LibGUI: Add GFile and base class GIODevice.

Working with the LibC API's is tedious, so let's add some comfy C++ API's.

Applications/ProcessManager/ProcessTableModel.cpp

@@ -1,4 +1,5 @@
 #include "ProcessTableModel.h"
+#include <LibGUI/GFile.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <pwd.h>
@@ -121,10 +122,11 @@ GVariant ProcessTableModel::data(const GModelIndex& index, Role role) const
 
 void ProcessTableModel::update()
 {
-    FILE* fp = fopen("/proc/all", "r");
-    if (!fp) {
-        perror("failed to open /proc/all");
+    GFile file("/proc/all");
+    if (!file.open(GIODevice::ReadOnly)) {
+        fprintf(stderr, "ProcessManager: Failed to open /proc/all: %s\n", file.error_string());
         exit(1);
+        return;
     }
 
     unsigned last_sum_nsched = 0;
@@ -134,11 +136,10 @@ void ProcessTableModel::update()
     HashTable<pid_t> live_pids;
     unsigned sum_nsched = 0;
     for (;;) {
-        char buf[BUFSIZ];
-        char* ptr = fgets(buf, sizeof(buf), fp);
-        if (!ptr)
+        auto line = file.read_line(1024);
+        if (line.is_empty())
             break;
-        auto parts = String(buf, Chomp).split(',');
+        auto parts = String((const char*)line.pointer(), line.size() - 1, Chomp).split(',');
         if (parts.size() < 17)
             break;
         bool ok;
@@ -178,8 +179,6 @@ void ProcessTableModel::update()
 
         live_pids.set(pid);
     }
-    int rc = fclose(fp);
-    ASSERT(rc == 0);
 
     m_pids.clear();
     Vector<pid_t> pids_to_remove;

LibGUI/GFile.cpp

@@ -0,0 +1,56 @@
+#include <LibGUI/GFile.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+GFile::GFile(const String& filename)
+    : m_filename(filename)
+{
+}
+
+GFile::~GFile()
+{
+    if (mode() != NotOpen)
+        close();
+}
+
+bool GFile::open(GIODevice::OpenMode mode)
+{
+    int flags = 0;
+    if ((mode & GIODevice::ReadWrite) == GIODevice::ReadWrite) {
+        flags |= O_RDWR | O_CREAT;
+    } else if (mode & GIODevice::ReadOnly) {
+        flags |= O_RDONLY;
+    } else if (mode & GIODevice::WriteOnly) {
+        flags |= O_WRONLY | O_CREAT;
+    }
+    if (mode & GIODevice::Append)
+        flags |= O_APPEND;
+    if (mode & GIODevice::Truncate)
+        flags |= O_TRUNC;
+    if (mode & GIODevice::MustBeNew)
+        flags |= O_EXCL;
+    int fd = ::open(m_filename.characters(), flags, 0666);
+    if (fd < 0) {
+        set_error(errno);
+        return false;
+    }
+
+    set_fd(fd);
+    set_mode(mode);
+    return true;
+}
+
+bool GFile::close()
+{
+    if (fd() < 0 || mode() == NotOpen)
+        return false;
+    int rc = ::close(fd());
+    if (rc < 0) {
+        set_error(rc);
+        return false;
+    }
+    set_fd(-1);
+    set_mode(GIODevice::NotOpen);
+    return true;
+}

LibGUI/GFile.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <LibGUI/GIODevice.h>
+#include <AK/AKString.h>
+
+class GFile final : public GIODevice {
+public:
+    GFile() { }
+    explicit GFile(const String&);
+    virtual ~GFile() override;
+
+    String filename() const { return m_filename; }
+    void set_filename(const String& filename) { m_filename = filename; }
+
+    virtual bool open(GIODevice::OpenMode) override;
+    virtual bool close() override;
+
+    virtual const char* class_name() const override { return "GFile"; }
+
+private:
+    String m_filename;
+};

LibGUI/GIODevice.cpp

@@ -0,0 +1,89 @@
+#include <LibGUI/GIODevice.h>
+#include <unistd.h>
+
+GIODevice::GIODevice(GObject* parent)
+    : GObject(parent)
+{
+}
+
+GIODevice::~GIODevice()
+{
+}
+
+const char* GIODevice::error_string() const
+{
+    return strerror(m_error);
+}
+
+ByteBuffer GIODevice::read(int max_size)
+{
+    if (m_fd < 0)
+        return { };
+    if (!max_size)
+        return { };
+    auto buffer = ByteBuffer::create_uninitialized(max_size);
+    auto* buffer_ptr = (char*)buffer.pointer();
+    int remaining_buffer_space = buffer.size();
+    if (!m_buffered_data.is_empty()) {
+        int taken_from_buffered = min(remaining_buffer_space, m_buffered_data.size());
+        memcpy(buffer_ptr, m_buffered_data.data(), taken_from_buffered);
+        Vector<byte> new_buffered_data;
+        new_buffered_data.append(m_buffered_data.data() + taken_from_buffered, m_buffered_data.size() - taken_from_buffered);
+        m_buffered_data = move(new_buffered_data);
+        remaining_buffer_space -= taken_from_buffered;
+        buffer_ptr += taken_from_buffered;
+    }
+    if (!remaining_buffer_space)
+        return buffer;
+    int nread = ::read(m_fd, buffer_ptr, remaining_buffer_space);
+    if (nread < 0) {
+        set_error(errno);
+        return { };
+    }
+    buffer.trim(nread);
+    return buffer;
+}
+
+ByteBuffer GIODevice::read_line(int max_size)
+{
+    if (m_fd < 0)
+        return { };
+    if (!max_size)
+        return { };
+    auto line = ByteBuffer::create_uninitialized(max_size);
+    int line_index = 0;
+    while (line_index < line.size()) {
+        if (line_index >= m_buffered_data.size()) {
+            if (!populate_read_buffer())
+                return { };
+        }
+        byte ch = m_buffered_data[line_index];
+        line[line_index++] = ch;
+        if (ch == '\n') {
+            Vector<byte> new_buffered_data;
+            new_buffered_data.append(m_buffered_data.data() + line_index, m_buffered_data.size() - line_index);
+            m_buffered_data = move(new_buffered_data);
+            line.trim(line_index);
+            return line;
+        }
+    }
+    return { };
+}
+
+bool GIODevice::populate_read_buffer()
+{
+    if (m_fd < 0)
+        return false;
+    auto buffer = ByteBuffer::create_uninitialized(1024);
+    int nread = ::read(m_fd, buffer.pointer(), buffer.size());
+    if (nread < 0) {
+        set_error(errno);
+        return false;
+    }
+    if (nread == 0) {
+        set_eof(true);
+        return false;
+    }
+    m_buffered_data.append(buffer.pointer(), buffer.size());
+    return true;
+}

LibGUI/GIODevice.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <LibGUI/GObject.h>
+#include <AK/ByteBuffer.h>
+
+class GIODevice : public GObject {
+public:
+    enum OpenMode {
+        NotOpen      = 0,
+        ReadOnly     = 1,
+        WriteOnly    = 2,
+        ReadWrite    = 3,
+        Append       = 4,
+        Truncate     = 8,
+        MustBeNew    = 16,
+    };
+
+    virtual ~GIODevice() override;
+
+    int fd() const { return m_fd; }
+    unsigned mode() const { return m_mode; }
+    bool eof() const { return m_eof; }
+
+    int error() const { return m_error; }
+    const char* error_string() const;
+
+    bool has_error() const { return m_error != 0; }
+
+    ByteBuffer read(int max_size);
+    ByteBuffer read_line(int max_size);
+
+    virtual bool open(GIODevice::OpenMode) = 0;
+    virtual bool close() = 0;
+
+    virtual const char* class_name() const override { return "GIODevice"; }
+
+protected:
+    explicit GIODevice(GObject* parent = nullptr);
+
+    void set_fd(int fd) { m_fd = fd; }
+    void set_mode(OpenMode mode) { m_mode = mode; }
+    void set_error(int error) { m_error = error; }
+    void set_eof(bool eof) { m_eof = eof; }
+
+private:
+    bool populate_read_buffer();
+
+    int m_fd { -1 };
+    int m_error { 0 };
+    bool m_eof { false };
+    OpenMode m_mode { NotOpen };
+    Vector<byte> m_buffered_data;
+};

LibGUI/Makefile

@@ -7,6 +7,8 @@ SHAREDGRAPHICS_OBJS = \
     ../SharedGraphics/Color.o
 
 LIBGUI_OBJS = \
+    GIODevice.o \
+    GFile.o \
     GButton.o \
     GCheckBox.o \
     GEventLoop.o \