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
9 #include "SkData.h"
10 #include "SkDeflate.h"
11 #include "SkMakeUnique.h"
12 #include "SkMalloc.h"
13
14 #include "zlib.h"
15
16 namespace {
17
18 // Different zlib implementations use different T.
19 // We've seen size_t and unsigned.
skia_alloc_func(void *,T items,T size)20 template <typename T> void* skia_alloc_func(void*, T items, T size) {
21 return sk_calloc_throw(SkToSizeT(items) * SkToSizeT(size));
22 }
23
skia_free_func(void *,void * address)24 void skia_free_func(void*, void* address) { sk_free(address); }
25
26 } // namespace
27
28 #define SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE 4096
29 #define SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE 4224 // 4096 + 128, usually big
30 // enough to always do a
31 // single loop.
32
33 // called by both write() and finalize()
do_deflate(int flush,z_stream * zStream,SkWStream * out,unsigned char * inBuffer,size_t inBufferSize)34 static void do_deflate(int flush,
35 z_stream* zStream,
36 SkWStream* out,
37 unsigned char* inBuffer,
38 size_t inBufferSize) {
39 zStream->next_in = inBuffer;
40 zStream->avail_in = SkToInt(inBufferSize);
41 unsigned char outBuffer[SKDEFLATEWSTREAM_OUTPUT_BUFFER_SIZE];
42 SkDEBUGCODE(int returnValue;)
43 do {
44 zStream->next_out = outBuffer;
45 zStream->avail_out = sizeof(outBuffer);
46 SkDEBUGCODE(returnValue =) deflate(zStream, flush);
47 SkASSERT(!zStream->msg);
48
49 out->write(outBuffer, sizeof(outBuffer) - zStream->avail_out);
50 } while (zStream->avail_in || !zStream->avail_out);
51 SkASSERT(flush == Z_FINISH
52 ? returnValue == Z_STREAM_END
53 : returnValue == Z_OK);
54 }
55
56 // Hide all zlib impl details.
57 struct SkDeflateWStream::Impl {
58 SkWStream* fOut;
59 unsigned char fInBuffer[SKDEFLATEWSTREAM_INPUT_BUFFER_SIZE];
60 size_t fInBufferIndex;
61 z_stream fZStream;
62 };
63
SkDeflateWStream(SkWStream * out,int compressionLevel,bool gzip)64 SkDeflateWStream::SkDeflateWStream(SkWStream* out,
65 int compressionLevel,
66 bool gzip)
67 : fImpl(skstd::make_unique<SkDeflateWStream::Impl>()) {
68 fImpl->fOut = out;
69 fImpl->fInBufferIndex = 0;
70 if (!fImpl->fOut) {
71 return;
72 }
73 fImpl->fZStream.next_in = nullptr;
74 fImpl->fZStream.zalloc = &skia_alloc_func;
75 fImpl->fZStream.zfree = &skia_free_func;
76 fImpl->fZStream.opaque = nullptr;
77 SkASSERT(compressionLevel <= 9 && compressionLevel >= -1);
78 SkDEBUGCODE(int r =) deflateInit2(&fImpl->fZStream, compressionLevel,
79 Z_DEFLATED, gzip ? 0x1F : 0x0F,
80 8, Z_DEFAULT_STRATEGY);
81 SkASSERT(Z_OK == r);
82 }
83
~SkDeflateWStream()84 SkDeflateWStream::~SkDeflateWStream() { this->finalize(); }
85
finalize()86 void SkDeflateWStream::finalize() {
87 if (!fImpl->fOut) {
88 return;
89 }
90 do_deflate(Z_FINISH, &fImpl->fZStream, fImpl->fOut, fImpl->fInBuffer,
91 fImpl->fInBufferIndex);
92 (void)deflateEnd(&fImpl->fZStream);
93 fImpl->fOut = nullptr;
94 }
95
write(const void * void_buffer,size_t len)96 bool SkDeflateWStream::write(const void* void_buffer, size_t len) {
97 if (!fImpl->fOut) {
98 return false;
99 }
100 const char* buffer = (const char*)void_buffer;
101 while (len > 0) {
102 size_t tocopy =
103 SkTMin(len, sizeof(fImpl->fInBuffer) - fImpl->fInBufferIndex);
104 memcpy(fImpl->fInBuffer + fImpl->fInBufferIndex, buffer, tocopy);
105 len -= tocopy;
106 buffer += tocopy;
107 fImpl->fInBufferIndex += tocopy;
108 SkASSERT(fImpl->fInBufferIndex <= sizeof(fImpl->fInBuffer));
109
110 // if the buffer isn't filled, don't call into zlib yet.
111 if (sizeof(fImpl->fInBuffer) == fImpl->fInBufferIndex) {
112 do_deflate(Z_NO_FLUSH, &fImpl->fZStream, fImpl->fOut,
113 fImpl->fInBuffer, fImpl->fInBufferIndex);
114 fImpl->fInBufferIndex = 0;
115 }
116 }
117 return true;
118 }
119
bytesWritten() const120 size_t SkDeflateWStream::bytesWritten() const {
121 return fImpl->fZStream.total_in + fImpl->fInBufferIndex;
122 }
123