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authorJeff King <peff@peff.net>2016-08-11 09:24:35 (GMT)
committerJunio C Hamano <gitster@pobox.com>2016-08-11 17:42:23 (GMT)
commit27b5c1a0653026645bd6908ee5abfdceb1c95082 (patch)
tree57d9b7f106d335340624d4fec151c018f467af35 /builtin
parent56dfeb62638760fa78a442a97f19abf1af374d29 (diff)
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provide an initializer for "struct object_info"
An all-zero initializer is fine for this struct, but because the first element is a pointer, call sites need to know to use "NULL" instead of "0". Otherwise some static checkers like "sparse" will complain; see d099b71 (Fix some sparse warnings, 2013-07-18) for example. So let's provide an initializer to make this easier to get right. But let's also comment that memset() to zero is explicitly OK[1]. One of the callers embeds object_info in another struct which is initialized via memset (expand_data in builtin/cat-file.c). Since our subset of C doesn't allow assignment from a compound literal, handling this in any other way is awkward, so we'd like to keep the ability to initialize by memset(). By documenting this property, it should make anybody who wants to change the initializer think twice before doing so. There's one other caller of interest. In parse_sha1_header(), we did not initialize the struct fully in the first place. This turned out not to be a bug because the sub-function it calls does not look at any other fields except the ones we did initialize. But that assumption might not hold in the future, so it's a dangerous construct. This patch switches it to initializing the whole struct, which protects us against unexpected reads of the other fields. [1] Obviously using memset() to initialize a pointer violates the C standard, but we long ago decided that it was an acceptable tradeoff in the real world. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin')
-rw-r--r--builtin/cat-file.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 618103f..8e57998 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -28,7 +28,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
char *buf;
unsigned long size;
struct object_context obj_context;
- struct object_info oi = {NULL};
+ struct object_info oi = OBJECT_INFO_INIT;
struct strbuf sb = STRBUF_INIT;
unsigned flags = LOOKUP_REPLACE_OBJECT;
@@ -378,8 +378,7 @@ static int batch_objects(struct batch_options *opt)
data.mark_query = 0;
if (opt->all_objects) {
- struct object_info empty;
- memset(&empty, 0, sizeof(empty));
+ struct object_info empty = OBJECT_INFO_INIT;
if (!memcmp(&data.info, &empty, sizeof(empty)))
data.skip_object_info = 1;
}