Changes between Version 58 and Version 59 of HashSourceCodes

Timestamp:

Dec 15, 2014, 7:32:35 PM (9 years ago)

Author:

os

Comment:

--

HashSourceCodes

@@ -1877 +1877 @@
 echo "61f7751fc2a72bfb <- should be" 
 }}}
+
+=== GO ===
+https://github.com/oz/osdb/blob/6a89d7f831a6a3874260fe4677e546d551cad79d/osdb.go#L42
+{{{
+    import (
+        "bytes"
+        "encoding/binary"
+        "fmt"
+        "os"
+    )
+
+    const (
+        ChunkSize = 65536 // 64k
+    )
+
+    // Generate an OSDB hash for an *os.File.
+    func HashFile(file *os.File) (hash uint64, err error) {
+        fi, err := file.Stat()
+        if err != nil {
+            return
+        }
+        if fi.Size() < ChunkSize {
+            return 0, fmt.Errorf("File is too small")
+        }
+
+        // Read head and tail blocks.
+        buf := make([]byte, ChunkSize*2)
+        err = readChunk(file, 0, buf[:ChunkSize])
+        if err != nil {
+            return
+        }
+        err = readChunk(file, fi.Size()-ChunkSize, buf[ChunkSize:])
+        if err != nil {
+            return
+        }
+
+        // Convert to uint64, and sum.
+        var nums [(ChunkSize * 2) / 8]uint64
+        reader := bytes.NewReader(buf)
+        err = binary.Read(reader, binary.LittleEndian, &nums)
+        if err != nil {
+            return 0, err
+        }
+        for _, num := range nums {
+            hash += num
+        }
+
+        return hash + uint64(fi.Size()), nil
+    }
+
+    // Read a chunk of a file at `offset` so as to fill `buf`.
+    func readChunk(file *os.File, offset int64, buf []byte) (err error) {
+        n, err := file.ReadAt(buf, offset)
+        if err != nil {
+            return
+        }
+        if n != ChunkSize {
+            return fmt.Errorf("Invalid read %v", n)
+        }
+        return
+    }
+}}}