diff: improve --binary implementation

Commit 82f0d19b1 (diff: implement --binary flag) was both over-
complicated and incorrect.  If stdin was seekable it was left in
binary mode even if the --binary flag wasn't supplied.

Always open files in binary mode.  Only switch to text mode at the
last moment, if necessary.

Saves 48 bytes.

1 files changed, 7 insertions, 13 deletions

diff --git a/editors/diff.c b/editors/diff.c
index d91ecea51..b6716455f 100644
--- a/editors/diff.c
+++ b/editors/diff.c
@@ -718,6 +718,7 @@ static int diffreg(char *file[2])
 #if ENABLE_PLATFORM_MINGW32
         char *tmpfile[2] = { NULL, NULL };
         char *tmpdir;
+        const char *mode;
 #endif
 
         fp[0] = stdin;
@@ -726,12 +727,7 @@ static int diffreg(char *file[2])
                 int fd = STDIN_FILENO;
                 if (!LONE_DASH(file[i])) {
                         if (!(option_mask32 & FLAG(N))) {
-#if ENABLE_PLATFORM_MINGW32
-                                int flag = (option_mask32 & FLAG(binary)) ? 0 : _O_TEXT;
-                                fd = open_or_warn(file[i], O_RDONLY | flag);
-#else
                                 fd = open_or_warn(file[i], O_RDONLY);
-#endif
                                 if (fd == -1)
                                         goto out;
                         } else {
@@ -762,18 +758,16 @@ static int diffreg(char *file[2])
                                 xfunc_die();
                         if (fd != STDIN_FILENO)
                                 close(fd);
-#if ENABLE_PLATFORM_MINGW32
-                        if (!(option_mask32 & FLAG(binary))) {
-                                /* Close and reopen tmpfile to get text mode */
-                                close(fd_tmp);
-                                fd_tmp = xopen(tmpfile[i], O_RDONLY | _O_TEXT);
-                        }
-#endif
                         fd = fd_tmp;
                         xlseek(fd, 0, SEEK_SET);
                 }
 #if ENABLE_PLATFORM_MINGW32
-                fp[i] = fdopen(fd, (option_mask32 & FLAG(binary)) ? "r" : "rt");
+                mode = "r";
+                if (!(option_mask32 & FLAG(binary))) {
+                        _setmode(fd, _O_TEXT);
+                        mode = "rt";
+                }
+                fp[i] = fdopen(fd, mode);
 #else
                 fp[i] = fdopen(fd, "r");
 #endif