Kernel: Support O_APPEND

As per the manpage, this acts as a transparent lseek() before write.
luteresa · May 25, 2019 · c6e79bd · c6e79bd
1 parent 90dbf68
commit c6e79bd
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Showing 3 changed files with 13 additions and 2 deletions.
diff --git a/Kernel/FileSystem/FileDescriptor.cpp b/Kernel/FileSystem/FileDescriptor.cpp
@@ -75,6 +75,7 @@ Retained<FileDescriptor> FileDescriptor::clone()
  ASSERT(descriptor);
  descriptor->m_current_offset = m_current_offset;
  descriptor->m_is_blocking = m_is_blocking;
+ descriptor->m_should_append = m_should_append;
  descriptor->m_file_flags = m_file_flags;
  return *descriptor;
 }

diff --git a/Kernel/FileSystem/FileDescriptor.h b/Kernel/FileSystem/FileDescriptor.h
@@ -70,6 +70,8 @@ class FileDescriptor : public Retainable<FileDescriptor> {
 
  bool is_blocking() const { return m_is_blocking; }
  void set_blocking(bool b) { m_is_blocking = b; }
+ bool should_append() const { return m_should_append; }
+ void set_should_append(bool s) { m_should_append = s; }
 
  dword file_flags() const { return m_file_flags; }
  void set_file_flags(dword flags) { m_file_flags = flags; }
@@ -113,6 +115,7 @@ class FileDescriptor : public Retainable<FileDescriptor> {
  dword m_file_flags { 0 };
 
  bool m_is_blocking { true };
+ bool m_should_append { false };
  SocketRole m_socket_role { SocketRole::None };
  FIFO::Direction m_fifo_direction { FIFO::Direction::Neither };
 };

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
@@ -861,6 +861,13 @@ ssize_t Process::do_write(FileDescriptor& descriptor, const byte* data, int data
  return -EAGAIN;
  }
 
+ if (descriptor.should_append()) {
+#ifdef IO_DEBUG
+ dbgprintf("seeking to end (O_APPEND)\n");
+#endif
+ descriptor.seek(0, SEEK_END);
+ }
+
  while (nwritten < data_size) {
 #ifdef IO_DEBUG
  dbgprintf("while %u < %u\n", nwritten, size);
@@ -1118,8 +1125,8 @@ int Process::sys$open(const char* path, int options, mode_t mode)
  auto descriptor = result.value();
  if (options & O_DIRECTORY && !descriptor->is_directory())
  return -ENOTDIR; // FIXME: This should be handled by VFS::open.
- if (options & O_NONBLOCK)
-  descriptor->set_blocking(false);
+ descriptor->set_blocking(!(options & O_NONBLOCK));
+ descriptor->set_should_append(options & O_APPEND);
  dword flags = (options & O_CLOEXEC) ? FD_CLOEXEC : 0;
  m_fds[fd].set(move(descriptor), flags);
  return fd;