istream-limit.c revision bcd286622779a93f809b11993db0550f8c7cc9b5
/* Copyright (c) 2003-2017 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "istream-private.h"
struct limit_istream {
struct istream_private istream;
uoff_t v_size;
};
static void i_stream_limit_destroy(struct iostream_private *stream)
{
struct limit_istream *lstream = (struct limit_istream *) stream;
uoff_t v_offset;
v_offset = lstream->istream.parent_start_offset +
lstream->istream.istream.v_offset;
if (lstream->istream.parent->seekable ||
v_offset > lstream->istream.parent->v_offset) {
/* get to same position in parent stream */
i_stream_seek(lstream->istream.parent, v_offset);
}
}
static ssize_t i_stream_limit_read(struct istream_private *stream)
{
struct limit_istream *lstream = (struct limit_istream *) stream;
uoff_t left;
ssize_t ret;
size_t pos;
i_stream_seek(stream->parent, lstream->istream.parent_start_offset +
stream->istream.v_offset);
if (stream->istream.v_offset +
(stream->pos - stream->skip) >= lstream->v_size) {
stream->istream.eof = TRUE;
return -1;
}
stream->pos -= stream->skip;
stream->skip = 0;
stream->buffer = i_stream_get_data(stream->parent, &pos);
if (pos > stream->pos)
ret = 0;
else do {
if ((ret = i_stream_read_memarea(stream->parent)) == -2)
return -2;
stream->istream.stream_errno = stream->parent->stream_errno;
stream->istream.eof = stream->parent->eof;
stream->buffer = i_stream_get_data(stream->parent, &pos);
} while (pos <= stream->pos && ret > 0);
if (lstream->v_size != (uoff_t)-1) {
left = lstream->v_size - stream->istream.v_offset;
if (pos >= left) {
pos = left;
stream->istream.eof = TRUE;
}
}
ret = pos > stream->pos ? (ssize_t)(pos - stream->pos) :
(ret == 0 ? 0 : -1);
stream->pos = pos;
i_assert(ret != -1 || stream->istream.eof ||
stream->istream.stream_errno != 0);
return ret;
}
static int
i_stream_limit_stat(struct istream_private *stream, bool exact)
{
struct limit_istream *lstream = (struct limit_istream *) stream;
const struct stat *st;
if (i_stream_stat(stream->parent, exact, &st) < 0) {
stream->istream.stream_errno = stream->parent->stream_errno;
return -1;
}
stream->statbuf = *st;
if (lstream->v_size != (uoff_t)-1)
stream->statbuf.st_size = lstream->v_size;
return 0;
}
static int i_stream_limit_get_size(struct istream_private *stream,
bool exact, uoff_t *size_r)
{
struct limit_istream *lstream = (struct limit_istream *) stream;
const struct stat *st;
if (lstream->v_size != (uoff_t)-1) {
*size_r = lstream->v_size;
return 1;
}
if (i_stream_stat(&stream->istream, exact, &st) < 0)
return -1;
if (st->st_size == -1)
return 0;
*size_r = st->st_size;
return 1;
}
struct istream *i_stream_create_limit(struct istream *input, uoff_t v_size)
{
struct limit_istream *lstream;
lstream = i_new(struct limit_istream, 1);
lstream->v_size = v_size;
lstream->istream.max_buffer_size = input->real_stream->max_buffer_size;
lstream->istream.iostream.destroy = i_stream_limit_destroy;
lstream->istream.read = i_stream_limit_read;
lstream->istream.stat = i_stream_limit_stat;
lstream->istream.get_size = i_stream_limit_get_size;
lstream->istream.istream.readable_fd = input->readable_fd;
lstream->istream.istream.blocking = input->blocking;
lstream->istream.istream.seekable = input->seekable;
return i_stream_create(&lstream->istream, input,
i_stream_get_fd(input), 0);
}
struct istream *i_stream_create_range(struct istream *input,
uoff_t v_offset, uoff_t v_size)
{
uoff_t orig_offset = input->v_offset;
struct istream *ret;
input->v_offset = v_offset;
ret = i_stream_create_limit(input, v_size);
input->v_offset = orig_offset;
return ret;
}