Allow partial decompression (Bug#33133)

* src/decompress.c (Fzlib_decompress_region): Add optional
ALLOW-PARTIAL parameter.
* lisp/url/url-http.el (url-handle-content-transfer-encoding): Use it.
* doc/lispref/text.texi (Decompression): Document it.
* etc/NEWS: Announce it.

1 files changed, 7 insertions, 4 deletions

diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index b430adf5976..86f9fa0e5f5 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -4513,14 +4513,17 @@ This function returns non-@code{nil} if built-in zlib decompression is
 available.
 @end defun
 
-@defun zlib-decompress-region start end
+@defun zlib-decompress-region start end &optional allow-partial
 This function decompresses the region between @var{start} and
 @var{end}, using built-in zlib decompression.  The region should
 contain data that were compressed with gzip or zlib.  On success, the
 function replaces the contents of the region with the decompressed
-data.  On failure, the function leaves the region unchanged and
-returns @code{nil}.  This function can be called only in unibyte
-buffers.
+data.  If @var{allow-partial} is @code{nil} or omitted, then on
+failure, the function leaves the region unchanged and returns
+@code{nil}.  Otherwise, it returns the number of bytes that were not
+decompressed and replaces the region text by whatever data was
+successfully decompressed.  This function can be called only in
+unibyte buffers.
 @end defun