Merge pull request #2261 from jacquesg/format-patch

Support for format-patch

include/git2/diff.h

@@ -1072,6 +1072,179 @@ GIT_EXTERN(int) git_diff_buffers(
 	git_diff_line_cb line_cb,
 	void *payload);
 
+/**
+ * This is an opaque structure which is allocated by `git_diff_get_stats`.
+ * You are responsible for releasing the object memory when done, using the
+ * `git_diff_stats_free()` function.
+ */
+typedef struct git_diff_stats git_diff_stats;
+
+/**
+ * Formatting options for diff stats
+ */
+typedef enum {
+	/** No stats*/
+	GIT_DIFF_STATS_NONE = 0,
+
+	/** Full statistics, equivalent of `--stat` */
+	GIT_DIFF_STATS_FULL = (1u << 0),
+
+	/** Short statistics, equivalent of `--shortstat` */
+	GIT_DIFF_STATS_SHORT = (1u << 1),
+
+	/** Number statistics, equivalent of `--numstat` */
+	GIT_DIFF_STATS_NUMBER = (1u << 2),
+
+	/** Extended header information such as creations, renames and mode changes, equivalent of `--summary` */
+	GIT_DIFF_STATS_INCLUDE_SUMMARY = (1u << 3),
+} git_diff_stats_format_t;
+
+/**
+ * Accumlate diff statistics for all patches.
+ *
+ * @param out Structure containg the diff statistics.
+ * @param diff A git_diff generated by one of the above functions.
+ * @return 0 on success; non-zero on error
+ */
+GIT_EXTERN(int) git_diff_get_stats(
+	git_diff_stats **out,
+	git_diff *diff);
+
+/**
+ * Get the total number of files changed in a diff
+ *
+ * @param stats A `git_diff_stats` generated by one of the above functions.
+ * @return total number of files changed in the diff
+ */
+GIT_EXTERN(size_t) git_diff_stats_files_changed(
+	const git_diff_stats *stats);
+
+/**
+ * Get the total number of insertions in a diff
+ *
+ * @param stats A `git_diff_stats` generated by one of the above functions.
+ * @return total number of insertions in the diff
+ */
+GIT_EXTERN(size_t) git_diff_stats_insertions(
+	const git_diff_stats *stats);
+
+/**
+ * Get the total number of deletions in a diff
+ *
+ * @param stats A `git_diff_stats` generated by one of the above functions.
+ * @return total number of deletions in the diff
+ */
+GIT_EXTERN(size_t) git_diff_stats_deletions(
+	const git_diff_stats *stats);
+
+/**
+ * Print diff statistics to a `git_buf`.
+ *
+ * @param out buffer to store the formatted diff statistics in.
+ * @param stats A `git_diff_stats` generated by one of the above functions.
+ * @param format Formatting option.
+ * @return 0 on success; non-zero on error
+ */
+GIT_EXTERN(int) git_diff_stats_to_buf(
+	git_buf *out,
+	const git_diff_stats *stats,
+	git_diff_stats_format_t format);
+
+/**
+ * Deallocate a `git_diff_stats`.
+ *
+ * @param stats The previously created statistics object;
+ * cannot be used after free.
+ */
+GIT_EXTERN(void) git_diff_stats_free(git_diff_stats *stats);
+
+/**
+ * Formatting options for diff e-mail generation
+ */
+typedef enum {
+	/** Normal patch, the default */
+	GIT_DIFF_FORMAT_EMAIL_NONE = 0,
+
+	/** Don't insert "[PATCH]" in the subject header*/
+	GIT_DIFF_FORMAT_EMAIL_EXCLUDE_SUBJECT_PATCH_MARKER = (1 << 0),
+
+} git_diff_format_email_flags_t;
+
+/**
+ * Options for controlling the formatting of the generated e-mail.
+ */
+typedef struct {
+	unsigned int version;
+
+	git_diff_format_email_flags_t flags;
+
+	/** This patch number */
+	size_t patch_no;
+
+	/** Total number of patches in this series */
+	size_t total_patches;
+
+	/** id to use for the commit */
+	const git_oid *id;
+
+	/** Summary of the change */
+	const char *summary;
+
+	/** Author of the change */
+	const git_signature *author;
+} git_diff_format_email_options;
+
+#define GIT_DIFF_FORMAT_EMAIL_OPTIONS_VERSION 1
+#define GIT_DIFF_FORMAT_EMAIL_OPTIONS_INIT {GIT_DIFF_FORMAT_EMAIL_OPTIONS_VERSION, 0, 1, 1, NULL, NULL, NULL}
+
+/**
+ * Create an e-mail ready patch from a diff.
+ *
+ * @param out buffer to store the e-mail patch in
+ * @param diff containing the commit
+ * @param opts structure with options to influence content and formatting.
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_diff_format_email(
+	git_buf *out,
+	git_diff *diff,
+	const git_diff_format_email_options *opts);
+
+/**
+ * Create an e-mail ready patch for a commit.
+ *
+ * Does not support creating patches for merge commits (yet).
+ *
+ * @param out buffer to store the e-mail patch in
+ * @param repo containing the commit
+ * @param commit pointer to up commit
+ * @param patch_no patch number of the commit
+ * @param total_patches total number of patches in the patch set
+ * @param flags determines the formatting of the e-mail
+ * @param diff_opts structure with options to influence diff or NULL for defaults.
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_diff_commit_as_email(
+	git_buf *out,
+	git_repository *repo,
+	git_commit *commit,
+	size_t patch_no,
+	size_t total_patches,
+	git_diff_format_email_flags_t flags,
+	const git_diff_options *diff_opts);
+
+/**
+* Initializes a `git_diff_format_email_options` with default values. Equivalent to
+* creating an instance with GIT_DIFF_FORMAT_EMAIL_OPTIONS_INIT.
+*
+* @param opts the `git_diff_format_email_options` instance to initialize.
+* @param version the version of the struct; you should pass
+* `GIT_DIFF_FORMAT_EMAIL_OPTIONS_VERSION` here.
+* @return Zero on success; -1 on failure.
+*/
+GIT_EXTERN(int) git_diff_format_email_init_options(
+	git_diff_format_email_options *opts,
+	int version);
 
 GIT_END_DECL
 

include/git2/patch.h

@@ -141,12 +141,12 @@ GIT_EXTERN(void) git_patch_free(git_patch *patch);
 /**
  * Get the delta associated with a patch
  */
-GIT_EXTERN(const git_diff_delta *) git_patch_get_delta(git_patch *patch);
+GIT_EXTERN(const git_diff_delta *) git_patch_get_delta(const git_patch *patch);
 
 /**
  * Get the number of hunks in a patch
  */
-GIT_EXTERN(size_t) git_patch_num_hunks(git_patch *patch);
+GIT_EXTERN(size_t) git_patch_num_hunks(const git_patch *patch);
 
 /**
  * Get line counts of each type in a patch.
@@ -197,7 +197,7 @@ GIT_EXTERN(int) git_patch_get_hunk(
  * @return Number of lines in hunk or -1 if invalid hunk index
  */
 GIT_EXTERN(int) git_patch_num_lines_in_hunk(
-	git_patch *patch,
+	const git_patch *patch,
 	size_t hunk_idx);
 
 /**

src/buffer.c

@@ -148,6 +148,15 @@ int git_buf_putc(git_buf *buf, char c)
 	return 0;
 }
 
+int git_buf_putcn(git_buf *buf, char c, size_t len)
+{
+	ENSURE_SIZE(buf, buf->size + len + 1);
+	memset(buf->ptr + buf->size, c, len);
+	buf->size += len;
+	buf->ptr[buf->size] = '\0';
+	return 0;
+}
+
 int git_buf_put(git_buf *buf, const char *data, size_t len)
 {
 	ENSURE_SIZE(buf, buf->size + len + 1);

src/buffer.h

@@ -88,6 +88,7 @@ GIT_INLINE(bool) git_buf_oom(const git_buf *buf)
  */
 int git_buf_sets(git_buf *buf, const char *string);
 int git_buf_putc(git_buf *buf, char c);
+int git_buf_putcn(git_buf *buf, char c, size_t len);
 int git_buf_put(git_buf *buf, const char *data, size_t len);
 int git_buf_puts(git_buf *buf, const char *string);
 int git_buf_printf(git_buf *buf, const char *format, ...) GIT_FORMAT_PRINTF(2, 3);

src/date.c

@@ -874,3 +874,31 @@ int git__date_parse(git_time_t *out, const char *date)
 	*out = approxidate_str(date, time_sec, &error_ret);
    return error_ret;
 }
+
+int git__date_rfc2822_fmt(char *out, size_t len, const git_time *date)
+{
+	int written;
+	struct tm gmt;
+	time_t t;
+
+	assert(out && date);
+
+	t = (time_t) (date->time + date->offset * 60);
+
+	if (p_gmtime_r (&t, &gmt) == NULL)
+		return -1;
+
+	written = p_snprintf(out, len, "%.3s, %u %.3s %.4u %02u:%02u:%02u %+03d%02d",
+		weekday_names[gmt.tm_wday],
+		gmt.tm_mday,
+		month_names[gmt.tm_mon],
+		gmt.tm_year + 1900,
+		gmt.tm_hour, gmt.tm_min, gmt.tm_sec,
+		date->offset / 60, date->offset % 60);
+
+	if (written < 0 || (written > (int) len - 1))
+		return -1;
+
+	return 0;
+}
+

src/diff.c

@@ -1427,6 +1427,216 @@ int git_diff__paired_foreach(
 	return error;
 }
 
+int git_diff__commit(
+	git_diff **diff,
+	git_repository *repo,
+	const git_commit *commit,
+	const git_diff_options *opts)
+{
+	git_commit *parent = NULL;
+	git_diff *commit_diff = NULL;
+	git_tree *old_tree = NULL, *new_tree = NULL;
+	size_t parents;
+	int error = 0;
+
+	if ((parents = git_commit_parentcount(commit)) > 1) {
+		char commit_oidstr[GIT_OID_HEXSZ + 1];
+
+		error = -1;
+		giterr_set(GITERR_INVALID, "Commit %s is a merge commit",
+			git_oid_tostr(commit_oidstr, GIT_OID_HEXSZ + 1, git_commit_id(commit)));
+		goto on_error;
+	}
+
+	if (parents > 0)
+		if ((error = git_commit_parent(&parent, commit, 0)) < 0 ||
+			(error = git_commit_tree(&old_tree, parent)) < 0)
+				goto on_error;
+
+	if ((error = git_commit_tree(&new_tree, commit)) < 0 ||
+		(error = git_diff_tree_to_tree(&commit_diff, repo, old_tree, new_tree, opts)) < 0)
+			goto on_error;
+
+	*diff = commit_diff;
+
+on_error:
+	git_tree_free(new_tree);
+	git_tree_free(old_tree);
+	git_commit_free(parent);
+
+	return error;
+}
+
+int git_diff_format_email__append_header_tobuf(
+	git_buf *out,
+	const git_oid *id,
+	const git_signature *author,
+	const char *summary,
+	size_t patch_no,
+	size_t total_patches,
+	bool exclude_patchno_marker)
+{
+	char idstr[GIT_OID_HEXSZ + 1];
+	char date_str[GIT_DATE_RFC2822_SZ];
+	int error = 0;
+
+	git_oid_fmt(idstr, id);
+	idstr[GIT_OID_HEXSZ] = '\0';
+
+	if ((error = git__date_rfc2822_fmt(date_str, sizeof(date_str), &author->when)) < 0)
+		return error;
+
+	error = git_buf_printf(out,
+				"From %s Mon Sep 17 00:00:00 2001\n" \
+				"From: %s <%s>\n" \
+				"Date: %s\n" \
+				"Subject: ",
+				idstr,
+				author->name, author->email,
+				date_str);
+
+	if (error < 0)
+		return error;
+
+	if (!exclude_patchno_marker) {
+		if (total_patches == 1) {
+			error = git_buf_puts(out, "[PATCH] ");
+		} else {
+			error = git_buf_printf(out, "[PATCH %"PRIuZ"/%"PRIuZ"] ", patch_no, total_patches);
+		}
+
+		if (error < 0)
+			return error;
+	}
+
+	error = git_buf_printf(out, "%s\n\n", summary);
+
+	return error;
+}
+
+int git_diff_format_email__append_patches_tobuf(
+	git_buf *out,
+	git_diff *diff)
+{
+	size_t i, deltas;
+	int error = 0;
+
+	deltas = git_diff_num_deltas(diff);
+
+	for (i = 0; i < deltas; ++i) {
+		git_patch *patch = NULL;
+
+		if ((error = git_patch_from_diff(&patch, diff, i)) >= 0)
+			error = git_patch_to_buf(out, patch);
+
+		git_patch_free(patch);
+
+		if (error < 0)
+			break;
+	}
+
+	return error;
+}
+
+int git_diff_format_email(
+	git_buf *out,
+	git_diff *diff,
+	const git_diff_format_email_options *opts)
+{
+	git_diff_stats *stats = NULL;
+	char *summary = NULL, *loc = NULL;
+	bool ignore_marker;
+	unsigned int format_flags = 0;
+	int error;
+
+	assert(out && diff && opts);
+	assert(opts->summary && opts->id && opts->author);
+
+	GITERR_CHECK_VERSION(opts, GIT_DIFF_FORMAT_EMAIL_OPTIONS_VERSION, "git_format_email_options");
+
+	if ((ignore_marker = opts->flags & GIT_DIFF_FORMAT_EMAIL_EXCLUDE_SUBJECT_PATCH_MARKER) == false) {
+		if (opts->patch_no > opts->total_patches) {
+			giterr_set(GITERR_INVALID, "patch %"PRIuZ" out of range. max %"PRIuZ, opts->patch_no, opts->total_patches);
+			return -1;
+		}
+
+		if (opts->patch_no == 0) {
+			giterr_set(GITERR_INVALID, "invalid patch no %"PRIuZ". should be >0", opts->patch_no);
+			return -1;
+		}
+	}
+
+	/* the summary we receive may not be clean.
+	 * it could potentially contain new line characters
+	 * or not be set, sanitize, */
+	if ((loc = strpbrk(opts->summary, "\r\n")) != NULL) {
+		size_t offset = 0;
+
+		if ((offset = (loc - opts->summary)) == 0) {
+			giterr_set(GITERR_INVALID, "summary is empty");
+			error = -1;
+		}
+
+		summary = git__calloc(offset + 1, sizeof(char));
+		GITERR_CHECK_ALLOC(summary);
+		strncpy(summary, opts->summary, offset);
+	}
+
+	error = git_diff_format_email__append_header_tobuf(out,
+				opts->id, opts->author, summary == NULL ? opts->summary : summary,
+				opts->patch_no, opts->total_patches, ignore_marker);
+
+	if (error < 0)
+		goto on_error;
+
+	format_flags = GIT_DIFF_STATS_FULL | GIT_DIFF_STATS_INCLUDE_SUMMARY;
+
+	if ((error = git_buf_puts(out, "---\n")) < 0 ||
+		(error = git_diff_get_stats(&stats, diff)) < 0 ||
+		(error = git_diff_stats_to_buf(out, stats, format_flags)) < 0 ||
+		(error = git_diff_format_email__append_patches_tobuf(out, diff)) < 0)
+			goto on_error;
+
+	error = git_buf_puts(out, "--\nlibgit2 " LIBGIT2_VERSION "\n\n");
+
+on_error:
+	git__free(summary);
+	git_diff_stats_free(stats);
+
+	return error;
+}
+
+int git_diff_commit_as_email(
+	git_buf *out,
+	git_repository *repo,
+	git_commit *commit,
+	size_t patch_no,
+	size_t total_patches,
+	git_diff_format_email_flags_t flags,
+	const git_diff_options *diff_opts)
+{
+	git_diff *diff = NULL;
+	git_diff_format_email_options opts = GIT_DIFF_FORMAT_EMAIL_OPTIONS_INIT;
+	int error;
+
+	assert (out && repo && commit);
+
+	opts.flags = flags;
+	opts.patch_no = patch_no;
+	opts.total_patches = total_patches;
+	opts.id = git_commit_id(commit);
+	opts.summary = git_commit_summary(commit);
+	opts.author = git_commit_author(commit);
+
+	if ((error = git_diff__commit(&diff, repo, commit, diff_opts)) < 0)
+		return error;
+
+	error = git_diff_format_email(out, diff, &opts);
+
+	git_diff_free(diff);
+	return error;
+}
+
 int git_diff_init_options(git_diff_options* opts, int version)
 {
 	if (version != GIT_DIFF_OPTIONS_VERSION) {
@@ -1450,3 +1660,15 @@ int git_diff_find_init_options(git_diff_find_options* opts, int version)
 		return 0;
 	}
 }
+
+int git_diff_format_email_init_options(git_diff_format_email_options* opts, int version)
+{
+	if (version != GIT_DIFF_FORMAT_EMAIL_OPTIONS_VERSION) {
+		giterr_set(GITERR_INVALID, "Invalid version %d for git_diff_format_email_options", version);
+		return -1;
+	} else {
+		git_diff_format_email_options o = GIT_DIFF_FORMAT_EMAIL_OPTIONS_INIT;
+		memcpy(opts, &o, sizeof(o));
+		return 0;
+	}
+}

src/diff.h

@@ -116,6 +116,9 @@ extern void git_diff_find_similar__hashsig_free(void *sig, void *payload);
 extern int git_diff_find_similar__calc_similarity(
 	int *score, void *siga, void *sigb, void *payload);
 
+extern int git_diff__commit(
+	git_diff **diff, git_repository *repo, const git_commit *commit, const git_diff_options *opts);
+
 /*
  * Sometimes a git_diff_file will have a zero size; this attempts to
  * fill in the size without loading the blob if possible.  If that is

src/diff_patch.c

@@ -631,13 +631,13 @@ void git_patch_free(git_patch *patch)
 		GIT_REFCOUNT_DEC(patch, diff_patch_free);
 }
 
-const git_diff_delta *git_patch_get_delta(git_patch *patch)
+const git_diff_delta *git_patch_get_delta(const git_patch *patch)
 {
 	assert(patch);
 	return patch->delta;
 }
 
-size_t git_patch_num_hunks(git_patch *patch)
+size_t git_patch_num_hunks(const git_patch *patch)
 {
 	assert(patch);
 	return git_array_size(patch->hunks);
@@ -708,7 +708,7 @@ int git_patch_get_hunk(
 	return 0;
 }
 
-int git_patch_num_lines_in_hunk(git_patch *patch, size_t hunk_idx)
+int git_patch_num_lines_in_hunk(const git_patch *patch, size_t hunk_idx)
 {
 	diff_patch_hunk *hunk;
 	assert(patch);

src/diff_stats.c

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#include "common.h"
+#include "vector.h"
+#include "diff.h"
+#include "diff_patch.h"
+
+#define DIFF_RENAME_FILE_SEPARATOR " => "
+
+struct git_diff_stats {
+	git_vector patches;
+
+	size_t files_changed;
+	size_t insertions;
+	size_t deletions;
+};
+
+static size_t diff_get_filename_padding(
+	int has_renames,
+	const git_diff_stats *stats)
+{
+	const git_patch *patch = NULL;
+	size_t i, max_padding = 0;
+
+	if (has_renames) {
+		git_vector_foreach(&stats->patches, i, patch) {
+			const git_diff_delta *delta = NULL;
+			size_t len;
+
+			delta = git_patch_get_delta(patch);
+			if (strcmp(delta->old_file.path, delta->new_file.path) == 0)
+				continue;
+
+			if ((len = strlen(delta->old_file.path) + strlen(delta->new_file.path)) > max_padding)
+				max_padding = len;
+		}
+	}
+
+	git_vector_foreach(&stats->patches, i, patch) {
+		const git_diff_delta *delta = NULL;
+		size_t len;
+
+		delta = git_patch_get_delta(patch);
+		len = strlen(delta->new_file.path);
+
+		if (strcmp(delta->old_file.path, delta->new_file.path) != 0)
+			continue;
+
+		if (len > max_padding)
+			max_padding = len;
+	}
+
+	return max_padding;
+}
+
+int git_diff_file_stats__full_to_buf(
+	git_buf *out,
+	size_t max_padding,
+	int has_renames,
+	const git_patch *patch)
+{
+	const char *old_path = NULL, *new_path = NULL;
+	const git_diff_delta *delta = NULL;
+	size_t padding, old_size, new_size;
+	int error;
+
+	delta = git_patch_get_delta(patch);
+
+	old_path = delta->old_file.path;
+	new_path = delta->new_file.path;
+	old_size = delta->old_file.size;
+	new_size = delta->new_file.size;
+
+	if ((error = git_buf_printf(out, " %s", old_path)) < 0)
+		goto on_error;
+
+	if (strcmp(old_path, new_path) != 0) {
+		padding = max_padding - strlen(old_path) - strlen(new_path);
+
+		if ((error = git_buf_printf(out, DIFF_RENAME_FILE_SEPARATOR "%s", new_path)) < 0)
+			goto on_error;
+	}
+	else {
+		padding = max_padding - strlen(old_path);
+
+		if (has_renames)
+			padding += strlen(DIFF_RENAME_FILE_SEPARATOR);
+	}
+
+	if ((error = git_buf_putcn(out, ' ', padding)) < 0 ||
+		(error = git_buf_puts(out, " | ")) < 0)
+			goto on_error;
+
+	if (delta->flags & GIT_DIFF_FLAG_BINARY) {
+		if ((error = git_buf_printf(out, "Bin %" PRIuZ " -> %" PRIuZ " bytes", old_size, new_size)) < 0)
+			goto on_error;
+	}
+	else {
+		size_t insertions, deletions;
+
+		if ((error = git_patch_line_stats(NULL, &insertions, &deletions, patch)) < 0)
+			goto on_error;
+
+		if ((error = git_buf_printf(out, "%" PRIuZ, insertions + deletions)) < 0)
+			goto on_error;
+
+		if (insertions || deletions) {
+			if ((error = git_buf_putc(out, ' ')) < 0 ||
+				(error = git_buf_putcn(out, '+', insertions)) < 0 ||
+				(error = git_buf_putcn(out, '-', deletions)) < 0)
+					goto on_error;
+		}
+	}
+
+	error = git_buf_putc(out, '\n');
+
+on_error:
+	return error;
+}
+
+int git_diff_file_stats__number_to_buf(
+	git_buf *out,
+	const git_patch *patch)
+{
+	const git_diff_delta *delta = NULL;
+	const char *path = NULL;
+	size_t insertions, deletions;
+	int error;
+
+	delta = git_patch_get_delta(patch);
+	path = delta->new_file.path;
+
+	if ((error = git_patch_line_stats(NULL, &insertions, &deletions, patch)) < 0)
+		return error;
+
+	if (delta->flags & GIT_DIFF_FLAG_BINARY)
+		error = git_buf_printf(out, "%-8c" "%-8c" "%s\n", '-', '-', path);
+	else
+		error = git_buf_printf(out, "%-8" PRIuZ "%-8" PRIuZ "%s\n", insertions, deletions, path);
+
+	return error;
+}
+
+int git_diff_file_stats__summary_to_buf(
+	git_buf *out,
+	const git_patch *patch)
+{
+	const git_diff_delta *delta = NULL;
+
+	delta = git_patch_get_delta(patch);
+
+	if (delta->old_file.mode != delta->new_file.mode) {
+		if (delta->old_file.mode == 0) {
+			git_buf_printf(out, " create mode %06o %s\n",
+				delta->new_file.mode, delta->new_file.path);
+		}
+		else if (delta->new_file.mode == 0) {
+			git_buf_printf(out, " delete mode %06o %s\n",
+				delta->old_file.mode, delta->old_file.path);
+		}
+		else {
+			git_buf_printf(out, " mode change %06o => %06o %s\n",
+				delta->old_file.mode, delta->new_file.mode, delta->new_file.path);
+		}
+	}
+
+	return 0;
+}
+
+int git_diff_stats__has_renames(
+	const git_diff_stats *stats)
+{
+	git_patch *patch = NULL;
+	size_t i;
+
+	git_vector_foreach(&stats->patches, i, patch) {
+		const git_diff_delta *delta = git_patch_get_delta(patch);
+
+		if (strcmp(delta->old_file.path, delta->new_file.path) != 0) {
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int git_diff_stats__add_file_stats(
+	git_diff_stats *stats,
+	git_patch *patch)
+{
+	const git_diff_delta *delta = NULL;
+	int error = 0;
+
+	if ((delta = git_patch_get_delta(patch)) == NULL)
+		return -1;
+
+	if ((error = git_vector_insert(&stats->patches, patch)) < 0)
+		return error;
+
+	return error;
+}
+
+int git_diff_get_stats(
+	git_diff_stats **out,
+	git_diff *diff)
+{
+	size_t i, deltas;
+	size_t total_insertions = 0, total_deletions = 0;
+	git_diff_stats *stats = NULL;
+	int error = 0;
+
+	assert(out && diff);
+
+	stats = git__calloc(1, sizeof(git_diff_stats));
+	GITERR_CHECK_ALLOC(stats);
+
+	deltas = git_diff_num_deltas(diff);
+
+	for (i = 0; i < deltas; ++i) {
+		git_patch *patch = NULL;
+		size_t add, remove;
+
+		if ((error = git_patch_from_diff(&patch, diff, i)) < 0)
+			goto on_error;
+
+		if ((error = git_patch_line_stats(NULL, &add, &remove, patch)) < 0 ||
+			(error = git_diff_stats__add_file_stats(stats, patch)) < 0) {
+			git_patch_free(patch);
+			goto on_error;
+		}
+
+		total_insertions += add;
+		total_deletions += remove;
+	}
+
+	stats->files_changed = deltas;
+	stats->insertions = total_insertions;
+	stats->deletions = total_deletions;
+
+	*out = stats;
+
+	goto done;
+
+on_error:
+	git_diff_stats_free(stats);
+
+done:
+	return error;
+}
+
+size_t git_diff_stats_files_changed(
+	const git_diff_stats *stats)
+{
+	assert(stats);
+
+	return stats->files_changed;
+}
+
+size_t git_diff_stats_insertions(
+	const git_diff_stats *stats)
+{
+	assert(stats);
+
+	return stats->insertions;
+}
+
+size_t git_diff_stats_deletions(
+	const git_diff_stats *stats)
+{
+	assert(stats);
+
+	return stats->deletions;
+}
+
+int git_diff_stats_to_buf(
+	git_buf *out,
+	const git_diff_stats *stats,
+	git_diff_stats_format_t format)
+{
+	git_patch *patch = NULL;
+	size_t i;
+	int has_renames = 0, error = 0;
+
+	assert(out && stats);
+
+	/* check if we have renames, it affects the padding */
+	has_renames = git_diff_stats__has_renames(stats);
+
+	git_vector_foreach(&stats->patches, i, patch) {
+		if (format & GIT_DIFF_STATS_FULL) {
+			size_t max_padding = diff_get_filename_padding(has_renames, stats);
+
+			error = git_diff_file_stats__full_to_buf(out, max_padding, has_renames, patch);
+		}
+		else if (format & GIT_DIFF_STATS_NUMBER) {
+			error = git_diff_file_stats__number_to_buf(out, patch);
+		}
+
+		if (error < 0)
+			return error;
+	}
+
+	if (format & GIT_DIFF_STATS_FULL || format & GIT_DIFF_STATS_SHORT) {
+		error = git_buf_printf(out, " %" PRIuZ " file%s changed, %" PRIuZ " insertions(+), %" PRIuZ " deletions(-)\n",
+					stats->files_changed, stats->files_changed > 1 ? "s" : "",
+					stats->insertions, stats->deletions);
+
+		if (error < 0)
+			return error;
+	}
+
+	if (format & GIT_DIFF_STATS_INCLUDE_SUMMARY) {
+		git_vector_foreach(&stats->patches, i, patch) {
+			if ((error = git_diff_file_stats__summary_to_buf(out, patch)) < 0)
+				return error;
+		}
+
+		if (git_vector_length(&stats->patches) > 0)
+			git_buf_putc(out, '\n');
+	}
+
+	return error;
+}
+
+void git_diff_stats_free(git_diff_stats *stats)
+{
+	size_t i;
+	git_patch *patch;
+
+	if (stats == NULL)
+		return;
+
+	git_vector_foreach(&stats->patches, i, patch)
+		git_patch_free(patch);
+
+	git_vector_free(&stats->patches);
+	git__free(stats);
+}
+

src/util.h

@@ -20,6 +20,8 @@
 # define max(a,b) ((a) > (b) ? (a) : (b))
 #endif
 
+#define GIT_DATE_RFC2822_SZ  32
+
 /*
  * Custom memory allocation wrappers
  * that set error code and error message
@@ -329,6 +331,16 @@ extern int git__parse_bool(int *out, const char *value);
 extern int git__date_parse(git_time_t *out, const char *date);
 
 /*
+ * Format a git_time as a RFC2822 string
+ *
+ * @param out buffer to store formatted date; a '\\0' terminator will automatically be added.
+ * @param len size of the buffer; should be atleast `GIT_DATE_RFC2822_SZ` in size;
+ * @param date the date to be formatted
+ * @return 0 if successful; -1 on error
+ */
+extern int git__date_rfc2822_fmt(char *out, size_t len, const git_time *date);
+
+/*
  * Unescapes a string in-place.
  *
  * Edge cases behavior:

tests/date/rfc2822.c

+#include "clar_libgit2.h"
+
+#include "util.h"
+
+void test_date_rfc2822__format_rfc2822_no_offset(void)
+{
+	git_time t = {1397031663, 0};
+	char buf[GIT_DATE_RFC2822_SZ];
+
+	cl_git_pass(git__date_rfc2822_fmt(buf, sizeof(buf), &t));
+	cl_assert(strcmp(buf, "Wed, 9 Apr 2014 08:21:03 +0000") == 0);
+}
+
+void test_date_rfc2822__format_rfc2822_positive_offset(void)
+{
+	git_time t = {1397031663, 120};
+	char buf[GIT_DATE_RFC2822_SZ];
+
+	cl_git_pass(git__date_rfc2822_fmt(buf, sizeof(buf), &t));
+	cl_assert(strcmp(buf, "Wed, 9 Apr 2014 10:21:03 +0200") == 0);
+}
+
+void test_date_rfc2822__format_rfc2822_negative_offset(void)
+{
+	git_time t = {1397031663, -120};
+	char buf[GIT_DATE_RFC2822_SZ];
+
+	cl_git_pass(git__date_rfc2822_fmt(buf, sizeof(buf), &t));
+	cl_assert(strcmp(buf, "Wed, 9 Apr 2014 06:21:03 -0200") == 0);
+}
+
+void test_date_rfc2822__format_rfc2822_buffer_too_small(void)
+{
+	// "Wed, 10 Apr 2014 08:21:03 +0000"
+	git_time t = {1397031663 + 86400, 0};
+	char buf[GIT_DATE_RFC2822_SZ-1];
+
+	cl_git_fail(git__date_rfc2822_fmt(buf, sizeof(buf), &t));
+}
+

tests/resources/diff_format_email/.gitted/HEAD

+ref: refs/heads/master

tests/resources/diff_format_email/.gitted/config

+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = false
+	logallrefupdates = true
+	ignorecase = true
+	precomposeunicode = true

tests/resources/diff_format_email/.gitted/info/exclude

+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

tests/resources/diff_format_email/.gitted/refs/heads/binary

+a3ac918e3a6604294b239cb956363e83d71abb3b

tests/resources/diff_format_email/.gitted/refs/heads/master

+873806f6f27e631eb0b23e4b56bea2bfac14a373

tests/resources/diff_format_email/.gitted/refs/heads/multihunk

+cd471f0d8770371e1bc78bcbb38db4c7e4106bd2

tests/resources/diff_format_email/.gitted/refs/heads/rename

+4ca10087e696d2ba78d07b146a118e9a7096ed4f

tests/resources/diff_format_email/file1.txt.renamed

+file1.txt
+file1.txt
+_file1.txt_
+file1.txt
+file1.txt
+file1.txt_renamed
+file1.txt
+
+
+file1.txt
+file1.txt
+file1.txt_renamed
+file1.txt
+file1.txt
+_file1.txt_
+_file1.txt_
+file1.txt