Consider md5sum no longer a usable hash

The md5sum hash is broken since some time and we should no longer
consider it a usable hash. Also update the tests to reflect this.

2 files changed, 12 insertions, 4 deletions

diff --git a/apt-pkg/contrib/hashes.cc b/apt-pkg/contrib/hashes.cc
index 4481321c4..41a0037cd 100644
--- a/apt-pkg/contrib/hashes.cc
+++ b/apt-pkg/contrib/hashes.cc
@@ -129,6 +129,13 @@ APT_PURE bool HashString::empty() const					/*{{{*/
    return (Type.empty() || Hash.empty());
 }
 									/*}}}*/
+APT_PURE bool HashString::usable() const				/*{{{*/
+{
+   return (
+      (Type != "Checksum-FileSize") &&
+      (Type != "MD5Sum")
+   );
+}
 std::string HashString::toStr() const					/*{{{*/
 {
    return Type + ":" + Hash;
@@ -151,10 +158,10 @@ bool HashStringList::usable() const					/*{{{*/
    std::string const forcedType = _config->Find("Acquire::ForceHash", "");
    if (forcedType.empty() == true)
    {
-      // FileSize alone isn't usable
-      for (std::vector<HashString>::const_iterator hs = list.begin(); hs != list.end(); ++hs)
-	 if (hs->HashType() != "Checksum-FileSize")
-	    return true;
+      // See if there is at least one usable hash
+      for (auto const &hs: list)
+         if (hs.usable())
+            return true;
       return false;
    }
    return find(forcedType) != NULL;
diff --git a/apt-pkg/contrib/hashes.h b/apt-pkg/contrib/hashes.h
index 0e6ff9ef1..74024befd 100644
--- a/apt-pkg/contrib/hashes.h
+++ b/apt-pkg/contrib/hashes.h
@@ -68,6 +68,7 @@ class HashString
    // helper
    std::string toStr() const;                    // convert to str as "type:hash"
    bool empty() const;
+   bool usable() const;
    bool operator==(HashString const &other) const;
    bool operator!=(HashString const &other) const;