From b8345246dcc2121bcb6d1515a9341789de20199f Mon Sep 17 00:00:00 2001
From: Dominick Allen <djallen@librehumanitas.org>
Date: Sun, 27 Oct 2024 09:04:05 -0500
Subject: First crack at file objects.

---
 source/fud_file.cpp | 201 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 201 insertions(+)
 create mode 100644 source/fud_file.cpp

(limited to 'source/fud_file.cpp')

diff --git a/source/fud_file.cpp b/source/fud_file.cpp
new file mode 100644
index 0000000..e27a46d
--- /dev/null
+++ b/source/fud_file.cpp
@@ -0,0 +1,201 @@
+/*
+ * libfud
+ * Copyright 2024 Dominick Allen
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "fud_file.hpp"
+
+#include <cerrno>
+#include <fcntl.h>
+#include <linux/openat2.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+namespace fud {
+
+FileResult RegularFile::open(
+    StringView filename,
+    FileAccessMode mode,
+    OpenFlags flags,
+    Option<int> dirFdOption,
+    Allocator* allocator)
+{
+    if (allocator == nullptr) {
+        return FudStatus::NullPointer;
+    }
+
+    if (!filename.nullTerminated()) {
+        return FudStatus::ArgumentInvalid;
+    }
+
+    int dirFd = dirFdOption.valueOr(AT_FDCWD);
+
+    RegularFile file{};
+
+    uint32_t openFlags = 0;
+    switch (mode) {
+    case FileAccessMode::Read:
+        openFlags = O_RDONLY;
+        break;
+    case FileAccessMode::Write:
+        openFlags = O_WRONLY;
+        break;
+    case FileAccessMode::ReadWrite:
+        openFlags = O_RDWR;
+        break;
+    default:
+        return FudStatus::ArgumentInvalid;
+    }
+
+    if (flags.hasFlag(OpenFlagEnum::Append) && flags.hasFlag(OpenFlagEnum::Truncate)) {
+        return FudStatus::OperationInvalid;
+    }
+
+    openFlags |= flags.flags();
+
+    open_how openHow{};
+    zeroObject(openHow);
+    openHow.flags = openFlags;
+    openHow.resolve = RESOLVE_NO_SYMLINKS;
+
+    auto status = syscall(SYS_openat2, dirFd, filename.data(), &openHow, sizeof(openHow));
+    if (status == -1) {
+        if constexpr (EAGAIN != EWOULDBLOCK && status == EWOULDBLOCK) {
+            return FudStatus::Partial;
+        }
+        switch (errno) {
+        case ETXTBSY:
+        case EAGAIN:
+            return FudStatus::Partial;
+        case ENOENT:
+            return FudStatus::NotFound;
+        case EFBIG:
+        case EOVERFLOW:
+        case EINVAL:
+        case EISDIR:
+        case ENAMETOOLONG:
+            return FudStatus::ArgumentInvalid;
+        case EROFS:
+        case EACCES:
+        case EPERM:
+            return FudStatus::PermissionDenied;
+        case ELOOP:
+        case EXDEV:
+        case ENFILE:
+        case E2BIG:
+        default:
+            return FudStatus::Failure;
+        }
+    }
+    fudAssert(status <= std::numeric_limits<decltype(file.m_fd)>::max());
+    file.m_fd = static_cast<decltype(file.m_fd)>(status);
+
+    using Stat = struct stat;
+    Stat sBuffer{};
+    auto fStatus = fstat(file.m_fd, &sBuffer);
+    if (fStatus == -1) {
+        return FudStatus::Failure;
+    }
+
+    if ((sBuffer.st_mode & S_IFMT) != S_IFREG) {
+        return FudStatus::ObjectInvalid;
+    }
+
+    return file;
+}
+
+/*
+    static FileResult RegularFile::create(
+        StringView filename,
+        FileAccessMode mode,
+        OpenFlags flags,
+        bool exclusive,
+        Option<int> dirFdOption,
+        Allocator* allocator = &globalFudAllocator);
+{
+}
+*/
+
+RegularFile::~RegularFile()
+{
+    static_cast<void>(this->close());
+}
+
+RegularFile::RegularFile(RegularFile&& rhs) noexcept : m_fd{rhs.m_fd}, m_modeFlags{rhs.m_modeFlags}
+{
+    rhs.m_fd = -1;
+}
+
+RegularFile& RegularFile::operator=(RegularFile&& rhs) noexcept
+{
+    if (&rhs == this) {
+        return *this;
+    }
+
+    static_cast<void>(this->close());
+
+    m_fd = rhs.m_fd;
+    m_modeFlags = rhs.m_modeFlags;
+
+    rhs.m_fd = -1;
+    return *this;
+}
+
+FudStatus RegularFile::take(RegularFile& rhs)
+{
+    if (&rhs == this) {
+        return FudStatus::Success;
+    }
+
+    auto status = this->close();
+    if (status != FudStatus::Success) {
+        return status;
+    }
+
+    m_fd = rhs.m_fd;
+    m_modeFlags = rhs.m_modeFlags;
+
+    rhs.m_fd = -1;
+    return status;
+}
+
+FudStatus RegularFile::close()
+{
+    FudStatus status = FudStatus::Success;
+    if (m_fd != -1) {
+        auto closeStatus = ::close(m_fd);
+        if (closeStatus == -1) {
+            switch (errno) {
+            case EBADF:
+                status = FudStatus::HandleInvalid;
+                break;
+            case EINTR:
+            case EIO:
+            case ENOSPC:
+            case EDQUOT:
+                status = FudStatus::Partial;
+                break;
+            default:
+                status = FudStatus::Failure;
+                break;
+            }
+        }
+        m_fd = -1;
+    }
+    return status;
+}
+
+} // namespace fud
-- 
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