iobuf: Add the IOBUF_INPUT_TEMP type to improve input temp handling.

* common/iobuf.h (enum iobuf_use): Add new member, IOBUF_INPUT_TEMP.
* common/iobuf.c (iobuf_temp_with_content): Create the iobuf as an
IOBUF_INPUT_TEMP, not an IOBUF_INPUT buffer.  Assert that LENGTH ==
A->D.SIZE.
(iobuf_push_filter2): If A is an IOBUF_INPUT_TEMP, then make the new
filter an IOBUF_INPUT filter and set its buffer size to
IOBUF_BUFFER_SIZE.
(underflow): If A is an IOBUF_INPUT_TEMP, then just return EOF; don't
remove already read data.
(iobuf_seek): If A is an IOBUF_INPUT_TEMP, don't discard the buffered
data.
(iobuf_alloc): Allow USE == IOBUF_INPUT_TEMP.
(pop_filter): Allow USE == IOBUF_INPUT_TEMP.
(iobuf_peek): Allow USE == IOBUF_INPUT_TEMP.
(iobuf_writebyte): Fail if USE == IOBUF_INPUT_TEMP.
(iobuf_write): Fail if USE == IOBUF_INPUT_TEMP.
(iobuf_writestr): Fail if USE == IOBUF_INPUT_TEMP.
(iobuf_flush_temp): Fail if USE == IOBUF_INPUT_TEMP.

--
Signed-off-by: Neal H. Walfield <[email protected]>.

Introduce a new iobuf type, IOBUF_INPUT_TEMP.  Use this for the iobuf
created by iobuf_temp_with_content instead of IOBUF_INPUT.  This was
necessary so that seeking and peeking correctly work on this type of
iobuf.  In particular, seeking didn't work because we discarded the
buffered data and peeking didn't work because we discarded data which
was already read, which made seeking later impossible.

1 files changed, 7 insertions, 3 deletions

diff --git a/common/iobuf.h b/common/iobuf.h
index b65ea60d7..bce6c3162 100644
--- a/common/iobuf.h
+++ b/common/iobuf.h
@@ -124,12 +124,15 @@ enum iobuf_use
     /* Pipeline is in input mode.  The data flows from the end to the
        beginning.  That is, when reading from the pipeline, the first
        filter gets its input from the second filter, etc.  */
-    IOBUF_INPUT=1,
+    IOBUF_INPUT,
+    /* Pipeline is in input mode.  The last filter in the pipeline is
+       a temporary buffer from which the data is "read".  */
+    IOBUF_INPUT_TEMP,
     /* Pipeline is in output mode.  The data flows from the beginning
        to the end.  That is, when writing to the pipeline, the user
        writes to the first filter, which transforms the data and sends
        it to the second filter, etc.  */
-    IOBUF_OUTPUT=2,
+    IOBUF_OUTPUT,
     /* Pipeline is in output mode.  The last filter in the pipeline is
        a temporary buffer that grows as necessary.  */
     IOBUF_OUTPUT_TEMP
@@ -274,7 +277,8 @@ int  iobuf_is_pipe_filename (const char *fname);
    create a new primary source or primary sink, i.e., the last filter
    in the pipeline.
 
-   USE is IOBUF_INPUT, IOBUF_OUTPUT or IOBUF_OUTPUT_TEMP.
+   USE is IOBUF_INPUT, IOBUF_INPUT_TEMP, IOBUF_OUTPUT or
+   IOBUF_OUTPUT_TEMP.
 
    BUFSIZE is the desired internal buffer size (that is, the size of
    the typical read / write request).  */