[PATCH v2 1/2] cli: introduce the concept of user defined hooks

[Jani Nikula <jani@nikula.org>]

Add mechanism for running user defined hooks. Hooks are executables or
symlinks to executables stored under the new notmuch hooks directory,
<database-path>/.notmuch/hooks.

No hooks are introduced here, but adding support for a hook is now a simple
matter of calling the new notmuch_run_hook() function at an appropriate
location with the hook name.

Signed-off-by: Jani Nikula <jani@nikula.org>

---

v2: Switch to git style hooks in a hook directory as suggested by Austin
Clements in IRC. Update manpage and add polish.
---
 Makefile.local   |    1 +
 notmuch-client.h |    3 ++
 notmuch-hook.c   |   63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 0 deletions(-)
 create mode 100644 notmuch-hook.c

diff --git a/Makefile.local b/Makefile.local
index c94402b..a1665e1 100644
--- a/Makefile.local
+++ b/Makefile.local
@@ -302,6 +302,7 @@ notmuch_client_srcs =		\
 	notmuch-config.c	\
 	notmuch-count.c		\
 	notmuch-dump.c		\
+	notmuch-hook.c		\
 	notmuch-new.c		\
 	notmuch-reply.c		\
 	notmuch-restore.c	\
diff --git a/notmuch-client.h b/notmuch-client.h
index b50cb38..a91ad6c 100644
--- a/notmuch-client.h
+++ b/notmuch-client.h
@@ -235,6 +235,9 @@ void
 notmuch_config_set_maildir_synchronize_flags (notmuch_config_t *config,
 					      notmuch_bool_t synchronize_flags);
 
+int
+notmuch_run_hook (const char *db_path, const char *hook);
+
 notmuch_bool_t
 debugger_is_active (void);
 
diff --git a/notmuch-hook.c b/notmuch-hook.c
new file mode 100644
index 0000000..fc32044
--- /dev/null
+++ b/notmuch-hook.c
@@ -0,0 +1,63 @@
+/* notmuch - Not much of an email program, (just index and search)
+ *
+ * This file is part of notmuch.
+ *
+ * Copyright © 2011 Jani Nikula
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see http://www.gnu.org/licenses/ .
+ *
+ * Author: Jani Nikula <jani@nikula.org>
+ */
+
+#include "notmuch-client.h"
+
+int
+notmuch_run_hook (const char *db_path, const char *hook)
+{
+    char *hook_path;
+    int status = 0;
+
+    if (asprintf (&hook_path, "%s/%s/%s/%s", db_path, ".notmuch", "hooks",
+		  hook) == -1)
+	return NOTMUCH_STATUS_OUT_OF_MEMORY;
+
+    if (access (hook_path, X_OK) == -1) {
+	/* Ignore ENOENT. It's okay not to have a hook, hook dir, or even
+	 * notmuch dir. Dangling symbolic links also result in ENOENT, but
+	 * we'll ignore that too for simplicity. */
+	if (errno != ENOENT) {
+	    fprintf (stderr, "Error: %s hook access failed: %s\n", hook,
+		     strerror (errno));
+	    status = NOTMUCH_STATUS_FILE_ERROR;
+	}
+	goto DONE;
+    }
+
+    status = system (hook_path);
+    if (status) {
+	if (WIFSIGNALED(status))
+	    fprintf(stderr, "Error: %s hook terminated with signal %d\n", hook,
+		    WTERMSIG(status));
+	else
+	    fprintf(stderr, "Error: %s hook failed with status %d\n", hook,
+		    WEXITSTATUS(status));
+
+	status = NOTMUCH_STATUS_FILE_ERROR; /* Close enough */
+    }
+
+  DONE:
+    free (hook_path);
+
+    return status;
+}
-- 
1.7.5.4