Move sway-specific functions in common/util.c into sway/

Modifier handling functions were moved into sway/input/keyboard.c;
opposite_direction for enum wlr_direction into sway/tree/output.c;
and get_parent_pid into sway/tree/root.c .

sway/tree/output.c

@@ -1,4 +1,5 @@
 #define _POSIX_C_SOURCE 200809L
+#include <assert.h>
 #include <ctype.h>
 #include <string.h>
 #include <strings.h>
@@ -12,6 +13,21 @@
 #include "log.h"
 #include "util.h"
 
+enum wlr_direction opposite_direction(enum wlr_direction d) {
+	switch (d) {
+	case WLR_DIRECTION_UP:
+		return WLR_DIRECTION_DOWN;
+	case WLR_DIRECTION_DOWN:
+		return WLR_DIRECTION_UP;
+	case WLR_DIRECTION_RIGHT:
+		return WLR_DIRECTION_LEFT;
+	case WLR_DIRECTION_LEFT:
+		return WLR_DIRECTION_RIGHT;
+	}
+	assert(false);
+	return 0;
+}
+
 static void restore_workspaces(struct sway_output *output) {
 	// Workspace output priority
 	for (int i = 0; i < root->outputs->length; i++) {

sway/tree/root.c

@@ -169,6 +169,41 @@ struct pid_workspace {
 
 static struct wl_list pid_workspaces;
 
+/**
+ * Get the pid of a parent process given the pid of a child process.
+ *
+ * Returns the parent pid or NULL if the parent pid cannot be determined.
+ */
+static pid_t get_parent_pid(pid_t child) {
+	pid_t parent = -1;
+	char file_name[100];
+	char *buffer = NULL;
+	char *token = NULL;
+	const char *sep = " ";
+	FILE *stat = NULL;
+	size_t buf_size = 0;
+
+	sprintf(file_name, "/proc/%d/stat", child);
+
+	if ((stat = fopen(file_name, "r"))) {
+		if (getline(&buffer, &buf_size, stat) != -1) {
+			token = strtok(buffer, sep); // pid
+			token = strtok(NULL, sep);   // executable name
+			token = strtok(NULL, sep);   // state
+			token = strtok(NULL, sep);   // parent pid
+			parent = strtol(token, NULL, 10);
+		}
+		free(buffer);
+		fclose(stat);
+	}
+
+	if (parent) {
+		return (parent == child) ? -1 : parent;
+	}
+
+	return -1;
+}
+
 struct sway_workspace *root_workspace_for_pid(pid_t pid) {
 	if (!pid_workspaces.prev && !pid_workspaces.next) {
 		wl_list_init(&pid_workspaces);