Add pledge(2) support on OpenBSD

[worr]

On other platforms, this will be a no-op. Fixes #164

I'm currently running it on a recent amd64 snapshot.

[gonzalo-]

Hello, please can you check this one?

https://marc.info/?l=openbsd-ports&m=153797184227204&w=2

After that, looks safe to switch to pledge(2) so far.

[worr]

Hmm, I did I not run into the issues that Björn did.

That said, I've updated it with the additional pledge that they proposed, as well as moved the call to pledge(2) before the call to 1getpwuid(3) and getuid(3).

[bket]

@worr, I ran into a pledge() related issue after doing a rm -rf ~/.cache/fontconfig and restarting xenodm. It seems that spectrwm assumes that ~/.cache/fontconfig, including its contents, exists. If the latter is missing spectrwm tries to create it, which is hindered by pledge(). For reference purposes, I'm using OpenBSD current on amd64.

The issue is reproducible using rm -rf ~/.cache/fontconfig; doas pkill X.

Workaround is to have something like spectrwm || cwm in ~/.xsession. Assuming that ~/.cache/fontconfig does not exist:

1. spectrwm fails because of pledge()
2. instead cwm is run, which creates the missing ~/.cache/fontconfig, and its contents
3. upon a restart, spectrwm starts successfully

After some digging I think the diff below (using your pull request as starting point) fixes the issue:

diff --git spectrwm.c spectrwm.c
index d8d8c62..4d8e903 100644
--- spectrwm.c
+++ spectrwm.c
@@ -3883,9 +3883,6 @@ spawn(int ws_idx, union arg *args, bool close_fd)
 	if (args == NULL || args->argv[0] == NULL)
 		return;
 
-	if (pledge("stdio proc exec", NULL) == -1)
-		err(1, "pledge");
-
 	DNPRINTF(SWM_D_MISC, "%s\n", args->argv[0]);
 
 	close(xcb_get_file_descriptor(conn));
@@ -12475,7 +12472,8 @@ main(int argc, char *argv[])
 	if (setlocale(LC_CTYPE, "") == NULL || setlocale(LC_TIME, "") == NULL)
 		warnx("no locale support");
 
-	if (pledge("stdio rpath proc exec getpw dns unix", NULL) == -1)
+	if (pledge("stdio proc exec cpath rpath wpath fattr getpw dns inet "
+	    "unix", NULL) == -1)
 		err(1, "pledge");
 
 	/* handle some signals */
@@ -12495,6 +12493,10 @@ main(int argc, char *argv[])
 	if ((display = XOpenDisplay(0)) == NULL)
 		errx(1, "can not open display");
 
+	if (pledge("stdio proc exec cpath rpath wpath fattr getpw",
+	    NULL) == -1)
+		err(1, "pledge");
+
 	conn = XGetXCBConnection(display);
 	if (xcb_connection_has_error(conn))
 		errx(1, "can not get XCB connection");
@@ -12504,9 +12506,6 @@ main(int argc, char *argv[])
 	xcb_prefetch_extension_data(conn, &xcb_randr_id);
 	xfd = xcb_get_file_descriptor(conn);
 
-	if (pledge("stdio rpath proc exec getpw", NULL) == -1)
-		err(1, "pledge");
-
 	/* look for local and global conf file */
 	pwd = getpwuid(getuid());
 	if (pwd == NULL)
@@ -12591,6 +12590,9 @@ noconfig:
 	if (cfile)
 		conf_load(cfile, SWM_CONF_DEFAULT);
 
+	if (pledge("stdio proc exec cpath rpath wpath fattr", NULL) == -1)
+		err(1, "pledge");
+
 	validate_spawns();
 
 	if (getenv("SWM_STARTED") == NULL)
@@ -12602,6 +12604,9 @@ noconfig:
 		TAILQ_FOREACH(r, &screens[i].rl, entry)
 			bar_setup(r);
 
+	if (pledge("stdio proc exec", NULL) == -1)
+		err(1, "pledge");
+
 	/* Manage existing windows. */
 	grab_windows();
 
@@ -12685,6 +12690,9 @@ noconfig:
 		xcb_flush(conn);
 	}
 done:
+	if (pledge("stdio proc", NULL) == -1)
+		err(1, "pledge");
+
 	shutdown_cleanup();
 
 	return (0);

[dajohi]

ok