From 19947785bf0837edceacfce3fa643fa6e28fcd84 Mon Sep 17 00:00:00 2001
From: Andreas Gruenbacher <agruen@suse.de>
Date: Wed, 25 Mar 2009 23:03:42 +0100
Subject: [PATCH] When applying an empty patch to a file and -o is given, copy
 the input file to the output file

---
 ChangeLog              |  4 ++++
 patch.c                | 13 ++++++++++---
 tests/unmodified-files | 21 +++++++++++++++++++++
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 2c9c031..2c0aaea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -20,6 +20,10 @@
 	* tests/unmodified-files: New test case.
 	* Makefile.in (TESTS): Add test case.
 
+	* patch.c (main): New apply_empty_patch variable. When applying an
+	empty patch to a file and -o is given, copy the input file to the
+	output file.
+
 2009-03-24  Andreas Gruenbacher  <agruen@suse.de>
 
 	* patch.c (abort_hunk_unified, abort_hunk_context): Preserve
diff --git a/patch.c b/patch.c
index 24a4665..b18f5bc 100644
--- a/patch.c
+++ b/patch.c
@@ -123,6 +123,7 @@ main (int argc, char **argv)
     struct stat outst;
     char numbuf[LINENUM_LENGTH_BOUND + 1];
     bool written_to_rejname = false;
+    bool apply_empty_patch = false;
 
     exit_failure = 2;
     program_name = argv[0];
@@ -178,10 +179,17 @@ main (int argc, char **argv)
     /* Make sure we clean up in case of disaster.  */
     set_signals (false);
 
+    if (inname && outfile)
+      {
+	apply_empty_patch = true;
+	inerrno = -1;
+      }
     for (
 	open_patch_file (patchname);
-	there_is_another_patch (! (inname || posixly_correct));
-	reinitialize_almost_everything()
+	there_is_another_patch (! (inname || posixly_correct))
+	  || apply_empty_patch;
+	reinitialize_almost_everything(),
+	  apply_empty_patch = false
     ) {					/* for each patch in patch file */
       int hunk = 0;
       int failed = 0;
@@ -343,7 +351,6 @@ main (int argc, char **argv)
 	      }
 
 	    /* Finish spewing out the new file.  */
-	    assert (hunk);
 	    if (! spew_output (&outstate, &outst))
 	      {
 		say ("Skipping patch.\n");
diff --git a/tests/unmodified-files b/tests/unmodified-files
index ae71d3e..7e0f109 100644
--- a/tests/unmodified-files
+++ b/tests/unmodified-files
@@ -37,3 +37,24 @@ Status: 1
 EOF
 
 ncheck 'test a -ef a.first'
+
+# ==============================================================
+
+# When applying an empty patch to a file with -o, copy the input file.
+
+cat > a.diff <<EOF
+EOF
+
+echo three > a
+
+check 'patch -o b a < a.diff' <<EOF
+patching file a
+EOF
+
+check 'cat b' <<EOF
+three
+EOF
+
+check 'patch -b -o b a < a.diff' <<EOF
+patching file a
+EOF