*: shrink by using [f]open_or_warn_stdin where appropriate

function                                             old     new   delta
lsattr_main                                           62     143     +81
open_or_warn_stdin                                     -      36     +36
fclose_if_not_stdin                                   20      47     +27
xfopen_stdin                                           -      20     +20
tac_main                                             336     356     +20
cksum_main                                           249     259     +10
bb_argv_dash                                           -       8      +8
su_main                                              448     455      +7
cmp_main                                             630     633      +3
passwd_main                                         1072    1074      +2
uudecode_main                                        317     315      -2
text_yank                                            110     108      -2
handle_incoming_and_exit                            2653    2651      -2
flags                                                  5       1      -4
write_leases                                         235     230      -5
fopen_or_warn_stdin                                   48      42      -6
fold_main                                            648     642      -6
static.argv_dash                                       8       -      -8
sum_main                                             142     128     -14
tail_main                                           1237    1221     -16
sed_main                                             711     695     -16
cmp_xfopen_input                                      17       -     -17
bb_cat                                               113      96     -17
catv_main                                            328     306     -22
strings_main                                         457     434     -23
hash_file                                            298     274     -24
sum_file                                             353     325     -28
sort_main                                            904     859     -45
expand_main                                          736     686     -50
cut_main                                            1116    1065     -51
md5_sha1_sum_main                                    549     493     -56
lsattr_args                                           90       -     -90
read_stduu                                           408     255    -153
------------------------------------------------------------------------------
(add/remove: 3/3 grow/shrink: 7/20 up/down: 214/-657)        Total: -443 bytes
   text    data     bss     dec     hex filename
 797417     658    7428  805503   c4a7f busybox_old
 796973     658    7428  805059   c48c3 busybox_unstripped

3 files changed, 29 insertions, 8 deletions

diff --git a/libbb/fclose_nonstdin.c b/libbb/fclose_nonstdin.c
index 88e8474f2..768ee946d 100644
--- a/libbb/fclose_nonstdin.c
+++ b/libbb/fclose_nonstdin.c
@@ -16,8 +16,10 @@
 
 int fclose_if_not_stdin(FILE *f)
 {
-	if (f != stdin) {
-		return fclose(f);
-	}
-	return 0;
+	/* Some more paranoid applets want ferror() check too */
+	int r = ferror(f); /* NB: does NOT set errno! */
+	if (r) errno = EIO; /* so we'll help it */
+	if (f != stdin)
+		return (r | fclose(f)); /* fclose does set errno on error */
+	return r;
 }
diff --git a/libbb/getopt32.c b/libbb/getopt32.c
index f48ccaa6a..9e53dfd08 100644
--- a/libbb/getopt32.c
+++ b/libbb/getopt32.c
@@ -281,6 +281,8 @@ Special characters:
 
 /* Code here assumes that 'unsigned' is at least 32 bits wide */
 
+const char *const bb_argv_dash[] = { "-", NULL };
+
 const char *opt_complementary;
 
 enum {
diff --git a/libbb/wfopen_input.c b/libbb/wfopen_input.c
index 1b4928e1f..a7c1c32f5 100644
--- a/libbb/wfopen_input.c
+++ b/libbb/wfopen_input.c
@@ -10,8 +10,6 @@
 /* A number of applets need to open a file for reading, where the filename
  * is a command line arg.  Since often that arg is '-' (meaning stdin),
  * we avoid testing everywhere by consolidating things in this routine.
- *
- * Note: we also consider "" to mean stdin (for 'cmp' at least).
  */
 
 #include "libbb.h"
@@ -21,11 +19,30 @@ FILE *fopen_or_warn_stdin(const char *filename)
 	FILE *fp = stdin;
 
 	if (filename != bb_msg_standard_input
-	 && filename[0]
 	 && NOT_LONE_DASH(filename)
 	) {
 		fp = fopen_or_warn(filename, "r");
 	}
-
 	return fp;
 }
+
+FILE *xfopen_stdin(const char *filename)
+{
+	FILE *fp = fopen_or_warn_stdin(filename);
+	if (fp)
+		return fp;
+	xfunc_die();	/* We already output an error message. */
+}
+
+int open_or_warn_stdin(const char *filename)
+{
+	int fd = STDIN_FILENO;
+
+	if (filename != bb_msg_standard_input
+	 && NOT_LONE_DASH(filename)
+	) {
+		fd = open_or_warn(filename, O_RDONLY);
+	}
+
+	return fd;
+}