commit-msg: Don't create message with only Change-Id

If a user aborts a commit, the commit-msg hook is still called,
but with an empty file.  We need to leave the empty file alone.

Change-Id: I13766135dac267823cb08ab76f67d2000ba2d1ce
Signed-off-by: Shawn O. Pearce <sop@google.com>

1 files changed, 19 insertions, 6 deletions

diff --git a/hooks/commit-msg b/hooks/commit-msg
index 5b1fe3ae..fd76c074 100755
--- a/hooks/commit-msg
+++ b/hooks/commit-msg
@@ -1,5 +1,5 @@
 #!/bin/sh
-# From Gerrit Code Review v2.0.18-100-g98fc90a
+# From Gerrit Code Review v2.0.19.1-4-g21d307b
 #
 # Part of Gerrit Code Review (http://code.google.com/p/gerrit/)
 #
@@ -23,21 +23,34 @@ MSG="$1"
 # Check for, and add if missing, a unique Change-Id
 #
 add_ChangeId() {
-        if grep '^Change-Id: ' "$MSG" >/dev/null
+        clean_message=$(sed -e '
+                /^diff --git a\/.*/{
+                        s///
+                        q
+                }
+                /^Signed-off-by:/d
+                /^#/d
+        ' "$MSG" | git stripspace)
+        if test -z "$clean_message"
+        then
+                return
+        fi
+
+        if grep -i '^Change-Id:' "$MSG" >/dev/null
         then
                 return
         fi
 
         id=$(_gen_ChangeId)
-        out="$MSG.new"
-        ftt="$MSG.footers"
+        out="$MSG.OUT"
+        ftt="$MSG.FTT"
         sed -e  '2,${
                         /^[A-Za-z][A-Za-z0-9-]*: /,$d
                 }' <"$MSG" >"$out"
         sed -ne '2,${
                         /^[A-Za-z][A-Za-z0-9-]*: /,$p
                 }' <"$MSG" >"$ftt"
-        if ! [ -s "$ftt" ]
+        if ! test -s "$ftt"
         then
                 echo >>"$out"
         fi
@@ -55,7 +68,7 @@ _gen_ChangeIdInput() {
         echo "author $(git var GIT_AUTHOR_IDENT)"
         echo "committer $(git var GIT_COMMITTER_IDENT)"
         echo
-        cat "$MSG"
+        printf '%s' "$clean_message"
 }
 _gen_ChangeId() {
         _gen_ChangeIdInput |