tools: change prototype of the builddir lookup function

Only one place really needs the return argument, so we might as well just pass
the memory to be returned in.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

tools/libinput-quirks.c

@@ -162,12 +162,8 @@ main(int argc, char **argv)
 
 	/* Overriding the data dir means no custom override file */
 	if (!data_path) {
-		char *builddir;
-
-		builddir = tools_execdir_is_builddir();
-		if (builddir) {
+		if (tools_execdir_is_builddir(NULL, 0)) {
 			data_path = LIBINPUT_QUIRKS_SRCDIR;
-			free(builddir);
 		} else {
 			data_path = LIBINPUT_QUIRKS_DIR;
 			override_file = LIBINPUT_QUIRKS_OVERRIDE_FILE;

tools/shared.c

@@ -467,56 +467,70 @@ is_touchpad_device(const char *devnode)
 	return is_touchpad;
 }
 
-/* Try to read the directory we're executing from and if it matches the
- * builddir, return it as path. Otherwise, return NULL.
+/**
+ * Try to read the directory we're executing from and if it matches the
+ * builddir, return it.
+ *
+ * @param execdir_out If not NULL, set to the exec directory
+ * @param sz Size of execdir_out
+ *
+ * @return true if the execdir is the builddir, false otherwise.
+ *
+ * If execdir_out is NULL and szt is 0, it merely returns true/false.
  */
-char *
-tools_execdir_is_builddir(void)
+bool
+tools_execdir_is_builddir(char *execdir_out, size_t sz)
 {
 	char execdir[PATH_MAX] = {0};
 	char *pathsep;
-	ssize_t sz;
+	ssize_t nread;
 
 	/* In the case of release builds, the builddir is
 	   the empty string */
 	if (streq(MESON_BUILD_ROOT, ""))
-		return NULL;
+		return false;
 
-	sz = readlink("/proc/self/exe", execdir, sizeof(execdir) - 1);
-	if (sz <= 0 || sz == sizeof(execdir) - 1)
-		return NULL;
+	nread = readlink("/proc/self/exe", execdir, sizeof(execdir) - 1);
+	if (nread <= 0 || nread == sizeof(execdir) - 1)
+		return false;
 
 	/* readlink doesn't terminate the string and readlink says
 	   anything past sz is undefined */
-	execdir[sz + 1] = '\0';
+	execdir[++nread] = '\0';
 
 	pathsep = strrchr(execdir, '/');
 	if (!pathsep)
-		return NULL;
+		return false;
 
 	*pathsep = '\0';
 	if (!streq(execdir, MESON_BUILD_ROOT))
-		return NULL;
+		return false;
 
-	return safe_strdup(execdir);
+	if (sz > 0) {
+		assert(execdir_out != NULL);
+		assert(sz >= (size_t)nread);
+		snprintf(execdir_out, nread, "%s", execdir);
+	}
+	return true;
 }
 
 static inline void
 setup_path(void)
 {
 	const char *path = getenv("PATH");
 	char new_path[PATH_MAX];
-	char *builddir;
+	char builddir[PATH_MAX];
+	const char *extra_path = LIBINPUT_TOOL_PATH;
 
-	builddir = tools_execdir_is_builddir();
+	if (tools_execdir_is_builddir(builddir, sizeof(builddir)))
+		extra_path = builddir;
 
 	snprintf(new_path,
 		 sizeof(new_path),
 		 "%s:%s",
-		 builddir ? builddir : LIBINPUT_TOOL_PATH,
+		 extra_path,
 		 path ? path : "");
 	setenv("PATH", new_path, 1);
-	free(builddir);
 }
 
 int

tools/shared.h

@@ -25,6 +25,7 @@
 #define _SHARED_H_
 
 #include <stdbool.h>
+#include <limits.h>
 
 #include <quirks.h>
 #include <libinput.h>
@@ -119,7 +120,7 @@ tools_list_device_quirks(struct quirks_context *ctx,
 			 void (*callback)(void *userdata, const char *str),
 			 void *userdata);
 
-char *
-tools_execdir_is_builddir(void);
+bool
+tools_execdir_is_builddir(char *execdir_out, size_t sz);
 
 #endif

tools/test-builddir-lookup.c

@@ -26,25 +26,28 @@
 #include "shared.h"
 
 int main(int argc, char **argv) {
-	char *builddir;
+	char builddir[PATH_MAX];
 	char *mode;
+	bool rc, rc2;
 
 	assert(argc == 2);
 	mode = argv[1];
 
-	builddir = tools_execdir_is_builddir();
+	rc = tools_execdir_is_builddir(builddir, sizeof(builddir));
+	rc2 = tools_execdir_is_builddir(NULL, 0);
 	if (streq(mode, "--builddir-is-null")) {
-		assert(builddir == NULL);
+		assert(rc == false);
+		assert(rc == rc2);
 	} else if (streq(mode, "--builddir-is-set")) {
 		/* In the case of release builds, the builddir is
 		   the empty string */
 		if (streq(MESON_BUILD_ROOT, "")) {
-			assert(builddir == NULL);
+			assert(rc == false);
 		} else {
-			assert(builddir != NULL);
+			assert(rc == true);
 			assert(streq(MESON_BUILD_ROOT, builddir));
-			free(builddir);
 		}
+		assert(rc == rc2);
 	} else {
 		abort();
 	}