src/lib/ostream.h

	ostream.h revision 981139bb2e446bb2050c1158614725f8413fd709
#ifndef OSTREAM_H
#define OSTREAM_H

#include "ioloop.h"

struct ostream {
    uoff_t offset;

    /* errno for the last operation send/seek operation. cleared before
       each call. */
    int stream_errno;
    /* errno of the last failed send/seek. never cleared. */
    int last_failed_errno;

    /* overflow is set when some of the data given to send()
       functions was neither sent nor buffered. It's never unset inside
       ostream code. */
    unsigned int overflow:1;
    unsigned int closed:1;

    struct ostream_private *real_stream;
};

/* Returns 1 if all data is sent (not necessarily flushed), 0 if not.
   Pretty much the only real reason to return 0 is if you wish to send more
   data to client which isn't buffered, eg. o_stream_send_istream(). */
typedef int stream_flush_callback_t(void *context);
typedef void ostream_callback_t(void *context);

/* Create new output stream from given file descriptor.
   If max_buffer_size is 0, an "optimal" buffer size is used (max 128kB). */
struct ostream *
o_stream_create_fd(int fd, size_t max_buffer_size, bool autoclose_fd);
/* The fd is set to -1 immediately to avoid accidentally closing it twice. */
struct ostream *o_stream_create_fd_autoclose(int *fd, size_t max_buffer_size);
/* Create an output stream from a regular file which begins at given offset.
   If offset==(uoff_t)-1, the current offset isn't known. */
struct ostream *
o_stream_create_fd_file(int fd, uoff_t offset, bool autoclose_fd);
struct ostream *o_stream_create_fd_file_autoclose(int *fd, uoff_t offset);
/* Create an output stream to a buffer. */
struct ostream *o_stream_create_buffer(buffer_t *buf);
/* Create an output streams that always fails the writes. */
struct ostream *o_stream_create_error(int stream_errno);
struct ostream *
o_stream_create_error_str(int stream_errno, const char *fmt, ...)
    ATTR_FORMAT(2, 3);
/* Create an output stream that simply passes through data. This is mainly
   useful as a wrapper when combined with destroy callbacks. */
struct ostream *o_stream_create_passthrough(struct ostream *output);

/* Set name (e.g. path) for output stream. */
void o_stream_set_name(struct ostream *stream, const char *name);
/* Get output stream's name. Returns "" if stream has no name. */
const char *o_stream_get_name(struct ostream *stream);

/* Return file descriptor for stream, or -1 if none is available. */
int o_stream_get_fd(struct ostream *stream);
/* Returns error string for the previous error (stream_errno,
   not last_failed_errno). */
const char *o_stream_get_error(struct ostream *stream);

/* Close this stream (but not its parents) and unreference it. */
void o_stream_destroy(struct ostream **stream);
/* Reference counting. References start from 1, so calling o_stream_unref()
   destroys the stream if o_stream_ref() is never used. */
void o_stream_ref(struct ostream *stream);
/* Unreferences the stream and sets stream pointer to NULL. */
void o_stream_unref(struct ostream **stream);
/* Call the given callback function when stream is destroyed. */
void o_stream_add_destroy_callback(struct ostream *stream,
                   ostream_callback_t *callback, void *context)
    ATTR_NULL(3);
#define o_stream_add_destroy_callback(stream, callback, context) \
    o_stream_add_destroy_callback(stream + \
        CALLBACK_TYPECHECK(callback, void (*)(typeof(context))), \
        (ostream_callback_t *)callback, context)
/* Remove the destroy callback. */
void o_stream_remove_destroy_callback(struct ostream *stream,
                      void (*callback)());

/* Mark the stream and all of its parent streams closed. Nothing will be
   sent after this call. */
void o_stream_close(struct ostream *stream);

/* Set IO_WRITE callback. Default will just try to flush the output and
   finishes when the buffer is empty.  */
void o_stream_set_flush_callback(struct ostream *stream,
                 stream_flush_callback_t *callback,
                 void *context) ATTR_NULL(3);
#define o_stream_set_flush_callback(stream, callback, context) \
    o_stream_set_flush_callback(stream + \
        CALLBACK_TYPECHECK(callback, int (*)(typeof(context))), \
        (stream_flush_callback_t *)callback, context)
void o_stream_unset_flush_callback(struct ostream *stream);
/* Change the maximum size for stream's output buffer to grow. */
void o_stream_set_max_buffer_size(struct ostream *stream, size_t max_size);
/* Returns the current max. buffer size. */
size_t o_stream_get_max_buffer_size(struct ostream *stream);

/* Delays sending as far as possible, writing only full buffers. Also sets
   TCP_CORK on if supported. */
void o_stream_cork(struct ostream *stream);
void o_stream_uncork(struct ostream *stream);
bool o_stream_is_corked(struct ostream *stream);
/* Try to flush the output stream. Returns 1 if all sent, 0 if not,
   -1 if error. */
int o_stream_flush(struct ostream *stream);
/* Set "flush pending" state of stream. If set, the flush callback is called
   when more data is allowed to be sent, even if the buffer itself is empty. */
void o_stream_set_flush_pending(struct ostream *stream, bool set);
/* Returns number of bytes currently in buffer. */
size_t o_stream_get_buffer_used_size(const struct ostream *stream) ATTR_PURE;
/* Returns number of bytes we can still write without failing. */
size_t o_stream_get_buffer_avail_size(const struct ostream *stream) ATTR_PURE;

/* Seek to specified position from beginning of file. This works only for
   files. Returns 1 if successful, -1 if error. */
int o_stream_seek(struct ostream *stream, uoff_t offset);
/* Returns number of bytes sent, -1 = error */
ssize_t o_stream_send(struct ostream *stream, const void *data, size_t size);
ssize_t o_stream_sendv(struct ostream *stream, const struct const_iovec *iov,
               unsigned int iov_count);
ssize_t o_stream_send_str(struct ostream *stream, const char *str);
/* Send with delayed error handling. o_stream_has_errors() or
   o_stream_ignore_last_errors() must be called after these functions before
   the stream is destroyed. */
void o_stream_nsend(struct ostream *stream, const void *data, size_t size);
void o_stream_nsendv(struct ostream *stream, const struct const_iovec *iov,
             unsigned int iov_count);
void o_stream_nsend_str(struct ostream *stream, const char *str);
void o_stream_nflush(struct ostream *stream);
/* Flushes the stream and returns -1 if stream->last_failed_errno is
   non-zero. Marks the stream's error handling as completed. errno is also set
   to last_failed_errno. */
int o_stream_nfinish(struct ostream *stream);
/* Marks the stream's error handling as completed to avoid i_panic() on
   destroy. */
void o_stream_ignore_last_errors(struct ostream *stream);
/* If error handling is disabled, the i_panic() on destroy is never called.
   This function can be called immediately after the stream is created.
   When creating wrapper streams, they copy this behavior from the parent
   stream. */
void o_stream_set_no_error_handling(struct ostream *stream, bool set);
/* Send data from input stream. Returns number of bytes sent, or -1 if error
   in either outstream or instream. Note that this function may block if either
   instream or outstream is blocking.

   Also note that this function may not add anything to the output buffer, so
   if you want the flush callback to be called when more data can be written,
   you'll need to call o_stream_set_flush_pending() manually.

   It's also possible to use this function to copy data within same file
   descriptor. If the file must be grown, you have to do it manually before
   calling this function. */
off_t o_stream_send_istream(struct ostream *outstream,
                struct istream *instream);

/* Write data to specified offset. Returns 0 if successful, -1 if error. */
int o_stream_pwrite(struct ostream *stream, const void *data, size_t size,
            uoff_t offset);

/* If there are any I/O loop items associated with the stream, move all of
   them to current_ioloop. */
void o_stream_switch_ioloop(struct ostream *stream);

#endif