Improve handling of LF vs. CRLF line endings

* src/patch.c (check_line_endings): New function.
(main): When a hunk fails, report when the line endings differ between the
input file and the patch.
* src/pch.c (there_is_another_patch): When saying that we strip trailing CRs,
also say how to turn this off.
* tests/crlf-handling: Update changed messages.  Add test case that fails.

3 files changed, 47 insertions, 9 deletions

diff --git a/src/patch.c b/src/patch.c
index 8b2f8c0..97eea5b 100644
--- a/src/patch.c
+++ b/src/patch.c
@@ -38,6 +38,7 @@
 
 static FILE *create_output_file (char const *, int);
 static lin locate_hunk (lin);
+static bool check_line_endings (lin);
 static bool apply_hunk (struct outstate *, lin);
 static bool patch_match (lin, lin, lin, lin);
 static bool spew_output (struct outstate *, struct stat *);
@@ -445,9 +446,11 @@ main (int argc, char **argv)
 		failed++;
 		if (verbosity == VERBOSE ||
 		    (! skip_rest_of_patch && verbosity != SILENT))
-		  say ("Hunk #%d %s at %s.\n", hunk,
+		  say ("Hunk #%d %s at %s%s.\n", hunk,
 		       skip_rest_of_patch ? "ignored" : "FAILED",
-		       format_linenum (numbuf, newwhere));
+		       format_linenum (numbuf, newwhere),
+		       ! skip_rest_of_patch && check_line_endings (newwhere)
+			 ?  " (different line endings)" : "");
 	      }
 	    else if (! merge &&
 		     (verbosity == VERBOSE
@@ -1659,6 +1662,33 @@ patch_match (lin base, lin offset, lin prefix_fuzz, lin suffix_fuzz)
     return true;
 }
 
+/* Check if the line endings in the input file and in the patch differ. */
+
+static bool
+check_line_endings (lin where)
+{
+  char const *p;
+  size_t size;
+  bool input_crlf, patch_crlf;
+
+  p = pfetch (1);
+  size = pch_line_len (1);
+  if (! size)
+    return false;
+  patch_crlf = size >= 2 && p[size - 2] == '\r' && p[size - 1] == '\n';
+
+  if (! input_lines)
+    return false;
+  if (where > input_lines)
+    where = input_lines;
+  p = ifetch (where, false, &size);
+  if (! size)
+    return false;
+  input_crlf = size >= 2 && p[size - 2] == '\r' && p[size - 1] == '\n';
+
+  return patch_crlf != input_crlf;
+}
+
 /* Do two lines match with canonicalized white space? */
 
 bool
diff --git a/src/pch.c b/src/pch.c
index 3616bc8..75a642b 100644
--- a/src/pch.c
+++ b/src/pch.c
@@ -266,7 +266,7 @@ there_is_another_patch (bool need_header, mode_t *file_type)
 	  say ("(Patch is indented %lu space%s.)\n",
 	       (unsigned long int) p_indent, p_indent==1?"":"s");
 	if (p_strip_trailing_cr)
-	  say ("(Stripping trailing CRs from patch.)\n");
+	  say ("(Stripping trailing CRs from patch; use --binary to disable.)\n");
 	if (! inname)
 	  {
 	    char numbuf[LINENUM_LENGTH_BOUND + 1];
diff --git a/tests/crlf-handling b/tests/crlf-handling
index b86bf38..b704dc8 100644
--- a/tests/crlf-handling
+++ b/tests/crlf-handling
@@ -23,21 +23,21 @@ echo 1b > b
 diff a b | lf2crlf > ab.diff
 echo 1 > c
 check 'patch c < ab.diff' <<EOF
-(Stripping trailing CRs from patch.)
+(Stripping trailing CRs from patch; use --binary to disable.)
 patching file c
 EOF
 
 diff -c a b | lf2crlf > ab.diff
 echo 1 > c
 check 'patch c < ab.diff' <<EOF
-(Stripping trailing CRs from patch.)
+(Stripping trailing CRs from patch; use --binary to disable.)
 patching file c
 EOF
 
 diff -u a b | lf2crlf > ab.diff
 echo 1 > c
 check 'patch c < ab.diff' <<EOF
-(Stripping trailing CRs from patch.)
+(Stripping trailing CRs from patch; use --binary to disable.)
 patching file c
 EOF
 
@@ -109,8 +109,16 @@ echo 1b > b
 
 diff a b | lf2crlf > ab.diff
 cp a c
+
+check 'patch --binary c < ab.diff || echo status: $?' <<EOF
+patching file c
+Hunk #1 FAILED at 1 (different line endings).
+1 out of 1 hunk FAILED -- saving rejects to file c.rej
+status: 1
+EOF
+
 check 'patch c < ab.diff' <<EOF
-(Stripping trailing CRs from patch.)
+(Stripping trailing CRs from patch; use --binary to disable.)
 patching file c
 EOF
 
@@ -132,7 +140,7 @@ EOF
 diff -u a b | lf2crlf > ab.diff
 cp a c
 check 'patch c < ab.diff' <<EOF
-(Stripping trailing CRs from patch.)
+(Stripping trailing CRs from patch; use --binary to disable.)
 patching file c
 EOF
 
@@ -154,7 +162,7 @@ EOF
 diff -c a b | lf2crlf > ab.diff
 cp a c
 check 'patch c < ab.diff' <<EOF
-(Stripping trailing CRs from patch.)
+(Stripping trailing CRs from patch; use --binary to disable.)
 patching file c
 EOF