Fix bugs in ext2 found by clang static analyzer

servers/ext2/link.c

@@ -183,7 +183,7 @@ PUBLIC int fs_unlink()
 PUBLIC int fs_rdlink()
 {
   block_t b;                   /* block containing link text */
-  struct buf *bp;              /* buffer containing link text */
+  struct buf *bp = NULL;       /* buffer containing link text */
   char* link_text;             /* either bp->b_data or rip->i_block */
   register struct inode *rip;  /* target inode */
   register int r;              /* return value */
@@ -195,8 +195,6 @@ PUBLIC int fs_rdlink()
   if( (rip = get_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR)) == NULL)
 	  return(EINVAL);
 
-  if (!S_ISLNK(rip->i_mode))
-	  r = EACCES;
   if (rip->i_size > MAX_FAST_SYMLINK_LENGTH) {
   /* normal symlink */
 	if ((b = read_map(rip, (off_t) 0)) == NO_BLOCK) {
@@ -219,7 +217,6 @@ PUBLIC int fs_rdlink()
   /* We can safely cast to unsigned, because copylen is guaranteed to be
      below max file size */
 	copylen = min( copylen, (unsigned) rip->i_size);
-	bp = get_block(rip->i_dev, b, NORMAL);
 	r = sys_safecopyto(VFS_PROC_NR, (cp_grant_id_t) fs_m_in.REQ_GRANT,
 	                   (vir_bytes) 0, (vir_bytes) link_text,
 			   (size_t) copylen, D);
@@ -353,12 +350,16 @@ PUBLIC int fs_rename()
 	old_ip = NULL;
 	if (r == EENTERMOUNT) r = EXDEV;	/* should this fail at all? */
 	else if (r == ELEAVEMOUNT) r = EINVAL;	/* rename on dot-dot */
+  } else if (old_ip == NULL) {
+	return(err_code);
   }
 
   /* Get new dir inode */
-  if( (new_dirp = get_inode(fs_dev, (ino_t) fs_m_in.REQ_REN_NEW_DIR)) == NULL)
+  if( (new_dirp = get_inode(fs_dev, (ino_t) fs_m_in.REQ_REN_NEW_DIR)) == NULL) {
-	r = err_code;
+	put_inode(old_ip);
-  else {
+	put_inode(old_dirp);
+	return(err_code);
+  } else {
 	if (new_dirp->i_links_count == NO_LINK) { /* Dir does not actually exist */
 		put_inode(old_ip);
 		put_inode(old_dirp);
@@ -699,7 +700,6 @@ int half;
   } else {
 	len = offset;
 	pos -= offset;
-	offset = 0;
   }
 
   zeroblock_range(rip, pos, len);

servers/ext2/main.c

@@ -46,7 +46,7 @@ PUBLIC int main(int argc, char *argv[])
  * three major activities: getting new work, processing the work, and
  * sending the reply. The loop never terminates, unless a panic occurs.
  */
-  int error, ind, transid;
+  int error = OK, ind, transid;
   unsigned short test_endian = 1;
 
   /* SEF local startup. */
@@ -74,7 +74,6 @@ PUBLIC int main(int argc, char *argv[])
 		assert(IS_VFS_FS_TRANSID(transid));
 
 	src = fs_m_in.m_source;
-	error = OK;
 	caller_uid = INVAL_UID;	/* To trap errors */
 	caller_gid = INVAL_GID;
 	req_nr = fs_m_in.m_type;

servers/ext2/open.c

@@ -229,13 +229,16 @@ PUBLIC int fs_slink()
 		sip->i_dirt = DIRTY;
 		link_target_buf = (char*) sip->i_block;
         } else {
-		r = (bp = new_block(sip, (off_t) 0)) == NULL ? err_code :
+		if ((bp = new_block(sip, (off_t) 0)) != NULL) {
 			sys_safecopyfrom(VFS_PROC_NR,
 					 (cp_grant_id_t) fs_m_in.REQ_GRANT3,
 					 (vir_bytes) 0, (vir_bytes) bp->b_data,
 					 (vir_bytes) fs_m_in.REQ_MEM_SIZE, D);
 			bp->b_dirt = DIRTY;
 			link_target_buf = bp->b_data;
+		} else {
+			r = err_code;
+		}
 	}
 	if (r == OK) {
 		link_target_buf[fs_m_in.REQ_MEM_SIZE] = '\0';

servers/ext2/read.c

@@ -432,7 +432,7 @@ unsigned bytes_ahead;           /* bytes beyond position for immediate use */
   block_t block, blocks_left;
   off_t ind1_pos;
   dev_t dev;
-  struct buf *bp;
+  struct buf *bp = NULL;
   static unsigned int readqsize = 0;
   static struct buf **read_q;
 
@@ -456,6 +456,7 @@ unsigned bytes_ahead;           /* bytes beyond position for immediate use */
 
   block = baseblock;
   bp = get_block(dev, block, PREFETCH);
+  assert(bp != NULL);
   if (bp->b_dev != NO_DEV) return(bp);
 
   /* The best guess for the number of blocks to prefetch:  A lot.

servers/ext2/write.c

@@ -106,7 +106,7 @@ int op;				/* special actions */
 		 * or newly created.
 		 * If there wasn't one and WMAP_FREE is set, 'b3' is NO_BLOCK.
 		 */
-		if (b3 == NO_BLOCK) {
+		if (b3 == NO_BLOCK && (op & WMAP_FREE)) {
 		/* WMAP_FREE and no triple indirect block - then no
 		 * double and single indirect blocks either.
 		 */
@@ -147,7 +147,7 @@ int op;				/* special actions */
 	 * or newly created.
 	 * If there wasn't one and WMAP_FREE is set, 'b2' is NO_BLOCK.
 	 */
-	if (b2 == NO_BLOCK) {
+	if (b2 == NO_BLOCK && (op & WMAP_FREE)) {
 	/* WMAP_FREE and no double indirect block - then no
 	 * single indirect block either.
 	 */