ash: better fix for ash -c 'echo 5&' and ash -c 'sleep 5&'

 with testcase

3 files changed, 56 insertions, 29 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 66bfa67ba..e1df89418 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -9079,8 +9079,6 @@ breakcmd(int argc UNUSED_PARAM, char **argv)
  * This implements the input routines used by the parser.
  */
 
-#define EOF_NLEFT -99           /* value of parsenleft when EOF pushed back */
-
 enum {
         INPUT_PUSH_FILE = 1,
         INPUT_NOFILE_OK = 2,
@@ -9121,7 +9119,6 @@ popstring(void)
 #endif
         parsenextc = sp->prevstring;
         parsenleft = sp->prevnleft;
-/*dprintf("*** calling popstring: restoring to '%s'\n", parsenextc);*/
         g_parsefile->strpush = sp->prev;
         if (sp != &(g_parsefile->basestrpush))
                 free(sp);
@@ -9137,7 +9134,7 @@ preadfd(void)
 
 #if ENABLE_FEATURE_EDITING
  retry:
-        if (!iflag || g_parsefile->fd)
+        if (!iflag || g_parsefile->fd != STDIN_FILENO)
                 nr = nonblock_safe_read(g_parsefile->fd, buf, BUFSIZ - 1);
         else {
 #if ENABLE_FEATURE_TAB_COMPLETION
@@ -9185,56 +9182,76 @@ preadfd(void)
  * Refill the input buffer and return the next input character:
  *
  * 1) If a string was pushed back on the input, pop it;
- * 2) If an EOF was pushed back (parsenleft == EOF_NLEFT) or we are reading
+ * 2) If an EOF was pushed back (parsenleft < -BIGNUM) or we are reading
  *    from a string so we can't refill the buffer, return EOF.
  * 3) If the is more stuff in this buffer, use it else call read to fill it.
  * 4) Process input up to the next newline, deleting nul characters.
  */
+//#define pgetc_debug(...) bb_error_msg(__VA_ARGS__)
+#define pgetc_debug(...) ((void)0)
 static int
 preadbuffer(void)
 {
         char *q;
         int more;
-        char savec;
 
         while (g_parsefile->strpush) {
 #if ENABLE_ASH_ALIAS
                 if (parsenleft == -1 && g_parsefile->strpush->ap
                  && parsenextc[-1] != ' ' && parsenextc[-1] != '\t'
                 ) {
+                        pgetc_debug("preadbuffer PEOA");
                         return PEOA;
                 }
 #endif
                 popstring();
+                /* try "pgetc" now: */
+                pgetc_debug("internal pgetc at %d:%p'%s'", parsenleft, parsenextc, parsenextc);
                 if (--parsenleft >= 0)
                         return signed_char2int(*parsenextc++);
         }
-        if (parsenleft == EOF_NLEFT || g_parsefile->buf == NULL)
+        /* on both branches above parsenleft < 0.
+         * "pgetc" needs refilling.
+         */
+
+        /* -90 is -BIGNUM. Below we use -99 to mark "EOF on read",
+         * pungetc() may decrement it a few times. -90 is enough.
+         */
+        if (parsenleft < -90 || g_parsefile->buf == NULL) {
+                pgetc_debug("preadbuffer PEOF1");
+                /* even in failure keep them in lock step,
+                 * for correct pungetc. */
+                parsenextc++;
                 return PEOF;
-        flush_stdout_stderr();
+        }
 
         more = parselleft;
         if (more <= 0) {
+                flush_stdout_stderr();
  again:
                 more = preadfd();
                 if (more <= 0) {
-                        parselleft = parsenleft = EOF_NLEFT;
+                        parselleft = parsenleft = -99;
+                        pgetc_debug("preadbuffer PEOF2");
+                        parsenextc++;
                         return PEOF;
                 }
         }
 
+        /* Find out where's the end of line.
+         * Set parsenleft/parselleft acordingly.
+         * NUL chars are deleted.
+         */
         q = parsenextc;
-
-        /* delete nul characters */
         for (;;) {
-                int c;
+                char c;
 
                 more--;
-                c = *q;
 
-                if (!c)
+                c = *q;
+                if (c == '\0') {
                         memmove(q, q + 1, more);
-                else {
+                } else {
                         q++;
                         if (c == '\n') {
                                 parsenleft = q - parsenextc - 1;
@@ -9251,22 +9268,23 @@ preadbuffer(void)
         }
         parselleft = more;
 
-        savec = *q;
-        *q = '\0';
-
         if (vflag) {
+                char save = *q;
+                *q = '\0';
                 out2str(parsenextc);
+                *q = save;
         }
 
-        *q = savec;
-
+        pgetc_debug("preadbuffer at %d:%p'%s'", parsenleft, parsenextc, parsenextc);
         return signed_char2int(*parsenextc++);
 }
 
 #define pgetc_as_macro() (--parsenleft >= 0 ? signed_char2int(*parsenextc++) : preadbuffer())
+
 static int
 pgetc(void)
 {
+        pgetc_debug("pgetc at %d:%p'%s'", parsenleft, parsenextc, parsenextc);
         return pgetc_as_macro();
 }
 
@@ -9325,11 +9343,9 @@ pfgets(char *line, int len)
 static void
 pungetc(void)
 {
-        /* check is needed for ash -c 'echo 5&' + BASH_COMPAT to work */
-        if (parsenleft < 0)
-                return;
         parsenleft++;
         parsenextc--;
+        pgetc_debug("pushed back to %d:%p'%s'", parsenleft, parsenextc, parsenextc);
 }
 
 /*
@@ -9343,16 +9359,17 @@ static void
 pushstring(char *s, struct alias *ap)
 {
         struct strpush *sp;
-        size_t len;
+        int len;
 
         len = strlen(s);
         INT_OFF;
         if (g_parsefile->strpush) {
-                sp = ckzalloc(sizeof(struct strpush));
+                sp = ckzalloc(sizeof(*sp));
                 sp->prev = g_parsefile->strpush;
-                g_parsefile->strpush = sp;
-        } else
-                sp = g_parsefile->strpush = &(g_parsefile->basestrpush);
+        } else {
+                sp = &(g_parsefile->basestrpush);
+        }
+        g_parsefile->strpush = sp;
         sp->prevstring = parsenextc;
         sp->prevnleft = parsenleft;
 #if ENABLE_ASH_ALIAS
@@ -9442,7 +9459,7 @@ setinputfd(int fd, int push)
         close_on_exec_on(fd);
         if (push) {
                 pushfile();
-                g_parsefile->buf = 0;
+                g_parsefile->buf = NULL;
         }
         g_parsefile->fd = fd;
         if (g_parsefile->buf == NULL)
diff --git a/shell/ash_test/ash-misc/last_amp.right b/shell/ash_test/ash-misc/last_amp.right
new file mode 100644
index 000000000..3da21aec2
--- /dev/null
+++ b/shell/ash_test/ash-misc/last_amp.right
@@ -0,0 +1,2 @@
+3
+End
diff --git a/shell/ash_test/ash-misc/last_amp.tests b/shell/ash_test/ash-misc/last_amp.tests
new file mode 100755
index 000000000..160937644
--- /dev/null
+++ b/shell/ash_test/ash-misc/last_amp.tests
@@ -0,0 +1,8 @@
+$THIS_SH -c 'echo 3&'
+d=`date`
+while test "`date`" = "$d"; do true; done
+d1=`date`
+$THIS_SH -c 'sleep 1&'
+d2=`date`
+test "$d1" = "$d2" || echo BAD
+echo End