gfx/skia/trunk/src/core/SkWriter32.cpp@97036ab72558 (annotated)
gfx/skia/trunk/src/core/SkWriter32.cpp
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
| michael@0 | 1 | /* |
| michael@0 | 2 | * Copyright 2011 Google Inc. |
| michael@0 | 3 | * |
| michael@0 | 4 | * Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 5 | * found in the LICENSE file. |
| michael@0 | 6 | */ |
| michael@0 | 7 | |
| michael@0 | 8 | #include "SkReader32.h" |
| michael@0 | 9 | #include "SkString.h" |
| michael@0 | 10 | #include "SkWriter32.h" |
| michael@0 | 11 | |
| michael@0 | 12 | /* |
| michael@0 | 13 | * Strings are stored as: length[4-bytes] + string_data + '\0' + pad_to_mul_4 |
| michael@0 | 14 | */ |
| michael@0 | 15 | |
| michael@0 | 16 | const char* SkReader32::readString(size_t* outLen) { |
| michael@0 | 17 | size_t len = this->readInt(); |
| michael@0 | 18 | const void* ptr = this->peek(); |
| michael@0 | 19 | |
| michael@0 | 20 | // skip over the string + '\0' and then pad to a multiple of 4 |
| michael@0 | 21 | size_t alignedSize = SkAlign4(len + 1); |
| michael@0 | 22 | this->skip(alignedSize); |
| michael@0 | 23 | |
| michael@0 | 24 | if (outLen) { |
| michael@0 | 25 | *outLen = len; |
| michael@0 | 26 | } |
| michael@0 | 27 | return (const char*)ptr; |
| michael@0 | 28 | } |
| michael@0 | 29 | |
| michael@0 | 30 | size_t SkReader32::readIntoString(SkString* copy) { |
| michael@0 | 31 | size_t len; |
| michael@0 | 32 | const char* ptr = this->readString(&len); |
| michael@0 | 33 | if (copy) { |
| michael@0 | 34 | copy->set(ptr, len); |
| michael@0 | 35 | } |
| michael@0 | 36 | return len; |
| michael@0 | 37 | } |
| michael@0 | 38 | |
| michael@0 | 39 | void SkWriter32::writeString(const char str[], size_t len) { |
| michael@0 | 40 | if (NULL == str) { |
| michael@0 | 41 | str = ""; |
| michael@0 | 42 | len = 0; |
| michael@0 | 43 | } |
| michael@0 | 44 | if ((long)len < 0) { |
| michael@0 | 45 | len = strlen(str); |
| michael@0 | 46 | } |
| michael@0 | 47 | |
| michael@0 | 48 | // [ 4 byte len ] [ str ... ] [1 - 4 \0s] |
| michael@0 | 49 | uint32_t* ptr = this->reservePad(sizeof(uint32_t) + len + 1); |
| michael@0 | 50 | *ptr = len; |
| michael@0 | 51 | char* chars = (char*)(ptr + 1); |
| michael@0 | 52 | memcpy(chars, str, len); |
| michael@0 | 53 | chars[len] = '\0'; |
| michael@0 | 54 | } |
| michael@0 | 55 | |
| michael@0 | 56 | size_t SkWriter32::WriteStringSize(const char* str, size_t len) { |
| michael@0 | 57 | if ((long)len < 0) { |
| michael@0 | 58 | SkASSERT(str); |
| michael@0 | 59 | len = strlen(str); |
| michael@0 | 60 | } |
| michael@0 | 61 | const size_t lenBytes = 4; // we use 4 bytes to record the length |
| michael@0 | 62 | // add 1 since we also write a terminating 0 |
| michael@0 | 63 | return SkAlign4(lenBytes + len + 1); |
| michael@0 | 64 | } |
| michael@0 | 65 | |
| michael@0 | 66 | void SkWriter32::growToAtLeast(size_t size) { |
| michael@0 | 67 | const bool wasExternal = (fExternal != NULL) && (fData == fExternal); |
| michael@0 | 68 | |
| michael@0 | 69 | fCapacity = 4096 + SkTMax(size, fCapacity + (fCapacity / 2)); |
| michael@0 | 70 | fInternal.realloc(fCapacity); |
| michael@0 | 71 | fData = fInternal.get(); |
| michael@0 | 72 | |
| michael@0 | 73 | if (wasExternal) { |
| michael@0 | 74 | // we were external, so copy in the data |
| michael@0 | 75 | memcpy(fData, fExternal, fUsed); |
| michael@0 | 76 | } |
| michael@0 | 77 | // Invalidate the snapshot, we know it is no longer useful. |
| michael@0 | 78 | fSnapshot.reset(NULL); |
| michael@0 | 79 | } |
| michael@0 | 80 | |
| michael@0 | 81 | SkData* SkWriter32::snapshotAsData() const { |
| michael@0 | 82 | // get a non const version of this, we are only conceptually const |
| michael@0 | 83 | SkWriter32& mutable_this = *const_cast<SkWriter32*>(this); |
| michael@0 | 84 | // we use size change detection to invalidate the cached data |
| michael@0 | 85 | if ((fSnapshot.get() != NULL) && (fSnapshot->size() != fUsed)) { |
| michael@0 | 86 | mutable_this.fSnapshot.reset(NULL); |
| michael@0 | 87 | } |
| michael@0 | 88 | if (fSnapshot.get() == NULL) { |
| michael@0 | 89 | uint8_t* buffer = NULL; |
| michael@0 | 90 | if ((fExternal != NULL) && (fData == fExternal)) { |
| michael@0 | 91 | // We need to copy to an allocated buffer before returning. |
| michael@0 | 92 | buffer = (uint8_t*)sk_malloc_throw(fUsed); |
| michael@0 | 93 | memcpy(buffer, fData, fUsed); |
| michael@0 | 94 | } else { |
| michael@0 | 95 | buffer = mutable_this.fInternal.detach(); |
| michael@0 | 96 | // prepare us to do copy on write, by pretending the data buffer |
| michael@0 | 97 | // is external and size limited |
| michael@0 | 98 | mutable_this.fData = buffer; |
| michael@0 | 99 | mutable_this.fCapacity = fUsed; |
| michael@0 | 100 | mutable_this.fExternal = buffer; |
| michael@0 | 101 | } |
| michael@0 | 102 | mutable_this.fSnapshot.reset(SkData::NewFromMalloc(buffer, fUsed)); |
| michael@0 | 103 | } |
| michael@0 | 104 | return SkRef(fSnapshot.get()); // Take an extra ref for the caller. |
| michael@0 | 105 | } |
