From ab6b8ab64d5afb5393a9aa826fce26490127f785 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Mon, 14 Jul 1997 19:28:55 +0000
Subject: [PATCH] ChangeLog, Makefile.in, e2label.c:   e2label.c: New file
 contributed by Andries Brouwer which provides an   easy-to-use interface to
 modify the filesystem label.

---
 misc/ChangeLog   |  8 +++++
 misc/Makefile.in |  6 +++-
 misc/e2label.c   | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 105 insertions(+), 1 deletion(-)
 create mode 100644 misc/e2label.c

diff --git a/misc/ChangeLog b/misc/ChangeLog
index 37a9dec..e98d756 100644
--- a/misc/ChangeLog
+++ b/misc/ChangeLog
@@ -1,3 +1,11 @@
+Mon Jul 14 15:27:29 1997  Theodore Y. Ts'o  <tytso@mit.edu>
+
+	* e2label.c: New file contributed by Andries Brouwer which
+ 		provides an easy-to-use interface to modify the filesystem
+ 		label.
+	
+	* Makefile.in (SPROGS): Add Makefile support to build e2label
+
 Tue Jun 17 01:33:20 1997  Theodore Ts'o  <tytso@rsts-11.mit.edu>
 
 	* Release of E2fsprogs 1.11
diff --git a/misc/Makefile.in b/misc/Makefile.in
index b0d06a2..0c3126a 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -11,7 +11,7 @@ INSTALL = @INSTALL@
 
 @MCONFIG@
 
-SPROGS=		mke2fs badblocks tune2fs dumpe2fs @FSCK_PROG@
+SPROGS=		mke2fs badblocks tune2fs dumpe2fs e2label @FSCK_PROG@
 USPROGS=	mklost+found
 SMANPAGES=	tune2fs.8 mklost+found.8 mke2fs.8 dumpe2fs.8 badblocks.8 \
 			@FSCK_MAN@
@@ -26,6 +26,7 @@ CHATTR_OBJS=	chattr.o
 LSATTR_OBJS=	lsattr.o
 DUMPE2FS_OBJS=	dumpe2fs.o
 BADBLOCKS_OBJS=	badblocks.o
+E2LABEL_OBJS=	e2label.o
 FSCK_OBJS=	fsck.o
 
 SRCS=	$(srcdir)/tune2fs.c $(srcdir)/mklost+found.c $(srcdir)/mke2fs.c \
@@ -49,6 +50,9 @@ all:: $(SPROGS) $(UPROGS) $(USPROGS) fix_substitute $(SMANPAGES) $(UMANPAGES)
 tune2fs: $(TUNE2FS_OBJS) $(DEPLIBS_E2P) $(LIBUUID)
 	$(CC) $(ALL_LDFLAGS) -o tune2fs $(TUNE2FS_OBJS) $(LIBS_E2P) $(LIBUUID)
 
+e2label: $(E2LABEL_OBJS) 
+	$(CC) $(ALL_LDFLAGS) -o e2label $(E2LABEL_OBJS) 
+
 mklost+found: $(MKLPF_OBJS)
 	$(CC) $(ALL_LDFLAGS) -o mklost+found $(MKLPF_OBJS)
 
diff --git a/misc/e2label.c b/misc/e2label.c
new file mode 100644
index 0000000..2b4f171
--- /dev/null
+++ b/misc/e2label.c
@@ -0,0 +1,92 @@
+/*
+ * e2label.c		- Print or change the volume label on an ext2 fs
+ *
+ * aeb, 970714
+ *
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+
+#define EXT2_SUPER_MAGIC 0xEF53
+
+#define VOLNAMSZ 16
+
+struct ext2_super_block {
+	char  s_dummy0[56];
+	unsigned char  s_magic[2];
+	char  s_dummy1[62];
+	char  s_volume_name[VOLNAMSZ];
+	char  s_last_mounted[64];
+	char  s_dummy2[824];
+} sb;
+
+int
+open_e2fs (char *dev, int mode) {
+	int fd;
+
+	fd = open(dev, mode);
+	if (fd < 0) {
+	     perror(dev);
+	     fprintf (stderr, "e2label: cannot open %s\n", dev);
+	     exit(1);
+	}
+	if (lseek(fd, 1024, SEEK_SET) != 1024) {
+	     perror(dev);
+	     fprintf (stderr, "e2label: cannot seek to superblock\n");
+	     exit(1);
+	}
+	if (read(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) {
+	     perror(dev);
+	     fprintf (stderr, "e2label: error reading superblock\n");
+	     exit(1);
+	}
+	if (sb.s_magic[0] + 256*sb.s_magic[1] != EXT2_SUPER_MAGIC) {
+	     fprintf (stderr, "e2label: not an ext2 filesystem\n");
+	     exit(1);
+	}
+
+	return fd;
+}
+
+void
+print_label (char *dev) {
+	char label[VOLNAMSZ+1];
+
+	open_e2fs (dev, O_RDONLY);
+	label[VOLNAMSZ] = 0;
+	strncpy(label, sb.s_volume_name, VOLNAMSZ);
+	printf("%s\n", label);
+}
+
+void
+change_label (char *dev, char *label) {
+	int fd;
+
+	fd = open_e2fs(dev, O_RDWR);
+	memset(sb.s_volume_name, 0, VOLNAMSZ);
+	strncpy(sb.s_volume_name, label, VOLNAMSZ);
+	if (lseek(fd, 1024, SEEK_SET) != 1024) {
+	     perror(dev);
+	     fprintf (stderr, "e2label: cannot seek to superblock again\n");
+	     exit(1);
+	}
+	if (write(fd, (char *) &sb, sizeof(sb)) != sizeof(sb)) {
+	     perror(dev);
+	     fprintf (stderr, "e2label: error writing superblock\n");
+	     exit(1);
+	}
+}
+
+int
+main (int argc, char ** argv) {
+	if (argc == 2)
+	     print_label(argv[1]);
+	else if (argc == 3)
+	     change_label(argv[1], argv[2]);
+	else {
+	     fprintf(stderr, "Usage: e2label device [newlabel]\n");
+	     exit(1);
+	}
+	return 0;
+}
-- 
1.8.3.1