[PATCH v5 00/44] Make git-am a builtin

@@ -71,8 +71,8 @@ static int linelen(const char *msg)
  */
 static int str_isspace(const char *str)
 {
-	while (*str)
-		if (!isspace(*(str)++))
+	for (; *str; str++)
+		if (!isspace(*str))
 			return 0;
 
 	return 1;

@@ -94,8 +94,8 @@ enum keep_type {
 
 enum scissors_type {
 	SCISSORS_UNSET = -1,
-	SCISSORS_TRUE,  /* pass --scissors to git-mailinfo */
-	SCISSORS_FALSE  /* pass --no-scissors to git-mailinfo */
+	SCISSORS_FALSE = 0,  /* pass --no-scissors to git-mailinfo */
+	SCISSORS_TRUE        /* pass --scissors to git-mailinfo */
 };
 
 struct am_state {

@@ -160,8 +160,7 @@ struct am_state {
  */
 static void am_state_init(struct am_state *state, const char *dir)
 {
-	const char *quiet;
-	int sign_commit;
+	int gpgsign;
 
 	memset(state, 0, sizeof(*state));
 

@@ -172,10 +171,6 @@ static void am_state_init(struct am_state *state, const char *dir)
 
 	git_config_get_bool("am.threeway", &state->threeway);
 
-	quiet = getenv("GIT_QUIET");
-	if (quiet && *quiet)
-		state->quiet = 1;
-
 	state->utf8 = 1;
 
 	git_config_get_bool("am.messageid", &state->message_id);

@@ -184,8 +179,8 @@ static void am_state_init(struct am_state *state, const char *dir)
 
 	argv_array_init(&state->git_apply_opts);
 
-	if (!git_config_get_bool("commit.gpgsign", &sign_commit))
-		state->sign_commit = sign_commit ? "" : NULL;
+	if (!git_config_get_bool("commit.gpgsign", &gpgsign))
+		state->sign_commit = gpgsign ? "" : NULL;
 }
 
 /**

@@ -918,7 +913,7 @@ static int hg_patch_to_mail(FILE *out, FILE *in, int keep_cr)
 			fprintf(out, "From: %s\n", str);
 		else if (skip_prefix(sb.buf, "# Date ", &str)) {
 			unsigned long timestamp;
-			long tz;
+			long tz, tz2;
 			char *end;
 
 			errno = 0;

@@ -942,10 +937,11 @@ static int hg_patch_to_mail(FILE *out, FILE *in, int keep_cr)
 			 * however git's timezone is in hours + minutes east of
 			 * UTC. Convert it.
 			 */
-			tz = tz / (60 * 60) * 100 + tz % (60 * 60);
-			tz = -tz;
+			tz2 = labs(tz) / 3600 * 100 + labs(tz) % 3600 / 60;
+			if (tz > 0)
+				tz2 = -tz2;
 
-			fprintf(out, "Date: %s\n", show_date(timestamp, tz, DATE_RFC2822));
+			fprintf(out, "Date: %s\n", show_date(timestamp, tz2, DATE_RFC2822));
 		} else if (starts_with(sb.buf, "# ")) {
 			continue;
 		} else {

@@ -1555,7 +1551,7 @@ static int run_apply(const struct am_state *state, const char *index_file)
 }
 
 /**
- * Builds a index that contains just the blobs needed for a 3way merge.
+ * Builds an index that contains just the blobs needed for a 3way merge.
  */
 static int build_fake_ancestor(const struct am_state *state, const char *index_file)
 {

@@ -197,20 +197,30 @@ int xopen(const char *path, int oflag, ...)
 	mode_t mode = 0;
 	va_list ap;
 
+	/*
+	 * va_arg() will have undefined behavior if the specified type is not
+	 * compatible with the argument type. Since integers are promoted to
+	 * ints, we fetch the next argument as an int, and then cast it to a
+	 * mode_t to avoid undefined behavior.
+	 */
 	va_start(ap, oflag);
 	if (oflag & O_CREAT)
-		mode = va_arg(ap, mode_t);
+		mode = va_arg(ap, int);
 	va_end(ap);
 
-	assert(path);
-
 	for (;;) {
 		int fd = open(path, oflag, mode);
 		if (fd >= 0)
 			return fd;
 		if (errno == EINTR)
 			continue;
-		die_errno(_("could not open '%s'"), path);
+
+		if ((oflag & O_RDWR) == O_RDWR)
+			die_errno(_("could not open '%s' for reading and writing"), path);
+		else if ((oflag & O_WRONLY) == O_WRONLY)
+			die_errno(_("could not open '%s' for writing"), path);
+		else
+			die_errno(_("could not open '%s' for reading"), path);
 	}
 }
 

@@ -341,16 +351,19 @@ int xdup(int fd)
  */
 FILE *xfopen(const char *path, const char *mode)
 {
-	assert(path);
-	assert(mode);
-
 	for (;;) {
 		FILE *fp = fopen(path, mode);
 		if (fp)
 			return fp;
 		if (errno == EINTR)
 			continue;
-		die_errno(_("could not open '%s'"), path);
+
+		if (*mode && mode[1] == '+')
+			die_errno(_("could not open '%s' for reading and writing"), path);
+		else if (*mode == 'w' || *mode == 'a')
+			die_errno(_("could not open '%s' for writing"), path);
+		else
+			die_errno(_("could not open '%s' for reading"), path);
 	}
 }
 

@@ -717,6 +717,7 @@ extern void *xrealloc(void *ptr, size_t size);
 extern void *xcalloc(size_t nmemb, size_t size);
 extern void *xmmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);
 extern void *xmmap_gently(void *start, size_t length, int prot, int flags, int fd, off_t offset);
+extern int xopen(const char *path, int flags, ...);
 extern ssize_t xread(int fd, void *buf, size_t len);
 extern ssize_t xwrite(int fd, const void *buf, size_t len);
 extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset);

@@ -189,6 +189,41 @@ void *xcalloc(size_t nmemb, size_t size)
 # endif
 #endif
 
+/**
+ * xopen() is the same as open(), but it die()s if the open() fails.
+ */
+int xopen(const char *path, int oflag, ...)
+{
+	mode_t mode = 0;
+	va_list ap;
+
+	/*
+	 * va_arg() will have undefined behavior if the specified type is not
+	 * compatible with the argument type. Since integers are promoted to
+	 * ints, we fetch the next argument as an int, and then cast it to a
+	 * mode_t to avoid undefined behavior.
+	 */
+	va_start(ap, oflag);
+	if (oflag & O_CREAT)
+		mode = va_arg(ap, int);
+	va_end(ap);
+
+	for (;;) {
+		int fd = open(path, oflag, mode);
+		if (fd >= 0)
+			return fd;
+		if (errno == EINTR)
+			continue;
+
+		if ((oflag & O_RDWR) == O_RDWR)
+			die_errno(_("could not open '%s' for reading and writing"), path);
+		else if ((oflag & O_WRONLY) == O_WRONLY)
+			die_errno(_("could not open '%s' for writing"), path);
+		else
+			die_errno(_("could not open '%s' for reading"), path);
+	}
+}
+
 /*
  * xread() is the same a read(), but it automatically restarts read()
  * operations with a recoverable error (EAGAIN and EINTR). xread()

@@ -811,6 +811,7 @@ LIB_OBJS += xdiff-interface.o
 LIB_OBJS += zlib.o
 
 BUILTIN_OBJS += builtin/add.o
+BUILTIN_OBJS += builtin/am.o
 BUILTIN_OBJS += builtin/annotate.o
 BUILTIN_OBJS += builtin/apply.o
 BUILTIN_OBJS += builtin/archive.o

@@ -30,6 +30,7 @@ extern int textconv_object(const char *path, unsigned mode, const unsigned char
 extern int is_builtin(const char *s);
 
 extern int cmd_add(int argc, const char **argv, const char *prefix);
+extern int cmd_am(int argc, const char **argv, const char *prefix);
 extern int cmd_annotate(int argc, const char **argv, const char *prefix);
 extern int cmd_apply(int argc, const char **argv, const char *prefix);
 extern int cmd_archive(int argc, const char **argv, const char *prefix);

@@ -0,0 +1,29 @@
+/*
+ * Builtin "git am"
+ *
+ * Based on git-am.sh by Junio C Hamano.
+ */
+#include "cache.h"
+#include "builtin.h"
+#include "exec_cmd.h"
+
+int cmd_am(int argc, const char **argv, const char *prefix)
+{
+
+	/*
+	 * NEEDSWORK: Once all the features of git-am.sh have been
+	 * re-implemented in builtin/am.c, this preamble can be removed.
+	 */
+	if (!getenv("_GIT_USE_BUILTIN_AM")) {
+		const char *path = mkpath("%s/git-am", git_exec_path());
+
+		if (sane_execvp(path, (char **)argv) < 0)
+			die_errno("could not exec %s", path);
+	} else {
+		prefix = setup_git_directory();
+		trace_repo_setup(prefix);
+		setup_work_tree();
+	}
+
+	return 0;
+}

@@ -370,6 +370,12 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 
 static struct cmd_struct commands[] = {
 	{ "add", cmd_add, RUN_SETUP | NEED_WORK_TREE },
+	/*
+	 * NEEDSWORK: Once the redirection to git-am.sh in builtin/am.c has
+	 * been removed, this entry should be changed to
+	 * RUN_SETUP | NEED_WORK_TREE
+	 */
+	{ "am", cmd_am },
 	{ "annotate", cmd_annotate, RUN_SETUP },
 	{ "apply", cmd_apply, RUN_SETUP_GENTLY },
 	{ "archive", cmd_archive },

@@ -722,6 +722,7 @@ extern ssize_t xread(int fd, void *buf, size_t len);
 extern ssize_t xwrite(int fd, const void *buf, size_t len);
 extern ssize_t xpread(int fd, void *buf, size_t len, off_t offset);
 extern int xdup(int fd);
+extern FILE *xfopen(const char *path, const char *mode);
 extern FILE *xfdopen(int fd, const char *mode);
 extern int xmkstemp(char *template);
 extern int xmkstemp_mode(char *template, int mode);

@@ -346,6 +346,27 @@ int xdup(int fd)
 	return ret;
 }
 
+/**
+ * xfopen() is the same as fopen(), but it die()s if the fopen() fails.
+ */
+FILE *xfopen(const char *path, const char *mode)
+{
+	for (;;) {
+		FILE *fp = fopen(path, mode);
+		if (fp)
+			return fp;
+		if (errno == EINTR)
+			continue;
+
+		if (*mode && mode[1] == '+')
+			die_errno(_("could not open '%s' for reading and writing"), path);
+		else if (*mode == 'w' || *mode == 'a')
+			die_errno(_("could not open '%s' for writing"), path);
+		else
+			die_errno(_("could not open '%s' for reading"), path);
+	}
+}
+
 FILE *xfdopen(int fd, const char *mode)
 {
 	FILE *stream = fdopen(fd, mode);

@@ -6,9 +6,174 @@
 #include "cache.h"
 #include "builtin.h"
 #include "exec_cmd.h"
+#include "parse-options.h"
+#include "dir.h"
+
+struct am_state {
+	/* state directory path */
+	char *dir;
+
+	/* current and last patch numbers, 1-indexed */
+	int cur;
+	int last;
+};
+
+/**
+ * Initializes am_state with the default values. The state directory is set to
+ * dir.
+ */
+static void am_state_init(struct am_state *state, const char *dir)
+{
+	memset(state, 0, sizeof(*state));
+
+	assert(dir);
+	state->dir = xstrdup(dir);
+}
+
+/**
+ * Releases memory allocated by an am_state.
+ */
+static void am_state_release(struct am_state *state)
+{
+	if (state->dir)
+		free(state->dir);
+}
+
+/**
+ * Returns path relative to the am_state directory.
+ */
+static inline const char *am_path(const struct am_state *state, const char *path)
+{
+	assert(state->dir);
+	assert(path);
+	return mkpath("%s/%s", state->dir, path);
+}
+
+/**
+ * Returns 1 if there is an am session in progress, 0 otherwise.
+ */
+static int am_in_progress(const struct am_state *state)
+{
+	struct stat st;
+
+	if (lstat(state->dir, &st) < 0 || !S_ISDIR(st.st_mode))
+		return 0;
+	if (lstat(am_path(state, "last"), &st) || !S_ISREG(st.st_mode))
+		return 0;
+	if (lstat(am_path(state, "next"), &st) || !S_ISREG(st.st_mode))
+		return 0;
+	return 1;
+}
+
+/**
+ * Reads the contents of `file` in the `state` directory into `sb`. Returns the
+ * number of bytes read on success, -1 if the file does not exist. If `trim` is
+ * set, trailing whitespace will be removed.
+ */
+static int read_state_file(struct strbuf *sb, const struct am_state *state,
+			const char *file, int trim)
+{
+	strbuf_reset(sb);
+
+	if (strbuf_read_file(sb, am_path(state, file), 0) >= 0) {
+		if (trim)
+			strbuf_trim(sb);
+
+		return sb->len;
+	}
+
+	if (errno == ENOENT)
+		return -1;
+
+	die_errno(_("could not read '%s'"), am_path(state, file));
+}
+
+/**
+ * Loads state from disk.
+ */
+static void am_load(struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	if (read_state_file(&sb, state, "next", 1) < 0)
+		die("BUG: state file 'next' does not exist");
+	state->cur = strtol(sb.buf, NULL, 10);
+
+	if (read_state_file(&sb, state, "last", 1) < 0)
+		die("BUG: state file 'last' does not exist");
+	state->last = strtol(sb.buf, NULL, 10);
+
+	strbuf_release(&sb);
+}
+
+/**
+ * Removes the am_state directory, forcefully terminating the current am
+ * session.
+ */
+static void am_destroy(const struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+
+	strbuf_addstr(&sb, state->dir);
+	remove_dir_recursively(&sb, 0);
+	strbuf_release(&sb);
+}
+
+/**
+ * Setup a new am session for applying patches
+ */
+static void am_setup(struct am_state *state)
+{
+	if (mkdir(state->dir, 0777) < 0 && errno != EEXIST)
+		die_errno(_("failed to create directory '%s'"), state->dir);
+
+	/*
+	 * NOTE: Since the "next" and "last" files determine if an am_state
+	 * session is in progress, they should be written last.
+	 */
+
+	write_file(am_path(state, "next"), 1, "%d", state->cur);
+
+	write_file(am_path(state, "last"), 1, "%d", state->last);
+}
+
+/**
+ * Increments the patch pointer, and cleans am_state for the application of the
+ * next patch.
+ */
+static void am_next(struct am_state *state)
+{
+	state->cur++;
+	write_file(am_path(state, "next"), 1, "%d", state->cur);
+}
+
+/**
+ * Applies all queued mail.
+ */
+static void am_run(struct am_state *state)
+{
+	while (state->cur <= state->last) {
+
+		/* NEEDSWORK: Patch application not implemented yet */
+
+		am_next(state);
+	}
+
+	am_destroy(state);
+}
 
 int cmd_am(int argc, const char **argv, const char *prefix)
 {
+	struct am_state state;
+
+	const char * const usage[] = {
+		N_("git am [options] [(<mbox>|<Maildir>)...]"),
+		NULL
+	};
+
+	struct option options[] = {
+		OPT_END()
+	};
 
 	/*
 	 * NEEDSWORK: Once all the features of git-am.sh have been

@@ -25,5 +190,20 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		setup_work_tree();
 	}
 
+	git_config(git_default_config, NULL);
+
+	am_state_init(&state, git_path("rebase-apply"));
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+
+	if (am_in_progress(&state))
+		am_load(&state);
+	else
+		am_setup(&state);
+
+	am_run(&state);
+
+	am_state_release(&state);
+
 	return 0;
 }

@@ -8,6 +8,12 @@
 #include "exec_cmd.h"
 #include "parse-options.h"
 #include "dir.h"
+#include "run-command.h"
+
+enum patch_format {
+	PATCH_FORMAT_UNKNOWN = 0,
+	PATCH_FORMAT_MBOX
+};
 
 struct am_state {
 	/* state directory path */

@@ -16,6 +22,9 @@ struct am_state {
 	/* current and last patch numbers, 1-indexed */
 	int cur;
 	int last;
+
+	/* number of digits in patch filename */
+	int prec;
 };
 
 /**

@@ -28,6 +37,8 @@ static void am_state_init(struct am_state *state, const char *dir)
 
 	assert(dir);
 	state->dir = xstrdup(dir);
+
+	state->prec = 4;
 }
 
 /**

@@ -120,13 +131,71 @@ static void am_destroy(const struct am_state *state)
 }
 
 /**
+ * Splits out individual email patches from `paths`, where each path is either
+ * a mbox file or a Maildir. Returns 0 on success, -1 on failure.
+ */
+static int split_mail_mbox(struct am_state *state, const char **paths)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct strbuf last = STRBUF_INIT;
+
+	cp.git_cmd = 1;
+	argv_array_push(&cp.args, "mailsplit");
+	argv_array_pushf(&cp.args, "-d%d", state->prec);
+	argv_array_pushf(&cp.args, "-o%s", state->dir);
+	argv_array_push(&cp.args, "-b");
+	argv_array_push(&cp.args, "--");
+	argv_array_pushv(&cp.args, paths);
+
+	if (capture_command(&cp, &last, 8))
+		return -1;
+
+	state->cur = 1;
+	state->last = strtol(last.buf, NULL, 10);
+
+	return 0;
+}
+
+/**
+ * Splits a list of files/directories into individual email patches. Each path
+ * in `paths` must be a file/directory that is formatted according to
+ * `patch_format`.
+ *
+ * Once split out, the individual email patches will be stored in the state
+ * directory, with each patch's filename being its index, padded to state->prec
+ * digits.
+ *
+ * state->cur will be set to the index of the first mail, and state->last will
+ * be set to the index of the last mail.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+static int split_mail(struct am_state *state, enum patch_format patch_format,
+			const char **paths)
+{
+	switch (patch_format) {
+	case PATCH_FORMAT_MBOX:
+		return split_mail_mbox(state, paths);
+	default:
+		die("BUG: invalid patch_format");
+	}
+	return -1;
+}
+
+/**
  * Setup a new am session for applying patches
  */
-static void am_setup(struct am_state *state)
+static void am_setup(struct am_state *state, enum patch_format patch_format,
+			const char **paths)
 {
 	if (mkdir(state->dir, 0777) < 0 && errno != EEXIST)
 		die_errno(_("failed to create directory '%s'"), state->dir);
 
+	if (split_mail(state, patch_format, paths) < 0) {
+		am_destroy(state);
+		die(_("Failed to split patches."));
+	}
+
 	/*
 	 * NOTE: Since the "next" and "last" files determine if an am_state
 	 * session is in progress, they should be written last.

@@ -162,9 +231,25 @@ static void am_run(struct am_state *state)
 	am_destroy(state);
 }
 
+/**
+ * parse_options() callback that validates and sets opt->value to the
+ * PATCH_FORMAT_* enum value corresponding to `arg`.
+ */
+static int parse_opt_patchformat(const struct option *opt, const char *arg, int unset)
+{
+	int *opt_value = opt->value;
+
+	if (!strcmp(arg, "mbox"))
+		*opt_value = PATCH_FORMAT_MBOX;
+	else
+		return error(_("Invalid value for --patch-format: %s"), arg);
+	return 0;
+}
+
 int cmd_am(int argc, const char **argv, const char *prefix)
 {
 	struct am_state state;
+	int patch_format = PATCH_FORMAT_UNKNOWN;
 
 	const char * const usage[] = {
 		N_("git am [options] [(<mbox>|<Maildir>)...]"),

@@ -172,6 +257,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	};
 
 	struct option options[] = {
+		OPT_CALLBACK(0, "patch-format", &patch_format, N_("format"),
+			N_("format the patch(es) are in"),
+			parse_opt_patchformat),
 		OPT_END()
 	};
 

@@ -198,8 +286,21 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 
 	if (am_in_progress(&state))
 		am_load(&state);
-	else
-		am_setup(&state);
+	else {
+		struct argv_array paths = ARGV_ARRAY_INIT;
+		int i;
+
+		for (i = 0; i < argc; i++) {
+			if (is_absolute_path(argv[i]) || !prefix)
+				argv_array_push(&paths, argv[i]);
+			else
+				argv_array_push(&paths, mkpath("%s/%s", prefix, argv[i]));
+		}
+
+		am_setup(&state, patch_format, paths.argv);
+
+		argv_array_clear(&paths);
+	}
 
 	am_run(&state);
 

@@ -10,6 +10,21 @@
 #include "dir.h"
 #include "run-command.h"
 
+/**
+ * Like strbuf_getline(), but treats both '\n' and "\r\n" as line terminators.
+ */
+static int strbuf_getline_crlf(struct strbuf *sb, FILE *fp)
+{
+	if (strbuf_getwholeline(sb, fp, '\n'))
+		return EOF;
+	if (sb->buf[sb->len - 1] == '\n') {
+		strbuf_setlen(sb, sb->len - 1);
+		if (sb->len > 0 && sb->buf[sb->len - 1] == '\r')
+			strbuf_setlen(sb, sb->len - 1);
+	}
+	return 0;
+}
+
 enum patch_format {
 	PATCH_FORMAT_UNKNOWN = 0,
 	PATCH_FORMAT_MBOX

@@ -131,6 +146,92 @@ static void am_destroy(const struct am_state *state)
 }
 
 /**
+ * Determines if the file looks like a piece of RFC2822 mail by grabbing all
+ * non-indented lines and checking if they look like they begin with valid
+ * header field names.
+ *
+ * Returns 1 if the file looks like a piece of mail, 0 otherwise.
+ */
+static int is_mail(FILE *fp)
+{
+	const char *header_regex = "^[!-9;-~]+:";
+	struct strbuf sb = STRBUF_INIT;
+	regex_t regex;
+	int ret = 1;
+
+	if (fseek(fp, 0L, SEEK_SET))
+		die_errno(_("fseek failed"));
+
+	if (regcomp(&regex, header_regex, REG_NOSUB | REG_EXTENDED))
+		die("invalid pattern: %s", header_regex);
+
+	while (!strbuf_getline_crlf(&sb, fp)) {
+		if (!sb.len)
+			break; /* End of header */
+
+		/* Ignore indented folded lines */
+		if (*sb.buf == '\t' || *sb.buf == ' ')
+			continue;
+
+		/* It's a header if it matches header_regex */
+		if (regexec(&regex, sb.buf, 0, NULL, 0)) {
+			ret = 0;
+			goto done;
+		}
+	}
+
+done:
+	regfree(&regex);
+	strbuf_release(&sb);
+	return ret;
+}
+
+/**
+ * Attempts to detect the patch_format of the patches contained in `paths`,
+ * returning the PATCH_FORMAT_* enum value. Returns PATCH_FORMAT_UNKNOWN if
+ * detection fails.
+ */
+static int detect_patch_format(const char **paths)
+{
+	enum patch_format ret = PATCH_FORMAT_UNKNOWN;
+	struct strbuf l1 = STRBUF_INIT;
+	FILE *fp;
+
+	/*
+	 * We default to mbox format if input is from stdin and for directories
+	 */
+	if (!*paths || !strcmp(*paths, "-") || is_directory(*paths))
+		return PATCH_FORMAT_MBOX;
+
+	/*
+	 * Otherwise, check the first few lines of the first patch, starting
+	 * from the first non-blank line, to try to detect its format.
+	 */
+
+	fp = xfopen(*paths, "r");
+
+	while (!strbuf_getline_crlf(&l1, fp)) {
+		if (l1.len)
+			break;
+	}
+
+	if (starts_with(l1.buf, "From ") || starts_with(l1.buf, "From: ")) {
+		ret = PATCH_FORMAT_MBOX;
+		goto done;
+	}
+
+	if (l1.len && is_mail(fp)) {
+		ret = PATCH_FORMAT_MBOX;
+		goto done;
+	}
+
+done:
+	fclose(fp);
+	strbuf_release(&l1);
+	return ret;
+}
+
+/**
  * Splits out individual email patches from `paths`, where each path is either
  * a mbox file or a Maildir. Returns 0 on success, -1 on failure.
  */

@@ -188,6 +289,14 @@ static int split_mail(struct am_state *state, enum patch_format patch_format,
 static void am_setup(struct am_state *state, enum patch_format patch_format,
 			const char **paths)
 {
+	if (!patch_format)
+		patch_format = detect_patch_format(paths);
+
+	if (!patch_format) {
+		fprintf_ln(stderr, _("Patch format detection failed."));
+		exit(128);
+	}
+
 	if (mkdir(state->dir, 0777) < 0 && errno != EEXIST)
 		die_errno(_("failed to create directory '%s'"), state->dir);
 

@@ -11,6 +11,9 @@
 #include "run-command.h"
 #include "quote.h"
 #include "lockfile.h"
+#include "cache-tree.h"
+#include "refs.h"
+#include "commit.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.

@@ -696,10 +699,56 @@ static int run_apply(const struct am_state *state)
 }
 
 /**
+ * Commits the current index with state->msg as the commit message and
+ * state->author_name, state->author_email and state->author_date as the author
+ * information.
+ */
+static void do_commit(const struct am_state *state)
+{
+	unsigned char tree[GIT_SHA1_RAWSZ], parent[GIT_SHA1_RAWSZ],
+		      commit[GIT_SHA1_RAWSZ];
+	unsigned char *ptr;
+	struct commit_list *parents = NULL;
+	const char *reflog_msg, *author;
+	struct strbuf sb = STRBUF_INIT;
+
+	if (write_cache_as_tree(tree, 0, NULL))
+		die(_("git write-tree failed to write a tree"));
+
+	if (!get_sha1_commit("HEAD", parent)) {
+		ptr = parent;
+		commit_list_insert(lookup_commit(parent), &parents);
+	} else {
+		ptr = NULL;
+		fprintf_ln(stderr, _("applying to an empty history"));
+	}
+
+	author = fmt_ident(state->author_name, state->author_email,
+			state->author_date, IDENT_STRICT);
+
+	if (commit_tree(state->msg, state->msg_len, tree, parents, commit,
+				author, NULL))
+		die(_("failed to write commit object"));
+
+	reflog_msg = getenv("GIT_REFLOG_ACTION");
+	if (!reflog_msg)
+		reflog_msg = "am";
+
+	strbuf_addf(&sb, "%s: %.*s", reflog_msg, linelen(state->msg),
+			state->msg);
+
+	update_ref(sb.buf, "HEAD", commit, ptr, 0, UPDATE_REFS_DIE_ON_ERR);
+
+	strbuf_release(&sb);
+}
+
+/**
  * Applies all queued mail.
  */
 static void am_run(struct am_state *state)
 {
+	const char *argv_gc_auto[] = {"gc", "--auto", NULL};
+
 	refresh_and_write_cache();
 
 	while (state->cur <= state->last) {