[PATCH 1/7] ui-blob.c: Use a context structure in walk_tree()

[Lukas Fleischer]

On Sun, Mar 03, 2013 at 09:33:36PM +0100, Ferry Huberts wrote:
> 
> 
> On 03/03/13 21:25, John Keeping wrote:
> >On Sun, Mar 03, 2013 at 08:56:18PM +0100, Ferry Huberts wrote:
> >>
> >>
> >>On 03/03/13 18:06, Lukas Fleischer wrote:
> >>>Do not misuse global variables to save the context. Instead, use the
> >>>context pointer which was designed to share information between a
> >>>read_tree_fn and the caller.
> >>>
> >>>This also prevents from potential misuse of the global pointers
> >>>match_path and matched_sha1 after the referenced values have been
> >>>overwritten on the stack.
> >>>
> >>>Signed-off-by: Lukas Fleischer <cgit at cryptocrack.de>
> >>>---
> >>>   ui-blob.c | 42 ++++++++++++++++++++++++++----------------
> >>>   1 file changed, 26 insertions(+), 16 deletions(-)
> >>>
> >>>diff --git a/ui-blob.c b/ui-blob.c
> >>>index 3d07ce5..4bcbc82 100644
> >>>--- a/ui-blob.c
> >>>+++ b/ui-blob.c
> >>>@@ -11,17 +11,22 @@
> >>>   #include "html.h"
> >>>   #include "ui-shared.h"
> >>>
> >>>-static char *match_path;
> >>>-static unsigned char *matched_sha1;
> >>>-static int found_path;
> >>>+struct walk_tree_context {
> >>>+	char *match_path;
> >>>+	unsigned char *matched_sha1;
> >>>+	int found_path;
> >>>+};
> >>>
> >>>   static int walk_tree(const unsigned char *sha1, const char *base, int baselen,
> >>>-	const char *pathname, unsigned mode, int stage, void *cbdata) {
> >>>-	if(strncmp(base, match_path, baselen)
> >>>-		|| strcmp(match_path + baselen, pathname))
> >>>+	const char *pathname, unsigned mode, int stage, void *cbdata)
> >>>+{
> >>>+	struct walk_tree_context *walk_tree_ctx = cbdata;
> >>>+
> >>>+	if(strncmp(base, walk_tree_ctx->match_path, baselen)
> >>>+		|| strcmp(walk_tree_ctx->match_path + baselen, pathname))
> >>>   		return READ_TREE_RECURSIVE;
> >>>-	memmove(matched_sha1, sha1, 20);
> >>>-	found_path = 1;
> >>>+	memmove(walk_tree_ctx->matched_sha1, sha1, 20);
> >>>+	walk_tree_ctx->found_path = 1;
> >>>   	return 0;
> >>>   }
> >>>
> >>>@@ -33,16 +38,19 @@ int cgit_print_file(char *path, const char *head)
> >>>   	unsigned long size;
> >>>   	struct commit *commit;
> >>>   	const char *paths[] = {path, NULL};
> >>>+	struct walk_tree_context walk_tree_ctx = {
> >>>+		.match_path = path,
> >>>+		.matched_sha1 = sha1,
> >>>+		.found_path = 0
> >>>+	};
> >>>+
> >>>   	if (get_sha1(head, sha1))
> >>>   		return -1;
> >>>   	type = sha1_object_info(sha1, &size);
> >>>   	if(type == OBJ_COMMIT && path) {
> >>>   		commit = lookup_commit_reference(sha1);
> >>>-		match_path = path;
> >>>-		matched_sha1 = sha1;
> >>>-		found_path = 0;
> >>>-		read_tree_recursive(commit->tree, "", 0, 0, paths, walk_tree, NULL);
> >>>-		if (!found_path)
> >>>+		read_tree_recursive(commit->tree, "", 0, 0, paths, walk_tree, &walk_tree_ctx);
> >>>+		if (!walk_tree_ctx.found_path)
> >>>   			return -1;
> >>>   		type = sha1_object_info(sha1, &size);
> >>>   	}
> >>>@@ -64,6 +72,10 @@ void cgit_print_blob(const char *hex, char *path, const char *head)
> >>>   	unsigned long size;
> >>>   	struct commit *commit;
> >>>   	const char *paths[] = {path, NULL};
> >>>+	struct walk_tree_context walk_tree_ctx = {
> >>>+		.match_path = path,
> >>>+		.matched_sha1 = sha1,
> >>
> >>forgot to initialise found_path
> >
> >Unnecessary - C99 6.7.8:
> >
> >     If there are fewer initializers in a brace-enclosed list than there
> >     are elements or members of an aggregate, or fewer characters in a
> >     string literal used to initialize an array of known size than there
> >     are elements in the array, the remainder of the aggregate shall be
> >     initialized implicitly the same as objects that have static storage
> >     duration.
> 
> which is what? zero?

We don't care, since "found_path" is not used (read) in this code path.
It should be fine to leave it uninitialized.

> 
> >
> >>
> >>>+	};
> >>>
> >>>   	if (hex) {
> >>>   		if (get_sha1_hex(hex, sha1)){
> >>>@@ -81,9 +93,7 @@ void cgit_print_blob(const char *hex, char *path, const char *head)
> >>>
> >>>   	if((!hex) && type == OBJ_COMMIT && path) {
> >>>   		commit = lookup_commit_reference(sha1);
> >>>-		match_path = path;
> >>>-		matched_sha1 = sha1;
> >>>-		read_tree_recursive(commit->tree, "", 0, 0, paths, walk_tree, NULL);
> >>>+		read_tree_recursive(commit->tree, "", 0, 0, paths, walk_tree, &walk_tree_ctx);
> >>>   		type = sha1_object_info(sha1,&size);
> >>>   	}
> >>>
> >>>
> >>
> >>--
> >>Ferry Huberts
> 
> -- 
> Ferry Huberts