Refactor catv. Move visible() from stty to libbb.

Fixes the following TODO:

  stty's visible() function and catv's guts are identical. Merge them into
  an appropriate libbb function.

Also makes catv behave exactly like coreutils' cat -v e.g. it'll print 'M-^I'
instead of 'M-   '.

function                                             old     new   delta
visible                                                -      70     +70
do_display                                           431     379     -52
catv_main                                            306     250     -56
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/2 up/down: 70/-108)           Total: -38 bytes

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

5 files changed, 51 insertions, 58 deletions

diff --git a/TODO b/TODO
index 8d0850cd7..d2a085ede 100644
--- a/TODO
+++ b/TODO
@@ -128,10 +128,6 @@ patch
   And while we're at it, a new patch filename quoting format is apparently
   coming soon:  http://marc.theaimsgroup.com/?l=git&m=112927316408690&w=2
 ---
-stty / catv
-  stty's visible() function and catv's guts are identical. Merge them into
-  an appropriate libbb function.
----
 tail
   ./busybox tail -f foo.c~ TODO
   should not print fmt=header_fmt for subsequent date >> TODO; i.e. only
diff --git a/coreutils/catv.c b/coreutils/catv.c
index 214b4311a..18b18104e 100644
--- a/coreutils/catv.c
+++ b/coreutils/catv.c
@@ -25,14 +25,20 @@ int catv_main(int argc UNUSED_PARAM, char **argv)
 {
         int retval = EXIT_SUCCESS;
         int fd;
-        unsigned flags;
+        unsigned opts;
+        int flags = 0;
 
-        flags = getopt32(argv, "etv");
+        opts = getopt32(argv, "etv");
 #define CATV_OPT_e (1<<0)
 #define CATV_OPT_t (1<<1)
 #define CATV_OPT_v (1<<2)
-        flags ^= CATV_OPT_v;
         argv += optind;
+        if (opts & (CATV_OPT_e | CATV_OPT_t))
+                opts &= ~CATV_OPT_v;
+        if (opts & CATV_OPT_e)
+                flags |= VISIBLE_ENDLINE;
+        if (opts & CATV_OPT_t)
+                flags |= VISIBLE_SHOW_TABS;
 
         /* Read from stdin if there's nothing else to do. */
         if (!argv[0])
@@ -50,29 +56,17 @@ int catv_main(int argc UNUSED_PARAM, char **argv)
                         res = read(fd, read_buf, COMMON_BUFSIZE);
                         if (res < 0)
                                 retval = EXIT_FAILURE;
-                        if (res < 1)
+                        if (res <= 0)
                                 break;
                         for (i = 0; i < res; i++) {
                                 unsigned char c = read_buf[i];
-
-                                if (c > 126 && (flags & CATV_OPT_v)) {
-                                        if (c == 127) {
-                                                printf("^?");
-                                                continue;
-                                        }
-                                        printf("M-");
-                                        c -= 128;
-                                }
-                                if (c < 32) {
-                                        if (c == 10) {
-                                                if (flags & CATV_OPT_e)
-                                                        bb_putchar('$');
-                                        } else if (flags & (c==9 ? CATV_OPT_t : CATV_OPT_v)) {
-                                                printf("^%c", c+'@');
-                                                continue;
-                                        }
+                                if (opts & CATV_OPT_v) {
+                                        putchar(c);
+                                } else {
+                                        char buf[sizeof("M-^c")];
+                                        visible(c, buf, flags);
+                                        fputs(buf, stdout);
                                 }
-                                bb_putchar(c);
                         }
                 }
                 if (ENABLE_FEATURE_CLEAN_UP && fd)
diff --git a/coreutils/stty.c b/coreutils/stty.c
index d1e74f437..378a848e7 100644
--- a/coreutils/stty.c
+++ b/coreutils/stty.c
@@ -781,36 +781,6 @@ struct globals {
         G.max_col = 80; \
 } while (0)
 
-
-/* Return a string that is the printable representation of character CH */
-/* Adapted from 'cat' by Torbjorn Granlund */
-static const char *visible(unsigned ch)
-{
-        char *bpout = G.buf;
-
-        if (ch == _POSIX_VDISABLE)
-                return "<undef>";
-
-        if (ch >= 128) {
-                ch -= 128;
-                *bpout++ = 'M';
-                *bpout++ = '-';
-        }
-
-        if (ch < 32) {
-                *bpout++ = '^';
-                *bpout++ = ch + 64;
-        } else if (ch < 127) {
-                *bpout++ = ch;
-        } else {
-                *bpout++ = '^';
-                *bpout++ = '?';
-        }
-
-        *bpout = '\0';
-        return G.buf;
-}
-
 static void set_speed_or_die(enum speed_setting type, const char *arg,
                                         struct termios *mode)
 {
@@ -1038,6 +1008,7 @@ static void do_display(const struct termios *mode, int all)
 #endif
 
         for (i = 0; i != CIDX_min; ++i) {
+                char ch;
                 /* If swtch is the same as susp, don't print both */
 #if VSWTCH == VSUSP
                 if (i == CIDX_swtch)
@@ -1051,8 +1022,12 @@ static void do_display(const struct termios *mode, int all)
                         continue;
                 }
 #endif
-                wrapf("%s = %s;", nth_string(control_name, i),
-                                visible(mode->c_cc[control_info[i].offset]));
+                ch = mode->c_cc[control_info[i].offset];
+                if (ch == _POSIX_VDISABLE)
+                        strcpy(G.buf, "<undef>");
+                else
+                        visible(ch, G.buf, 0);
+                wrapf("%s = %s;", nth_string(control_name, i), G.buf);
         }
 #if VEOF == VMIN
         if ((mode->c_lflag & ICANON) == 0)
diff --git a/include/libbb.h b/include/libbb.h
index 83e9b5fb9..0c3734cdb 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -678,6 +678,10 @@ const char* FAST_FUNC printable_string(uni_stat_t *stats, const char *str);
  * else it is printed as-is (except for ch = 0x9b) */
 enum { PRINTABLE_META = 0x100 };
 void fputc_printable(int ch, FILE *file) FAST_FUNC;
+/* Return a string that is the printable representation of character ch.
+ * Buffer must hold at least four characters. */
+enum { VISIBLE_SHOW_TABS = 1, VISIBLE_ENDLINE = 2 };
+void visible(unsigned ch, char *buf, int flags) FAST_FUNC;
 
 /* dmalloc will redefine these to it's own implementation. It is safe
  * to have the prototypes here unconditionally.  */
diff --git a/libbb/printable.c b/libbb/printable.c
index f6ada4904..9a423431e 100644
--- a/libbb/printable.c
+++ b/libbb/printable.c
@@ -32,3 +32,27 @@ void FAST_FUNC fputc_printable(int ch, FILE *file)
         }
         fputc(ch, file);
 }
+
+void FAST_FUNC visible(unsigned ch, char *buf, int flags)
+{
+        if (ch == '\t' && !(flags & VISIBLE_SHOW_TABS)) {
+                goto raw;
+        }
+        if (ch == '\n') {
+                if (flags & VISIBLE_ENDLINE)
+                        *buf++ = '$';
+        } else {
+                if (ch >= 128) {
+                        ch -= 128;
+                        *buf++ = 'M';
+                        *buf++ = '-';
+                }
+                if (ch < 32 || ch == 127) {
+                        *buf++ = '^';
+                        ch ^= 0x40;
+                }
+        }
+ raw:
+        *buf++ = ch;
+        *buf = '\0';
+}