Accept write-pid-path option from the config file

Signed-off-by: jialeens <[email protected]>

man/picom.1.asciidoc

@@ -80,7 +80,7 @@ OPTIONS
 	Look for configuration file at the path. See *CONFIGURATION FILES* section below for where picom looks for a configuration file by default. Use `/dev/null` to avoid loading configuration file.
 
 *--write-pid-path* 'PATH'::
-	Write process ID to a file.
+	Write process ID to a file. it is recommended to use an absolute path.
 
 *--shadow-color* 'STRING'::
 	Color of shadow, as a hex string ('#000000')

src/config_libconfig.c

@@ -643,6 +643,15 @@ char *parse_config_libconfig(options_t *opt, const char *config_file, bool *shad
 		config_setting_lookup_int(blur_cfg, "strength", &opt->blur_strength);
 	}
 
+	// --write-pid-path
+	if (config_lookup_string(&cfg, "write-pid-path", &sval)) {
+		if (*sval != '/') {
+			log_warn("The write-pid-path in your configuration file is not"
+			         " an absolute path");
+		}
+		opt->write_pid_path = strdup(sval);
+	}
+
 	// Wintype settings
 
 	// XXX ! Refactor all the wintype_* arrays into a struct

src/options.c

@@ -795,7 +795,11 @@ bool get_cfg(options_t *opt, int argc, char *const *argv, bool shadow_enable,
 		P_CASELONG(309, unredir_if_possible_delay);
 		case 310:
 			// --write-pid-path
+			free(opt->write_pid_path);
 			opt->write_pid_path = strdup(optarg);
+			if (*opt->write_pid_path != '/') {
+				log_warn("--write-pid-path is not an absolute path");
+			}
 			break;
 		P_CASEBOOL(311, vsync_use_glfinish);
 		case 312: