apply --whitespace fixes and enhancements.

In addition to fixing obvious command line parsing bugs in the
previous round, this changes the following:

 * Adds "--whitespace=strip".  This applies after stripping the
   new trailing whitespaces introduced to the patch.

 * The output error message format is changed to say
   "patch-filename:linenumber:contents of the line".  This makes
   it similar to typical compiler error message format, and
   helps C-x ` (next-error) in Emacs compilation buffer.

 * --whitespace=error and --whitespace=warn do not stop at the
   first error.  We might want to limit the output to say first
   20 such lines to prevent cluttering, but on the other hand if
   you are willing to hand-fix after inspecting them, getting
   everything with a single run might be easier to work with.
   After all, somebody has to do the clean-up work somewhere.

Signed-off-by: Junio C Hamano <junkio@cox.net>

apply.c

@@ -37,8 +37,11 @@ static const char apply_usage[] =
 static enum whitespace_eol {
 	nowarn,
 	warn_on_whitespace,
-	error_on_whitespace
+	error_on_whitespace,
+	strip_and_apply,
 } new_whitespace = nowarn;
+static int whitespace_error = 0;
+static const char *patch_input_file = NULL;
 
 /*
  * For "diff-stat" like behaviour, we keep track of the biggest change
@@ -823,19 +826,17 @@ static int parse_fragment(char *line, unsigned long size, struct patch *patch, s
 		case '+':
 			/*
 			 * We know len is at least two, since we have a '+' and
-			 * we checked that the last character was a '\n' above
+			 * we checked that the last character was a '\n' above.
+			 * That is, an addition of an empty line would check
+			 * the '+' here.  Sneaky...
 			 */
-			if (isspace(line[len-2])) {
-				switch (new_whitespace) {
-				case nowarn:
-					break;
-				case warn_on_whitespace:
-					new_whitespace = nowarn;	/* Just once */
-					error("Added whitespace at end of line at line %d", linenr);
-					break;
-				case error_on_whitespace:
-					die("Added whitespace at end of line at line %d", linenr);
-				}
+			if ((new_whitespace != nowarn) &&
+			    isspace(line[len-2])) {
+				fprintf(stderr, "Added whitespace\n");
+				fprintf(stderr, "%s:%d:%.*s\n",
+					patch_input_file,
+					linenr, len-2, line+1);
+				whitespace_error = 1;
 			}
 			added++;
 			newlines--;
@@ -1114,6 +1115,27 @@ struct buffer_desc {
 	unsigned long alloc;
 };
 
+static int apply_line(char *output, const char *patch, int plen)
+{
+	/* plen is number of bytes to be copied from patch,
+	 * starting at patch+1 (patch[0] is '+').  Typically
+	 * patch[plen] is '\n'.
+	 */
+	int add_nl_to_tail = 0;
+	if ((new_whitespace == strip_and_apply) &&
+	    1 < plen && isspace(patch[plen-1])) {
+		if (patch[plen] == '\n')
+			add_nl_to_tail = 1;
+		plen--;
+		while (0 < plen && isspace(patch[plen]))
+			plen--;
+	}
+	memcpy(output, patch + 1, plen);
+	if (add_nl_to_tail)
+		output[plen++] = '\n';
+	return plen;
+}
+
 static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag)
 {
 	char *buf = desc->buffer;
@@ -1149,10 +1171,9 @@ static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag)
 				break;
 		/* Fall-through for ' ' */
 		case '+':
-			if (*patch != '+' || !no_add) {
-				memcpy(new + newsize, patch + 1, plen);
-				newsize += plen;
-			}
+			if (*patch != '+' || !no_add)
+				newsize += apply_line(new + newsize, patch,
+						      plen);
 			break;
 		case '@': case '\\':
 			/* Ignore it, we already handled it */
@@ -1713,7 +1734,7 @@ static int use_patch(struct patch *p)
 	return 1;
 }
 
-static int apply_patch(int fd)
+static int apply_patch(int fd, const char *filename)
 {
 	int newfd;
 	unsigned long offset, size;
@@ -1721,6 +1742,7 @@ static int apply_patch(int fd)
 	struct patch *list = NULL, **listp = &list;
 	int skipped_patch = 0;
 
+	patch_input_file = filename;
 	if (!buffer)
 		return -1;
 	offset = 0;
@@ -1747,6 +1769,9 @@ static int apply_patch(int fd)
 	}
 
 	newfd = -1;
+	if (whitespace_error && (new_whitespace == error_on_whitespace))
+		apply = 0;
+
 	write_index = check_index && apply;
 	if (write_index)
 		newfd = hold_index_file_for_update(&cache_file, get_index_file());
@@ -1793,7 +1818,7 @@ int main(int argc, char **argv)
 		int fd;
 
 		if (!strcmp(arg, "-")) {
-			apply_patch(0);
+			apply_patch(0, "<stdin>");
 			read_stdin = 0;
 			continue;
 		}
@@ -1854,14 +1879,18 @@ int main(int argc, char **argv)
 			continue;
 		}
 		if (!strncmp(arg, "--whitespace=", 13)) {
-			if (strcmp(arg+13, "warn")) {
+			if (!strcmp(arg+13, "warn")) {
 				new_whitespace = warn_on_whitespace;
 				continue;
 			}
-			if (strcmp(arg+13, "error")) {
+			if (!strcmp(arg+13, "error")) {
 				new_whitespace = error_on_whitespace;
 				continue;
 			}
+			if (!strcmp(arg+13, "strip")) {
+				new_whitespace = strip_and_apply;
+				continue;
+			}
 			die("unrecognixed whitespace option '%s'", arg+13);
 		}
 
@@ -1877,10 +1906,12 @@ int main(int argc, char **argv)
 		if (fd < 0)
 			usage(apply_usage);
 		read_stdin = 0;
-		apply_patch(fd);
+		apply_patch(fd, arg);
 		close(fd);
 	}
 	if (read_stdin)
-		apply_patch(0);
+		apply_patch(0, "<stdin>");
+	if (whitespace_error && new_whitespace == error_on_whitespace)
+		return 1;
 	return 0;
 }