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options/ansi: Small refactoring of FILE internals

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This commit is contained in:
Alexander van der Grinten 2018-04-03 21:05:55 +02:00
parent 5644b9dd88
commit 04feb80b2f
1 changed files with 40 additions and 43 deletions
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83
options/ansi/generic/file-io.cpp
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@ -15,7 +15,8 @@
namespace mlibc {
static bool disableBuffering = false;
// Useful when debugging the FILE implementation.
static bool globallyDisableBuffering = false;
enum class stream_type {
unknown,
@ -51,7 +52,7 @@ public:
int read(char *buffer, size_t max_size, size_t *actual_size) {
__ensure(max_size);
if(disableBuffering)
if(globallyDisableBuffering)
return io_read(buffer, max_size, actual_size);
// Ensure correct buffer type for pipe-like streams.
@ -72,11 +73,8 @@ public:
}
// Clear the buffer, then buffer new data.
if(_write_back())
if(_internal_flush(true))
return -1;
__offset = 0;
__io_offset = 0;
__valid_limit = 0;
_ensure_allocation();
size_t io_size;
@ -101,16 +99,13 @@ public:
int write(const char *buffer, size_t max_size, size_t *actual_size) {
__ensure(max_size);
if(disableBuffering)
if(globallyDisableBuffering)
return io_write(buffer, max_size, actual_size);
// Flush the buffer if necessary.
if(__offset == __buffer_size) {
if(_write_back())
if(_internal_flush(true))
return -1;
__offset = 0;
__io_offset = 0;
__valid_limit = 0;
}
// Ensure correct buffer type for pipe-like streams.
@ -138,24 +133,20 @@ public:
// TODO: For input files, discard the buffer.
int flush() {
if(_write_back())
if(_internal_flush(false))
return -1;
return 0;
}
int seek(off_t offset, int whence) {
if(_write_back())
return -1;
if(whence == SEEK_SET || whence == SEEK_END) {
// For absolute seeks we can just forget the current buffer.
if(_internal_flush(true))
return -1;
if(io_seek(offset, whence))
return -1;
// For absolute seeks we can just forget the current buffer.
__offset = 0;
__io_offset = 0;
__valid_limit = 0;
return 0;
}else{
__ensure(whence == SEEK_CUR); // TODO: Handle errors.
@ -171,38 +162,44 @@ protected:
virtual int io_seek(off_t offset, int whence) = 0;
private:
int _write_back() {
if(!__is_dirty)
return 0;
int _internal_flush(bool reset) {
if(_type == stream_type::unknown && determine_type(&_type))
return -1;
// We need to write back all data in [0, __valid_limit].
// For non-pipe streams, first do a seek to reset the
// I/O position to zero, then do a write().
// TODO: Actually do the seek.
__ensure(!__io_offset);
__ensure(__offset == __valid_limit);
size_t progress = 0;
while(progress < __valid_limit) {
size_t chunk;
if(io_write(__buffer_ptr + progress, __valid_limit - progress, &chunk))
return -1;
progress += chunk;
}
if(__is_dirty) {
// We need to write back all data in [0, __valid_limit].
// For non-pipe streams, first do a seek to reset the
// I/O position to zero, then do a write().
// TODO: Actually do the seek.
__ensure(!__io_offset);
// For file-like streams, it might be worth to keep some data buffered.
if(_type == stream_type::pipe_like) {
size_t progress = 0;
while(progress < __valid_limit) {
size_t chunk;
if(io_write(__buffer_ptr + progress, __valid_limit - progress, &chunk))
return -1;
progress += chunk;
}
// For file-like streams, it might be worth to keep some data buffered.
if(_type == stream_type::pipe_like) {
__offset = 0;
__io_offset = 0;
__valid_limit = 0;
}else{
__ensure(_type == stream_type::file_like);
__io_offset = __valid_limit;
}
}
__is_dirty = 0;
if(reset) {
__offset = 0;
__io_offset = 0;
__valid_limit = 0;
}else{
__ensure(_type == stream_type::file_like);
__io_offset = __valid_limit;
}
__is_dirty = 0;
return 0;
}