diff: exclude D_EMPTY code if there is no support for -r

function                                             old     new   delta
diffreg                                             1808    1825     +17
files_differ                                         189     166     -23

1 files changed, 22 insertions, 16 deletions

diff --git a/editors/diff.c b/editors/diff.c
index 27c8365cc..08729177c 100644
--- a/editors/diff.c
+++ b/editors/diff.c
@@ -22,9 +22,13 @@
 /*
  * Output flags
  */
-#define D_HEADER        1       /* Print a header/footer between files */
-#define D_EMPTY1        2       /* Treat first file as empty (/dev/null) */
-#define D_EMPTY2        4       /* Treat second file as empty (/dev/null) */
+enum {
+        /* Print a header/footer between files */
+        /* D_HEADER = 1, - unused */
+        /* Treat file as empty (/dev/null) */
+        D_EMPTY1 = 2 * ENABLE_FEATURE_DIFF_DIR,
+        D_EMPTY2 = 4 * ENABLE_FEATURE_DIFF_DIR,
+};
 
 /*
  * Status values for print_status() and diffreg() return values
@@ -308,15 +312,11 @@ static char *make_temp(FILE *f, struct stat *sb)
  * Check to see if the given files differ.
  * Returns 0 if they are the same, 1 if different, and -1 on error.
  */
-static NOINLINE int files_differ(FILE *f1, FILE *f2, int flags)
+static NOINLINE int files_differ(FILE *f1, FILE *f2)
 {
         size_t i, j;
 
         /* Prevent making copies for "/dev/null" (too common) */
-        tempname1 = tempname2 = NULL;
-        if (flags & (D_EMPTY1 | D_EMPTY2)) {
-                return 1;
-        }
         /* Deal with input from pipes etc */
         tempname1 = make_temp(f1, &stb1);
         tempname2 = make_temp(f2, &stb2);
@@ -1008,6 +1008,7 @@ static unsigned diffreg(char *file1, char *file2, int flags)
 
         anychange = 0;
         context_vec_ptr = context_vec_start - 1;
+        tempname1 = tempname2 = NULL;
 
         /* Is any of them a directory? Then it's simple */
         if (S_ISDIR(stb1.st_mode) != S_ISDIR(stb2.st_mode))
@@ -1025,13 +1026,18 @@ static unsigned diffreg(char *file1, char *file2, int flags)
         else
                 f2 = xfopen_stdin(file2);
 
-        /* Quick check whether they are different */
-        /* NB: copies non-REG files to tempfiles and fills tempname1/2 */
-        i = files_differ(f1, f2, flags);
-        if (i != 1) { /* not different? */
-                if (i != 0) /* error? */
-                        exit_status |= 2;
-                goto closem;
+        /* NB: if D_EMPTY1/2 is set, other file is always a regular file,
+         * not pipe/fifo/chardev/etc - D_EMPTY is used by "diff -r" only,
+         * and it never diffs non-ordinary files in subdirs. */
+        if (!(flags & (D_EMPTY1 | D_EMPTY2))) {
+                /* Quick check whether they are different */
+                /* NB: copies non-REG files to tempfiles and fills tempname1/2 */
+                i = files_differ(f1, f2);
+                if (i != 1) { /* not different? */
+                        if (i != 0) /* error? */
+                                exit_status |= 2;
+                        goto closem;
+                }
         }
 
         if (!asciifile(f1) || !asciifile(f2)) {
@@ -1098,7 +1104,7 @@ static unsigned diffreg(char *file1, char *file2, int flags)
 #if ENABLE_FEATURE_DIFF_DIR
 static void do_diff(char *dir1, char *path1, char *dir2, char *path2)
 {
-        int flags = D_HEADER;
+        int flags = 0; /*D_HEADER;*/
         int val;
         char *fullpath1 = NULL; /* if -N */
         char *fullpath2 = NULL;