*: 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

1 files changed, 19 insertions, 5 deletions

diff --git a/coreutils/tac.c b/coreutils/tac.c
index ddadcc7bc..af70f3092 100644
--- a/coreutils/tac.c
+++ b/coreutils/tac.c
@@ -22,7 +22,7 @@
 
 struct lstring {
         int size;
-        char buf[];
+        char buf[1];
 };
 
 int tac_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -34,7 +34,21 @@ int tac_main(int argc ATTRIBUTE_UNUSED, char **argv)
         llist_t *list = NULL;
         int retval = EXIT_SUCCESS;
 
+#if ENABLE_DESKTOP
+/* tac from coreutils 6.9 supports:
+       -b, --before
+              attach the separator before instead of after
+       -r, --regex
+              interpret the separator as a regular expression
+       -s, --separator=STRING
+              use STRING as the separator instead of newline
+We support none, but at least we will complain or handle "--":
+*/
+        getopt32(argv, "");
+        argv += optind;
+#else
         argv++;
+#endif
         if (!*argv)
                 *--argv = (char *)"-";
         /* We will read from last file to first */
@@ -48,6 +62,7 @@ int tac_main(int argc ATTRIBUTE_UNUSED, char **argv)
                 name--;
                 f = fopen_or_warn_stdin(*name);
                 if (f == NULL) {
+                        /* error message is printed by fopen_or_warn_stdin */
                         retval = EXIT_FAILURE;
                         continue;
                 }
@@ -61,7 +76,7 @@ int tac_main(int argc ATTRIBUTE_UNUSED, char **argv)
                                         line = xrealloc(line, i + 0x7f + sizeof(int) + 1);
                                 line->buf[i++] = ch;
                         }
-                        if ((ch == '\n' || ch == EOF) && i) {
+                        if (ch == '\n' || (ch == EOF && i != 0)) {
                                 line = xrealloc(line, i + sizeof(int));
                                 line->size = i;
                                 llist_add_to(&list, line);
@@ -69,9 +84,8 @@ int tac_main(int argc ATTRIBUTE_UNUSED, char **argv)
                                 i = 0;
                         }
                 } while (ch != EOF);
-                /* fgetc sets errno to ENOENT on EOF, but     */
-                /* fopen_or_warn_stdin would catch this error */
-                /* so we can filter it out here.              */
+                /* fgetc sets errno to ENOENT on EOF, we don't want
+                 * to warn on this non-error! */
                 if (errno && errno != ENOENT) {
                         bb_simple_perror_msg(*name);
                         retval = EXIT_FAILURE;