From c55983415ae3bd360deb04ede20bc482bd2c41b7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dan=20Hor=C3=A1k?= <dan@danny.cz>
Date: Mon, 7 Mar 2011 15:13:45 +0100
Subject: [PATCH] cmsfs-fuse: fix read and write errors in text mode

Description: cmsfs-fuse: fix read and write errors in text mode.
Symptom:     Copying a file in text mode fails with read or write errors.
Problem:     Miscalculation of file size in text mode and off-by-one error
             in record length check for fixed files.
Solution:    Correct the calculation of the file size by using the displacement
             value for the last block of a variable file and by limiting
             the size of the last record of a fixed file to the actual size.
             Additionally scan for the correct length of a fixed record in text
             mode.
Problem-ID:  70230
---
 cmsfs-fuse/cmsfs-fuse.c |   67 ++++++++++++++++++++++++++---------------------
 cmsfs-fuse/dasd.c       |    2 +-
 2 files changed, 38 insertions(+), 31 deletions(-)

diff --git a/cmsfs-fuse/cmsfs-fuse.c b/cmsfs-fuse/cmsfs-fuse.c
index 6c5b0b5..fd87774 100644
--- a/cmsfs-fuse/cmsfs-fuse.c
+++ b/cmsfs-fuse/cmsfs-fuse.c
@@ -917,6 +917,33 @@ static void set_record_extension(struct file *f, int *record, off_t addr,
 	f->record_scan_state = RSS_DATA_BLOCK_EXT;
 }
 
+/* check for file end via byte count and return count of bytes left */
+static size_t crop_file_end(struct file *f, int record, size_t done,
+			    int first)
+{
+	size_t filesize = f->fst->nr_records * f->fst->record_len;
+	struct record *rec = &f->rlist[record];
+	struct record_ext *rext = rec->ext;
+
+	/* done already includes the complete record length incl. extensions */
+	done -= rec->total_len;
+	/* remove possible linefeeds before comparing with on-disk file size */
+	if (f->linefeed && record)
+		done -= record;
+	done += rec->first_block_len;
+
+	/* add length of all existing extensions */
+	while (rext != NULL) {
+		done += rext->len;
+		rext = rext->next;
+	}
+
+	if (done + first > filesize)
+		first = filesize - done;
+	return first;
+}
+
+/* check for file end by record number */
 static int end_of_file(struct file *f, int record)
 {
 	if (record == f->fst->nr_records)
@@ -936,6 +963,8 @@ static void walk_fixed_data_block(struct file *f, off_t addr, int *record,
 
 	if (first) {
 		BUG(first > left);
+
+		first = crop_file_end(f, *record, *total, first);
 		set_record_extension(f, record, addr, first, block);
 		left -= first;
 		if (addr != NULL_BLOCK)
@@ -1572,28 +1601,6 @@ static ssize_t get_file_size_fixed(struct fst_entry *fst)
 	return fst->nr_records * fst->record_len;
 }
 
-static ssize_t get_file_size_variable_slow(struct fst_entry *fst)
-{
-	struct record *rec;
-	ssize_t total = 0;
-	int rc = 0;
-	struct file *f = create_file_object(fst, &rc);
-
-	if (f == NULL)
-		return rc;
-
-	rec = get_record(f, f->fst->nr_records - 1);
-	total = rec->file_start + rec->total_len;
-
-	/*
-	 * Note: need to add header bytes since the record information does
-	 * not contain them but get_file_size_logical will remove them...
-	 */
-	total += f->fst->nr_records * VAR_RECORD_HEADER_SIZE;
-	destroy_file_object(f);
-	return total;
-}
-
 static ssize_t get_file_size_variable(struct fst_entry *fst)
 {
 	struct var_ptr vptr;
@@ -1608,11 +1615,11 @@ static ssize_t get_file_size_variable(struct fst_entry *fst)
 			return rc;
 		if (vptr.next == 0) {
 			/*
-			 * Last block is a null block. Cannot scan that block,
-			 * need to scan the whole file instead...
+			 * Last block is a null block. No more records can
+			 * follow, so the displacement value points to EOF.
 			 */
-			total = get_file_size_variable_slow(fst);
-			goto skip;
+			total = vptr.disp;
+			goto skip_scan;
 		}
 		ptr = ABS(vptr.next);
 		if (vptr.disp != VAR_RECORD_SPANNED) {
@@ -1638,7 +1645,6 @@ skip_scan:
 	 */
 	if (fst->nr_blocks)
 		total += (fst->nr_blocks - 1) * cmsfs.blksize;
-skip:
 	return total;
 }
 
@@ -3896,7 +3902,8 @@ static int do_write(struct file *f, const char *buf, size_t size, off_t offset)
 			return rc;
 		f->ptr_dirty = 0;
 	} else
-		if (f->fst->levels > 0) {
+		if (f->fst->levels > 0 &&
+		    f->fst->record_format == RECORD_LEN_VARIABLE) {
 			rc = update_last_block_vptr(f, ABS(f->fst->fop),
 						    f->fst->levels, &vptr);
 			if (rc < 0)
@@ -3962,7 +3969,7 @@ static int cmsfs_write(const char *path, const char *buf, size_t size,
 		return do_write(f, buf, size, offset);
 
 	/* remove already comitted bytes */
-	offset -= f->wcache_used;
+	offset -= f->wcache_commited;
 
 	/* write offset must be at the end of the file */
 	if (offset + f->null_records + f->pad_bytes != f->session_size)
@@ -3981,7 +3988,7 @@ static int cmsfs_write(const char *path, const char *buf, size_t size,
 			return -EINVAL;
 		} else {
 			if (f->fst->record_format == RECORD_LEN_FIXED &&
-			    f->wcache_commited + scan_len >= f->fst->record_len) {
+			    f->wcache_commited + scan_len > f->fst->record_len) {
 				purge_wcache(f);
 				return -EINVAL;
 			}
diff --git a/cmsfs-fuse/dasd.c b/cmsfs-fuse/dasd.c
index d79d34d..1b9af9a 100644
--- a/cmsfs-fuse/dasd.c
+++ b/cmsfs-fuse/dasd.c
@@ -196,7 +196,7 @@ int get_device_info(struct cmsfs *cmsfs)
 	 */
 	fd = open(cmsfs->device, O_RDWR);
 	if (fd < 0) {
-		if (errno == EROFS) {
+		if (errno == EROFS || errno == EACCES) {
 			cmsfs->readonly = 1;
 			fd = open(cmsfs->device, O_RDONLY);
 			if (fd < 0)
-- 
1.7.4