1 #include "SkStream.h"
2 #include <unistd.h>
3
4 //#define TRACE_FDSTREAM
5
SkFDStream(int fileDesc,bool closeWhenDone)6 SkFDStream::SkFDStream(int fileDesc, bool closeWhenDone)
7 : fFD(fileDesc), fCloseWhenDone(closeWhenDone) {
8 }
9
~SkFDStream()10 SkFDStream::~SkFDStream() {
11 if (fFD >= 0 && fCloseWhenDone) {
12 ::close(fFD);
13 }
14 }
15
rewind()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
read(void * buffer,size_t size)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