1 2 /* 3 * Copyright 2011 Google Inc. 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 #include "SkStream.h" 9 #include <unistd.h> 10 11 //#define TRACE_FDSTREAM 12 13 SkFDStream::SkFDStream(int fileDesc, bool closeWhenDone) 14 : fFD(fileDesc), fCloseWhenDone(closeWhenDone) { 15 } 16 17 SkFDStream::~SkFDStream() { 18 if (fFD >= 0 && fCloseWhenDone) { 19 ::close(fFD); 20 } 21 } 22 23 bool SkFDStream::rewind() { 24 if (fFD >= 0) { 25 off_t value = ::lseek(fFD, 0, SEEK_SET); 26 #ifdef TRACE_FDSTREAM 27 if (value) { 28 SkDebugf("xxxxxxxxxxxxxx rewind failed %d\n", value); 29 } 30 #endif 31 return value == 0; 32 } 33 return false; 34 } 35 36 size_t SkFDStream::read(void* buffer, size_t size) { 37 if (fFD >= 0) { 38 if (buffer == NULL && size == 0) { // request total size 39 off_t curr = ::lseek(fFD, 0, SEEK_CUR); 40 if (curr < 0) { 41 #ifdef TRACE_FDSTREAM 42 SkDebugf("xxxxxxxxxxxxx lseek failed 0 CURR\n"); 43 #endif 44 return 0; // error 45 } 46 off_t size = ::lseek(fFD, 0, SEEK_END); 47 if (size < 0) { 48 #ifdef TRACE_FDSTREAM 49 SkDebugf("xxxxxxxxxxxxx lseek failed 0 END\n"); 50 #endif 51 size = 0; // error 52 } 53 if (::lseek(fFD, curr, SEEK_SET) != curr) { 54 // can't restore, error 55 #ifdef TRACE_FDSTREAM 56 SkDebugf("xxxxxxxxxxxxx lseek failed %d SET\n", curr); 57 #endif 58 return 0; 59 } 60 return size; 61 } else if (NULL == buffer) { // skip 62 off_t oldCurr = ::lseek(fFD, 0, SEEK_CUR); 63 if (oldCurr < 0) { 64 #ifdef TRACE_FDSTREAM 65 SkDebugf("xxxxxxxxxxxxx lseek1 failed %d CUR\n", oldCurr); 66 #endif 67 return 0; // error; 68 } 69 off_t newCurr = ::lseek(fFD, size, SEEK_CUR); 70 if (newCurr < 0) { 71 #ifdef TRACE_FDSTREAM 72 SkDebugf("xxxxxxxxxxxxx lseek2 failed %d CUR\n", newCurr); 73 #endif 74 return 0; // error; 75 } 76 // return the actual amount we skipped 77 return newCurr - oldCurr; 78 } else { // read 79 ssize_t actual = ::read(fFD, buffer, size); 80 // our API can't return an error, so we return 0 81 if (actual < 0) { 82 #ifdef TRACE_FDSTREAM 83 SkDebugf("xxxxxxxxxxxxx read failed %d actual %d\n", size, actual); 84 #endif 85 actual = 0; 86 } 87 return actual; 88 } 89 } 90 return 0; 91 } 92 93
