win32: override `fspathcmp()` with a directory separator-aware version

On Windows, the backslash is the directory separator, even if the
forward slash can be used, too, at least since Windows NT.

This means that the paths `a/b` and `a\b` are equivalent, and
`fspathcmp()` needs to be made aware of that fact.

Note that we have to override both `fspathcmp()` and `fspathncmp()`, and
the former cannot be a mere pre-processor constant that transforms calls
to `fspathcmp(a, b)` into `fspathncmp(a, b, (size_t)-1)` because the
function `report_collided_checkout()` in `unpack-trees.c` wants to
assign `list.cmp = fspathcmp`.

Also note that `fspatheq()` does _not_ need to be overridden because it
calls `fspathcmp()` internally.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/compat/win32/path-utils.c b/compat/win32/path-utils.c
index ebf2f12eb6..b658ca3f81 100644
--- a/compat/win32/path-utils.c
+++ b/compat/win32/path-utils.c
@@ -1,4 +1,5 @@
 #include "../../git-compat-util.h"
+#include "../../environment.h"
 
 int win32_has_dos_drive_prefix(const char *path)
 {
@@ -50,3 +51,39 @@ int win32_offset_1st_component(const char *path)
 
 	return pos + is_dir_sep(*pos) - path;
 }
+
+int win32_fspathncmp(const char *a, const char *b, size_t count)
+{
+	int diff;
+
+	for (;;) {
+		if (!count--)
+			return 0;
+		if (!*a)
+			return *b ? -1 : 0;
+		if (!*b)
+			return +1;
+
+		if (is_dir_sep(*a)) {
+			if (!is_dir_sep(*b))
+				return -1;
+			a++;
+			b++;
+			continue;
+		} else if (is_dir_sep(*b))
+			return +1;
+
+		diff = ignore_case ?
+			(unsigned char)tolower(*a) - (int)(unsigned char)tolower(*b) :
+			(unsigned char)*a - (int)(unsigned char)*b;
+		if (diff)
+			return diff;
+		a++;
+		b++;
+	}
+}
+
+int win32_fspathcmp(const char *a, const char *b)
+{
+	return win32_fspathncmp(a, b, (size_t)-1);
+}