Index: tools/hook-scripts/commit-email.pl.in
===================================================================
--- tools/hook-scripts/commit-email.pl.in	(revision 12754)
+++ tools/hook-scripts/commit-email.pl.in	(working copy)
@@ -57,6 +57,9 @@
 # $no_diff_added to 1.
 my $no_diff_added = 0;
 
+# This controls the size of the commit email.
+my $max_email_body_size = 1_000_000;   # characters
+
 # Since the path to svnlook depends upon the local installation
 # preferences, check that the required programs exist to insure that
 # the administrator has set up the script properly.
@@ -368,6 +371,7 @@
 push(@body, @log);
 push(@body, "\n");
 push(@body, map { /[\r\n]+$/ ? $_ : "$_\n" } @difflines);
+&check_truncate (\@body, $max_email_body_size);
 
 # Go through each project and see if there are any matches for this
 # project.  If so, send the log out.
@@ -598,3 +602,22 @@
       return @output;
     }
 }
+
+# This truncates @{$r_array} if the cumulative length of strings in
+# @{$r_array} exceeds $max_size. The array is truncated at the line
+# whose string length would cause this to happen.
+sub check_truncate
+{
+  my ($r_array, $max_size) = @_;
+
+  for (my ($line, $size) = (0, 0); $line <= $#{$r_array}; $line++)
+    {
+      if (($size + length $r_array->[$line]) > $max_size)
+        {
+          splice(@{$r_array}, $line, 0,
+                 "[truncated - reached $max_size ...]\n");
+          last;
+        }
+      $size += length($r_array->[$line]);
+    }
+}