Libraries: Move to Userland/Libraries/

Userland/Libraries/LibCore/File.cpp

@@ -0,0 +1,270 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef __serenity__
+#    include <Kernel/API/Syscall.h>
+#endif
+#include <AK/ScopeGuard.h>
+#include <LibCore/File.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+namespace Core {
+
+Result<NonnullRefPtr<File>, String> File::open(const String& filename, IODevice::OpenMode mode, mode_t permissions)
+{
+    auto file = File::construct(filename);
+    if (!file->open_impl(mode, permissions))
+        return String(file->error_string());
+    return file;
+}
+
+File::File(const StringView& filename, Object* parent)
+    : IODevice(parent)
+    , m_filename(filename)
+{
+}
+
+File::~File()
+{
+    if (m_should_close_file_descriptor == ShouldCloseFileDescriptor::Yes && mode() != NotOpen)
+        close();
+}
+
+bool File::open(int fd, IODevice::OpenMode mode, ShouldCloseFileDescriptor should_close)
+{
+    set_fd(fd);
+    set_mode(mode);
+    m_should_close_file_descriptor = should_close;
+    return true;
+}
+
+bool File::open(IODevice::OpenMode mode)
+{
+    return open_impl(mode, 0666);
+}
+
+bool File::open_impl(IODevice::OpenMode mode, mode_t permissions)
+{
+    ASSERT(!m_filename.is_null());
+    int flags = 0;
+    if ((mode & IODevice::ReadWrite) == IODevice::ReadWrite) {
+        flags |= O_RDWR | O_CREAT;
+    } else if (mode & IODevice::ReadOnly) {
+        flags |= O_RDONLY;
+    } else if (mode & IODevice::WriteOnly) {
+        flags |= O_WRONLY | O_CREAT;
+        bool should_truncate = !((mode & IODevice::Append) || (mode & IODevice::MustBeNew));
+        if (should_truncate)
+            flags |= O_TRUNC;
+    }
+    if (mode & IODevice::Append)
+        flags |= O_APPEND;
+    if (mode & IODevice::Truncate)
+        flags |= O_TRUNC;
+    if (mode & IODevice::MustBeNew)
+        flags |= O_EXCL;
+    int fd = ::open(m_filename.characters(), flags, permissions);
+    if (fd < 0) {
+        set_error(errno);
+        return false;
+    }
+
+    set_fd(fd);
+    set_mode(mode);
+    return true;
+}
+
+bool File::is_directory() const
+{
+    struct stat stat;
+    if (fstat(fd(), &stat) < 0)
+        return false;
+    return S_ISDIR(stat.st_mode);
+}
+
+bool File::is_directory(const String& filename)
+{
+    struct stat st;
+    if (stat(filename.characters(), &st) < 0)
+        return false;
+    return S_ISDIR(st.st_mode);
+}
+
+bool File::exists(const String& filename)
+{
+    struct stat st;
+    return stat(filename.characters(), &st) == 0;
+}
+
+String File::real_path_for(const String& filename)
+{
+    if (filename.is_null())
+        return {};
+    auto* path = realpath(filename.characters(), nullptr);
+    String real_path(path);
+    free(path);
+    return real_path;
+}
+
+bool File::ensure_parent_directories(const String& path)
+{
+    ASSERT(path.starts_with("/"));
+
+    int saved_errno = 0;
+    ScopeGuard restore_errno = [&saved_errno] { errno = saved_errno; };
+
+    char* parent_buffer = strdup(path.characters());
+    ScopeGuard free_buffer = [parent_buffer] { free(parent_buffer); };
+
+    const char* parent = dirname(parent_buffer);
+
+    int rc = mkdir(parent, 0755);
+    saved_errno = errno;
+
+    if (rc == 0 || errno == EEXIST)
+        return true;
+
+    if (errno != ENOENT)
+        return false;
+
+    bool ok = ensure_parent_directories(parent);
+    saved_errno = errno;
+    if (!ok)
+        return false;
+
+    rc = mkdir(parent, 0755);
+    saved_errno = errno;
+    return rc == 0;
+}
+
+#ifdef __serenity__
+
+String File::read_link(const StringView& link_path)
+{
+    // First, try using a 64-byte buffer, that ought to be enough for anybody.
+    char small_buffer[64];
+    Syscall::SC_readlink_params small_params {
+        { link_path.characters_without_null_termination(), link_path.length() },
+        { small_buffer, sizeof(small_buffer) }
+    };
+    int rc = syscall(SC_readlink, &small_params);
+    if (rc < 0) {
+        errno = -rc;
+        return {};
+    }
+    size_t size = rc;
+    // If the call was successful, the syscall (unlike the LibC wrapper)
+    // returns the full size of the link. Let's see if our small buffer
+    // was enough to read the whole link.
+    if (size <= sizeof(small_buffer))
+        return { small_buffer, size };
+    // Nope, but at least now we know the right size.
+    char* large_buffer_ptr;
+    auto large_buffer = StringImpl::create_uninitialized(size, large_buffer_ptr);
+    Syscall::SC_readlink_params large_params {
+        { link_path.characters_without_null_termination(), link_path.length() },
+        { large_buffer_ptr, (size_t)size }
+    };
+    rc = syscall(SC_readlink, &large_params);
+    if (rc < 0) {
+        errno = -rc;
+        return {};
+    }
+    size_t new_size = rc;
+    if (new_size == size)
+        return { *large_buffer };
+
+    // If we're here, the symlink has changed while we were looking at it.
+    // If it became shorter, our buffer is valid, we just have to trim it a bit.
+    if (new_size < size)
+        return { large_buffer_ptr, new_size };
+    // Otherwise, here's not much we can do, unless we want to loop endlessly
+    // in this case. Let's leave it up to the caller whether to loop.
+    errno = -EAGAIN;
+    return {};
+}
+
+#else
+
+// This is a sad version for other systems. It has to always make a copy of the
+// link path, and to always make two syscalls to get the right size first.
+String File::read_link(const StringView& link_path)
+{
+    String link_path_str = link_path;
+    struct stat statbuf;
+    int rc = lstat(link_path_str.characters(), &statbuf);
+    if (rc < 0)
+        return {};
+    char* buffer_ptr;
+    auto buffer = StringImpl::create_uninitialized(statbuf.st_size, buffer_ptr);
+    rc = readlink(link_path_str.characters(), buffer_ptr, statbuf.st_size);
+    if (rc < 0)
+        return {};
+    // (See above.)
+    if (rc == statbuf.st_size)
+        return { *buffer };
+    return { buffer_ptr, (size_t)rc };
+}
+
+#endif
+
+static RefPtr<File> stdin_file;
+static RefPtr<File> stdout_file;
+static RefPtr<File> stderr_file;
+
+NonnullRefPtr<File> File::standard_input()
+{
+    if (!stdin_file) {
+        stdin_file = File::construct();
+        stdin_file->open(STDIN_FILENO, IODevice::ReadOnly, ShouldCloseFileDescriptor::No);
+    }
+    return *stdin_file;
+}
+
+NonnullRefPtr<File> File::standard_output()
+{
+    if (!stdout_file) {
+        stdout_file = File::construct();
+        stdout_file->open(STDOUT_FILENO, IODevice::WriteOnly, ShouldCloseFileDescriptor::No);
+    }
+    return *stdout_file;
+}
+
+NonnullRefPtr<File> File::standard_error()
+{
+    if (!stderr_file) {
+        stderr_file = File::construct();
+        stderr_file->open(STDERR_FILENO, IODevice::WriteOnly, ShouldCloseFileDescriptor::No);
+    }
+    return *stderr_file;
+}
+}