From 61d36330b422237b6be9581cdbade07782ab61a8 Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Wed, 27 Sep 2017 02:00:28 -0400
Subject: [PATCH] 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>
---
builtin/get-tar-commit-id.c | 2 +-
csum-file.c | 2 +-
pkt-line.c | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
index 6d9a79f9b3..cd3e656828 100644
--- 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 a172199e44..2adae04073 100644
--- 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 647bbd3bce..93ea311443 100644
--- 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;