Add the concept of a per-disk error string, and a function which prints it

along with the errno, if one is set.

lib/libufs/Makefile

@@ -1,7 +1,7 @@
 # $FreeBSD$
 
 LIB=	ufs
-SRCS=	block.c inode.c sblock.c type.c
+SRCS=	block.c error.c inode.c sblock.c type.c
 INCS=	libufs.h
 CFLAGS+= -I${.CURDIR} -D_LIBUFS
 .if defined(LIBUFS_DEBUG)

lib/libufs/block.c

@@ -63,6 +63,7 @@ bread(struct uufsd *disk, ufs2_daddr_t blockno, void *data, size_t size)
 	 */
 	if (cnt != size) {
 		DEBUG("short read");
+		disk->d_error = "short read from block device";
 		for (cnt = 0; cnt < disk->d_fs.fs_bsize; cnt++)
 			buf[cnt] = 0;
 		return -1;
@@ -80,6 +81,7 @@ bwrite(struct uufsd *disk, ufs2_daddr_t blockno, const void *data, size_t size)
 	cnt = pwrite(disk->d_fd, data, size, (off_t)(blockno * disk->d_bsize));
 	if (cnt != size) {
 		DEBUG("short write");
+		disk->d_error = "short write to block device";
 		return -1;
 	}
 	

lib/libufs/error.c

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2002 Juli Mallett.  All rights reserved.
+ *
+ * This software was written by Juli Mallett <jmallett@FreeBSD.org> for the
+ * FreeBSD project.  Redistribution and use in source and binary forms, with
+ * or without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * 1. Redistribution of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistribution in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/mount.h>
+#include <sys/disklabel.h>
+#include <sys/stat.h>
+
+#include <ufs/ufs/ufsmount.h>
+#include <ufs/ufs/dinode.h>
+#include <ufs/ffs/fs.h>
+
+#include <errno.h>
+#include <stdio.h>
+
+#include <libufs.h>
+
+void
+libufs_printerror(struct uufsd *disk)
+{
+	if (disk == NULL) {
+		fprintf(stderr, "no disk\n");
+		return;
+	}
+	if (disk->d_error != NULL) {
+		fprintf(stderr, "disk error: %s", disk->d_error);
+		/*
+		 * XXX
+		 * Should there be a per-disk errno?
+		 */
+		if (errno)
+			fprintf(stderr, ": %s", strerror(errno));
+		fprintf(stderr, "\n");
+	}
+}

lib/libufs/libufs.h

@@ -73,6 +73,7 @@ struct uufsd {
 		char d_sb[MAXBSIZE];
 				/* superblock as buffer */
 	} d_sbunion;
+	const char *d_error;	/* human readable disk error */
 #define	d_fs	d_sbunion.d_fs
 #define	d_sb	d_sbunion.d_sb
 };
@@ -89,6 +90,11 @@ __BEGIN_DECLS
 ssize_t bread(struct uufsd *, ufs2_daddr_t, void *, size_t);
 ssize_t bwrite(struct uufsd *, ufs2_daddr_t, const void *, size_t);
 
+/*
+ * error.c
+ */
+void libufs_printerror(struct uufsd *);
+
 /*
  * inode.c
  */

lib/libufs/sblock.c

@@ -60,6 +60,7 @@ sbread(struct uufsd *disk)
 
 	for (sb = 0; (superblock = superblocks[sb]) != -1; sb++) {
 		if (bread(disk, superblock, disk->d_sb, SBLOCKSIZE) == -1) {
+			disk->d_error = "truncated superblock";
 			DEBUG(NULL);
 			return -1;
 		}
@@ -82,6 +83,7 @@ sbread(struct uufsd *disk)
 		 * which to associate this disk/filesystem.
 		 */
 		DEBUG("no superblock found");
+		disk->d_error = "no superblock found";
 		errno = ENOENT;
 		return -1;
 	}
@@ -104,10 +106,12 @@ sbwrite(struct uufsd *disk, int all)
 	disk->d_fd = open(disk->d_name, O_WRONLY);
 	if (disk->d_fd < 0) {
 		DEBUG("open");
+		disk->d_error = "failed to open disk";
 		return -1;
 	}
 	if (bwrite(disk, disk->d_sblock, fs, SBLOCKSIZE) == -1) {
 		DEBUG(NULL);
+		disk->d_error = "failed to write superblock";
 		return -1;
 	}
 	if (all) {
@@ -115,6 +119,7 @@ sbwrite(struct uufsd *disk, int all)
 			if (bwrite(disk, fsbtodb(fs, cgsblock(fs, i)),
 			    fs, SBLOCKSIZE) == -1) {
 				DEBUG(NULL);
+				disk->d_error = "failed to update a superblock";
 				return -1;
 			}
 	}

lib/libufs/type.c

@@ -99,6 +99,7 @@ ufs_disk_fillout(struct uufsd *disk, const char *name)
 	fd = open(name, O_RDONLY);
 	if (fd == -1) {
 		DEBUG("open");
+		disk->d_error = "failed to open disk for reading";
 		return -1;
 	}
 
@@ -109,6 +110,7 @@ ufs_disk_fillout(struct uufsd *disk, const char *name)
 	disk->d_inomax = 0;
 	disk->d_name = name;
 	disk->d_ufs = 0;
+	disk->d_error = NULL;
 
 	if (sbread(disk) == -1) {
 		DEBUG(NULL);