#65 add ON_CHANGE_CMD to run a shell command in handle_success

doc/CONTRIBUTING.md

@@ -69,7 +69,7 @@ See all violations:
 
 ## Documentation
 
-Please update `README.md` and `doc/configuration.md`.
+Please update `README.md`.
 
 Please update the man page:
 * update `way-displays.1.pandoc`
@@ -83,7 +83,7 @@ Please match the style of the surrounding code and obey `.editorconfig`. Default
 
 ## Adding Options
 
-Please add the option to `config.yaml` with a descriptive comment.
+Please add the option to `cfg.yaml` with a descriptive comment.
 
 Please add a command line option and update the usage message.
 

examples/cfg.yaml

@@ -67,6 +67,12 @@ VRR_OFF:
   # - '!.*my monitor.*'
 
 
+# Sets a command to be executed when display configurations are
+# successfully changed.
+# NOTE: Depending on your compositor this could get executed multiple times when
+# a change happens. Especially likely on a (dis-)connect.
+#CHANGE_SUCCESS_CMD: 'notify-send "Monitor changed"'
+
 # Laptop displays usually start with eDP e.g. eDP-1. This may be overridden if
 # your laptop is different.
 #LAPTOP_DISPLAY_PREFIX: 'eDP'

inc/cfg.h

@@ -61,6 +61,7 @@ struct Cfg {
 
 	bool updated;
 
+	char *change_success_cmd;
 	char *laptop_display_prefix;
 	struct SList *order_name_desc;
 	enum Arrange arrange;
@@ -89,6 +90,7 @@ enum CfgElement {
 	MODE,
 	TRANSFORM,
 	VRR_OFF,
+	CHANGE_SUCCESS_CMD,
 	LAPTOP_DISPLAY_PREFIX,
 	MAX_PREFERRED_REFRESH,
 	LOG_THRESHOLD,

inc/process.h

@@ -9,6 +9,8 @@ pid_t pid_active_server(void);
 
 void pid_file_create(void);
 
+void spawn_async(const char * const command);
+
 // exit; caller should return afterwards
 void wd_exit(int __status);
 

src/cfg.c

@@ -266,6 +266,11 @@ struct Cfg *clone_cfg(struct Cfg *from) {
 		slist_append(&to->adaptive_sync_off_name_desc, strdup((char*)i->val));
 	}
 
+	// CHANGE_SUCCESS_CMD
+	if (from->change_success_cmd) {
+		to->change_success_cmd = strdup(from->change_success_cmd);
+	}
+
 	// LAPTOP_DISPLAY_PREFIX
 	if (from->laptop_display_prefix) {
 		to->laptop_display_prefix = strdup(from->laptop_display_prefix);
@@ -345,6 +350,13 @@ bool cfg_equal(struct Cfg *a, struct Cfg *b) {
 		return false;
 	}
 
+	// CHANGE_SUCCESS_CMD
+	char *ao = a->change_success_cmd;
+	char *bo = b->change_success_cmd;
+	if ((ao && !bo) || (!ao && bo) || (ao && bo && strcmp(ao, bo) != 0)) {
+		return false;
+	}
+
 	// LAPTOP_DISPLAY_PREFIX
 	char *al = a->laptop_display_prefix;
 	char *bl = b->laptop_display_prefix;
@@ -643,6 +655,14 @@ struct Cfg *merge_set(struct Cfg *to, struct Cfg *from) {
 		}
 	}
 
+	// CHANGE_SUCCESS_CMD
+	if (from->change_success_cmd) {
+		if (merged->change_success_cmd) {
+			free(merged->change_success_cmd);
+		}
+		merged->change_success_cmd = strdup(from->change_success_cmd);
+	}
+
 	return merged;
 }
 
@@ -680,6 +700,12 @@ struct Cfg *merge_del(struct Cfg *to, struct Cfg *from) {
 		slist_remove_all_free(&merged->disabled_name_desc, slist_predicate_strcmp, i->val, NULL);
 	}
 
+	// CHANGE_SUCCESS_CMD
+	if (from->change_success_cmd && strlen(from->change_success_cmd) == 0) {
+		free(merged->change_success_cmd);
+		merged->change_success_cmd = NULL;
+	}
+
 	return merged;
 }
 
@@ -845,6 +871,8 @@ void cfg_free(struct Cfg *cfg) {
 
 	cfg_free_paths(cfg);
 
+	free(cfg->change_success_cmd);
+
 	free(cfg->laptop_display_prefix);
 
 	slist_free_vals(&cfg->order_name_desc, NULL);

src/cli.c

@@ -156,6 +156,19 @@ struct Cfg *parse_element(enum IpcCommand command, enum CfgElement element, int
 			}
 			parsed = true;
 			break;
+		case CHANGE_SUCCESS_CMD:
+			switch (command) {
+				case CFG_SET:
+					cfg->change_success_cmd = strdup(argv[optind]);
+					parsed = true;
+					break;
+				case CFG_DEL:
+					cfg->change_success_cmd = strdup("");
+					parsed = true;
+					break;
+				default:
+					break;
+			}
 		default:
 			break;
 	}
@@ -226,6 +239,7 @@ struct IpcRequest *parse_set(int argc, char **argv) {
 		case AUTO_SCALE:
 		case DISABLED:
 		case VRR_OFF:
+		case CHANGE_SUCCESS_CMD:
 			if (optind + 1 != argc) {
 				log_error("%s requires one argument", cfg_element_name(element));
 				wd_exit(EXIT_FAILURE);
@@ -266,6 +280,13 @@ struct IpcRequest *parse_del(int argc, char **argv) {
 				return NULL;
 			}
 			break;
+		case CHANGE_SUCCESS_CMD:
+			if (optind != argc) {
+				log_error("%s takes no arguments", cfg_element_name(element));
+				wd_exit(EXIT_FAILURE);
+				return NULL;
+			}
+			break;
 		default:
 			log_error("invalid %s: %s", ipc_command_friendly(CFG_DEL), element ? cfg_element_name(element) : optarg);
 			wd_exit(EXIT_FAILURE);

src/convert.c

@@ -24,6 +24,7 @@ static struct NameVal cfg_elements[] = {
 	{ .val = SCALE,                 .name = "SCALE",                 },
 	{ .val = MODE,                  .name = "MODE",                  },
 	{ .val = VRR_OFF,               .name = "VRR_OFF",               },
+	{ .val = CHANGE_SUCCESS_CMD,    .name = "CHANGE_SUCCESS_CMD"     },
 	{ .val = LAPTOP_DISPLAY_PREFIX, .name = "LAPTOP_DISPLAY_PREFIX", },
 	{ .val = MAX_PREFERRED_REFRESH, .name = "MAX_PREFERRED_REFRESH", },
 	{ .val = TRANSFORM,             .name = "TRANSFORM",             },

src/info.c

@@ -205,6 +205,11 @@ void print_cfg(enum LogThreshold t, struct Cfg *cfg, bool del) {
 		}
 	}
 
+	if (cfg->change_success_cmd) {
+		log_(t, "  Change success command:");
+		log_(t, "    %s", cfg->change_success_cmd);
+	}
+
 	if (cfg->laptop_display_prefix) {
 		log_(t, "  Laptop display prefix: %s", cfg->laptop_display_prefix);
 	}
@@ -293,6 +298,12 @@ void print_cfg_commands(enum LogThreshold t, struct Cfg *cfg) {
 		print_newline(t, &newline);
 		log_(t, "way-displays -s VRR_OFF '%s'", (char*)i->val);
 	}
+
+	newline = true;
+	if (cfg->change_success_cmd) {
+		print_newline(t, &newline);
+		log_(t, "way-displays -s CHANGE_SUCCESS_CMD '%s'", cfg->change_success_cmd);
+	}
 }
 
 void print_head_current(enum LogThreshold t, struct Head *head) {

src/layout.c

@@ -333,7 +333,7 @@ void report_adaptive_sync_fail(struct Head *head) {
 void handle_success(void) {
 	if (head_changing_mode) {
 
-		// succesful mode change is not always reported
+		// successful mode change is not always reported
 		head_changing_mode->current.mode = head_changing_mode->desired.mode;
 
 		head_changing_mode = NULL;
@@ -351,6 +351,13 @@ void handle_success(void) {
 		}
 	}
 
+	if (!head_changing_adaptive_sync && cfg->change_success_cmd) {
+		log_info("\nExecuting CHANGE_SUCCESS_CMD:");
+		log_info("  %s", cfg->change_success_cmd);
+
+		spawn_async(cfg->change_success_cmd);
+	}
+
 	log_info("\nChanges successful");
 }
 

src/marshalling.cpp

@@ -262,6 +262,10 @@ YAML::Emitter& operator << (YAML::Emitter& e, struct Cfg& cfg) {
 		e << YAML::EndSeq;												// MAX_PREFERRED_REFRESH
 	}
 
+	if (cfg.change_success_cmd) {
+		e << YAML::Key << "CHANGE_SUCCESS_CMD" << YAML::Value << cfg.change_success_cmd;
+	}
+
 	if (cfg.laptop_display_prefix) {
 		e << YAML::Key << "LAPTOP_DISPLAY_PREFIX" << YAML::Value << cfg.laptop_display_prefix;
 	}
@@ -373,6 +377,14 @@ struct CfgValidated*& operator << (struct CfgValidated*& cfg_validated, const YA
 		}
 	}
 
+	if (node["CHANGE_SUCCESS_CMD"]) {
+		if (cfg->change_success_cmd) {
+			free(cfg->change_success_cmd);
+		}
+
+		cfg->change_success_cmd = strdup(node["CHANGE_SUCCESS_CMD"].as<std::string>().c_str());
+	}
+
 	if (node["LAPTOP_DISPLAY_PREFIX"]) {
 		if (cfg->laptop_display_prefix) {
 			free(cfg->laptop_display_prefix);
@@ -709,6 +721,8 @@ struct Cfg*& operator << (struct Cfg*& cfg, const YAML::Node& node) {
 		}
 	}
 
+	TI(cfg->change_success_cmd = strdup(node["CHANGE_SUCCESS_CMD"].as<std::string>().c_str()));
+
 	TI(cfg->laptop_display_prefix = strdup(node["LAPTOP_DISPLAY_PREFIX"].as<std::string>().c_str()));
 
 	TI(cfg->log_threshold = log_threshold_val(node["LOG_THRESHOLD"].as<std::string>().c_str()));

src/process.c

@@ -6,6 +6,7 @@
 #include <stdlib.h>
 #include <sys/file.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 #include "process.h"
@@ -103,6 +104,42 @@ void pid_file_create(void) {
 	free(path);
 }
 
+void spawn_async(const char * const command) {
+	pid_t pid = fork();
+	if (pid < 0) {
+		log_error_errno("\nunable to fork");
+		return;
+	}
+
+	if (pid == 0) {
+		// fork again to "disown"
+		setsid();
+		sigset_t mask;
+		sigemptyset(&mask);
+		sigprocmask(SIG_SETMASK, &mask, NULL);
+
+		pid_t pid2 = fork();
+		if (pid2 < 0) {
+			log_error_errno("\nunable to fork");
+			exit(-1);
+		}
+
+		if (pid2 == 0) {
+			// execute command in the child's child process
+			execl("/bin/sh", "/bin/sh", "-c", command, (char *)NULL);
+			log_error_errno("\nfailed to execute /bin/sh");
+			exit(-1);
+		}
+		// primary child exits here
+		exit(0);
+	}
+
+	// wait for the primary child to exit
+	if (waitpid(pid, NULL, 0) != pid) {
+		log_error("\nfailed to wait for child process");
+	};
+}
+
 void wd_exit(int __status) {
 	exit(__status);
 }

tst/GNUmakefile

@@ -14,7 +14,7 @@ WRAPS_COMMON = -Wl,$\
 	--wrap=log_set_threshold,$\
 	--wrap=log_,--wrap=log_error,--wrap=log_warn,--wrap=log_info,--wrap=log_debug,--wrap=log_error_errno,$\
 	--wrap=print_head,--wrap=print_mode,$\
-	--wrap=wd_exit,--wrap=wd_exit_message
+	--wrap=spawn_async,--wrap=wd_exit,--wrap=wd_exit_message
 
 tst-head: WRAPS=,$\
 	--wrap=mode_dpi,$\

tst/marshalling/cfg-all.yaml

@@ -29,6 +29,7 @@ TRANSFORM:
 VRR_OFF:
   - ten
   - ELEVEN
+CHANGE_SUCCESS_CMD: cmd
 LAPTOP_DISPLAY_PREFIX: ldp
 LOG_THRESHOLD: ERROR
 DISABLED:

tst/marshalling/ipc-request-cfg-set.yaml

@@ -32,6 +32,7 @@ CFG:
   VRR_OFF:
     - ten
     - ELEVEN
+  CHANGE_SUCCESS_CMD: cmd
   LAPTOP_DISPLAY_PREFIX: ldp
   LOG_THRESHOLD: ERROR
   DISABLED:

tst/marshalling/ipc-responses-map.yaml

@@ -31,6 +31,7 @@ CFG:
   VRR_OFF:
     - ten
     - ELEVEN
+  CHANGE_SUCCESS_CMD: cmd
   LAPTOP_DISPLAY_PREFIX: ldp
   LOG_THRESHOLD: ERROR
   DISABLED:

tst/tst-cfg.c

@@ -221,6 +221,21 @@ void merge_set__disabled(void **state) {
 	cfg_free(merged);
 }
 
+void merge_set__change_success_cmd(void **state) {
+	struct State *s = *state;
+
+	s->to->change_success_cmd = strdup("to");
+	s->from->change_success_cmd = strdup("from");
+
+	s->expected->change_success_cmd = strdup("from");
+
+	struct Cfg *merged = merge_set(s->to, s->from);
+
+	assert_cfg_equal(merged, s->expected);
+
+	cfg_free(merged);
+}
+
 void merge_del__scale(void **state) {
 	struct State *s = *state;
 
@@ -311,6 +326,21 @@ void merge_del__disabled(void **state) {
 	cfg_free(merged);
 }
 
+void merge_del__change_success_cmd(void **state) {
+	struct State *s = *state;
+
+	s->to->change_success_cmd = strdup("to");
+	s->from->change_success_cmd = strdup("");
+
+	s->expected->change_success_cmd = NULL;
+
+	struct Cfg *merged = merge_del(s->to, s->from);
+
+	assert_cfg_equal(merged, s->expected);
+
+	cfg_free(merged);
+}
+
 void validate_fix__col(void **state) {
 	struct State *s = *state;
 
@@ -436,12 +466,14 @@ int main(void) {
 		TEST(merge_set__mode),
 		TEST(merge_set__adaptive_sync_off),
 		TEST(merge_set__disabled),
+		TEST(merge_set__change_success_cmd),
 
 		TEST(merge_del__scale),
 		TEST(merge_del__mode),
 		TEST(merge_del__transform),
 		TEST(merge_del__adaptive_sync_off),
 		TEST(merge_del__disabled),
+		TEST(merge_del__change_success_cmd),
 
 		TEST(validate_fix__col),
 		TEST(validate_fix__row),