Christian Weisgerber <naddy@mips.inka.de> wrote:
> Omar Polo:
> 
> > The last patch from Mark reminded me that I thought some time ago to add
> > a "-w" flag for got patch to ignore white spaces.  It's conceptually
> > similar to patch(1) -l/--ignore-whitespace or git-apply(1)
> > --ignore-whitespace.
> > 
> > The diff does exactly what one would expect.
> 
> Well, I'm dense.  What does "ignore whitespace" mean exactly?

you're not dense.  I should have included more context, sorry.

> Note that diff(1) has two ways to do this, -b and -w.

TIL about -b!

> If I understand linecmp() correctly, it's like diff -w?
> 
> Meanwhile patch -l seems to be more like diff -b?

the documentation of patch -l says that:

: Any sequence of whitespace in the pattern line will match any sequence
: in the input file.  Normal characters must still match exactly

This is implemented at the end of usr.bin/patch/patch.c in similar(),
which I assume it's fundamentally equal to my linecmp.  So, I think
we're following the same behavior of patch -l here,.  (which is
conceptually the same as diff -w.)

However, this got me thinking: maybe ignoring _every_ whitespace is too
lax?  What about ignoring only the leading and trailing ones?  Regress
passes and the mangled patch sent by Mark still applies.

(the diff cheats a bit, but we're only interested in if the lines are
"equal" or not, we don't use it for ordering.)

diff /home/op/w/got
commit - 4d5ee9564a9e46a1f634f619833c62f636cfbdc1
path + /home/op/w/got
blob - f12c747f214e8e4ae165a7c3b1b15212bfdfa531
file + lib/patch.c
--- lib/patch.c
+++ lib/patch.c
@@ -414,16 +414,20 @@ linecmp(const char *a, const char *b, int *mangled)
 		return c;
 
 	*mangled = 1;
-	for (;;) {
-		while (isspace(*a))
-			a++;
-		while (isspace(*b))
-			b++;
-		if (*a == '\0' || *b == '\0' || *a != *b)
-			break;
+
+	while (isspace(*a))
+		a++;
+	while (isspace(*b))
+		b++;
+
+	while (*a != '\0' && *a == *b)
 		a++, b++;
-	}
 
+	while (isspace(*a))
+		a++;
+	while (isspace(*b))
+		b++;
+
 	return *a - *b;
 }