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