Kernel: Make chdir() take path+length

Kernel/Process.cpp

@@ -1555,12 +1555,13 @@ int Process::sys$readlink(const char* path, char* buffer, ssize_t size)
     return 0;
 }
 
-int Process::sys$chdir(const char* path)
+int Process::sys$chdir(const char* user_path, size_t path_length)
 {
     SmapDisabler disabler;
-    if (!validate_read_str(path))
+    if (!validate_read(user_path, path_length))
         return -EFAULT;
-    auto directory_or_error = VFS::the().open_directory(StringView(path), current_directory());
+    auto path = copy_string_from_user(user_path, path_length);
+    auto directory_or_error = VFS::the().open_directory(path, current_directory());
     if (directory_or_error.is_error())
         return directory_or_error.error();
     m_cwd = *directory_or_error.value();

Kernel/Process.h

@@ -144,7 +144,7 @@ public:
     int sys$poll(pollfd*, int nfds, int timeout);
     ssize_t sys$get_dir_entries(int fd, void*, ssize_t);
     int sys$getcwd(char*, ssize_t);
-    int sys$chdir(const char*);
+    int sys$chdir(const char*, size_t);
     int sys$fchdir(int fd);
     int sys$sleep(unsigned seconds);
     int sys$usleep(useconds_t usec);

Libraries/LibC/unistd.cpp

@@ -245,7 +245,7 @@ int fstat(int fd, struct stat* statbuf)
 
 int chdir(const char* path)
 {
-    int rc = syscall(SC_chdir, path);
+    int rc = syscall(SC_chdir, path, strlen(path));
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }