* Refactoring: hash class.

src/hash.cc

@@ -0,0 +1,87 @@
+extern "C" {
+#include "md5.h"
+}
+
+#include "hash.hh"
+#include <iostream>
+
+
+/* Create a zeroed hash object. */
+Hash::Hash()
+{
+    memset(hash, 0, sizeof(hash));
+}
+
+
+/* Check whether two hash are equal. */
+bool Hash::operator == (Hash & h2)
+{
+    for (unsigned int i = 0; i < hashSize; i++)
+        if (hash[i] != h2.hash[i]) return false;
+    return true;
+}
+
+
+/* Check whether two hash are not equal. */
+bool Hash::operator != (Hash & h2)
+{
+    return !(*this == h2);
+}
+
+
+/* Convert a hash code into a hexadecimal representation. */
+Hash::operator string() const
+{
+    ostringstream str;
+    for (unsigned int i = 0; i < hashSize; i++) {
+        str.fill('0');
+        str.width(2);
+        str << hex << (int) hash[i];
+    }
+    return str.str();
+}
+
+    
+/* Parse a hexadecimal representation of a hash code. */
+Hash parseHash(const string & s)
+{
+    Hash hash;
+    for (unsigned int i = 0; i < Hash::hashSize; i++) {
+        string s2(s, i * 2, 2);
+        if (!isxdigit(s2[0]) || !isxdigit(s2[1])) 
+            throw BadRefError("invalid hash: " + s);
+        istringstream str(s2);
+        int n;
+        str >> hex >> n;
+        hash.hash[i] = n;
+    }
+    return hash;
+}
+
+
+/* Verify that a reference is valid (that is, is a MD5 hash code). */
+bool isHash(const string & s)
+{
+    if (s.length() != 32) return false;
+    for (int i = 0; i < 32; i++) {
+        char c = s[i];
+        if (!((c >= '0' && c <= '9') ||
+              (c >= 'a' && c <= 'f')))
+            return false;
+    }
+    return true;
+}
+
+
+/* Compute the MD5 hash of a file. */
+Hash hashFile(const string & fileName)
+{
+    Hash hash;
+    FILE * file = fopen(fileName.c_str(), "rb");
+    if (!file)
+        throw Error("file `" + fileName + "' does not exist");
+    int err = md5_stream(file, hash.hash);
+    fclose(file);
+    if (err) throw Error("cannot hash file");
+    return hash;
+}