src/lib/istream-seekable.h

#ifndef ISTREAM_SEEKABLE_H
#define ISTREAM_SEEKABLE_H

/* Create a seekable stream from given NULL-terminated list of input streams.
   Try to keep it in memory, but use a temporary file if it's too large.

   When max_buffer_size is reached, fd_callback is called. It should return
   the fd and path of the created file. Typically the callback would also
   unlink the file before returning. */
struct istream *
i_streams_merge(struct istream *input[], size_t max_buffer_size,
        int (*fd_callback)(const char **path_r, void *context),
        void *context) ATTR_NULL(4);

/* Same as i_streams_merge(), but if all of the inputs are seekable already,
   create a concat stream instead. */
struct istream *
i_stream_create_seekable(struct istream *input[],
             size_t max_buffer_size,
             int (*fd_callback)(const char **path_r, void *context),
             void *context) ATTR_NULL(4);

struct istream *
i_stream_create_seekable_path(struct istream *input[],
                  size_t max_buffer_size,
                  const char *temp_path_prefix);

#endif