libos+init: Add a new Path class to handle both file descriptors and file paths

apps/init.cpp

@@ -132,9 +132,9 @@ static void start_service(Service& service)
     }
 }
 
-static Result<void> load_service(StringView path)
+static Result<void> load_service(const os::Path& path)
 {
-    fprintf(g_init_log, "[init] reading service file: %s\n", path.chars());
+    fprintf(g_init_log, "[init] reading service file: %s\n", path.name().chars());
 
     auto file = TRY(os::File::open(path, os::File::ReadOnly));
 
@@ -242,11 +242,7 @@ static Result<void> load_services()
     auto services = TRY(dir->list(os::Directory::Filter::ParentAndBase));
     sort(services.begin(), services.end(), String::compare);
 
-    for (const auto& entry : services)
-    {
-        auto service_path = TRY(PathParser::join("/etc/init"_sv, entry.view()));
-        TRY(load_service(service_path.view()));
-    }
+    for (const auto& entry : services) TRY(load_service({ dir->fd(), entry.view() }));
 
     return {};
 }

libos/CMakeLists.txt

@@ -10,6 +10,7 @@ set(SOURCES
     src/Process.cpp
     src/Directory.cpp
     src/Main.cpp
+    src/Path.cpp
 )
 
 add_library(os ${SOURCES})

libos/include/os/Directory.h

@@ -3,15 +3,14 @@
 #include <luna/SharedPtr.h>
 #include <luna/String.h>
 #include <luna/Vector.h>
+#include <os/Path.h>
 
 namespace os
 {
     class Directory
     {
       public:
-        static Result<SharedPtr<Directory>> open(StringView path);
-
-        static Result<SharedPtr<Directory>> openat(int dirfd, StringView path);
+        static Result<SharedPtr<Directory>> open(const Path& path);
 
         enum class Filter
         {

libos/include/os/File.h

@@ -4,6 +4,7 @@
 #include <luna/Result.h>
 #include <luna/SharedPtr.h>
 #include <luna/StringView.h>
+#include <os/Path.h>
 #include <sys/types.h>
 
 namespace os
@@ -20,9 +21,9 @@ namespace os
             ReadAppend = O_RDWR | O_APPEND,
         };
 
-        static Result<SharedPtr<File>> open(StringView path, OpenMode flags);
-        static Result<SharedPtr<File>> open_or_create(StringView path, OpenMode flags, mode_t mode = 0644);
-        static Result<SharedPtr<File>> create(StringView path, OpenMode flags, mode_t mode = 0644);
+        static Result<SharedPtr<File>> open(const Path& path, OpenMode flags);
+        static Result<SharedPtr<File>> open_or_create(const Path& path, OpenMode flags, mode_t mode = 0644);
+        static Result<SharedPtr<File>> create(const Path& path, OpenMode flags, mode_t mode = 0644);
 
         /*
           If path is "-", return standard input (as is common for many CLI apps). Otherwise, open path for reading.
@@ -58,7 +59,7 @@ namespace os
         ~File();
 
       private:
-        static Result<SharedPtr<File>> construct(StringView path, int flags, mode_t mode);
+        static Result<SharedPtr<File>> construct(const Path& path, int flags, mode_t mode);
         static void initialize_standard_streams();
 
         Result<usize> raw_read(u8* buf, usize length);

libos/include/os/FileSystem.h

@@ -1,23 +1,22 @@
 #pragma once
 #include <luna/Result.h>
 #include <luna/StringView.h>
+#include <os/Path.h>
 #include <sys/types.h>
 
 namespace os
 {
     namespace FileSystem
     {
-        bool exists(StringView path);
+        bool exists(const Path& path);
 
-        bool is_directory(StringView path);
+        bool is_directory(const Path& path);
 
         Result<void> create_directory(StringView path, mode_t mode);
 
-        Result<void> remove(StringView path);
-        Result<void> removeat(int dirfd, StringView path);
+        Result<void> remove(const Path& path);
 
-        Result<void> remove_tree(StringView path);
-        Result<void> remove_tree_at(int dirfd, StringView path);
+        Result<void> remove_tree(const Path& path);
 
         Result<String> working_directory();
         Result<String> home_directory();

libos/include/os/Path.h

@@ -0,0 +1,36 @@
+#pragma once
+#include <fcntl.h>
+#include <luna/StringView.h>
+
+namespace os
+{
+    class Path
+    {
+      public:
+        Path(const char* path);
+        Path(StringView path);
+        Path(int fd);
+        Path(int dirfd, StringView name);
+
+        int dirfd() const
+        {
+            return m_dirfd.value_or(AT_FDCWD);
+        }
+
+        StringView name() const
+        {
+            return m_name.value_or(""_sv);
+        }
+
+        int is_empty_path() const
+        {
+            if (m_dirfd.has_value() && !m_name.has_value()) return AT_EMPTY_PATH;
+
+            return 0;
+        }
+
+      private:
+        Option<int> m_dirfd;
+        Option<StringView> m_name;
+    };
+}

libos/src/Directory.cpp

@@ -18,23 +18,12 @@ static bool should_skip_entry(const char* name, os::Directory::Filter filter)
 
 namespace os
 {
-    Result<SharedPtr<Directory>> Directory::open(StringView path)
+
+    Result<SharedPtr<Directory>> Directory::open(const Path& path)
     {
         auto dir = TRY(adopt_shared_if_nonnull(new (std::nothrow) Directory({})));
 
-        DIR* dp = opendir(path.chars());
-        if (!dp) return err(errno);
-
-        dir->m_dirp = dp;
-
-        return dir;
-    }
-
-    Result<SharedPtr<Directory>> Directory::openat(int dirfd, StringView path)
-    {
-        auto dir = TRY(adopt_shared_if_nonnull(new (std::nothrow) Directory({})));
-
-        long rc = syscall(SYS_openat, dirfd, path.chars(), O_RDONLY | O_DIRECTORY, 0);
+        long rc = syscall(SYS_openat, path.dirfd(), path.name().chars(), O_RDONLY | O_DIRECTORY, 0);
         int fd = TRY(Result<int>::from_syscall(rc));
 
         DIR* dp = fdopendir(fd);

libos/src/File.cpp

@@ -55,11 +55,11 @@ namespace os
         return g_stderr;
     }
 
-    Result<SharedPtr<File>> File::construct(StringView path, int flags, mode_t mode)
+    Result<SharedPtr<File>> File::construct(const Path& path, int flags, mode_t mode)
     {
         auto file = TRY(adopt_shared_if_nonnull(new (std::nothrow) File({})));
 
-        long rc = syscall(SYS_openat, AT_FDCWD, path.chars(), flags, mode);
+        long rc = syscall(SYS_openat, path.dirfd(), path.name().chars(), flags, mode);
         int fd = TRY(Result<int>::from_syscall(rc));
 
         file->m_fd = fd;
@@ -67,17 +67,17 @@ namespace os
         return file;
     }
 
-    Result<SharedPtr<File>> File::open(StringView path, OpenMode flags)
+    Result<SharedPtr<File>> File::open(const Path& path, OpenMode flags)
     {
         return construct(path, (int)flags, 0);
     }
 
-    Result<SharedPtr<File>> File::open_or_create(StringView path, OpenMode flags, mode_t mode)
+    Result<SharedPtr<File>> File::open_or_create(const Path& path, OpenMode flags, mode_t mode)
     {
         return construct(path, (int)flags | O_CREAT, mode);
     }
 
-    Result<SharedPtr<File>> File::create(StringView path, OpenMode flags, mode_t mode)
+    Result<SharedPtr<File>> File::create(const Path& path, OpenMode flags, mode_t mode)
     {
         return construct(path, (int)flags | (O_CREAT | O_EXCL), mode);
     }

libos/src/FileSystem.cpp

@@ -12,20 +12,20 @@
 
 namespace os::FileSystem
 {
-    bool exists(StringView path)
+    bool exists(const Path& path)
     {
         struct stat st;
 
-        if (stat(path.chars(), &st) < 0) return false;
+        if (fstatat(path.dirfd(), path.name().chars(), &st, path.is_empty_path()) < 0) return false;
 
         return true;
     }
 
-    bool is_directory(StringView path)
+    bool is_directory(const Path& path)
     {
         struct stat st;
 
-        if (stat(path.chars(), &st) < 0) return false;
+        if (fstatat(path.dirfd(), path.name().chars(), &st, path.is_empty_path()) < 0) return false;
 
         return S_ISDIR(st.st_mode);
     }
@@ -37,36 +37,26 @@ namespace os::FileSystem
         return Result<void>::from_syscall(rc);
     }
 
-    Result<void> remove(StringView path)
+    Result<void> remove(const Path& path)
     {
-        return removeat(AT_FDCWD, path);
-    }
-
-    Result<void> removeat(int dirfd, StringView path)
-    {
-        long rc = syscall(SYS_unlinkat, dirfd, path.chars(), 0);
+        long rc = syscall(SYS_unlinkat, path.dirfd(), path.name().chars(), 0);
 
         return Result<void>::from_syscall(rc);
     }
 
-    Result<void> remove_tree(StringView path)
+    Result<void> remove_tree(const Path& path)
     {
-        return remove_tree_at(AT_FDCWD, path);
-    }
-
-    Result<void> remove_tree_at(int dirfd, StringView path)
-    {
-        auto rc = removeat(dirfd, path);
+        auto rc = remove(path);
         if (!rc.has_error()) return {};
         if (rc.error() != ENOTEMPTY) return rc.release_error();
 
-        auto dir = TRY(os::Directory::openat(dirfd, path));
+        auto dir = TRY(os::Directory::open(path));
 
         Vector<String> entries = TRY(dir->list(os::Directory::Filter::ParentAndBase));
 
-        for (const auto& entry : entries) { TRY(remove_tree_at(dir->fd(), entry.view())); }
+        for (const auto& entry : entries) { TRY(remove_tree({ dir->fd(), entry.view() })); }
 
-        return removeat(dirfd, path);
+        return remove(path);
     }
 
     Result<String> working_directory()

libos/src/Path.cpp

@@ -0,0 +1,20 @@
+#include <os/Path.h>
+
+namespace os
+{
+    Path::Path(const char* path) : m_dirfd(), m_name(path)
+    {
+    }
+
+    Path::Path(StringView path) : m_dirfd(), m_name(path)
+    {
+    }
+
+    Path::Path(int fd) : m_dirfd(fd), m_name()
+    {
+    }
+
+    Path::Path(int dirfd, StringView name) : m_dirfd(dirfd), m_name(name)
+    {
+    }
+}