Start a new top-level executable: notmuch.

Of course, there's not much that this program does yet. It's got
some structure for some sub-commands that don't do anything. And
it has a main command that prints some explanatory text and then
counts all the regular files in your mail archive.

Makefile

@@ -1,11 +1,15 @@
-PROGS=notmuch-index-message xapian-dump
+PROGS=notmuch notmuch-index-message xapian-dump
 
+MYCFLAGS=-Wall -O0 -g
 MYCXXFLAGS=-Wall -O0 -g
 
 all: $(PROGS)
 
+notmuch: notmuch.c
+	$(CC) $(CFLAGS) $(MYCFLAGS) notmuch.c `pkg-config --cflags --libs glib-2.0` -o notmuch
+
 notmuch-index-message: notmuch-index-message.cc
-	$(CC) $(CXXFLAGS) $(MYCXXFLAGS) notmuch-index-message.cc `pkg-config --cflags --libs gmime-2.4` `xapian-config --cxxflags --libs` -o notmuch-index-message
+	$(CXX) $(CXXFLAGS) $(MYCXXFLAGS) notmuch-index-message.cc `pkg-config --cflags --libs gmime-2.4` `xapian-config --cxxflags --libs` -o notmuch-index-message
 
 xapian-dump: xapian-dump.cc
 	$(CXX) $(CXXFLAGS) $(MYCXXFLAGS) xapian-dump.cc `xapian-config --libs --cxxflags` -o xapian-dump

notmuch.c

@@ -0,0 +1,267 @@
+/* notmuch - Not much of an email program, (just index and search)
+ *
+ * Copyright © 2009 Carl Worth
+ *
+ * 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: Carl Worth <cworth@cworth.org>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <errno.h>
+
+#include <glib.h>
+
+#define ARRAY_SIZE(arr) (sizeof (arr) / sizeof (arr[0]))
+
+typedef int (*command_function_t) (int argc, char *argv[]);
+
+typedef struct command {
+    const char *name;
+    command_function_t function;
+    const char *usage;
+} command_t;
+
+/* Read a line from stdin, without any line-terminator character.  The
+ * return value is a newly allocated string. The caller should free()
+ * the string when finished with it.
+ *
+ * This function returns NULL if EOF is encountered before any
+ * characters are input (otherwise it returns those characters).
+ */
+char *
+read_line (void)
+{
+    char *result = NULL;
+    GError *error = NULL;
+    GIOStatus g_io_status;
+    gsize length;
+
+    GIOChannel *channel = g_io_channel_unix_new (fileno (stdin));
+
+    g_io_status = g_io_channel_read_line (channel, &result,
+					  &length, NULL, &error);
+
+    if (g_io_status == EOF)
+	goto DONE;
+
+    if (g_io_status != G_IO_STATUS_NORMAL) {
+	fprintf(stderr, "Read error: %s\n", error->message);
+	exit (1);
+    }
+
+    if (length && result[length - 1] == '\n')
+	result[length - 1] = '\0';
+
+  DONE:
+    g_io_channel_unref (channel);
+    return result;
+}
+
+/* Recursively count all regular files in path and all sub-direcotries
+ * of path.  The result is added to *count (which should be
+ * initialized to zero by the top-level caller before calling
+ * count_files). */
+void
+count_files (const char *path, int *count)
+{
+    DIR *dir;
+    struct dirent *entry, *e;
+    int entry_length;
+    int err;
+    char *next;
+    struct stat st;
+
+    dir = opendir (path);
+
+    if (dir == NULL) {
+	fprintf (stderr, "Warning: failed to open directory %s: %s\n",
+		 path, strerror (errno));
+	return;
+    }
+
+    entry_length = offsetof (struct dirent, d_name) +
+	pathconf (path, _PC_NAME_MAX) + 1;
+    entry = malloc (entry_length);
+
+    while (1) {
+	err = readdir_r (dir, entry, &e);
+	if (err) {
+	    fprintf (stderr, "Error reading directory: %s\n",
+		     strerror (errno));
+	    free (entry);
+	    return;
+	}
+
+	if (e == NULL)
+	    break;
+
+	/* Skip these special directories to avoid infinite recursion. */
+	if (strcmp (entry->d_name, ".") == 0 ||
+	    strcmp (entry->d_name, "..") == 0)
+	{
+	    continue;
+	}
+
+	next = g_strdup_printf ("%s/%s", path, entry->d_name);
+
+	stat (next, &st);
+
+	if (S_ISREG (st.st_mode))
+	    *count = *count + 1;
+	else if (S_ISDIR (st.st_mode))
+	    count_files (next, count);
+
+	if (*count % 1000 == 0) {
+	    printf ("Found %d files so far.\r", *count);
+	    fflush (stdout);
+	}
+
+	free (next);
+    }
+
+    free (entry);
+
+    closedir (dir);
+}
+
+int
+setup_command (int argc, char *argv[])
+{
+    char *mail_directory;
+    int count;
+
+    printf ("Welcome to notmuch!\n\n");
+
+    printf ("The goal of notmuch is to help you manage and search your collection of\n"
+	    "email, and to efficiently keep up with the flow of email as it comes in.\n\n");
+
+    printf ("Notmuch needs to know the top-level directory of your email archive,\n"
+	    "(where you already have mail stored and where messages will be delivered\n"
+	    "in the future). This directory can contain any number of sub-directories\n"
+	    "but the only files it contains should be individual email messages.\n"
+	    "Either maildir or mh format directories are fine, but you will want to\n"
+	    "move away any auxiliary files maintained by other email programs.\n\n");
+
+    printf ("Mail storage that uses mbox format, (where one mbox file contains many\n"
+	    "messages), will not work with notmuch. If that's how your mail is currently\n"
+	    "stored, we recommend you first convert it to maildir format with a utility\n"
+	    "such as mb2md. In that case, press Control-C now and run notmuch again\n"
+	    "once the conversion is complete.\n\n");
+
+    printf ("Top-level mail directory [~/mail]: ");
+    fflush (stdout);
+
+    mail_directory = read_line ();
+
+    if (mail_directory == NULL || strlen (mail_directory) == 0) {
+	char *home;
+
+	if (mail_directory)
+	    free (mail_directory);
+
+	home = getenv ("HOME");
+	if (!home) {
+	    fprintf (stderr, "Error: No mail directory provided HOME environment variable is not set.\n");
+	    fprintf (stderr, "Cowardly refusing to just guess where your mail might be.\n");
+	    exit (1);
+	}
+
+	mail_directory = g_strdup_printf ("%s/mail", home);
+    }
+
+    printf ("OK. Let's take a look at the mail we can find in the directory\n");
+    printf ("%s ...\n", mail_directory);
+
+    count = 0;
+    count_files (mail_directory, &count);
+
+    printf ("Found %d total files. That's not much mail.\n", count);
+
+    free (mail_directory);
+    
+    return 0;
+}
+
+int
+search_command (int argc, char *argv[])
+{
+    fprintf (stderr, "Error: search is not implemented yet.\n");
+    return 1;
+}
+
+int
+show_command (int argc, char *argv[])
+{
+    fprintf (stderr, "Error: show-thread is not implemented yet.\n");
+    return 1;
+}
+
+command_t commands[] = {
+    { "setup", setup_command,
+      "Interactively setup notmuch for first use (no arguments).\n"
+      "\t\tInvoking notmuch with no command argument will run setup if\n"
+      "\t\the setup command has not previously been completed." },
+    { "search", search_command,
+      "Search for threads matching the given search terms." },
+    { "show", show_command,
+      "Show the thread with the given thread ID (see 'search')." }
+};
+
+void
+usage (void)
+{
+    command_t *command;
+    int i;
+
+    fprintf (stderr, "Usage: notmuch <command> [args...]\n");
+    fprintf (stderr, "\n");
+    fprintf (stderr, "Where <command> is one of the following:\n");
+    fprintf (stderr, "\n");
+
+    for (i = 0; i < ARRAY_SIZE (commands); i++) {
+	command = &commands[i];
+
+	fprintf (stderr, "\t%s\t%s\n\n", command->name, command->usage);
+    }
+}
+    
+int
+main (int argc, char *argv[])
+{
+    command_t *command;
+    int i;
+
+    if (argc == 1)
+	return setup_command (0, NULL);
+
+    for (i = 0; i < ARRAY_SIZE (commands); i++) {
+	command = &commands[i];
+
+	if (strcmp (argv[1], command->name) == 0)
+	    return (command->function) (argc - 2, &argv[2]);
+    }
+
+    fprintf (stderr, "Error: Unknown command '%s'\n\n", argv[1]);
+    usage ();
+    exit (1);
+
+    return 0;
+}