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-rw-r--r--src/lib/istream-limit.c144
1 files changed, 144 insertions, 0 deletions
diff --git a/src/lib/istream-limit.c b/src/lib/istream-limit.c
new file mode 100644
index 0000000..f66cef3
--- /dev/null
+++ b/src/lib/istream-limit.c
@@ -0,0 +1,144 @@
+/* Copyright (c) 2003-2018 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 =
+ container_of(stream, struct limit_istream, istream.iostream);
+ 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 =
+ container_of(stream, struct limit_istream, istream);
+ 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 {
+ ret = i_stream_read_memarea(stream->parent);
+ 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 (ret == -2)
+ return -2;
+
+ if (lstream->v_size != UOFF_T_MAX) {
+ 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 =
+ container_of(stream, struct limit_istream, istream);
+ 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_MAX)
+ 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 =
+ container_of(stream, struct limit_istream, istream);
+ const struct stat *st;
+
+ if (lstream->v_size != UOFF_T_MAX) {
+ *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;
+}