move SkFDStream out of images into core

git-svn-id: http://skia.googlecode.com/svn/trunk@7846 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 91 insertions, 0 deletions

diff --git a/src/core/SkFDStream.cpp b/src/core/SkFDStream.cpp
new file mode 100644
index 0000000000..d38813c54d
--- /dev/null
+++ b/src/core/SkFDStream.cpp
@@ -0,0 +1,91 @@
+
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SkStream.h"
+#include <unistd.h>
+
+//#define TRACE_FDSTREAM
+
+SkFDStream::SkFDStream(int fileDesc, bool closeWhenDone)
+    : fFD(fileDesc), fCloseWhenDone(closeWhenDone) {
+}
+
+SkFDStream::~SkFDStream() {
+    if (fFD >= 0 && fCloseWhenDone) {
+        ::close(fFD);
+    }
+}
+
+bool SkFDStream::rewind() {
+    if (fFD >= 0) {
+        off_t value = ::lseek(fFD, 0, SEEK_SET);
+#ifdef TRACE_FDSTREAM
+        if (value) {
+            SkDebugf("xxxxxxxxxxxxxx rewind failed %d\n", value);
+        }
+#endif
+        return value == 0;
+    }
+    return false;
+}
+
+size_t SkFDStream::read(void* buffer, size_t size) {
+    if (fFD >= 0) {
+        if (buffer == NULL && size == 0) {  // request total size
+            off_t curr = ::lseek(fFD, 0, SEEK_CUR);
+            if (curr < 0) {
+#ifdef TRACE_FDSTREAM
+                SkDebugf("xxxxxxxxxxxxx lseek failed 0 CURR\n");
+#endif
+                return 0;   // error
+            }
+            off_t size = ::lseek(fFD, 0, SEEK_END);
+            if (size < 0) {
+#ifdef TRACE_FDSTREAM
+                SkDebugf("xxxxxxxxxxxxx lseek failed 0 END\n");
+#endif
+                size = 0;   // error
+            }
+            if (::lseek(fFD, curr, SEEK_SET) != curr) {
+                // can't restore, error
+#ifdef TRACE_FDSTREAM
+                SkDebugf("xxxxxxxxxxxxx lseek failed %d SET\n", curr);
+#endif
+                return 0;
+            }
+            return (size_t) size;
+        } else if (NULL == buffer) {        // skip
+            off_t oldCurr = ::lseek(fFD, 0, SEEK_CUR);
+            if (oldCurr < 0) {
+#ifdef TRACE_FDSTREAM
+                SkDebugf("xxxxxxxxxxxxx lseek1 failed %d CUR\n", oldCurr);
+#endif
+                return 0;   // error;
+            }
+            off_t newCurr = ::lseek(fFD, size, SEEK_CUR);
+            if (newCurr < 0) {
+#ifdef TRACE_FDSTREAM
+                SkDebugf("xxxxxxxxxxxxx lseek2 failed %d CUR\n", newCurr);
+#endif
+                return 0;   // error;
+            }
+            // return the actual amount we skipped
+            return (size_t) (newCurr - oldCurr);
+        } else {                            // read
+            ssize_t actual = ::read(fFD, buffer, size);
+            // our API can't return an error, so we return 0
+            if (actual < 0) {
+#ifdef TRACE_FDSTREAM
+                SkDebugf("xxxxxxxxxxxxx read failed %d actual %d\n", size, actual);
+#endif
+                actual = 0;
+            }
+            return actual;
+        }
+    }
+    return 0;
+}