[klibc] [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>
[ merge fixups -maks ]
Signed-off-by: maximilian attems <max@stro.at>

4 files changed, 28 insertions, 13 deletions

diff --git a/usr/dash/expand.c b/usr/dash/expand.c
index 900d8c7e6ae2b..e177ee6114a09 100644
--- a/usr/dash/expand.c
+++ b/usr/dash/expand.c
@@ -1597,7 +1597,6 @@ char *
 _rmescapes(char *str, int flag)
 {
 	char *p, *q, *r;
-	static const char qchars[] = { CTLESC, CTLQUOTEMARK, 0 };
 	unsigned inquotes;
 	int notescaped;
 	int globbing;
diff --git a/usr/dash/miscbltin.c b/usr/dash/miscbltin.c
index f2acce8a03a94..ece66ced0220c 100644
--- a/usr/dash/miscbltin.c
+++ b/usr/dash/miscbltin.c
@@ -72,21 +72,22 @@
  *  @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;
@@ -138,11 +139,12 @@ int
 readcmd(int argc, char **argv)
 {
 	char **ap;
-	int backslash;
 	char c;
 	int rflag;
 	char *prompt;
 	char *p;
+	int startloc;
+	int newloc;
 	int status;
 	int timeout;
 	int i;
@@ -180,8 +182,8 @@ readcmd(int argc, char **argv)
 	}
 	if (*(ap = argptr) == NULL)
 		sh_error("arg count");
+
 	status = 0;
-	backslash = 0;
 	if (timeout) {
 		gettimeofday(&t0, NULL);
 
@@ -194,6 +196,9 @@ readcmd(int argc, char **argv)
 		ts.tv_sec += t0.tv_sec;
 	}
 	STARTSTACKSTR(p);
+
+	goto start;
+
 	for (;;) {
 		if (timeout) {
 			gettimeofday(&t1, NULL);
@@ -233,26 +238,35 @@ readcmd(int argc, char **argv)
 		}
 		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;
 }
 
diff --git a/usr/dash/mystring.c b/usr/dash/mystring.c
index ce48c825c3e0b..bbb6b776ce996 100644
--- a/usr/dash/mystring.c
+++ b/usr/dash/mystring.c
@@ -62,6 +62,7 @@ const char spcstr[] = " ";
 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";
 
diff --git a/usr/dash/mystring.h b/usr/dash/mystring.h
index 2e0540a1b4763..352252376abfe 100644
--- a/usr/dash/mystring.h
+++ b/usr/dash/mystring.h
@@ -41,6 +41,7 @@ extern const char snlfmt[];
 extern const char spcstr[];
 extern const char dolatstr[];
 #define DOLATSTRLEN 6
+extern const char qchars[];
 extern const char illnum[];
 extern const char homestr[];