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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, actua
l); | |
77 #endif | |
78 actual = 0; | |
79 } | |
80 return actual; | |
81 } | |
82 } | |
83 return 0; | |
84 } | |
85 | |
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