1 /*
2 * Copyright 2010 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "src/pdf/SkDeflate.h"
9
10 #include "include/core/SkData.h"
11 #include "include/private/SkMalloc.h"
12 #include "include/private/SkTFitsIn.h"
13 #include "include/private/SkTo.h"
14 #include "src/core/SkTraceEvent.h"
15
16 #include "zlib.h"
17
18 #include <algorithm>
19
20 namespace {
21
22 // Different zlib implementations use different T.
23 // We've seen size_t and unsigned.
skia_alloc_func(void *,T items,T size)24 template <typename T> void* skia_alloc_func(void*, T items, T size) {
25 if (!SkTFitsIn<size_t>(size)) {
26 return nullptr;
27 }
28 const size_t maxItems = SIZE_MAX / size;
29 if (maxItems < items) {
30 return nullptr;
31 }
32 return sk_calloc_throw(SkToSizeT(items) * SkToSizeT(size));
33 }
34
skia_free_func(void *,void * address)35 void skia_free_func(void*, void* address) { sk_free(address); }
36
37 } // namespace
38
39 #define SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE 4096
40 #define SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE 4224 // 4096 + 128, usually big
41 // enough to always do a
42 // single loop.
43
44 // called by both write() and finalize()
do_deflate(int flush,z_stream * zStream,SkWStream * out,unsigned char * inBuffer,size_t inBufferSize)45 static void do_deflate(int flush,
46 z_stream* zStream,
47 SkWStream* out,
48 unsigned char* inBuffer,
49 size_t inBufferSize) {
50 zStream->next_in = inBuffer;
51 zStream->avail_in = SkToInt(inBufferSize);
52 unsigned char outBuffer[SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE];
53 SkDEBUGCODE(int returnValue;)
54 do {
55 zStream->next_out = outBuffer;
56 zStream->avail_out = sizeof(outBuffer);
57 SkDEBUGCODE(returnValue =) deflate(zStream, flush);
58 SkASSERT(!zStream->msg);
59
60 out->write(outBuffer, sizeof(outBuffer) - zStream->avail_out);
61 } while (zStream->avail_in || !zStream->avail_out);
62 SkASSERT(flush == Z_FINISH
63 ? returnValue == Z_STREAM_END
64 : returnValue == Z_OK);
65 }
66
67 // Hide all zlib impl details.
68 struct SkDeflateWStream::Impl {
69 SkWStream* fOut;
70 unsigned char fInBuffer[SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE];
71 size_t fInBufferIndex;
72 z_stream fZStream;
73 };
74
SkDeflateWStream(SkWStream * out,int compressionLevel,bool gzip)75 SkDeflateWStream::SkDeflateWStream(SkWStream* out,
76 int compressionLevel,
77 bool gzip)
78 : fImpl(std::make_unique<SkDeflateWStream::Impl>()) {
79 fImpl->fOut = out;
80 fImpl->fInBufferIndex = 0;
81 if (!fImpl->fOut) {
82 return;
83 }
84 fImpl->fZStream.next_in = nullptr;
85 fImpl->fZStream.zalloc = &skia_alloc_func;
86 fImpl->fZStream.zfree = &skia_free_func;
87 fImpl->fZStream.opaque = nullptr;
88 SkASSERT(compressionLevel <= 9 && compressionLevel >= -1);
89 SkDEBUGCODE(int r =) deflateInit2(&fImpl->fZStream, compressionLevel,
90 Z_DEFLATED, gzip ? 0x1F : 0x0F,
91 8, Z_DEFAULT_STRATEGY);
92 SkASSERT(Z_OK == r);
93 }
94
~SkDeflateWStream()95 SkDeflateWStream::~SkDeflateWStream() { this->finalize(); }
96
finalize()97 void SkDeflateWStream::finalize() {
98 TRACE_EVENT0("skia", TRACE_FUNC);
99 if (!fImpl->fOut) {
100 return;
101 }
102 do_deflate(Z_FINISH, &fImpl->fZStream, fImpl->fOut, fImpl->fInBuffer,
103 fImpl->fInBufferIndex);
104 (void)deflateEnd(&fImpl->fZStream);
105 fImpl->fOut = nullptr;
106 }
107
write(const void * void_buffer,size_t len)108 bool SkDeflateWStream::write(const void* void_buffer, size_t len) {
109 TRACE_EVENT0("skia", TRACE_FUNC);
110 if (!fImpl->fOut) {
111 return false;
112 }
113 const char* buffer = (const char*)void_buffer;
114 while (len > 0) {
115 size_t tocopy =
116 std::min(len, sizeof(fImpl->fInBuffer) - fImpl->fInBufferIndex);
117 memcpy(fImpl->fInBuffer + fImpl->fInBufferIndex, buffer, tocopy);
118 len -= tocopy;
119 buffer += tocopy;
120 fImpl->fInBufferIndex += tocopy;
121 SkASSERT(fImpl->fInBufferIndex <= sizeof(fImpl->fInBuffer));
122
123 // if the buffer isn't filled, don't call into zlib yet.
124 if (sizeof(fImpl->fInBuffer) == fImpl->fInBufferIndex) {
125 do_deflate(Z_NO_FLUSH, &fImpl->fZStream, fImpl->fOut,
126 fImpl->fInBuffer, fImpl->fInBufferIndex);
127 fImpl->fInBufferIndex = 0;
128 }
129 }
130 return true;
131 }
132
bytesWritten() const133 size_t SkDeflateWStream::bytesWritten() const {
134 return fImpl->fZStream.total_in + fImpl->fInBufferIndex;
135 }
136