From b4869652775416dde95cfc103d4b03b04828bf60 Mon Sep 17 00:00:00 2001
From: Přemysl Janouch <p.janouch@gmail.com>
Date: Thu, 2 Jul 2015 01:02:06 +0200
Subject: kike: resolve the path to PID files better

---
 common.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 kike.c   | 35 ++++++++++++++++++++---------------
 2 files changed, 63 insertions(+), 15 deletions(-)

diff --git a/common.c b/common.c
index cc6221e..7b845d8 100644
--- a/common.c
+++ b/common.c
@@ -90,6 +90,49 @@ strncasecmp_ascii (const char *a, const char *b, size_t n)
 	return 0;
 }
 
+static char *
+resolve_relative_runtime_filename (const char *filename)
+{
+	struct str path;
+	str_init (&path);
+
+	const char *runtime_dir = getenv ("XDG_RUNTIME_DIR");
+	if (runtime_dir && *runtime_dir == '/')
+		str_append (&path, runtime_dir);
+	else
+		get_xdg_home_dir (&path, "XDG_DATA_HOME", ".local/share");
+	str_append_printf (&path, "/%s/%s", PROGRAM_NAME, filename);
+
+	// Try to create the file's ancestors
+	const char *last_slash = strrchr (path.str, '/');
+	if (last_slash && last_slash != path.str)
+	{
+		char *copy = xstrndup (path.str, last_slash - path.str);
+		(void) mkdir_with_parents (copy, NULL);
+		free (copy);
+	}
+	return str_steal (&path);
+}
+
+static char *
+resolve_filename (const char *filename, char *(*relative_cb) (const char *))
+{
+	// Absolute path is absolute
+	if (*filename == '/')
+		return xstrdup (filename);
+
+	// We don't want to use wordexp() for this as it may execute /bin/sh
+	if (*filename == '~')
+	{
+		// Paths to home directories ought to be absolute
+		char *expanded = try_expand_tilde (filename + 1);
+		if (expanded)
+			return expanded;
+		print_debug ("failed to expand the home directory in `%s'", filename);
+	}
+	return relative_cb (filename);
+}
+
 // --- Logging -----------------------------------------------------------------
 
 static void
diff --git a/kike.c b/kike.c
index b5bda0a..c5c36da 100644
--- a/kike.c
+++ b/kike.c
@@ -31,15 +31,7 @@
 
 static struct config_item g_config_table[] =
 {
-	// TODO: use XDG_RUNTIME_DIR if relative.  The last fallback is:
-	//
-	//   "$XDG_DATA_HOME defines the base directory relative to which user
-	//   specific data files should be stored.  If $XDG_DATA_HOME is either not
-	//   set or empty, a default equal to $HOME/.local/share should be used."
-	//
-	//   Note that when using XDG_RUNTIME_DIR, it either needs to have access
-	//   time bumped every 6 hours, or have the sticky bit set.
-	{ "pid_file",        NULL,              "Full path for the PID file"     },
+	{ "pid_file",        NULL,              "Path or name of the PID file"   },
 	{ "server_name",     NULL,              "Server name"                    },
 	{ "server_info",     "My server",       "Brief server description"       },
 	{ "motd",            NULL,              "MOTD filename"                  },
@@ -3671,14 +3663,12 @@ irc_initialize_server_name (struct server_context *ctx, struct error **e)
 }
 
 static bool
-irc_lock_pid_file (struct server_context *ctx, struct error **e)
+lock_pid_file (const char *path, struct error **e)
 {
-	const char *path = str_map_find (&ctx->config, "pid_file");
-	if (!path)
-		return true;
-
+	// When using XDG_RUNTIME_DIR, the file needs to either have its
+	// access time bumped every 6 hours, or have the sticky bit set
 	int fd = open (path, O_RDWR | O_CREAT,
-		S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH /* 644 */);
+		S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH /* 644 */ | S_ISVTX /* sticky */);
 	if (fd < 0)
 	{
 		error_set (e, "can't open `%s': %s", path, strerror (errno));
@@ -3695,6 +3685,7 @@ irc_lock_pid_file (struct server_context *ctx, struct error **e)
 	if (fcntl (fd, F_SETLK, &lock))
 	{
 		error_set (e, "can't lock `%s': %s", path, strerror (errno));
+		xclose (fd);
 		return false;
 	}
 
@@ -3706,6 +3697,7 @@ irc_lock_pid_file (struct server_context *ctx, struct error **e)
 	 || write (fd, pid.str, pid.len) != (ssize_t) pid.len)
 	{
 		error_set (e, "can't write to `%s': %s", path, strerror (errno));
+		xclose (fd);
 		return false;
 	}
 	str_free (&pid);
@@ -3715,6 +3707,19 @@ irc_lock_pid_file (struct server_context *ctx, struct error **e)
 	return true;
 }
 
+static bool
+irc_lock_pid_file (struct server_context *ctx, struct error **e)
+{
+	const char *path = str_map_find (&ctx->config, "pid_file");
+	if (!path)
+		return true;
+
+	char *resolved = resolve_filename (path, resolve_relative_runtime_filename);
+	bool result = lock_pid_file (resolved, e);
+	free (resolved);
+	return result;
+}
+
 static int
 irc_listen (struct addrinfo *gai_iter)
 {
-- 
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