reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 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 | |