Re: [PATCH] git-am: Ignore whitespace before patches

Change git-am to ignore whitespace (as defined by sh's read) at the
beginning of patches.

Empty lines are wont to creep in at the beginning of patches, here's
an example from a raw Gmail attachment:

   20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
   20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 0a  |               .|
   52 65 74 75 72 6e 2d 50  61 74 68 3a 20 3c 61 76  |Return-Path: <av|

Whitespace is also likely to appear if the user copy/pastes the patch
around, e.g. via a pastebin, or any any number of other cases. This
harms nothing and makes git-am's detection more fault tolerant.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---
 git-am.sh     |   16 +++++++++++++++-
 t/t4150-am.sh |   30 ++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletions(-)

diff --git a/git-am.sh b/git-am.sh
index 1056075..1b4baa8 100755
--- a/git-am.sh
+++ b/git-am.sh

@@ -172,7 +172,21 @@ check_patch_format () {

       # otherwise, check the first few lines of the first patch to try
       # to detect its format
       {
-               read l1
+               while read -r line
+               do
+                       case "$line" in
+                               "")
+                                       # Just skip whitespace
+                                       continue
+                                       ;;
+                               *)
+                                       # First non-empty line
+                                       l1=$line
+                                       break
+                                       ;;
+                       esac
+               done
+
               read l2
               read l3
               case "$l1" in

diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index 810b04b..3d089de 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh

@@ -318,6 +318,36 @@ test_expect_success 'am without --committer-date-is-author-date' '

       test "$at" != "$ct"
 '

+test_expect_success 'am applying a patch that begins with an empty line' '
+       git checkout first &&
+       test_tick &&
+       echo > patch1-white &&
+       cat patch1 >> patch1-white &&
+       git am patch1-white &&
+       git cat-file commit HEAD | sed -e "/^\$/q" >head1 &&
+       at=$(sed -ne "/^author /s/.*> //p" head1) &&
+       ct=$(sed -ne "/^committer /s/.*> //p" head1) &&
+       test "$at" != "$ct"
+'
+
+test_expect_success 'am applying a patch that begins with many empty lines' '
+       git checkout first &&
+       test_tick &&
+       echo "   " > patch1-white2 &&
+       echo "  " >> patch1-white2 &&
+       echo " " >> patch1-white2 &&
+       echo "" >> patch1-white2 &&
+       echo " " >> patch1-white2 &&
+       echo "  " >> patch1-white2 &&
+       echo "   " >> patch1-white2 &&
+       cat patch1 >> patch1-white2 &&
+       git am patch1-white2 &&
+       git cat-file commit HEAD | sed -e "/^\$/q" >head1 &&
+       at=$(sed -ne "/^author /s/.*> //p" head1) &&
+       ct=$(sed -ne "/^committer /s/.*> //p" head1) &&
+       test "$at" != "$ct"
+'
+
 # This checks for +0000 because TZ is set to UTC and that should
 # show up when the current time is used. The date in message is set
 # by test_tick that uses -0700 timezone; if this feature does not
--
1.7.1.84.gd92f8