Re: [PATCH/WIP v2 05/19] am: split out mbox/maildir patches with git-mailsplit

git-am.sh supports mbox, stgit and mercurial patches. Re-implement
support for splitting out mbox/maildirs using git-mailsplit, while also
implementing the framework required to support other patch formats in
the future.

Re-implement support for the --patch-format option (since a5a6755
(git-am foreign patch support: introduce patch_format, 2009-05-27)) to
allow the user to choose between the different patch formats.

Signed-off-by: Paul Tan <redacted>
---

Notes:
    v2

    * Declare int opt_patchformat as static.

    * Fix up indentation style for the switch()

 builtin/am.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 103 insertions(+), 4 deletions(-)

diff --git a/builtin/am.c b/builtin/am.c
index f061d21..5198a8e 100644
--- a/builtin/am.c
+++ b/builtin/am.c

@@ -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;
 };

 /**

@@ -26,6 +35,7 @@ static void am_state_init(struct am_state *state)
        memset(state, 0, sizeof(*state));

        strbuf_init(&state->dir, 0);
+       state->prec = 4;
 }

 /**

@@ -111,13 +121,67 @@ static void am_destroy(const struct am_state *state)
 }

 /**
+ * Splits out individual patches from `paths`, where each path is either a mbox
+ * file or a Maildir. Return 0 on success, -1 on failure.
+ */
+static int split_patches_mbox(struct am_state *state, struct string_list *paths)
+{
+       struct child_process cp = CHILD_PROCESS_INIT;
+       struct string_list_item *item;
+       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.buf);
+       argv_array_push(&cp.args, "-b");
+       argv_array_push(&cp.args, "--");
+
+       for_each_string_list_item(item, paths)
+               argv_array_push(&cp.args, item->string);
+
+       if (capture_command(&cp, &last, 8))
+               return -1;
+
+       state->cur = 1;
+       state->last = strtol(last.buf, NULL, 10);
+
+       return 0;
+}
+
+/**
+ * Splits out individual patches, of patch_format, contained within paths.
+ * These 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 patch, and state->last will be set to the
+ * index of the last patch. Returns 0 on success, -1 on failure.
+ */
+static int split_patches(struct am_state *state, enum patch_format patch_format,
+               struct string_list *paths)
+{
+       switch (patch_format) {
+       case PATCH_FORMAT_MBOX:
+               return split_patches_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,
+               struct string_list *paths)
 {
        if (mkdir(state->dir.buf, 0777) < 0 && errno != EEXIST)
                die_errno(_("failed to create directory '%s'"), state->dir.buf);

+       if (split_patches(state, patch_format, paths) < 0) {
+               am_destroy(state);
+               die(_("Failed to split patches."));
+       }
+
        write_file(am_path(state, "next"), 1, "%d", state->cur);

        write_file(am_path(state, "last"), 1, "%d", state->last);

@@ -138,13 +202,33 @@ static void am_next(struct am_state *state)
  */
 static void am_run(struct am_state *state)
 {
-       while (state->cur <= state->last)
+       while (state->cur <= state->last) {
+
+               /* TODO: Patch application not implemented yet */
+
                am_next(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 -1;
+       return 0;
+}
+
 static struct am_state state;
+static int opt_patch_format;

 static const char * const am_usage[] = {
        N_("git am [options] [(<mbox>|<Maildir>)...]"),

@@ -152,6 +236,8 @@ static const char * const am_usage[] = {
 };

 static struct option am_options[] = {
+       OPT_CALLBACK(0, "patch-format", &opt_patch_format, N_("format"),
+               N_("format the patch(es) are in"), parse_opt_patchformat),
        OPT_END()
 };

@@ -173,8 +259,21 @@ 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 string_list paths = STRING_LIST_INIT_DUP;
+               int i;
+
+               for (i = 0; i < argc; i++) {
+                       if (is_absolute_path(argv[i]) || !prefix)
+                               string_list_append(&paths, argv[i]);
+                       else
+                               string_list_append(&paths, mkpath("%s/%s", prefix, argv[i]));
+               }
+
+               am_setup(&state, opt_patch_format, &paths);
+
+               string_list_clear(&paths, 0);
+       }

        am_run(&state);

--

2.1.4