goto bad_uuid;
+	    uuid[i] = ((fromhex(s[0])<<4) | fromhex(s[1]));
+	    s += 2;
+	}
+	return get_spec_by_x(UUID, uuid);
+
+ bad_uuid:
+	die(EX_USAGE, "mount: bad UUID");
+}
+
+char *
+get_spec_by_volume_label(const char *s) {
+	return get_spec_by_x(VOL, s);
+}
+