Merge pull request #2188 from libgit2/cmn/config-snapshot

Configuration snapshotting

3 files changed, 43 insertions, 3 deletions

diff --git a/include/git2/config.h b/include/git2/config.h
index 663b4f6ba..21a5825a5 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -226,6 +226,22 @@ GIT_EXTERN(int) git_config_open_level(
  */
 GIT_EXTERN(int) git_config_open_global(git_config **out, git_config *config);
 
+/**
+ * Create a snapshot of the configuration
+ *
+ * Create a snapshot of the current state of a configuration, which
+ * allows you to look into a consistent view of the configuration for
+ * looking up complex values (e.g. a remote, submodule).
+ *
+ * The string returned when querying such a config object is valid
+ * until it is freed.
+ *
+ * @param out pointer in which to store the snapshot config object
+ * @param config configuration to snapshot
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_config_snapshot(git_config **out, git_config *config);
+
 
 /**
  * Reload changed config files
@@ -312,7 +328,8 @@ GIT_EXTERN(int) git_config_get_bool(int *out, const git_config *cfg, const char
  * Get the value of a string config variable.
  *
  * The string is owned by the variable and should not be freed by the
- * user.
+ * user. The pointer will be valid until the next operation on this
+ * config object.
  *
  * All config files will be looked into, in the order of their
  * defined level. A higher level means a higher priority. The
@@ -353,6 +370,9 @@ GIT_EXTERN(int) git_config_multivar_iterator_new(git_config_iterator **out, cons
 /**
  * Return the current entry and advance the iterator
  *
+ * The pointers returned by this function are valid until the iterator
+ * is freed.
+ *
  * @param entry pointer to store the entry
  * @param iter the iterator
  * @return 0 or an error code. GIT_ITEROVER if the iteration has completed
@@ -451,6 +471,9 @@ GIT_EXTERN(int) git_config_delete_multivar(git_config *cfg, const char *name, co
  * If the callback returns a non-zero value, the function stops iterating
  * and returns that value to the caller.
  *
+ * The pointers passed to the callback are only valid as long as the
+ * iteration is ongoing.
+ *
  * @param cfg where to get the variables from
  * @param callback the function to call on each variable
  * @param payload the data to pass to the callback
@@ -491,6 +514,9 @@ GIT_EXTERN(int) git_config_iterator_glob_new(git_config_iterator **out, const gi
  * regular expression that filters which config keys are passed to the
  * callback.
  *
+ * The pointers passed to the callback are only valid as long as the
+ * iteration is ongoing.
+ *
  * @param cfg where to get the variables from
  * @param regexp regular expression to match against config names
  * @param callback the function to call on each variable
diff --git a/include/git2/repository.h b/include/git2/repository.h
index 04df25fd3..0f7119b76 100644
--- a/include/git2/repository.h
+++ b/include/git2/repository.h
@@ -408,13 +408,25 @@ GIT_EXTERN(int) git_repository_is_bare(git_repository *repo);
  * The configuration file must be freed once it's no longer
  * being used by the user.
  *
- * @param out Pointer to store the loaded config file
+ * @param out Pointer to store the loaded configuration
  * @param repo A repository object
  * @return 0, or an error code
  */
 GIT_EXTERN(int) git_repository_config(git_config **out, git_repository *repo);
 
 /**
+ * Get a snapshot of the repository's configuration
+ *
+ * Convenience function to take a snapshot from the repository's
+ * configuration.
+ *
+ * @param out Pointer to store the loaded configuration
+ * @param repo the repository
+ * @return 0, or an error code
+ */
+GIT_EXTERN(int) git_repository_config_snapshot(git_config **out, git_repository *repo);
+
+/**
  * Get the Object Database for this repository.
  *
  * If a custom ODB has not been set, the default
diff --git a/include/git2/sys/config.h b/include/git2/sys/config.h
index 46bb65293..85e0d6417 100644
--- a/include/git2/sys/config.h
+++ b/include/git2/sys/config.h
@@ -57,13 +57,15 @@ struct git_config_backend {
 
 	/* Open means open the file/database and parse if necessary */
 	int (*open)(struct git_config_backend *, git_config_level_t level);
-	int (*get)(const struct git_config_backend *, const char *key, const git_config_entry **entry);
+	int (*get)(struct git_config_backend *, const char *key, const git_config_entry **entry);
 	int (*set)(struct git_config_backend *, const char *key, const char *value);
 	int (*set_multivar)(git_config_backend *cfg, const char *name, const char *regexp, const char *value);
 	int (*del)(struct git_config_backend *, const char *key);
 	int (*del_multivar)(struct git_config_backend *, const char *key, const char *regexp);
 	int (*iterator)(git_config_iterator **, struct git_config_backend *);
 	int (*refresh)(struct git_config_backend *);
+	/** Produce a read-only version of this backend */
+	int (*snapshot)(struct git_config_backend **, struct git_config_backend *);
 	void (*free)(struct git_config_backend *);
 };
 #define GIT_CONFIG_BACKEND_VERSION 1