225 lines
9.4 KiB
Diff
225 lines
9.4 KiB
Diff
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From 9aaec95e82117c1cb0f9624264c3618fc380cecb Mon Sep 17 00:00:00 2001
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From: Mark Adler <madler@alumni.caltech.edu>
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Date: Wed, 21 Sep 2016 22:25:21 -0700
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Subject: [PATCH] Use post-increment only in inffast.c.
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An old inffast.c optimization turns out to not be optimal anymore
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with modern compilers, and furthermore was not compliant with the
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C standard, for which decrementing a pointer before its allocated
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memory is undefined. Per the recommendation of a security audit of
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the zlib code by Trail of Bits and TrustInSoft, in support of the
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Mozilla Foundation, this "optimization" was removed, in order to
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avoid the possibility of undefined behavior.
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---
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inffast.c | 81 ++++++++++++++++++++++++---------------------------------------
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1 file changed, 31 insertions(+), 50 deletions(-)
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diff --git a/inffast.c b/inffast.c
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index bda59ce..f0d163d 100644
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--- a/inffast.c
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+++ b/inffast.c
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@@ -10,25 +10,6 @@
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#ifndef ASMINF
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-/* Allow machine dependent optimization for post-increment or pre-increment.
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- Based on testing to date,
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- Pre-increment preferred for:
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- - PowerPC G3 (Adler)
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- - MIPS R5000 (Randers-Pehrson)
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- Post-increment preferred for:
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- - none
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- No measurable difference:
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- - Pentium III (Anderson)
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- - M68060 (Nikl)
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- */
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-#ifdef POSTINC
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-# define OFF 0
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-# define PUP(a) *(a)++
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-#else
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-# define OFF 1
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-# define PUP(a) *++(a)
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-#endif
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-
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/*
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Decode literal, length, and distance codes and write out the resulting
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literal and match bytes until either not enough input or output is
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@@ -96,9 +77,9 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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/* copy state to local variables */
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state = (struct inflate_state FAR *)strm->state;
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- in = strm->next_in - OFF;
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+ in = strm->next_in;
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last = in + (strm->avail_in - 5);
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- out = strm->next_out - OFF;
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+ out = strm->next_out;
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beg = out - (start - strm->avail_out);
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end = out + (strm->avail_out - 257);
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#ifdef INFLATE_STRICT
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@@ -119,9 +100,9 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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input data or output space */
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do {
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if (bits < 15) {
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- hold += (unsigned long)(PUP(in)) << bits;
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+ hold += (unsigned long)(*in++) << bits;
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bits += 8;
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- hold += (unsigned long)(PUP(in)) << bits;
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+ hold += (unsigned long)(*in++) << bits;
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bits += 8;
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}
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here = lcode[hold & lmask];
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@@ -134,14 +115,14 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
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"inflate: literal '%c'\n" :
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"inflate: literal 0x%02x\n", here.val));
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- PUP(out) = (unsigned char)(here.val);
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+ *out++ = (unsigned char)(here.val);
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}
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else if (op & 16) { /* length base */
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len = (unsigned)(here.val);
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op &= 15; /* number of extra bits */
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if (op) {
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if (bits < op) {
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- hold += (unsigned long)(PUP(in)) << bits;
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+ hold += (unsigned long)(*in++) << bits;
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bits += 8;
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}
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len += (unsigned)hold & ((1U << op) - 1);
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@@ -150,9 +131,9 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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}
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Tracevv((stderr, "inflate: length %u\n", len));
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if (bits < 15) {
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- hold += (unsigned long)(PUP(in)) << bits;
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+ hold += (unsigned long)(*in++) << bits;
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bits += 8;
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- hold += (unsigned long)(PUP(in)) << bits;
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+ hold += (unsigned long)(*in++) << bits;
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bits += 8;
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}
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here = dcode[hold & dmask];
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@@ -165,10 +146,10 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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dist = (unsigned)(here.val);
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op &= 15; /* number of extra bits */
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if (bits < op) {
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- hold += (unsigned long)(PUP(in)) << bits;
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+ hold += (unsigned long)(*in++) << bits;
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bits += 8;
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if (bits < op) {
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- hold += (unsigned long)(PUP(in)) << bits;
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+ hold += (unsigned long)(*in++) << bits;
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bits += 8;
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}
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}
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@@ -196,30 +177,30 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
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if (len <= op - whave) {
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do {
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- PUP(out) = 0;
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+ *out++ = 0;
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} while (--len);
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continue;
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}
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len -= op - whave;
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do {
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- PUP(out) = 0;
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+ *out++ = 0;
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} while (--op > whave);
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if (op == 0) {
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from = out - dist;
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do {
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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} while (--len);
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continue;
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}
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#endif
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}
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- from = window - OFF;
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+ from = window;
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if (wnext == 0) { /* very common case */
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from += wsize - op;
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if (op < len) { /* some from window */
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len -= op;
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do {
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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} while (--op);
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from = out - dist; /* rest from output */
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}
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@@ -230,14 +211,14 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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if (op < len) { /* some from end of window */
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len -= op;
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do {
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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} while (--op);
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- from = window - OFF;
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+ from = window;
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if (wnext < len) { /* some from start of window */
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op = wnext;
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len -= op;
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do {
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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} while (--op);
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from = out - dist; /* rest from output */
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}
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@@ -248,35 +229,35 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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if (op < len) { /* some from window */
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len -= op;
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do {
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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} while (--op);
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from = out - dist; /* rest from output */
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}
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}
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while (len > 2) {
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- PUP(out) = PUP(from);
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- PUP(out) = PUP(from);
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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+ *out++ = *from++;
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+ *out++ = *from++;
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len -= 3;
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}
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if (len) {
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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if (len > 1)
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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}
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}
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else {
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from = out - dist; /* copy direct from output */
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do { /* minimum length is three */
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- PUP(out) = PUP(from);
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- PUP(out) = PUP(from);
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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+ *out++ = *from++;
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+ *out++ = *from++;
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len -= 3;
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} while (len > 2);
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if (len) {
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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if (len > 1)
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- PUP(out) = PUP(from);
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+ *out++ = *from++;
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}
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}
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}
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@@ -313,8 +294,8 @@ unsigned start; /* inflate()'s starting value for strm->avail_out */
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hold &= (1U << bits) - 1;
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/* update state and return */
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- strm->next_in = in + OFF;
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- strm->next_out = out + OFF;
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+ strm->next_in = in;
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+ strm->next_out = out;
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strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last));
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strm->avail_out = (unsigned)(out < end ?
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257 + (end - out) : 257 - (out - end));
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