>From 430ebd936b0bc41bd3e33e171938161846597196 Mon Sep 17 00:00:00 2001 From: Noam Postavsky Date: Sat, 27 Oct 2018 17:45:52 -0400 Subject: [PATCH v1] 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. --- doc/lispref/text.texi | 10 ++++++---- etc/NEWS | 6 ++++++ lisp/url/url-http.el | 5 +++-- src/decompress.c | 22 +++++++++++++++++----- 4 files changed, 32 insertions(+), 11 deletions(-) diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi index 6c38d8eed0..e39ba6a192 100644 --- a/doc/lispref/text.texi +++ b/doc/lispref/text.texi @@ -4462,14 +4462,16 @@ Decompression 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}, 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 diff --git a/etc/NEWS b/etc/NEWS index 3f86195695..395169253d 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -1159,6 +1159,12 @@ to mean that it is not known whether DST is in effect. 'json-insert', 'json-parse-string', and 'json-parse-buffer'. These are implemented in C using the Jansson library. ++++ +** 'zlib-decompress-region' can partially decompress corrupted data. +If the new optional ALLOW-PARTIAL argument is passed, then the data +that was decompressed successfully before failing will be inserted +into the buffer. + ** Mailcap --- diff --git a/lisp/url/url-http.el b/lisp/url/url-http.el index 6b5749e1bc..94ac660fcf 100644 --- a/lisp/url/url-http.el +++ b/lisp/url/url-http.el @@ -939,7 +939,8 @@ url-http-parse-headers (goto-char (point-min)) success)) -(declare-function zlib-decompress-region "decompress.c" (start end)) +(declare-function zlib-decompress-region "decompress.c" + (start end &optional allow-partial)) (defun url-handle-content-transfer-encoding () (let ((encoding (mail-fetch-field "content-encoding"))) @@ -951,7 +952,7 @@ url-handle-content-transfer-encoding (widen) (goto-char (point-min)) (when (search-forward "\n\n") - (zlib-decompress-region (point) (point-max))))))) + (zlib-decompress-region (point) (point-max) t)))))) ;; Miscellaneous (defun url-http-activate-callback () diff --git a/src/decompress.c b/src/decompress.c index 2836338216..3872014739 100644 --- a/src/decompress.c +++ b/src/decompress.c @@ -120,12 +120,18 @@ DEFUN ("zlib-available-p", Fzlib_available_p, Szlib_available_p, 0, 0, 0, DEFUN ("zlib-decompress-region", Fzlib_decompress_region, Szlib_decompress_region, - 2, 2, 0, + 2, 3, 0, doc: /* Decompress a gzip- or zlib-compressed region. Replace the text in the region by the decompressed data. -On failure, return nil and leave the data in place. + +If optional parameter ALLOW-PARTIAL is nil or omitted, on failure, +return nil and leave the data in place. Otherwise, return the number +of bytes that were not decompressed and replace the region text by +whatever data was successfully decompressed. If decompression is +completely successful return t. + This function can be called only in unibyte buffers. */) - (Lisp_Object start, Lisp_Object end) + (Lisp_Object start, Lisp_Object end, Lisp_Object allow_partial) { ptrdiff_t istart, iend, pos_byte; z_stream stream; @@ -206,8 +212,14 @@ DEFUN ("zlib-decompress-region", Fzlib_decompress_region, } while (inflate_status == Z_OK); + Lisp_Object ret = Qt; if (inflate_status != Z_STREAM_END) - return unbind_to (count, Qnil); + { + if (!NILP (allow_partial)) + ret = make_int (iend - pos_byte); + else + return unbind_to (count, Qnil); + } unwind_data.start = 0; @@ -218,7 +230,7 @@ DEFUN ("zlib-decompress-region", Fzlib_decompress_region, signal_after_change (istart, iend - istart, unwind_data.nbytes); update_compositions (istart, istart, CHECK_HEAD); - return unbind_to (count, Qt); + return unbind_to (count, ret); } -- 2.11.0