[BUILTIN] Fix backslash handling in read(1)

The new read(1) implementation incorrectly assumes that ifsbreakup
ignores characters escaped by CTLESC.  As such it fails to handle
backslashes except for escaping newlines.

This patch makes it use recordregion for every part that isn't
escaped by a backslash.

Reported-by: Jilles Tjoelker <jilles@stack.nl>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

ChangeLog

diff --git a/ChangeLog b/ChangeLog
index 8a832bb..e96bdc4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2011-03-11  Herbert Xu <herbert@gondor.apana.org.au>
+
+	* Fix backslash handling in read(1).
+
 2011-03-10  Jonathan Nieder <jrnieder@gmail.com>
 
 	* Dotcmd should exit with zero when doing nothing.

src/expand.c

diff --git a/src/expand.c b/src/expand.c
index 6bee5c5..7a9b157 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -1597,7 +1597,6 @@
 _rmescapes(char *str, int flag)
 {
 	char *p, *q, *r;
-	static const char qchars[] = { CTLESC, CTLQUOTEMARK, 0 };
 	unsigned inquotes;
 	int notescaped;
 	int globbing;

src/miscbltin.c

diff --git a/src/miscbltin.c b/src/miscbltin.c
index 800cbbb..f507381 100644
--- a/src/miscbltin.c
+++ b/src/miscbltin.c
@@ -71,21 +71,22 @@
  *  @param len length of line including trailing '\0'
  */
 static void
-readcmd_handle_line(char *line, char **ap, size_t len)
+readcmd_handle_line(char *s, char **ap)
 {
 	struct arglist arglist;
 	struct strlist *sl;
-	char *s, *backup;
+	char *backup;
+	char *line;
 
 	/* ifsbreakup will fiddle with stack region... */
-	s = grabstackstr(line + len);
+	line = stackblock();
+	s = grabstackstr(s);
 
 	/* need a copy, so that delimiters aren't lost
 	 * in case there are more fields than variables */
 	backup = sstrdup(line);
 
 	arglist.lastp = &arglist.list;
-	recordregion(0, len - 1, 0);
 	
 	ifsbreakup(s, &arglist);
 	*arglist.lastp = NULL;
@@ -137,11 +138,12 @@
 readcmd(int argc, char **argv)
 {
 	char **ap;
-	int backslash;
 	char c;
 	int rflag;
 	char *prompt;
 	char *p;
+	int startloc;
+	int newloc;
 	int status;
 	int i;
 
@@ -161,9 +163,12 @@
 	}
 	if (*(ap = argptr) == NULL)
 		sh_error("arg count");
+
 	status = 0;
-	backslash = 0;
 	STARTSTACKSTR(p);
+
+	goto start;
+
 	for (;;) {
 		switch (read(0, &c, 1)) {
 		case 1:
@@ -178,26 +183,35 @@
 		}
 		if (c == '\0')
 			continue;
-		if (backslash || c == CTLESC) {
+		if (newloc >= startloc) {
 			if (c == '\n')
 				goto resetbs;
-			STPUTC(CTLESC, p);
 			goto put;
 		}
 		if (!rflag && c == '\\') {
-			backslash++;
+			newloc = p - (char *)stackblock();
 			continue;
 		}
 		if (c == '\n')
 			break;
 put:
-		STPUTC(c, p);
+		CHECKSTRSPACE(2, p);
+		if (strchr(qchars, c))
+			USTPUTC(CTLESC, p);
+		USTPUTC(c, p);
+
+		if (newloc >= startloc) {
 resetbs:
-		backslash = 0;
+			recordregion(startloc, newloc, 0);
+start:
+			startloc = p - (char *)stackblock();
+			newloc = startloc - 1;
+		}
 	}
 out:
+	recordregion(startloc, p - (char *)stackblock(), 0);
 	STACKSTRNUL(p);
-	readcmd_handle_line(stackblock(), ap, p + 1 - (char *)stackblock());
+	readcmd_handle_line(p + 1, ap);
 	return status;
 }
 

src/mystring.c

diff --git a/src/mystring.c b/src/mystring.c
index ce48c82..bbb6b77 100644
--- a/src/mystring.c
+++ b/src/mystring.c
@@ -62,6 +62,7 @@
 const char snlfmt[] = "%s\n";
 const char dolatstr[] = { CTLQUOTEMARK, CTLVAR, VSNORMAL, '@', '=',
 			  CTLQUOTEMARK, '\0' };
+const char qchars[] = { CTLESC, CTLQUOTEMARK, 0 };
 const char illnum[] = "Illegal number: %s";
 const char homestr[] = "HOME";
 

src/mystring.h

diff --git a/src/mystring.h b/src/mystring.h
index 2e0540a..3522523 100644
--- a/src/mystring.h
+++ b/src/mystring.h
@@ -41,6 +41,7 @@
 extern const char spcstr[];
 extern const char dolatstr[];
 #define DOLATSTRLEN 6
+extern const char qchars[];
 extern const char illnum[];
 extern const char homestr[];