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-rw-r--r--gfx/graphite2/src/Decompressor.cpp115
1 files changed, 115 insertions, 0 deletions
diff --git a/gfx/graphite2/src/Decompressor.cpp b/gfx/graphite2/src/Decompressor.cpp
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+++ b/gfx/graphite2/src/Decompressor.cpp
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+/* GRAPHITE2 LICENSING
+
+ Copyright 2015, SIL International
+ All rights reserved.
+
+ This library is free software; you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as published
+ by the Free Software Foundation; either version 2.1 of License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should also have received a copy of the GNU Lesser General Public
+ License along with this library in the file named "LICENSE".
+ If not, write to the Free Software Foundation, 51 Franklin Street,
+ Suite 500, Boston, MA 02110-1335, USA or visit their web page on the
+ internet at http://www.fsf.org/licenses/lgpl.html.
+
+Alternatively, the contents of this file may be used under the terms of the
+Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
+License, as published by the Free Software Foundation, either version 2
+of the License or (at your option) any later version.
+*/
+#include <cassert>
+
+#include "inc/Decompressor.h"
+#include "inc/Compression.h"
+
+using namespace lz4;
+
+namespace {
+
+inline
+u32 read_literal(u8 const * &s, u8 const * const e, u32 l) {
+ if (l == 15 && s != e)
+ {
+ u8 b = 0;
+ do { l += b = *s++; } while(b==0xff && s != e);
+ }
+ return l;
+}
+
+bool read_sequence(u8 const * &src, u8 const * const end, u8 const * &literal, u32 & literal_len, u32 & match_len, u32 & match_dist)
+{
+ u8 const token = *src++;
+
+ literal_len = read_literal(src, end, token >> 4);
+ literal = src;
+ src += literal_len;
+
+ if (src > end - 2 || src < literal)
+ return false;
+
+ match_dist = *src++;
+ match_dist |= *src++ << 8;
+ match_len = read_literal(src, end, token & 0xf);
+
+ return src <= end-5;
+}
+
+}
+
+int lz4::decompress(void const *in, size_t in_size, void *out, size_t out_size)
+{
+ if (out_size <= in_size || in_size < sizeof(unsigned long)+1)
+ return -1;
+
+ u8 const * src = static_cast<u8 const *>(in),
+ * literal = 0,
+ * const src_end = src + in_size;
+
+ u8 * dst = static_cast<u8*>(out),
+ * const dst_end = dst + out_size;
+
+ u32 literal_len = 0,
+ match_len = 0,
+ match_dist = 0;
+
+ while (read_sequence(src, src_end, literal, literal_len, match_len, match_dist))
+ {
+ if (literal_len != 0)
+ {
+ // Copy in literal. At this point the last full sequence must be at
+ // least MINMATCH + 5 from the end of the output buffer.
+ if (align(literal_len) > unsigned(dst_end - dst - (MINMATCH+5)) || dst_end - dst < MINMATCH + 5)
+ return -1;
+ dst = overrun_copy(dst, literal, literal_len);
+ }
+
+ // Copy, possibly repeating, match from earlier in the
+ // decoded output.
+ u8 const * const pcpy = dst - match_dist;
+ if (pcpy < static_cast<u8*>(out)
+ || pcpy >= dst
+ || match_len > unsigned(dst_end - dst - (MINMATCH+5))
+ || dst_end - dst < MINMATCH + 5)
+ return -1;
+ if (dst > pcpy+sizeof(unsigned long)
+ && dst + align(match_len + MINMATCH) <= dst_end)
+ dst = overrun_copy(dst, pcpy, match_len + MINMATCH);
+ else
+ dst = safe_copy(dst, pcpy, match_len + MINMATCH);
+ }
+
+ if (literal_len > src_end - literal
+ || literal_len > dst_end - dst)
+ return -1;
+ dst = fast_copy(dst, literal, literal_len);
+
+ return dst - (u8*)out;
+}
+