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[PATCH 6/7] diff-lib, read-tree, unpack-trees: mark cache_entry array paramters const

From
René Scharfe <rene.scharfe@lsrfire.ath.cx>
Date
May 30, 2013, 11:34 UTC
Message-ID
<1369913664-49734-7-git-send-email-rene.scharfe@lsrfire.ath.cx>
In-Reply-To
<1369913664-49734-1-git-send-email-rene.scharfe@lsrfire.ath.cx>

Change the type merge_fn_t to accept the array of cache_entry pointers as const pointers to const pointers. This documents the fact that the merge functions don't modify the cache_entry contents or replace any of the pointers in the array.

Only a single cast is necessary in unpack_nondirectories because adding two const modifiers at once is not allowed in C. The cast is safe in that it doesn't mask any modfication; call_unpack_fn only needs the array for reading.

Signed-off-by: René Scharfe <rene.scharfe@lsrfire.ath.cx>
---
 builtin/read-tree.c |  3 ++-
 diff-lib.c          |  3 ++-
 unpack-trees.c      | 21 +++++++++++++--------
 unpack-trees.h      | 14 +++++++++-----
 4 files changed, 26 insertions(+), 15 deletions(-)
diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index b847486..0f5d7fe 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -80,7 +80,8 @@ static void debug_stage(const char *label, const struct cache_entry *ce,
 		       sha1_to_hex(ce->sha1));
 }
 
-static int debug_merge(struct cache_entry **stages, struct unpack_trees_options *o)
+static int debug_merge(const struct cache_entry * const *stages,
+		       struct unpack_trees_options *o)
 {
 	int i;
 
diff --git a/diff-lib.c b/diff-lib.c
index 83d0cb8..b6f4b21 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -424,7 +424,8 @@ static void do_oneway_diff(struct unpack_trees_options *o,
  * the fairly complex unpack_trees() semantic requirements, including
  * the skipping, the path matching, the type conflict cases etc.
  */
-static int oneway_diff(struct cache_entry **src, struct unpack_trees_options *o)
+static int oneway_diff(const struct cache_entry * const *src,
+		       struct unpack_trees_options *o)
 {
 	const struct cache_entry *idx = src[0];
 	const struct cache_entry *tree = src[1];
diff --git a/unpack-trees.c b/unpack-trees.c
index c5a40df..2dbc05d 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -300,7 +300,8 @@ static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_opt
 	return 0;
 }
 
-static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
+static inline int call_unpack_fn(const struct cache_entry * const *src,
+				 struct unpack_trees_options *o)
 {
 	int ret = o->fn(src, o);
 	if (ret > 0)
@@ -397,7 +398,7 @@ static void add_same_unmerged(struct cache_entry *ce,
 static int unpack_index_entry(struct cache_entry *ce,
 			      struct unpack_trees_options *o)
 {
-	struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
+	const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 	int ret;
 
 	src[0] = ce;
@@ -600,7 +601,8 @@ static int unpack_nondirectories(int n, unsigned long mask,
 	}
 
 	if (o->merge)
-		return call_unpack_fn(src, o);
+		return call_unpack_fn((const struct cache_entry * const *)src,
+				      o);
 
 	for (i = 0; i < n; i++)
 		if (src[i] && src[i] != o->df_conflict_entry)
@@ -1574,7 +1576,8 @@ static void show_stage_entry(FILE *o,
 }
 #endif
 
-int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
+int threeway_merge(const struct cache_entry * const *stages,
+		   struct unpack_trees_options *o)
 {
 	const struct cache_entry *index;
 	const struct cache_entry *head;
@@ -1746,7 +1749,8 @@ int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
  *
  */
-int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
+int twoway_merge(const struct cache_entry * const *src,
+		 struct unpack_trees_options *o)
 {
 	const struct cache_entry *current = src[0];
 	const struct cache_entry *oldtree = src[1];
@@ -1812,8 +1816,8 @@ int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
  * Keep the index entries at stage0, collapse stage1 but make sure
  * stage0 does not have anything there.
  */
-int bind_merge(struct cache_entry **src,
-		struct unpack_trees_options *o)
+int bind_merge(const struct cache_entry * const *src,
+	       struct unpack_trees_options *o)
 {
 	const struct cache_entry *old = src[0];
 	const struct cache_entry *a = src[1];
@@ -1836,7 +1840,8 @@ int bind_merge(struct cache_entry **src,
  * The rule is:
  * - take the stat information from stage0, take the data from stage1
  */
-int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
+int oneway_merge(const struct cache_entry * const *src,
+		 struct unpack_trees_options *o)
 {
 	const struct cache_entry *old = src[0];
 	const struct cache_entry *a = src[1];
diff --git a/unpack-trees.h b/unpack-trees.h
index 5e432f5..36a73a6 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -8,7 +8,7 @@
 struct unpack_trees_options;
 struct exclude_list;
 
-typedef int (*merge_fn_t)(struct cache_entry **src,
+typedef int (*merge_fn_t)(const struct cache_entry * const *src,
 		struct unpack_trees_options *options);
 
 enum unpack_trees_error_types {
@@ -77,9 +77,13 @@ struct unpack_trees_options {
 extern int unpack_trees(unsigned n, struct tree_desc *t,
 		struct unpack_trees_options *options);
 
-int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o);
-int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o);
-int bind_merge(struct cache_entry **src, struct unpack_trees_options *o);
-int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o);
+int threeway_merge(const struct cache_entry * const *stages,
+		   struct unpack_trees_options *o);
+int twoway_merge(const struct cache_entry * const *src,
+		 struct unpack_trees_options *o);
+int bind_merge(const struct cache_entry * const *src,
+	       struct unpack_trees_options *o);
+int oneway_merge(const struct cache_entry * const *src,
+		 struct unpack_trees_options *o);
 
 #endif

-- 
1.8.3
Previous: René ScharfeNext: René Scharfe
Message 8 of 12 in “unpack-trees: plug memory leak for merges”
  1. 0/7 unpack-trees: plug memory leak for mergesRené Scharfe, May 30, 2013
  2. 1/7 cache: mark cache_entry pointers constRené Scharfe, May 30, 2013
  3. 2/7 read-cache: mark cache_entry pointers constRené Scharfe, May 30, 2013
  4. 3/7 unpack-trees: factor out dup_entryRené Scharfe, May 30, 2013
  5. Peter KreftingJun 4, 2013
  6. 4/7 unpack-trees: create working copy of merge entry in merged_entryRené Scharfe, May 30, 2013
  7. 5/7 diff-lib, read-tree, unpack-trees: mark cache_entry pointers constRené Scharfe, May 30, 2013
  8. 6/7 diff-lib, read-tree, unpack-trees: mark cache_entry array paramters constRené Scharfe, May 30, 2013
  9. 7/7 unpack-trees: free cache_entry array members for mergesRené Scharfe, May 30, 2013
  10. Felipe ContrerasMay 30, 2013
  11. René ScharfeMay 30, 2013
  12. Felipe ContrerasMay 30, 2013

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