From 3b9f7885e0e2c4a334848bb1a4b461d1f6fd7cdf Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Sat, 21 Dec 2019 05:29:38 -0500
Subject: [PATCH] Stop using chdir

---
 native/jni/core/bootstages.cpp | 38 +++++++++++++++++-----------------
 native/jni/core/scripting.cpp  | 15 +++++++-------
 2 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/native/jni/core/bootstages.cpp b/native/jni/core/bootstages.cpp
index 71a37ba45..99831fafd 100644
--- a/native/jni/core/bootstages.cpp
+++ b/native/jni/core/bootstages.cpp
@@ -451,47 +451,47 @@ static void reboot() {
 
 void remove_modules() {
 	LOGI("* Remove all modules and reboot");
-	chdir(MODULEROOT);
-	rm_rf("lost+found");
-	auto dir = xopen_dir(".");
+	auto dir = xopen_dir(MODULEROOT);
+	int dfd = dirfd(dir.get());
 	for (dirent *entry; (entry = xreaddir(dir.get()));) {
 		if (entry->d_type == DT_DIR) {
 			if (entry->d_name == "."sv || entry->d_name == ".."sv || entry->d_name == ".core"sv)
 				continue;
-			chdir(entry->d_name);
-			close(creat("remove", 0644));
-			chdir("..");
+
+			int modfd = xopenat(dfd, entry->d_name, O_RDONLY | O_CLOEXEC);
+			close(xopenat(modfd, "remove", O_RDONLY | O_CREAT | O_CLOEXEC));
+			close(modfd);
 		}
 	}
-	chdir("/");
 	reboot();
 }
 
 static void collect_modules() {
-	chdir(MODULEROOT);
-	rm_rf("lost+found");
-	auto dir = xopen_dir(".");
+	auto dir = xopen_dir(MODULEROOT);
+	int dfd = dirfd(dir.get());
 	for (dirent *entry; (entry = xreaddir(dir.get()));) {
 		if (entry->d_type == DT_DIR) {
 			if (entry->d_name == "."sv || entry->d_name == ".."sv || entry->d_name == ".core"sv)
 				continue;
-			chdir(entry->d_name);
-			if (access("remove", F_OK) == 0) {
-				chdir("..");
+
+			int modfd = xopenat(dfd, entry->d_name, O_RDONLY);
+			run_finally f([=]{ close(modfd); });
+
+			if (faccessat(modfd, "remove", F_OK, 0) == 0) {
 				LOGI("%s: remove\n", entry->d_name);
-				sprintf(buf, "%s/uninstall.sh", entry->d_name);
+				fd_pathat(modfd, "uninstall.sh", buf, sizeof(buf));
 				if (access(buf, F_OK) == 0)
 					exec_script(buf);
-				rm_rf(entry->d_name);
+				frm_rf(modfd);
 				continue;
 			}
-			unlink("update");
-			if (access("disable", F_OK))
+
+			unlinkat(modfd, "update", 0);
+
+			if (faccessat(modfd, "disable", F_OK, 0) != 0)
 				module_list.emplace_back(entry->d_name);
-			chdir("..");
 		}
 	}
-	chdir("/");
 }
 
 static bool load_modules(node_entry *root) {
diff --git a/native/jni/core/scripting.cpp b/native/jni/core/scripting.cpp
index 5e4899847..3f4888133 100644
--- a/native/jni/core/scripting.cpp
+++ b/native/jni/core/scripting.cpp
@@ -26,30 +26,31 @@ void exec_script(const char *script) {
 
 void exec_common_script(const char *stage) {
 	char path[4096];
-	sprintf(path, SECURE_DIR "/%s.d", stage);
+	char *name = path + sprintf(path, SECURE_DIR "/%s.d", stage);
 	auto dir = xopen_dir(path);
 	if (!dir)
 		return;
-	chdir(path);
 
+	int dfd = dirfd(dir.get());
 	bool pfs = stage == "post-fs-data"sv;
+	*(name++) = '/';
+
 	for (dirent *entry; (entry = xreaddir(dir.get()));) {
 		if (entry->d_type == DT_REG) {
-			if (access(entry->d_name, X_OK) == -1)
+			if (faccessat(dfd, entry->d_name, X_OK, 0) != 0)
 				continue;
 			LOGI("%s.d: exec [%s]\n", stage, entry->d_name);
+			strcpy(name, entry->d_name);
 			exec_t exec {
 				.pre_exec = set_path,
 				.fork = pfs ? fork_no_zombie : fork_dont_care
 			};
 			if (pfs)
-				exec_command_sync(exec, "/system/bin/sh", entry->d_name);
+				exec_command_sync(exec, "/system/bin/sh", path);
 			else
-				exec_command(exec, "/system/bin/sh", entry->d_name);
+				exec_command(exec, "/system/bin/sh", path);
 		}
 	}
-
-	chdir("/");
 }
 
 void exec_module_script(const char *stage, const vector<string> &module_list) {