Change the behavior of IFS word-splitting: split words

when the current character is IFS space and the last
character was a word character or it was non-white IFS
space and the current character is non-white IFS space.
This deviates from the previous behavior because the
latter splits words when the last character is any IFS
space and the current is non-white IFS, resulting in
more fields most of the time.

This new behavior follows what the man page describes;
i.e., that a field is delimited by one or more IFS
whitespace characters followed by zero or one non-white
IFS characters.

Requires addition of a new substitution expansion state
to handle the special case of empty fields at the
beginning.

testing by naddy
ok jmc, millert, otto, deraadt

1 files changed, 18 insertions, 3 deletions

diff --git a/bin/ksh/eval.c b/bin/ksh/eval.c
index cf29ff9fee4..92c6e55ada9 100644
--- a/bin/ksh/eval.c
+++ b/bin/ksh/eval.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: eval.c,v 1.14 2003/11/10 21:26:39 millert Exp $	*/
+/*	$OpenBSD: eval.c,v 1.15 2004/11/25 04:36:47 jaredy Exp $	*/
 
 /*
  * Expansion - quoting, separation, substitution, globbing
@@ -34,6 +34,7 @@ typedef struct Expand {
 #define	XARG		3	/* expanding $*, $@ */
 #define	XCOM		4	/* expanding $() */
 #define XNULLSUB	5	/* "$@" when $# is 0 (don't generate word) */
+#define XSUBMID		6	/* middle of expanding ${} */
 
 /* States used for field splitting */
 #define IFS_WORD	0	/* word has chars (or quotes) */
@@ -278,7 +279,7 @@ expand(cp, wp, f)
 			  /* format is:
 			   *   OSUBST [{x] plain-variable-part \0
 			   *     compiled-word-part CSUBST [}x]
-			   * This is were all syntax checking gets done...
+			   * This is where all syntax checking gets done...
 			   */
 			  {
 				char *varname = ++sp; /* skip the { or x (}) */
@@ -477,6 +478,7 @@ expand(cp, wp, f)
 			continue;
 
 		  case XSUB:
+		  case XSUBMID:
 			if ((c = *x.str++) == 0) {
 				type = XBASE;
 				if (f&DOBLANK)
@@ -559,7 +561,7 @@ expand(cp, wp, f)
 			 * doesn't do this, but POSIX does).
 			 */
 			if (word == IFS_WORD
-			    || (!ctype(c, C_IFSWS) && (c || word == IFS_NWS)))
+			    || (!ctype(c, C_IFSWS) && c && word == IFS_NWS))
 			{
 				char *p;
 
@@ -590,6 +592,19 @@ expand(cp, wp, f)
 			if (word != IFS_NWS)
 				word = ctype(c, C_IFSWS) ? IFS_WS : IFS_NWS;
 		} else {
+			if (type == XSUB) {
+				if (word == IFS_NWS &&
+				    Xlength(ds, dp) == 0) {
+					char *p;
+
+					if ((p = strdup("")) == NULL)
+						internal_errorf(1, "unable "
+						    "to allocate memory");
+					XPput(*wp, p);
+				}
+				type = XSUBMID;
+			}
+
 			/* age tilde_ok info - ~ code tests second bit */
 			tilde_ok <<= 1;
 			/* mark any special second pass chars */