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/private/base/SkAssert.h"
11 #include "include/private/base/SkDebug.h"
12 #include "include/private/base/SkMalloc.h"
13 #include "include/private/base/SkTo.h"
14 #include "src/core/SkTraceEvent.h"
15
16 #include <algorithm>
17 #include <cstdint>
18 #include <cstring>
19
20 #include "zlib.h" // NO_G3_REWRITE
21
22 namespace {
23
24 // Different zlib implementations use different T.
25 // We've seen size_t and unsigned.
skia_alloc_func(void *,T items,T size)26 template <typename T> void* skia_alloc_func(void*, T items, T size) {
27 return sk_calloc_throw(SkToSizeT(items) * SkToSizeT(size));
28 }
29
skia_free_func(void *,void * address)30 void skia_free_func(void*, void* address) { sk_free(address); }
31
32 } // namespace
33
34 #define SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE 4096
35 #define SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE 4224 // 4096 + 128, usually big
36 // enough to always do a
37 // single loop.
38
39 // called by both write() and finalize()
do_deflate(int flush,z_stream * zStream,SkWStream * out,unsigned char * inBuffer,size_t inBufferSize)40 static void do_deflate(int flush,
41 z_stream* zStream,
42 SkWStream* out,
43 unsigned char* inBuffer,
44 size_t inBufferSize) {
45 zStream->next_in = inBuffer;
46 zStream->avail_in = SkToInt(inBufferSize);
47 unsigned char outBuffer[SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE];
48 SkDEBUGCODE(int returnValue;)
49 do {
50 zStream->next_out = outBuffer;
51 zStream->avail_out = sizeof(outBuffer);
52 SkDEBUGCODE(returnValue =) deflate(zStream, flush);
53 SkASSERT(!zStream->msg);
54
55 out->write(outBuffer, sizeof(outBuffer) - zStream->avail_out);
56 } while (zStream->avail_in || !zStream->avail_out);
57 SkASSERT(flush == Z_FINISH
58 ? returnValue == Z_STREAM_END
59 : returnValue == Z_OK);
60 }
61
62 // Hide all zlib impl details.
63 struct SkDeflateWStream::Impl {
64 SkWStream* fOut;
65 unsigned char fInBuffer[SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE];
66 size_t fInBufferIndex;
67 z_stream fZStream;
68 };
69
SkDeflateWStream(SkWStream * out,int compressionLevel,bool gzip)70 SkDeflateWStream::SkDeflateWStream(SkWStream* out,
71 int compressionLevel,
72 bool gzip)
73 : fImpl(std::make_unique<SkDeflateWStream::Impl>()) {
74
75 // There has existed at some point at least one zlib implementation which thought it was being
76 // clever by randomizing the compression level. This is actually not entirely incorrect, except
77 // for the no-compression level which should always be deterministically pass-through.
78 // Users should instead consider the zero compression level broken and handle it themselves.
79 SkASSERT(compressionLevel != 0);
80
81 fImpl->fOut = out;
82 fImpl->fInBufferIndex = 0;
83 if (!fImpl->fOut) {
84 return;
85 }
86 fImpl->fZStream.next_in = nullptr;
87 fImpl->fZStream.zalloc = &skia_alloc_func;
88 fImpl->fZStream.zfree = &skia_free_func;
89 fImpl->fZStream.opaque = nullptr;
90 SkASSERT(compressionLevel <= 9 && compressionLevel >= -1);
91 SkDEBUGCODE(int r =) deflateInit2(&fImpl->fZStream, compressionLevel,
92 Z_DEFLATED, gzip ? 0x1F : 0x0F,
93 8, Z_DEFAULT_STRATEGY);
94 SkASSERT(Z_OK == r);
95 }
96
~SkDeflateWStream()97 SkDeflateWStream::~SkDeflateWStream() { this->finalize(); }
98
finalize()99 void SkDeflateWStream::finalize() {
100 TRACE_EVENT0("skia", TRACE_FUNC);
101 if (!fImpl->fOut) {
102 return;
103 }
104 do_deflate(Z_FINISH, &fImpl->fZStream, fImpl->fOut, fImpl->fInBuffer,
105 fImpl->fInBufferIndex);
106 (void)deflateEnd(&fImpl->fZStream);
107 fImpl->fOut = nullptr;
108 }
109
write(const void * void_buffer,size_t len)110 bool SkDeflateWStream::write(const void* void_buffer, size_t len) {
111 TRACE_EVENT0("skia", TRACE_FUNC);
112 if (!fImpl->fOut) {
113 return false;
114 }
115 const char* buffer = (const char*)void_buffer;
116 while (len > 0) {
117 size_t tocopy =
118 std::min(len, sizeof(fImpl->fInBuffer) - fImpl->fInBufferIndex);
119 memcpy(fImpl->fInBuffer + fImpl->fInBufferIndex, buffer, tocopy);
120 len -= tocopy;
121 buffer += tocopy;
122 fImpl->fInBufferIndex += tocopy;
123 SkASSERT(fImpl->fInBufferIndex <= sizeof(fImpl->fInBuffer));
124
125 // if the buffer isn't filled, don't call into zlib yet.
126 if (sizeof(fImpl->fInBuffer) == fImpl->fInBufferIndex) {
127 do_deflate(Z_NO_FLUSH, &fImpl->fZStream, fImpl->fOut,
128 fImpl->fInBuffer, fImpl->fInBufferIndex);
129 fImpl->fInBufferIndex = 0;
130 }
131 }
132 return true;
133 }
134
bytesWritten() const135 size_t SkDeflateWStream::bytesWritten() const {
136 return fImpl->fZStream.total_in + fImpl->fInBufferIndex;
137 }
138