Don't require traditional patch header after "git --diff"

Reported by Tim Waugh <twaugh@redhat.com>.
* src/pch.c (intuit_diff_type): Don't require a traditional patch header
("--- old\n+++ new/n") after a "git --diff" header; the "git --diff" header
gives us enough information for being able to process subsequent hunks.  This
deals with corrupted patches more gracefully.
* tests/corrupt-patch: New test case.
* tests/Makefile.am (TESTS): Add test case.

3 files changed, 35 insertions, 0 deletions

diff --git a/src/pch.c b/src/pch.c
index 9d74471..84adba1 100644
--- a/src/pch.c
+++ b/src/pch.c
@@ -622,6 +622,7 @@ intuit_diff_type (bool need_header, mode_t *p_file_type)
 		  p_name[i] = 0;
 		}
 	    p_git_diff = true;
+	    need_header = false;
 	  }
 	else if (p_git_diff && strnEQ (s, "index ", 6))
 	  {
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 91c9dce..a3ef97a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -23,6 +23,7 @@ TESTS = \
 	bad-usage \
 	concat-git-diff \
 	copy-rename \
+	corrupt-patch \
 	corrupt-reject-files \
 	create-delete \
 	create-directory \
diff --git a/tests/corrupt-patch b/tests/corrupt-patch
new file mode 100644
index 0000000..4f8e121
--- /dev/null
+++ b/tests/corrupt-patch
@@ -0,0 +1,33 @@
+# Copyright (C) 2015 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+# Patch missing the traditional "--- old\n+++ new\n" header
+
+cat > test.diff <<EOF
+diff --git a/test b/test
+index 8e139fc..4c03766 100644
+@@ -1 +1 @@
+-a
++b
+EOF
+
+echo a > test
+
+check 'patch -p1 -i test.diff' <<EOF
+patching file test
+EOF
+
+check 'cat test' <<EOF
+b
+EOF