1 files changed, 205 insertions, 0 deletions
diff --git a/trailer.h b/trailer.h
new file mode 100644
index 0000000000..4740549586
--- /dev/null
+++ b/trailer.h
@@ -0,0 +1,205 @@
+#ifndef TRAILER_H
+#define TRAILER_H
+
+#include "list.h"
+#include "strbuf.h"
+
+struct trailer_block;
+struct strvec;
+
+enum trailer_where {
+	WHERE_DEFAULT,
+	WHERE_END,
+	WHERE_AFTER,
+	WHERE_BEFORE,
+	WHERE_START
+};
+enum trailer_if_exists {
+	EXISTS_DEFAULT,
+	EXISTS_ADD_IF_DIFFERENT_NEIGHBOR,
+	EXISTS_ADD_IF_DIFFERENT,
+	EXISTS_ADD,
+	EXISTS_REPLACE,
+	EXISTS_DO_NOTHING
+};
+enum trailer_if_missing {
+	MISSING_DEFAULT,
+	MISSING_ADD,
+	MISSING_DO_NOTHING
+};
+
+int trailer_set_where(enum trailer_where *item, const char *value);
+int trailer_set_if_exists(enum trailer_if_exists *item, const char *value);
+int trailer_set_if_missing(enum trailer_if_missing *item, const char *value);
+
+/*
+ * A list that represents newly-added trailers, such as those provided
+ * with the --trailer command line option of git-interpret-trailers.
+ */
+struct new_trailer_item {
+	struct list_head list;
+
+	const char *text;
+
+	enum trailer_where where;
+	enum trailer_if_exists if_exists;
+	enum trailer_if_missing if_missing;
+};
+
+struct process_trailer_options {
+	int in_place;
+	int trim_empty;
+	int only_trailers;
+	int only_input;
+	int unfold;
+	int no_divider;
+	int key_only;
+	int value_only;
+	const struct strbuf *separator;
+	const struct strbuf *key_value_separator;
+	int (*filter)(const struct strbuf *, void *);
+	void *filter_data;
+};
+
+#define PROCESS_TRAILER_OPTIONS_INIT {0}
+
+void parse_trailers_from_config(struct list_head *config_head);
+
+void parse_trailers_from_command_line_args(struct list_head *arg_head,
+					   struct list_head *new_trailer_head);
+
+void process_trailers_lists(struct list_head *head,
+			    struct list_head *arg_head);
+
+/*
+ * Given some input string "str", return a pointer to an opaque trailer_block
+ * structure. Also populate the trailer_objects list with parsed trailer
+ * objects. Internally this calls trailer_info_get() to get the opaque pointer,
+ * but does some extra work to populate the trailer_objects linked list.
+ *
+ * The opaque trailer_block pointer can be used to check the position of the
+ * trailer block as offsets relative to the beginning of "str" in
+ * trailer_block_start() and trailer_block_end().
+ * blank_line_before_trailer_block() returns 1 if there is a blank line just
+ * before the trailer block. All of these functions are useful for preserving
+ * the input before and after the trailer block, if we were to write out the
+ * original input (but with the trailer block itself modified); see
+ * builtin/interpret-trailers.c for an example.
+ *
+ * For iterating through the parsed trailer block (if you don't care about the
+ * position of the trailer block itself in the context of the larger string text
+ * from which it was parsed), please see trailer_iterator_init() which uses the
+ * trailer_block struct internally.
+ *
+ * Lastly, callers should call trailer_info_release() when they are done using
+ * the opaque pointer.
+ *
+ * NOTE: Callers should treat both trailer_block and trailer_objects as
+ * read-only items, because there is some overlap between the two (trailer_block
+ * has "char **trailers" string array, and trailer_objects will have the same
+ * data but as a linked list of trailer_item objects). This API does not perform
+ * any synchronization between the two. In the future we should be able to
+ * reduce the duplication and use just the linked list.
+ */
+struct trailer_block *parse_trailers(const struct process_trailer_options *,
+				     const char *str,
+				     struct list_head *trailer_objects);
+
+/*
+ * Return the offset of the start of the trailer block. That is, 0 is the start
+ * of the input ("str" in parse_trailers()) and some other positive number
+ * indicates how many bytes we have to skip over before we get to the beginning
+ * of the trailer block.
+ */
+size_t trailer_block_start(struct trailer_block *);
+
+/*
+ * Return the end of the trailer block, again relative to the start of the
+ * input.
+ */
+size_t trailer_block_end(struct trailer_block *);
+
+/*
+ * Return 1 if the trailer block had an extra newline (blank line) just before
+ * it.
+ */
+int blank_line_before_trailer_block(struct trailer_block *);
+
+/*
+ * Free trailer_block struct.
+ */
+void trailer_block_release(struct trailer_block *);
+
+void trailer_config_init(void);
+void format_trailers(const struct process_trailer_options *,
+		     struct list_head *trailers,
+		     struct strbuf *out);
+void free_trailers(struct list_head *);
+
+/*
+ * Convenience function to format the trailers from the commit msg "msg" into
+ * the strbuf "out". Reuses format_trailers() internally.
+ */
+void format_trailers_from_commit(const struct process_trailer_options *,
+				 const char *msg,
+				 struct strbuf *out);
+
+/*
+ * An interface for iterating over the trailers found in a particular commit
+ * message. Use like:
+ *
+ *   struct trailer_iterator iter;
+ *   trailer_iterator_init(&iter, msg);
+ *   while (trailer_iterator_advance(&iter))
+ *      ... do something with iter.key and iter.val ...
+ *   trailer_iterator_release(&iter);
+ */
+struct trailer_iterator {
+	/*
+	 * Raw line (e.g., "foo: bar baz") before being parsed as a trailer
+	 * key/val pair as part of a trailer block (as the "key" and "val"
+	 * fields below). If a line fails to parse as a trailer, then the "key"
+	 * will be the entire line and "val" will be the empty string.
+	 */
+	const char *raw;
+	struct strbuf key;
+	struct strbuf val;
+
+	/* private */
+	struct {
+		struct trailer_block *trailer_block;
+		size_t cur;
+	} internal;
+};
+
+/*
+ * Initialize "iter" in preparation for walking over the trailers in the commit
+ * message "msg". The "msg" pointer must remain valid until the iterator is
+ * released.
+ *
+ * After initializing, note that key/val will not yet point to any trailer.
+ * Call advance() to parse the first one (if any).
+ */
+void trailer_iterator_init(struct trailer_iterator *iter, const char *msg);
+
+/*
+ * Advance to the next trailer of the iterator. Returns 0 if there is no such
+ * trailer, and 1 otherwise. The key and value of the trailer can be
+ * fetched from the iter->key and iter->value fields (which are valid
+ * only until the next advance).
+ */
+int trailer_iterator_advance(struct trailer_iterator *iter);
+
+/*
+ * Release all resources associated with the trailer iteration.
+ */
+void trailer_iterator_release(struct trailer_iterator *iter);
+
+/*
+ * Augment a file to add trailers to it by running git-interpret-trailers.
+ * This calls run_command() and its return value is the same (i.e. 0 for
+ * success, various non-zero for other errors). See run-command.h.
+ */
+int amend_file_with_trailers(const char *path, const struct strvec *trailer_args);
+
+#endif /* TRAILER_H */