Adds HashFile(), a method that uses openssl to provide md5/sha1 sums of files. Much of the code was taken from tinderbox's implementation; openssl was chosen because it's just about guaranteed to exist on all the platforms we care about, and thus elimintes platform-specifics-parsing- and trying to figure out platform/which-binary-to-call-issues.

tools/release/MozBuild/Util.pm

@@ -90,8 +90,7 @@ sub RunShellCommand {
 ## it created in the pursuit of your request, and keeps its actual success 
 ## status in $@. 
 
-sub MkdirWithPath
-{
+sub MkdirWithPath {
     my %args = @_;
 
     my $dirToCreate = $args{'dir'};
@@ -108,4 +107,47 @@ sub MkdirWithPath
     return defined($@);
 }
 
+sub HashFile {
+   my %args = @_;
+   die "ASSERT: null file to hash\n" if (not defined($args{'file'}));
+
+   my $fileToHash = $args{'file'};
+   my $hashFunction = $args{'type'} || 'md5';
+   my $dumpOutput = $args{'output'} || 0;
+   my $ignoreErrors = $args{'ignoreErrors'} || 0;
+
+   die "ASSERT: unknown hashFunction; use 'md5' or 'sha1': $hashFunction\n" if 
+    ($hashFunction ne 'md5' && $hashFunction ne 'sha1');
+
+   if (not(-f $fileToHash) || not(-r $fileToHash)) {
+      if ($ignoreErrors) {
+         return '';
+      } else {
+         die "ASSERT: unusable/unreadable file to hash\n"; 
+      }
+   }
+
+   # We use openssl because that's pretty much guaranteed to be on all the
+   # platforms we want; md5sum and sha1sum aren't.
+   my $rv = RunShellCommand(command => "openssl dgst -$hashFunction " .
+                                       "\"$fileToHash\"",
+                            output => $dumpOutput);
+   
+   if ($rv->{'exitValue'} != 0) {
+      if ($ignoreErrors) {
+         return '';      
+      } else {
+         die "MozUtil::HashFile(): hash call failed: $rv->{'exitValue'}\n";
+      }
+   }
+
+   my $hashValue = $rv->{'output'};
+   chomp($hashValue);
+
+   # Expects input like MD5(mozconfig)= d7433cc4204b4f3c65d836fe483fa575
+   # Removes everything up to and including the "= "
+   $hashValue =~ s/^.+\s+(\w+)$/$1/;
+   return $hashValue;
+}
+
 1;