prefer "!=" when checking read_in_full() result

Comparing the result of read_in_full() using less-than is
potentially dangerous, as a negative return value may be
converted to an unsigned type and be considered a success.
This is discussed further in 561598cfcf (read_pack_header:
handle signed/unsigned comparison in read result,
2017-09-13).

Each of these instances is actually fine in practice:

- in get-tar-commit-id, the HEADERSIZE macro expands to a
signed integer. If it were switched to an unsigned type
(e.g., a size_t), then it would be a bug.

- the other two callers check for a short read only after
handling a negative return separately. This is a fine
practice, but we'd prefer to model "!=" as a general
rule.

So all of these cases can be considered cleanups and not
actual bugfixes.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
index 6d9a79f9b39834d953685b2641354915df3cfcbe..cd3e6568289c1a412882c9452a9d17055c352923 100644 (file)
--- a/builtin/get-tar-commit-id.c
+++ b/builtin/get-tar-commit-id.c
@@ -26,7 +26,7 @@ int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
                usage(builtin_get_tar_commit_id_usage);
 
        n = read_in_full(0, buffer, HEADERSIZE);
-       if (n < HEADERSIZE)
+       if (n != HEADERSIZE)
                die("git get-tar-commit-id: read error");
        if (header->typeflag[0] != 'g')
                return 1;

diff --git a/csum-file.c b/csum-file.c
index a172199e44bf370cd66ee7073f5a2228fd9679ef..2adae04073816a781d01d85433d8d8922baafd7f 100644 (file)
--- a/csum-file.c
+++ b/csum-file.c
@@ -19,7 +19,7 @@ static void flush(struct sha1file *f, const void *buf, unsigned int count)
 
                if (ret < 0)
                        die_errno("%s: sha1 file read error", f->name);
-               if (ret < count)
+               if (ret != count)
                        die("%s: sha1 file truncated", f->name);
                if (memcmp(buf, check_buffer, count))
                        die("sha1 file '%s' validation error", f->name);

diff --git a/pkt-line.c b/pkt-line.c
index 647bbd3bceda71f15fdf137a37f3fa53e6fa6d86..93ea311443a37b81b85a72dc569c715417d7ef29 100644 (file)
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -258,7 +258,7 @@ static int get_packet_data(int fd, char **src_buf, size_t *src_size,
        }
 
        /* And complain if we didn't get enough bytes to satisfy the read. */
-       if (ret < size) {
+       if (ret != size) {
                if (options & PACKET_READ_GENTLE_ON_EOF)
                        return -1;