If an asymmmetric hunk starts at a line > 1, it is not from the start of the file

4 files changed, 63 insertions, 19 deletions

diff --git a/ChangeLog b/ChangeLog
index 073d64e..d78a14e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -19,11 +19,15 @@
 	ed related tests if we don't have it.
 	* tests/merge: Use sed instead of ed: sed is more readily available.
 
+	* patch.c (locate_hunk): If a hunk starts at a line > 1, it obviously
+	is not from the start of the file.
+	* tests/asymmetric-hunks: Add tests for all possible cases.
+
 2009-04-02  Andreas Gruenbacher  <agruen@suse.de>
 
 	* patch.c (locate_hunk): Revert the assymmetric hunk fix from
 	2009-03-29.  Instead, allow such hunks to apply only when no
-	more context remains (and the hunk has become symmetric).
+	more context remains.
 
 	* patch.c (main): Restructure to get rid of some code duplication.
 	(copy_till, similar): Export these functions.
diff --git a/NEWS b/NEWS
index 289f4ca..8874d97 100644
--- a/NEWS
+++ b/NEWS
@@ -44,10 +44,11 @@
 * Reject more malformed normal format commands and check for trailing
   garbage.  Recognize ed commands without addresses.
 * As seemingly originally intended, patch will assume that hunks with fewer
-  lines of prefix than suffix context must apply at the beginning of the
-  file, while hunks with fewer lines of suffix context must apply at the end
-  of the file.  If a high-enough fuzz factor is allowed to strip off all
-  context (which is not the default), such hunks can also apply within a file.
+  lines of prefix than suffix context which start at line 1 must apply at the
+  beginning of the file, while hunks with fewer lines of suffix context must
+  apply at the end of the file.  If a high-enough fuzz factor is allowed to
+  strip off all context (which is not the default), such hunks can also apply
+  within a file.
 * Handle missing timestamps better.
 * Various bug fixes.
 
diff --git a/patch.c b/patch.c
index 70a4788..099d15f 100644
--- a/patch.c
+++ b/patch.c
@@ -904,10 +904,8 @@ locate_hunk (LINENUM fuzz)
     LINENUM pat_lines = pch_ptrn_lines();
     LINENUM prefix_context = pch_prefix_context ();
     LINENUM suffix_context = pch_suffix_context ();
-    LINENUM context = (prefix_context < suffix_context
-		       ? suffix_context : prefix_context);
-    LINENUM prefix_fuzz = fuzz + prefix_context - context;
-    LINENUM suffix_fuzz = fuzz + suffix_context - context;
+    LINENUM prefix_fuzz = (prefix_context < fuzz ? prefix_context : fuzz);
+    LINENUM suffix_fuzz = (suffix_context < fuzz ? suffix_context : fuzz);
     LINENUM max_where = input_lines - (pat_lines - suffix_fuzz) + 1;
     LINENUM min_where = last_frozen_line + 1 - (prefix_context - prefix_fuzz);
     LINENUM max_pos_offset = max_where - first_guess;
@@ -922,7 +920,8 @@ locate_hunk (LINENUM fuzz)
     if (first_guess <= max_neg_offset)
 	max_neg_offset = first_guess - 1;
 
-    if (prefix_context < suffix_context && fuzz < suffix_context)
+    if (prefix_context < suffix_context && fuzz < suffix_context
+	&& pch_first () <= 1)
       {
 	/* Can only match start of file.  */
 
diff --git a/tests/asymmetric-hunks b/tests/asymmetric-hunks
index ff657c1..83fb06d 100644
--- a/tests/asymmetric-hunks
+++ b/tests/asymmetric-hunks
@@ -13,7 +13,35 @@ use_tmpdir
 
 # ==============================================================
 
-# Bug #25833: Patch fails to correctly apply hunks with asymmetric context
+# Starts at a line <= 1 and prefix context < suffix context: start of file
+# until all context has been stripped.
+
+cat > a.diff <<EOF
+--- a
++++ a
+@@ -1,3 +1,4 @@
+ 2
++2a
+ 3
+ 4
+EOF
+
+seq 1 5 > a
+
+check 'patch < a.diff' <<EOF
+patching file a
+Hunk #1 succeeded at 1 with fuzz 2.
+EOF
+
+seq 2 5 > a
+
+check 'patch < a.diff' <<EOF
+patching file a
+EOF
+
+# ==============================================================
+
+# Starts at a line > 1: anywhere in the file
 
 cat > a.diff <<EOF
 --- a
@@ -25,18 +53,30 @@ cat > a.diff <<EOF
  4
 EOF
 
+# ==============================================================
+
+# Prefix context > suffix context: en dof file until all context has been
+# stripped.
+
 seq 1 5 > a
 
 check 'patch < a.diff' <<EOF
 patching file a
-Hunk #1 succeeded at 2 with fuzz 2.
 EOF
 
-check 'cat a' <<EOF
-1
-2
-2a
-3
-4
-5
+cat > a.diff <<EOF
+--- a
++++ a
+@@ -2,3 +2,4 @@
+ 2
+ 3
++3a
+ 4
+EOF
+
+seq 1 5 > a
+
+check 'patch < a.diff' <<EOF
+patching file a
+Hunk #1 succeeded at 2 with fuzz 2.
 EOF