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Implement stdio buffering #36

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apio merged 7 commits from stdio-buffers into main 2023-07-22 09:39:02 +00:00
Conversation 2 Commits 7 Files Changed 7 +56 -48
2 changed files with 56 additions and 48 deletions
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Showing only changes of commit d60ad184f1 - Show all commits

23
libc/include/stdio.h
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@ -14,16 +14,19 @@
typedef struct
{
int _fd;
int _err;
int _eof;
size_t _bufcap;
size_t _bufsize;
size_t _bufindex;
char* _buffer;
int _flags;
int _pending;
int _mode;
int _fd; // The underlying file descriptor.
int _err; // The error status flag.
int _eof; // The end-of-file status flag.
struct
{
size_t capacity; // The buffer's total capacity.
size_t size; // The buffer's used size.
size_t index; // The read index into the buffer.
char* buffer; // The memory used for the buffer.
int status; // The buffer status flags.
int mode; // The buffering mode.
} _buf;
int _flags; // The file access mode with which the file was opened.
} FILE;
#define EOF -1

81
libc/src/stdio.cpp
View File

@ -13,7 +13,12 @@ FILE* stdout = nullptr;
FILE* s_open_files[FOPEN_MAX];
#define FFLAG_FREE_AFTER_BUFFER_USE (1 << 0)
enum FileStatusFlags
{
BufferIsMalloced = (1 << 0),
LastRead = (1 << 1),
LastWrite = (1 << 2),
};
static const char* read_tmpdir()
{
@ -57,12 +62,12 @@ static int fdopen_check_compatible_mode(int fd, int new_flags)
static int flush_write_buffer(FILE* stream)
{
if (stream->_mode == _IONBF) return 0;
if (stream->_buf.mode == _IONBF) return 0;
ssize_t result = write(stream->_fd, stream->_buffer, stream->_bufsize);
ssize_t result = write(stream->_fd, stream->_buf.buffer, stream->_buf.size);
stream->_bufindex = 0;
stream->_bufsize = 0;
stream->_buf.index = 0;
stream->_buf.size = 0;
return result < 0 ? EOF : 0;
}
@ -74,20 +79,20 @@ static ssize_t write_into_buffer(FILE* stream, const u8* data, ssize_t size)
while (size > 0)
{
ssize_t nwritten;
if (stream->_mode != _IONBF)
if (stream->_buf.mode != _IONBF)
{
if ((stream->_bufsize + size) > stream->_bufcap)
if ((stream->_buf.size + size) > stream->_buf.capacity)
{
if (flush_write_buffer(stream) < 0) return -1;
}
ssize_t size_remaining = stream->_bufcap - stream->_bufsize;
ssize_t size_remaining = stream->_buf.capacity - stream->_buf.size;
nwritten = size > size_remaining ? size_remaining : size;
memcpy(stream->_buffer + stream->_bufsize, data, nwritten);
memcpy(stream->_buf.buffer + stream->_buf.size, data, nwritten);
stream->_bufsize += nwritten;
stream->_buf.size += nwritten;
if (stream->_mode == _IOLBF && memchr(data, '\n', nwritten))
if (stream->_buf.mode == _IOLBF && memchr(data, '\n', nwritten))
{
if (flush_write_buffer(stream) < 0) return -1;
}
@ -112,7 +117,7 @@ extern "C"
int fflush(FILE* stream)
{
if (stream && stream->_mode != _IONBF) flush_write_buffer(stream);
if (stream && stream->_buf.mode != _IONBF) flush_write_buffer(stream);
else if (!stream)
{
for (int i = 0; i < FOPEN_MAX; i++)
@ -142,12 +147,12 @@ extern "C"
f->_fd = fd;
clearerr(f);
f->_pending = 0;
f->_flags = flags;
f->_mode = isatty(fd) ? _IOLBF : _IOFBF;
f->_bufsize = f->_bufindex = 0;
f->_buffer = nullptr;
setvbuf(f, NULL, f->_mode, 0);
f->_buf.status = 0;
f->_buf.mode = isatty(fd) ? _IOLBF : _IOFBF;
f->_buf.size = f->_buf.index = 0;
f->_buf.buffer = nullptr;
setvbuf(f, NULL, f->_buf.mode, 0);
s_open_files[fd] = f;
@ -168,12 +173,12 @@ extern "C"
f->_fd = fd;
clearerr(f);
f->_pending = 0;
f->_flags = flags;
f->_mode = buffering_mode < 0 ? (isatty(fd) ? _IOLBF : _IOFBF) : buffering_mode;
f->_bufsize = f->_bufindex = 0;
f->_buffer = nullptr;
setvbuf(f, NULL, f->_mode, 0);
f->_buf.status = 0;
f->_buf.mode = buffering_mode < 0 ? (isatty(fd) ? _IOLBF : _IOFBF) : buffering_mode;
f->_buf.size = f->_buf.index = 0;
f->_buf.buffer = nullptr;
setvbuf(f, NULL, f->_buf.mode, 0);
s_open_files[fd] = f;
@ -195,7 +200,7 @@ extern "C"
s_open_files[stream->_fd] = nullptr;
if (stream->_buffer && (stream->_pending & FFLAG_FREE_AFTER_BUFFER_USE)) free(stream->_buffer);
if (stream->_buf.buffer && (stream->_buf.status & FileStatusFlags::BufferIsMalloced)) free(stream->_buf.buffer);
if (!path) { fail("FIXME: freopen() called with path=nullptr"); }
@ -205,12 +210,12 @@ extern "C"
stream->_fd = fd;
clearerr(stream);
stream->_pending = 0;
stream->_flags = flags;
stream->_mode = isatty(fd) ? _IOLBF : _IOFBF;
stream->_bufsize = stream->_bufindex = 0;
stream->_buffer = nullptr;
setvbuf(stream, NULL, stream->_mode, 0);
stream->_buf.status = 0;
stream->_buf.mode = isatty(fd) ? _IOLBF : _IOFBF;
stream->_buf.size = stream->_buf.index = 0;
stream->_buf.buffer = nullptr;
setvbuf(stream, NULL, stream->_buf.mode, 0);
s_open_files[fd] = stream;
@ -223,7 +228,7 @@ extern "C"
if (close(stream->_fd) < 0) return EOF;
if (stream->_buffer && (stream->_pending & FFLAG_FREE_AFTER_BUFFER_USE)) free(stream->_buffer);
if (stream->_buf.buffer && (stream->_buf.status & FileStatusFlags::BufferIsMalloced)) free(stream->_buf.buffer);
s_open_files[stream->_fd] = nullptr;
@ -610,28 +615,28 @@ extern "C"
int setvbuf(FILE* stream, char* buf, int mode, size_t size)
{
int pending = 0;
int status = 0;
if (mode < 0 || mode > _IOFBF) return errno = EINVAL, -1;
if (stream->_bufsize != 0 || stream->_bufindex != 0) return -1; // Buffer is already in use.
if (stream->_buf.size != 0 || stream->_buf.index != 0) return -1; // Buffer is already in use.
if (mode != _IONBF && buf == NULL)
{
size = BUFSIZ;
buf = (char*)calloc(size, 1);
if (!buf) return -1;
pending = FFLAG_FREE_AFTER_BUFFER_USE;
status = FileStatusFlags::BufferIsMalloced;
}
else
else if (mode == _IONBF)
{
buf = NULL;
size = 0;
}
if (stream->_buffer && (stream->_pending & FFLAG_FREE_AFTER_BUFFER_USE)) free(stream->_buffer);
if (stream->_buf.buffer && (stream->_buf.status & FileStatusFlags::BufferIsMalloced)) free(stream->_buf.buffer);
stream->_buffer = buf;
stream->_bufcap = size;
stream->_mode = mode;
stream->_pending = pending;
stream->_buf.buffer = buf;
stream->_buf.capacity = size;
stream->_buf.mode = mode;
stream->_buf.status = status;
return 0;
}