ash: [PARSER] Removed noexpand/length check on eofmark

Upstream comment:

	Date: Sun, 11 Nov 2007 14:21:23 +0800
	[PARSER] Removed noexpand/length check on eofmark

	On Tue, Oct 30, 2007 at 04:23:35AM +0000, Oleg Verych wrote:
	>
	> } 8<<""
	> ======================

	Actually this (the empty delim) only works with dash by accident.
	I've tried bash and pdksh and they both terminate on the first
	empty line which is what you would expect rather than EOF.  The
	real Korn shell does something completely different.

	I've fixed this in dash to conform to bash/pdksh.

	> In [0] it's stated, that delimiter isn't evaluated (expanded), only
	> quoiting must be checked. That if() seems to be completely bogus.

	OK I agree.  The reason it was there is because the parser would
	have already replaced the dollar sign by an internal representation.

	I've fixed it properly with this patch.

	Test case:

	        cat <<- $a
	                OK
	        $a

	        cat <<- ""
	                OK

	        echo OK

	Old result:

	        dash: Syntax error: Illegal eof marker for << redirection
	        OK

	        echo OK

	New result:

	        OK
	        OK
	        OK

function                                             old     new   delta
parsefname                                           227     152     -75
readtoken1                                          2819    2651    -168
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-243)           Total: -243 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 52 insertions, 70 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 02b21510e..2bfec83e6 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -9991,6 +9991,7 @@ static smallint checkkwd;
 #define CHKALIAS        0x1
 #define CHKKWD          0x2
 #define CHKNL           0x4
+#define CHKEOFMARK      0x8
 
 /*
  * Push a string back onto the input at this current parsefile level.
@@ -10303,31 +10304,6 @@ pgetc_without_PEOA(void)
 #endif
 
 /*
- * Read a line from the script.
- */
-static char *
-pfgets(char *line, int len)
-{
-        char *p = line;
-        int nleft = len;
-        int c;
-
-        while (--nleft > 0) {
-                c = pgetc_without_PEOA();
-                if (c == PEOF) {
-                        if (p == line)
-                                return NULL;
-                        break;
-                }
-                *p++ = c;
-                if (c == '\n')
-                        break;
-        }
-        *p = '\0';
-        return line;
-}
-
-/*
  * Undo a call to pgetc.  Only two characters may be pushed back.
  * PEOF may be pushed back.
  */
@@ -10960,8 +10936,6 @@ raise_error_unexpected_syntax(int token)
         /* NOTREACHED */
 }
 
-#define EOFMARKLEN 79
-
 /* parsing is heavily cross-recursive, need these forward decls */
 static union node *andor(void);
 static union node *pipeline(void);
@@ -11141,43 +11115,22 @@ fixredir(union node *n, const char *text, int err)
         }
 }
 
-/*
- * Returns true if the text contains nothing to expand (no dollar signs
- * or backquotes).
- */
-static int
-noexpand(const char *text)
-{
-        unsigned char c;
-
-        while ((c = *text++) != '\0') {
-                if (c == CTLQUOTEMARK)
-                        continue;
-                if (c == CTLESC)
-                        text++;
-                else if (SIT(c, BASESYNTAX) == CCTL)
-                        return 0;
-        }
-        return 1;
-}
-
 static void
 parsefname(void)
 {
         union node *n = redirnode;
 
+        if (n->type == NHERE)
+                checkkwd = CHKEOFMARK;
         if (readtoken() != TWORD)
                 raise_error_unexpected_syntax(-1);
         if (n->type == NHERE) {
                 struct heredoc *here = heredoc;
                 struct heredoc *p;
-                int i;
 
                 if (quoteflag == 0)
                         n->type = NXHERE;
                 TRACE(("Here document %d\n", n->type));
-                if (!noexpand(wordtext) || (i = strlen(wordtext)) == 0 || i > EOFMARKLEN)
-                        raise_error_syntax("illegal eof marker for << redirection");
                 rmescapes(wordtext, 0);
                 here->eofmark = wordtext;
                 here->next = NULL;
@@ -11593,7 +11546,6 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
         /* c parameter is an unsigned char or PEOF or PEOA */
         char *out;
         size_t len;
-        char line[EOFMARKLEN + 1];
         struct nodelist *bqlist;
         smallint quotef;
         smallint dblquote;
@@ -11816,6 +11768,9 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
  */
 checkend: {
         if (eofmark) {
+                int markloc;
+                char *p;
+
 #if ENABLE_ASH_ALIAS
                 if (c == PEOA)
                         c = pgetc_without_PEOA();
@@ -11825,27 +11780,42 @@ checkend: {
                                 c = pgetc_without_PEOA();
                         }
                 }
-                if (c == *eofmark) {
-                        if (pfgets(line, sizeof(line)) != NULL) {
-                                char *p, *q;
-                                int cc;
-
-                                p = line;
-                                for (q = eofmark + 1;; p++, q++) {
-                                        cc = *p;
-                                        if (cc == '\n')
-                                                cc = 0;
-                                        if (!*q || cc != *q)
-                                                break;
-                                }
-                                if (cc == *q) {
-                                        c = PEOF;
-                                        nlnoprompt();
-                                } else {
-                                        pushstring(line, NULL);
+
+                markloc = out - (char *)stackblock();
+                for (p = eofmark; STPUTC(c, out), *p; p++) {
+                        if (c != *p)
+                                goto more_heredoc;
+
+                        c = pgetc_without_PEOA();
+                }
+
+                if (c == '\n' || c == PEOF) {
+                        c = PEOF;
+                        g_parsefile->linno++;
+                        needprompt = doprompt;
+                } else {
+                        int len_here;
+
+ more_heredoc:
+                        p = (char *)stackblock() + markloc + 1;
+                        len_here = out - p;
+
+                        if (len_here) {
+                                len_here -= (c >= PEOF);
+                                c = p[-1];
+
+                                if (len_here) {
+                                        char *str;
+
+                                        str = alloca(len_here + 1);
+                                        *(char *)mempcpy(str, p, len_here) = '\0';
+
+                                        pushstring(str, NULL);
                                 }
                         }
                 }
+
+                STADJUST((char *)stackblock() + markloc - out, out);
         }
         goto checkend_return;
 }
@@ -11939,7 +11909,8 @@ parsesub: {
         int typeloc;
 
         c = pgetc_eatbnl();
-        if (c > 255 /* PEOA or PEOF */
+        if ((checkkwd & CHKEOFMARK)
+         || c > 255 /* PEOA or PEOF */
          || (c != '(' && c != '{' && !is_name(c) && !is_special(c))
         ) {
 #if BASH_DOLLAR_SQUOTE
diff --git a/shell/ash_test/ash-heredoc/heredoc_empty.right b/shell/ash_test/ash-heredoc/heredoc_empty.right
new file mode 100644
index 000000000..0eabe3671
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_empty.right
@@ -0,0 +1,3 @@
+OK
+OK
+OK
diff --git a/shell/ash_test/ash-heredoc/heredoc_empty.tests b/shell/ash_test/ash-heredoc/heredoc_empty.tests
new file mode 100755
index 000000000..3629bc6d1
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_empty.tests
@@ -0,0 +1,8 @@
+unset a
+cat <<- $a
+        OK
+$a
+cat <<- ""
+        OK
+
+echo OK