[PATCH 1/1] commit-graph: improve error messages

["Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>]

From: Derrick Stolee <dstolee@microsoft.com>

The error messages when reading a commit-graph have a few problems:

1. Some values are output in hexadecimal, but that is not made
   clear by the message. Prepend "0x" to these values.

2. The version number does not need to be hexadecimal, and also
   should mention a "maximum supported version". This has one
   possible confusing case: we could have a corrupt commit-graph
   file with version number zero, so the output would be

   "commit-graph has version 0, our maximum supported version is 1"

   This will only happen with corrupt data. This error message is
   designed instead for the case where a client is downgraded after
   writing a newer file version.

Update t5318-commit-graph.sh to watch for these new error messages.

Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 commit-graph.c          | 10 +++++-----
 t/t5318-commit-graph.sh |  6 +++---
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/commit-graph.c b/commit-graph.c
index 66865acbd7..aba591913e 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -167,21 +167,21 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 
 	graph_signature = get_be32(data);
 	if (graph_signature != GRAPH_SIGNATURE) {
-		error(_("commit-graph signature %X does not match signature %X"),
+		error(_("commit-graph signature 0x%X does not match signature 0x%X"),
 		      graph_signature, GRAPH_SIGNATURE);
 		return NULL;
 	}
 
 	graph_version = *(unsigned char*)(data + 4);
 	if (graph_version != GRAPH_VERSION) {
-		error(_("commit-graph version %X does not match version %X"),
+		error(_("commit-graph has version %d, our maximum supported version is %d"),
 		      graph_version, GRAPH_VERSION);
 		return NULL;
 	}
 
 	hash_version = *(unsigned char*)(data + 5);
 	if (hash_version != oid_version()) {
-		error(_("commit-graph hash version %X does not match version %X"),
+		error(_("commit-graph has hash version %d, our maximum supported version is %d"),
 		      hash_version, oid_version());
 		return NULL;
 	}
@@ -215,7 +215,7 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 		chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 
 		if (chunk_offset > graph_size - the_hash_algo->rawsz) {
-			error(_("commit-graph improper chunk offset %08x%08x"), (uint32_t)(chunk_offset >> 32),
+			error(_("commit-graph improper chunk offset 0x%08x%08x"), (uint32_t)(chunk_offset >> 32),
 			      (uint32_t)chunk_offset);
 			free(graph);
 			return NULL;
@@ -252,7 +252,7 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 		}
 
 		if (chunk_repeated) {
-			error(_("commit-graph chunk id %08x appears multiple times"), chunk_id);
+			error(_("commit-graph chunk id 0x%08x appears multiple times"), chunk_id);
 			free(graph);
 			return NULL;
 		}
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index e80c1cac02..264ebb15b1 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -420,17 +420,17 @@ test_expect_success 'detect too small' '
 
 test_expect_success 'detect bad signature' '
 	corrupt_graph_and_verify 0 "\0" \
-		"graph signature"
+		"commit-graph signature"
 '
 
 test_expect_success 'detect bad version' '
 	corrupt_graph_and_verify $GRAPH_BYTE_VERSION "\02" \
-		"graph version"
+		"commit-graph has version"
 '
 
 test_expect_success 'detect bad hash version' '
 	corrupt_graph_and_verify $GRAPH_BYTE_HASH "\02" \
-		"hash version"
+		"commit-graph has hash version"
 '
 
 test_expect_success 'detect low chunk count' '
-- 
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