tools: move the builddir lookup function out to a separate file

We want to use this from the tests as well soon, so let's move it to a more
generic location. This also changes the API to be slightly more sensible, a
free() is the same cost (and safer) than passing a static buffer in and hoping
we didn't get the size wrong.

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

meson.build

@@ -281,6 +281,7 @@ install_data(quirks_data, install_dir : dir_data)
 src_libquirks = [
 	'src/quirks.c',
 	'src/quirks.h',
+	'src/builddir.h',
 ]
 
 deps_libquirks = [dep_udev, dep_libinput_util]
@@ -393,7 +394,8 @@ endif
 libinput_tool_path = dir_libexec
 config_h.set_quoted('LIBINPUT_TOOL_PATH', libinput_tool_path)
 tools_shared_sources = [ 'tools/shared.c',
-			 'tools/shared.h' ]
+			 'tools/shared.h',
+			 'src/builddir.h' ]
 deps_tools_shared = [ dep_libinput, dep_libevdev ]
 lib_tools_shared = static_library('tools_shared',
 				  tools_shared_sources,
@@ -610,7 +612,7 @@ endif
 # the test to verify that lookup. We test twice, once as normal test
 # run from the builddir, once after copying to /tmp
 test_builddir_lookup = executable('test-builddir-lookup',
-				  'tools/test-builddir-lookup.c',
+				  'test/test-builddir-lookup.c',
 				  dependencies : [ dep_tools_shared],
 				  include_directories : [includes_src, includes_include],
 				  install : false)
@@ -618,7 +620,7 @@ test('tools-builddir-lookup',
      test_builddir_lookup,
      args : ['--builddir-is-set'])
 test('tools-builddir-lookup-installed',
-     find_program('tools/helper-copy-and-exec-from-tmp.sh'),
+     find_program('test/helper-copy-and-exec-from-tmp.sh'),
      args : [test_builddir_lookup.full_path(), '--builddir-is-null'],
      env : ['LD_LIBRARY_PATH=@0@'.format(meson.build_root())],
      workdir : '/tmp')

src/builddir.h

@@ -0,0 +1,61 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <config.h>
+
+#pragma once
+
+/**
+ * Try to figure out the directory we're executing from and if it matches
+ * the builddir, return that directory. Otherwise, return NULL.
+ */
+static inline char *
+builddir_lookup(void)
+{
+	char execdir[PATH_MAX] = {0};
+	char *pathsep;
+	ssize_t nread;
+
+	/* In the case of release builds, the builddir is
+	   the empty string */
+	if (streq(MESON_BUILD_ROOT, ""))
+		return NULL;
+
+	nread = readlink("/proc/self/exe", execdir, sizeof(execdir) - 1);
+	if (nread <= 0 || nread == sizeof(execdir) - 1)
+		return NULL;
+
+	/* readlink doesn't terminate the string and readlink says
+	   anything past sz is undefined */
+	execdir[++nread] = '\0';
+
+	pathsep = strrchr(execdir, '/');
+	if (!pathsep)
+		return NULL;
+
+	*pathsep = '\0';
+	if (!streq(execdir, MESON_BUILD_ROOT))
+		return NULL;
+
+	return safe_strdup(execdir);
+}

test/test-builddir-lookup.c

@@ -23,34 +23,34 @@
 
 #include "config.h"
 #include "libinput-util.h"
-#include "shared.h"
+#include "builddir.h"
 
-int main(int argc, char **argv) {
-	char builddir[PATH_MAX];
+int
+main(int argc, char **argv)
+{
+	char *builddir;
 	char *mode;
-	bool rc, rc2;
 
 	assert(argc == 2);
 	mode = argv[1];
 
-	rc = tools_execdir_is_builddir(builddir, sizeof(builddir));
-	rc2 = tools_execdir_is_builddir(NULL, 0);
+	builddir = builddir_lookup();
 	if (streq(mode, "--builddir-is-null")) {
-		assert(rc == false);
-		assert(rc == rc2);
+		assert(builddir == NULL);
 	} 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(rc == false);
+			assert(builddir == NULL);
 		} else {
-			assert(rc == true);
+			assert(builddir);
 			assert(streq(MESON_BUILD_ROOT, builddir));
 		}
-		assert(rc == rc2);
 	} else {
 		abort();
 	}
 
+	free(builddir);
+
 	return 0;
 }

tools/libinput-quirks.c

@@ -32,6 +32,7 @@
 #include "libinput-util.h"
 #include "quirks.h"
 #include "shared.h"
+#include "builddir.h"
 
 static bool verbose = false;
 
@@ -162,8 +163,10 @@ main(int argc, char **argv)
 
 	/* Overriding the data dir means no custom override file */
 	if (!data_path) {
-		if (tools_execdir_is_builddir(NULL, 0)) {
+		char *builddir = builddir_lookup();
+		if (builddir) {
 			data_path = LIBINPUT_QUIRKS_SRCDIR;
+			free(builddir);
 		} else {
 			data_path = LIBINPUT_QUIRKS_DIR;
 			override_file = LIBINPUT_QUIRKS_OVERRIDE_FILE;

tools/shared.c

@@ -36,6 +36,7 @@
 #include <libevdev/libevdev.h>
 #include <libinput-util.h>
 
+#include "builddir.h"
 #include "shared.h"
 
 LIBINPUT_ATTRIBUTE_PRINTF(3, 0)
@@ -313,8 +314,11 @@ tools_open_device(const char *path, bool verbose, bool *grab)
 static void
 tools_setenv_quirks_dir(void)
 {
-	if (tools_execdir_is_builddir(NULL, 0))
+	char *builddir = builddir_lookup();
+	if (builddir) {
 		setenv("LIBINPUT_QUIRKS_DIR", LIBINPUT_QUIRKS_SRCDIR, 0);
+		free(builddir);
+	}
 }
 
 struct libinput *
@@ -475,70 +479,21 @@ out:
 	return is_touchpad;
 }
 
-/**
- * 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.
- */
-bool
-tools_execdir_is_builddir(char *execdir_out, size_t sz)
-{
-	char execdir[PATH_MAX] = {0};
-	char *pathsep;
-	ssize_t nread;
-
-	/* In the case of release builds, the builddir is
-	   the empty string */
-	if (streq(MESON_BUILD_ROOT, ""))
-		return false;
-
-	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[++nread] = '\0';
-
-	pathsep = strrchr(execdir, '/');
-	if (!pathsep)
-		return false;
-
-	*pathsep = '\0';
-	if (!streq(execdir, MESON_BUILD_ROOT))
-		return false;
-
-	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[PATH_MAX];
 	const char *extra_path = LIBINPUT_TOOL_PATH;
-
-	if (tools_execdir_is_builddir(builddir, sizeof(builddir)))
-		extra_path = builddir;
+	char *builddir = builddir_lookup();
 
 	snprintf(new_path,
 		 sizeof(new_path),
 		 "%s:%s",
-		 extra_path,
+		 builddir ? builddir : extra_path,
 		 path ? path : "");
 	setenv("PATH", new_path, 1);
+	free(builddir);
 }
 
 int

tools/shared.h

@@ -123,7 +123,4 @@ tools_list_device_quirks(struct quirks_context *ctx,
 			 void (*callback)(void *userdata, const char *str),
 			 void *userdata);
 
-bool
-tools_execdir_is_builddir(char *execdir_out, size_t sz);
-
 #endif