debugfs: clean up read_journal_block() to avoid Coverity complaint

The read_journal_block() function was needlessly complicated, which
made it harder to read/maintain, and it also tripped up Coverity.
Cleaning it up also avoided some signed/unsigned casts, and allows us
to avoid passing got back to the caller, since it wasn't needed.

Addresses-Coverity-Bug: #709539

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/debugfs/logdump.c b/debugfs/logdump.c
index 66a5428..d2c3b30 100644 (file)
--- a/debugfs/logdump.c
+++ b/debugfs/logdump.c
@@ -273,42 +273,43 @@ print_usage:
 
 
 static int read_journal_block(const char *cmd, struct journal_source *source,
-                             off_t offset, char *buf, int size,
-                             unsigned int *got)
+                             off_t offset, char *buf, unsigned int size)
 {
        int retval;
+       unsigned int got;
 
        if (source->where == JOURNAL_IS_EXTERNAL) {
                if (lseek(source->fd, offset, SEEK_SET) < 0) {
                        retval = errno;
-                       com_err(cmd, retval, "while seeking in reading journal");
-                       return retval;
+                       goto seek_err;
                }
                retval = read(source->fd, buf, size);
-               if (retval >= 0) {
-                       *got = retval;
-                       retval = 0;
-               } else
+               if (retval < 0) {
                        retval = errno;
+                       goto read_err;
+               }
+               got = retval;
+               retval = 0;
        } else {
                retval = ext2fs_file_lseek(source->file, offset,
                                           EXT2_SEEK_SET, NULL);
                if (retval) {
+               seek_err:
                        com_err(cmd, retval, "while seeking in reading journal");
                        return retval;
                }
-
-               retval = ext2fs_file_read(source->file, buf, size, got);
+               retval = ext2fs_file_read(source->file, buf, size, &got);
+               if (retval) {
+               read_err:
+                       com_err(cmd, retval, "while reading journal");
+                       return retval;
+               }
        }
-
-       if (retval)
-               com_err(cmd, retval, "while reading journal");
-       else if (*got != (unsigned int) size) {
-               com_err(cmd, 0, "short read (read %d, expected %d) "
-                       "while reading journal", *got, size);
+       if (got != size) {
+               com_err(cmd, 0, "short read (read %u, expected %u) "
+                       "while reading journal", got, size);
                retval = -1;
        }
-
        return retval;
 }
 
@@ -338,7 +339,6 @@ static void dump_journal(char *cmdname, FILE *out_file,
        char                    buf[8192];
        journal_superblock_t    *jsb;
        unsigned int            blocksize = 1024;
-       unsigned int            got;
        int                     retval;
        __u32                   magic, sequence, blocktype;
        journal_header_t        *header;
@@ -347,8 +347,7 @@ static void dump_journal(char *cmdname, FILE *out_file,
        unsigned int            blocknr = 0;
 
        /* First, check to see if there's an ext2 superblock header */
-       retval = read_journal_block(cmdname, source, 0,
-                                   buf, 2048, &got);
+       retval = read_journal_block(cmdname, source, 0, buf, 2048);
        if (retval)
                return;
 
@@ -377,7 +376,7 @@ static void dump_journal(char *cmdname, FILE *out_file,
        /* Next, read the journal superblock */
 
        retval = read_journal_block(cmdname, source, blocknr*blocksize,
-                                   jsb_buffer, 1024, &got);
+                                   jsb_buffer, 1024);
        if (retval)
                return;
 
@@ -401,8 +400,8 @@ static void dump_journal(char *cmdname, FILE *out_file,
        while (1) {
                retval = read_journal_block(cmdname, source,
                                            blocknr*blocksize, buf,
-                                           blocksize, &got);
-               if (retval || got != blocksize)
+                                           blocksize);
+               if (retval)
                        return;
 
                header = (journal_header_t *) buf;
@@ -576,7 +575,6 @@ static void dump_metadata_block(FILE *out_file, struct journal_source *source,
                                int blocksize,
                                tid_t transaction)
 {
-       unsigned int    got;
        int             retval;
        char            buf[8192];
 
@@ -612,7 +610,7 @@ static void dump_metadata_block(FILE *out_file, struct journal_source *source,
 
        retval = read_journal_block("logdump", source,
                                    blocksize * log_blocknr,
-                                   buf, blocksize, &got);
+                                   buf, blocksize);
        if (retval)
                return;