input_cmd_xkb_file: allow shell path expansion

This allows for shell path expansion for input_cmd_xkb_file. The logic
has been extracted from output_cmd_background

common/stringop.c

@@ -5,6 +5,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <strings.h>
+#include <wordexp.h>
 #include "list.h"
 #include "log.h"
 #include "stringop.h"
@@ -309,3 +310,21 @@ char *argsep(char **stringp, const char *delim, char *matched) {
 	}
 	return start;
 }
+
+bool expand_path(char **path) {
+	wordexp_t p = {0};
+	while (strstr(*path, "  ")) {
+		*path = realloc(*path, strlen(*path) + 2);
+		char *ptr = strstr(*path, "  ") + 1;
+		memmove(ptr + 1, ptr, strlen(ptr) + 1);
+		*ptr = '\\';
+	}
+	if (wordexp(*path, &p, 0) != 0 || p.we_wordv[0] == NULL) {
+		wordfree(&p);
+		return false;
+	}
+	free(*path);
+	*path = join_args(p.we_wordv, p.we_wordc);
+	wordfree(&p);
+	return true;
+}

include/stringop.h

@@ -1,6 +1,7 @@
 #ifndef _SWAY_STRINGOP_H
 #define _SWAY_STRINGOP_H
 
+#include <stdbool.h>
 #include "list.h"
 
 void strip_whitespace(char *str);
@@ -26,4 +27,7 @@ char *join_args(char **argv, int argc);
 // Split string into 2 by delim, handle quotes
 char *argsep(char **stringp, const char *delim, char *matched_delim);
 
+// Expand a path using shell replacements such as $HOME and ~
+bool expand_path(char **path);
+
 #endif

sway/commands/input/xkb_file.c

@@ -1,7 +1,10 @@
 #define _POSIX_C_SOURCE 200809L
+#include <unistd.h>
+#include <errno.h>
 #include "sway/config.h"
 #include "sway/commands.h"
 #include "log.h"
+#include "stringop.h"
 
 struct cmd_results *input_cmd_xkb_file(int argc, char **argv) {
 	struct cmd_results *error = NULL;
@@ -18,6 +21,25 @@ struct cmd_results *input_cmd_xkb_file(int argc, char **argv) {
 		ic->xkb_file = NULL;
 	} else {
 		ic->xkb_file = strdup(argv[0]);
+		if (!expand_path(&ic->xkb_file)) {
+			error = cmd_results_new(CMD_INVALID, "Invalid syntax (%s)",
+					ic->xkb_file);
+			free(ic->xkb_file);
+			ic->xkb_file = NULL;
+			return error;
+		}
+		if (!ic->xkb_file) {
+			sway_log(SWAY_ERROR, "Failed to allocate expanded path");
+			return cmd_results_new(CMD_FAILURE, "Unable to allocate resource");
+		}
+
+		bool can_access = access(ic->xkb_file, F_OK) != -1;
+		if (!can_access) {
+			sway_log_errno(SWAY_ERROR, "Unable to access xkb file '%s'",
+					ic->xkb_file);
+			config_add_swaynag_warning("Unable to access xkb file '%s'",
+					ic->xkb_file);
+		}
 	}
 	ic->xkb_file_is_set = true;
 

sway/commands/output/background.c

@@ -4,7 +4,6 @@
 #include <string.h>
 #include <strings.h>
 #include <unistd.h>
-#include <wordexp.h>
 #include <errno.h>
 #include "sway/commands.h"
 #include "sway/config.h"
@@ -79,26 +78,15 @@ struct cmd_results *output_cmd_background(int argc, char **argv) {
 			return cmd_results_new(CMD_INVALID, "Missing background file");
 		}
 
-		wordexp_t p = {0};
 		char *src = join_args(argv, j);
-		while (strstr(src, "  ")) {
-			src = realloc(src, strlen(src) + 2);
-			char *ptr = strstr(src, "  ") + 1;
-			memmove(ptr + 1, ptr, strlen(ptr) + 1);
-			*ptr = '\\';
-		}
-		if (wordexp(src, &p, 0) != 0 || p.we_wordv[0] == NULL) {
+		if (!expand_path(&src)) {
 			struct cmd_results *cmd_res = cmd_results_new(CMD_INVALID,
 				"Invalid syntax (%s)", src);
 			free(src);
-			wordfree(&p);
 			return cmd_res;
 		}
-		free(src);
-		src = join_args(p.we_wordv, p.we_wordc);
-		wordfree(&p);
 		if (!src) {
-			sway_log(SWAY_ERROR, "Failed to duplicate string");
+			sway_log(SWAY_ERROR, "Failed to allocate expanded path");
 			return cmd_results_new(CMD_FAILURE, "Unable to allocate resource");
 		}