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From d09bb1ab8ef9bb91457c0ead09589e8807489260 Mon Sep 17 00:00:00 2001
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From: Ondrej Dubaj <odubaj@redhat.com>
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Date: Thu, 6 Aug 2020 08:09:53 +0200
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Subject: [PATCH] Permit a deflateParams() parameter change.
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This change allows a parameter change even if the input data has
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not all been compressed and copied to the application output
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buffer, so long as all of the input data has been compressed to
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the internal pending output buffer. This also allows an immediate
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deflateParams change so long as there have been no deflate calls
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since initialization or reset.
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---
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deflate.c | 6 +++---
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zlib.h | 11 ++++++-----
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2 files changed, 9 insertions(+), 8 deletions(-)
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diff --git a/deflate.c b/deflate.c
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index 9705c1c..f3c9924 100644
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--- a/deflate.c
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+++ b/deflate.c
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@@ -509,7 +509,7 @@ int ZEXPORT deflateResetKeep (strm)
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s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
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#endif
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adler32(0L, Z_NULL, 0);
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- s->last_flush = Z_NO_FLUSH;
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+ s->last_flush = -2;
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_tr_init(s);
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@@ -606,13 +606,13 @@ int ZEXPORT deflateParams(strm, level, strategy)
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func = configuration_table[s->level].func;
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if ((strategy != s->strategy || func != configuration_table[level].func ||
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- hook_flush != Z_NO_FLUSH) && s->high_water) {
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+ hook_flush != Z_NO_FLUSH) && s->last_flush != -2) {
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/* Flush the last buffer: */
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int err = deflate(strm, RANK(hook_flush) > RANK(Z_BLOCK) ?
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hook_flush : Z_BLOCK);
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if (err == Z_STREAM_ERROR)
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return err;
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- if (strm->avail_out == 0)
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+ if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead)
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return Z_BUF_ERROR;
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}
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if (s->level != level) {
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diff --git a/zlib.h b/zlib.h
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index f09cdaf..001624e 100644
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--- a/zlib.h
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+++ b/zlib.h
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@@ -712,11 +712,12 @@ ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
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used to switch between compression and straight copy of the input data, or
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to switch to a different kind of input data requiring a different strategy.
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If the compression approach (which is a function of the level) or the
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- strategy is changed, and if any input has been consumed in a previous
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- deflate() call, then the input available so far is compressed with the old
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- level and strategy using deflate(strm, Z_BLOCK). There are three approaches
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- for the compression levels 0, 1..3, and 4..9 respectively. The new level
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- and strategy will take effect at the next call of deflate().
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+ strategy is changed, and if there have been any deflate() calls since the
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+ state was initialized or reset, then the input available so far is
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+ compressed with the old level and strategy using deflate(strm, Z_BLOCK).
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+ There are three approaches for the compression levels 0, 1..3, and 4..9
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+ respectively. The new level and strategy will take effect at the next call
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+ of deflate().
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If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
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not have enough output space to complete, then the parameter change will not
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--
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2.26.0
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