read_line_input: fix it to not do any fancy editing if echoing is disabled.

ash: make read handling both more correct and smaller

read_line_input                                     4037    4101     +64
input_backward                                       140     139      -1
readcmd                                             1079    1070      -9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/2 up/down: 65/-10)             Total: 54 bytes
   text    data     bss     dec     hex filename
 777575    1000    9532  788107   c068b busybox_old
 777629    1000    9532  788161   c06c1 busybox_unstripped

1 files changed, 24 insertions, 21 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 52cf41ab5..58527bf9b 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -11491,7 +11491,7 @@ readcmd(int argc, char **argv)
         int status;
         int i;
 #if ENABLE_ASH_READ_NCHARS
-        int nch_flag = 0;
+        int n_flag = 0;
         int nchars = 0;
         int silent = 0;
         struct termios tty, old_tty;
@@ -11521,10 +11521,10 @@ readcmd(int argc, char **argv)
                         break;
 #if ENABLE_ASH_READ_NCHARS
                 case 'n':
-                        nchars = strtol(optionarg, &p, 10);
-                        if (*p)
+                        nchars = bb_strtou(optionarg, NULL, 10);
+                        if (nchars < 0 || errno)
                                 ash_msg_and_raise_error("invalid count");
-                        nch_flag = (nchars > 0);
+                        n_flag = nchars; /* just a flag "nchars is nonzero" */
                         break;
                 case 's':
                         silent = 1;
@@ -11532,14 +11532,15 @@ readcmd(int argc, char **argv)
 #endif
 #if ENABLE_ASH_READ_TIMEOUT
                 case 't':
-                        ts.tv_sec = strtol(optionarg, &p, 10);
+                        ts.tv_sec = bb_strtou(optionarg, &p, 10);
                         ts.tv_usec = 0;
-                        if (*p == '.') {
+                        /* EINVAL means number is ok, but not terminated by NUL */
+                        if (*p == '.' && errno == EINVAL) {
                                 char *p2;
                                 if (*++p) {
                                         int scale;
-                                        ts.tv_usec = strtol(p, &p2, 10);
-                                        if (*p2)
+                                        ts.tv_usec = bb_strtou(p, &p2, 10);
+                                        if (errno)
                                                 ash_msg_and_raise_error("invalid timeout");
                                         scale = p2 - p;
                                         /* normalize to usec */
@@ -11548,11 +11549,12 @@ readcmd(int argc, char **argv)
                                         while (scale++ < 6)
                                                 ts.tv_usec *= 10;
                                 }
-                        } else if (*p) {
+                        } else if (ts.tv_sec < 0 || errno) {
                                 ash_msg_and_raise_error("invalid timeout");
                         }
-                        if ( ! ts.tv_sec && ! ts.tv_usec)
+                        if (!(ts.tv_sec | ts.tv_usec)) { /* both are 0? */
                                 ash_msg_and_raise_error("invalid timeout");
+                        }
                         break;
 #endif
                 case 'r':
@@ -11572,16 +11574,15 @@ readcmd(int argc, char **argv)
         if (ifs == NULL)
                 ifs = defifs;
 #if ENABLE_ASH_READ_NCHARS
-        if (nch_flag || silent) {
+        if (n_flag || silent) {
                 tcgetattr(0, &tty);
                 old_tty = tty;
-                if (nch_flag) {
+                if (n_flag) {
                         tty.c_lflag &= ~ICANON;
                         tty.c_cc[VMIN] = nchars;
                 }
                 if (silent) {
                         tty.c_lflag &= ~(ECHO|ECHOK|ECHONL);
-
                 }
                 tcsetattr(0, TCSANOW, &tty);
         }
@@ -11595,7 +11596,7 @@ readcmd(int argc, char **argv)
                 i = select(FD_SETSIZE, &set, NULL, NULL, &ts);
                 if (!i) {
 #if ENABLE_ASH_READ_NCHARS
-                        if (nch_flag)
+                        if (n_flag)
                                 tcsetattr(0, TCSANOW, &old_tty);
 #endif
                         return 1;
@@ -11606,12 +11607,7 @@ readcmd(int argc, char **argv)
         startword = 1;
         backslash = 0;
         STARTSTACKSTR(p);
-#if ENABLE_ASH_READ_NCHARS
-        while (!nch_flag || nchars--)
-#else
-        for (;;)
-#endif
-        {
+        do {
                 if (read(0, &c, 1) != 1) {
                         status = 1;
                         break;
@@ -11645,8 +11641,15 @@ readcmd(int argc, char **argv)
                         STPUTC(c, p);
                 }
         }
+/* end of do {} while: */
+#if ENABLE_ASH_READ_NCHARS
+        while (!n_flag || --nchars);
+#else
+        while (1);
+#endif
+
 #if ENABLE_ASH_READ_NCHARS
-        if (nch_flag || silent)
+        if (n_flag || silent)
                 tcsetattr(0, TCSANOW, &old_tty);
 #endif