patchsubmodule recursion in git-archive

.gitignore, Makefile, submodule-config-cache.c, submodule-config-cache.h, submodule.c, submodule.h, test-submodule-config-cache.c

diff --git a/.gitignore b/.gitignore
index 66199ed..6c91e98 100644
--- a/.gitignore
+++ b/.gitignore
@@ -200,6 +200,7 @@
 /test-sha1
 /test-sigchain
 /test-string-list
+/test-submodule-config-cache
 /test-subprocess
 /test-svn-fe
 /test-urlmatch-normalization
diff --git a/Makefile b/Makefile
index af847f8..e3d869b 100644
--- a/Makefile
+++ b/Makefile
@@ -572,6 +572,7 @@ TEST_PROGRAMS_NEED_X += test-scrap-cache-tree
 TEST_PROGRAMS_NEED_X += test-sha1
 TEST_PROGRAMS_NEED_X += test-sigchain
 TEST_PROGRAMS_NEED_X += test-string-list
+TEST_PROGRAMS_NEED_X += test-submodule-config-cache
 TEST_PROGRAMS_NEED_X += test-subprocess
 TEST_PROGRAMS_NEED_X += test-svn-fe
 TEST_PROGRAMS_NEED_X += test-urlmatch-normalization
@@ -872,6 +873,7 @@ LIB_OBJS += strbuf.o
 LIB_OBJS += streaming.o
 LIB_OBJS += string-list.o
 LIB_OBJS += submodule.o
+LIB_OBJS += submodule-config-cache.o
 LIB_OBJS += symlinks.o
 LIB_OBJS += tag.o
 LIB_OBJS += trace.o
diff --git a/submodule-config-cache.c b/submodule-config-cache.c
new file mode 100644
index 0000000..7253fad
--- /dev/null
+++ b/submodule-config-cache.c
@@ -0,0 +1,96 @@
+#include "cache.h"
+#include "submodule-config-cache.h"
+#include "strbuf.h"
+#include "hash.h"
+
+void submodule_config_cache_init(struct submodule_config_cache *cache)
+{
+	init_hash(&cache->for_name);
+	init_hash(&cache->for_path);
+}
+
+static int free_one_submodule_config(void *ptr, void *data)
+{
+	struct submodule_config *entry = ptr;
+
+	strbuf_release(&entry->path);
+	strbuf_release(&entry->name);
+	free(entry);
+
+	return 0;
+}
+
+void submodule_config_cache_free(struct submodule_config_cache *cache)
+{
+	/* NOTE: its important to iterate over the name hash here
+	 * since paths might have multiple entries */
+	for_each_hash(&cache->for_name, free_one_submodule_config, NULL);
+	free_hash(&cache->for_path);
+	free_hash(&cache->for_name);
+}
+
+static unsigned int hash_sha1_string(const unsigned char *sha1, const char *string)
+{
+	int c;
+	unsigned int hash, string_hash = 5381;
+	memcpy(&hash, sha1, sizeof(hash));
+
+	/* djb2 hash */
+	while ((c = *string++))
+		string_hash = ((string_hash << 5) + hash) + c; /* hash * 33 + c */
+
+	return hash + string_hash;
+}
+
+void submodule_config_cache_update_path(struct submodule_config_cache *cache,
+		struct submodule_config *config)
+{
+	void **pos;
+	int hash = hash_sha1_string(config->gitmodule_sha1, config->path.buf);
+	pos = insert_hash(hash, config, &cache->for_path);
+	if (pos) {
+		config->next = *pos;
+		*pos = config;
+	}
+}
+
+void submodule_config_cache_insert(struct submodule_config_cache *cache, struct submodule_config *config)
+{
+	unsigned int hash;
+	void **pos;
+
+	hash = hash_sha1_string(config->gitmodule_sha1, config->name.buf);
+	pos = insert_hash(hash, config, &cache->for_name);
+	if (pos) {
+		config->next = *pos;
+		*pos = config;
+	}
+}
+
+struct submodule_config *submodule_config_cache_lookup_path(struct submodule_config_cache *cache,
+	const unsigned char *gitmodule_sha1, const char *path)
+{
+	unsigned int hash = hash_sha1_string(gitmodule_sha1, path);
+	struct submodule_config *config = lookup_hash(hash, &cache->for_path);
+
+	while (config &&
+		(hashcmp(config->gitmodule_sha1, gitmodule_sha1) ||
+		 strcmp(path, config->path.buf)))
+		config = config->next;
+
+	return config;
+}
+
+struct submodule_config *submodule_config_cache_lookup_name(struct submodule_config_cache *cache,
+	const unsigned char *gitmodule_sha1, const char *name)
+{
+	unsigned int hash = hash_sha1_string(gitmodule_sha1, name);
+	struct submodule_config *config = lookup_hash(hash, &cache->for_name);
+
+	while (config &&
+		(hashcmp(config->gitmodule_sha1, gitmodule_sha1) ||
+		 strcmp(name, config->name.buf)))
+		config = config->next;
+
+	return config;
+}
diff --git a/submodule-config-cache.h b/submodule-config-cache.h
new file mode 100644
index 0000000..7bb79b9
--- /dev/null
+++ b/submodule-config-cache.h
@@ -0,0 +1,33 @@
+#ifndef SUBMODULE_CONFIG_CACHE_H
+#define SUBMODULE_CONFIG_CACHE_H
+
+#include "hash.h"
+#include "strbuf.h"
+
+struct submodule_config_cache {
+	struct hash_table for_path;
+	struct hash_table for_name;
+};
+
+/* one submodule_config_cache entry */
+struct submodule_config {
+	struct strbuf path;
+	struct strbuf name;
+	unsigned char gitmodule_sha1[20];
+	struct submodule_config *next;
+};
+
+void submodule_config_cache_init(struct submodule_config_cache *cache);
+void submodule_config_cache_free(struct submodule_config_cache *cache);
+
+void submodule_config_cache_update_path(struct submodule_config_cache *cache,
+		struct submodule_config *config);
+void submodule_config_cache_insert(struct submodule_config_cache *cache,
+		struct submodule_config *config);
+
+struct submodule_config *submodule_config_cache_lookup_path(struct submodule_config_cache *cache,
+	const unsigned char *gitmodule_sha1, const char *path);
+struct submodule_config *submodule_config_cache_lookup_name(struct submodule_config_cache *cache,
+	const unsigned char *gitmodule_sha1, const char *name);
+
+#endif /* SUBMODULE_CONFIG_CACHE_H */
diff --git a/submodule.c b/submodule.c
index 1905d75..fa9e7ea 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "submodule.h"
+#include "submodule-config-cache.h"
 #include "dir.h"
 #include "diff.h"
 #include "commit.h"
@@ -616,6 +617,130 @@ static int is_submodule_commit_present(const char *path, unsigned char sha1[20])
 	return is_present;
 }
 
+struct parse_submodule_config_parameter {
+	unsigned char *gitmodule_sha1;
+	struct submodule_config_cache *cache;
+};
+
+static int name_and_item_from_var(const char *var, struct strbuf *name, struct strbuf *item)
+{
+	/* find the name and add it */
+	strbuf_addstr(name, var + strlen("submodule."));
+	char *end = strrchr(name->buf, '.');
+	if (!end) {
+		strbuf_release(name);
+		return 0;
+	}
+	*end = '\0';
+	if (((end + 1) - name->buf) < name->len)
+		strbuf_addstr(item, end + 1);
+
+	return 1;
+}
+
+static struct submodule_config *lookup_or_create_by_name(struct submodule_config_cache *cache,
+		unsigned char *gitmodule_sha1, const char *name)
+{
+	struct submodule_config *config;
+	config = submodule_config_cache_lookup_name(cache, gitmodule_sha1, name);
+	if (config)
+		return config;
+
+	config = xmalloc(sizeof(*config));
+
+	strbuf_init(&config->name, 1024);
+	strbuf_addstr(&config->name, name);
+
+	strbuf_init(&config->path, 1024);
+
+	hashcpy(config->gitmodule_sha1, gitmodule_sha1);
+	config->next = NULL;
+
+	submodule_config_cache_insert(cache, config);
+
+	return config;
+}
+
+static void warn_multiple_config(struct submodule_config *config, const char *option)
+{
+	warning("%s:.gitmodules, multiple configurations found for submodule.%s.%s. "
+			"Skipping second one!", sha1_to_hex(config->gitmodule_sha1),
+			option, config->name.buf);
+}
+
+static int parse_submodule_config_into_cache(const char *var, const char *value, void *data)
+{
+	struct parse_submodule_config_parameter *me = data;
+	struct submodule_config *submodule_config;
+	struct strbuf name = STRBUF_INIT, item = STRBUF_INIT;
+
+	/* We only read submodule.<name> entries */
+	if (prefixcmp(var, "submodule."))
+		return 0;
+
+	if (!name_and_item_from_var(var, &name, &item))
+		return 0;
+
+	submodule_config = lookup_or_create_by_name(me->cache, me->gitmodule_sha1, name.buf);
+
+	if (!suffixcmp(var, ".path")) {
+		if (*submodule_config->path.buf != '\0') {
+			warn_multiple_config(submodule_config, "path");
+			return 0;
+		}
+		strbuf_addstr(&submodule_config->path, value);
+		submodule_config_cache_update_path(me->cache, submodule_config);
+	}
+
+	strbuf_release(&name);
+	strbuf_release(&item);
+
+	return 0;
+}
+
+struct submodule_config *get_submodule_config_for_commit_path(struct submodule_config_cache *cache,
+		const unsigned char *commit_sha1, const char *path)
+{
+	struct strbuf rev = STRBUF_INIT;
+	unsigned long config_size;
+	char *config;
+	unsigned char sha1[20];
+	enum object_type type;
+	struct submodule_config *submodule_config = NULL;
+	struct parse_submodule_config_parameter parameter;
+
+
+	strbuf_addf(&rev, "%s:.gitmodules", sha1_to_hex(commit_sha1));
+	if (get_sha1(rev.buf, sha1) < 0)
+		goto free_rev;
+
+	submodule_config = submodule_config_cache_lookup_path(cache, sha1, path);
+	if (submodule_config)
+		goto free_rev;
+
+	config = read_sha1_file(sha1, &type, &config_size);
+	if (!config)
+		goto free_rev;
+
+	if (type != OBJ_BLOB) {
+		free(config);
+		goto free_rev;
+	}
+
+	/* fill the submodule config into the cache */
+	parameter.cache = cache;
+	parameter.gitmodule_sha1 = sha1;
+	git_config_from_buf(parse_submodule_config_into_cache, rev.buf,
+			config, config_size, &parameter);
+	free(config);
+
+	submodule_config = submodule_config_cache_lookup_path(cache, sha1, path);
+
+free_rev:
+	strbuf_release(&rev);
+	return submodule_config;
+}
+
 static void submodule_collect_changed_cb(struct diff_queue_struct *q,
 					 struct diff_options *options,
 					 void *data)
diff --git a/submodule.h b/submodule.h
index 7beec48..a26cc34 100644
--- a/submodule.h
+++ b/submodule.h
@@ -3,6 +3,8 @@
 
 struct diff_options;
 struct argv_array;
+struct submodule_config;
+struct submodule_config_cache;
 
 enum {
 	RECURSE_SUBMODULES_ON_DEMAND = -1,
@@ -41,5 +43,7 @@ int find_unpushed_submodules(unsigned char new_sha1[20], const char *remotes_nam
 		struct string_list *needs_pushing);
 int push_unpushed_submodules(unsigned char new_sha1[20], const char *remotes_name);
 void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir);
+struct submodule_config *get_submodule_config_for_commit_path(struct submodule_config_cache *cache,
+		const unsigned char *commit_sha1, const char *path);
 
 #endif
diff --git a/test-submodule-config-cache.c b/test-submodule-config-cache.c
new file mode 100644
index 0000000..239560f
--- /dev/null
+++ b/test-submodule-config-cache.c
@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "cache.h"
+#include "submodule-config-cache.h"
+#include "submodule.h"
+
+static void die_usage(int argc, char **argv, const char *msg)
+{
+	fprintf(stderr, "%s\n", msg);
+	fprintf(stderr, "Usage: %s <commit> <submodulepath>\n", argv[0]);
+	exit(1);
+}
+
+int main(int argc, char **argv)
+{
+	struct submodule_config_cache submodule_config_cache;
+	struct submodule_config *submodule_config;
+	unsigned char commit_sha1[20];
+	const char *commit;
+	const char *path;
+
+	if (argc < 3)
+		die_usage(argc, argv, "Wrong number of arguments.");
+
+	commit = argv[1];
+	path = argv[2];
+
+	if (get_sha1(commit, commit_sha1) < 0)
+		die_usage(argc, argv, "Commit not found.");
+
+	submodule_config_cache_init(&submodule_config_cache);
+
+	submodule_config = get_submodule_config_for_commit_path(&submodule_config_cache,
+				commit_sha1, path);
+	if (!submodule_config)
+		die_usage(argc, argv, "Submodule config not found.");
+
+	printf("Submodule name: '%s' for path '%s'\n", submodule_config->name.buf, path);
+
+	submodule_config_cache_free(&submodule_config_cache);
+
+	return 0;
+}