sh: Ensure the same command input file is on top after executing a builtin.

This avoids weirdness when 'fc -e vi' or the like is done and there is a
syntax error in the file. Formerly an interactive shell tried to execute
stuff after the syntax error and exited.

This should also avoid similar issues with 'command eval' and 'command .'
when 'command' is implemented properly as in NetBSD sh.

Special builtins did not have this problem since errors in them cause the
shell to exit or to reset various state such as the current command input
file.

bin/sh/eval.c

@@ -593,6 +593,7 @@ evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 	char *savecmdname;
 	struct shparam saveparam;
 	struct localvar *savelocalvars;
+	struct parsefile *savetopfile;
 	volatile int e;
 	char *lastarg;
 	int realstatus;
@@ -833,6 +834,7 @@ evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 			mode |= REDIR_BACKQ;
 		}
 		savecmdname = commandname;
+		savetopfile = getcurrentfile();
 		cmdenviron = varlist.list;
 		e = -1;
 		savehandler = handler;
@@ -867,6 +869,7 @@ evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 			if ((e != EXERROR && e != EXEXEC)
 			    || cmdentry.special)
 				exraise(e);
+			popfilesupto(savetopfile);
 			FORCEINTON;
 		}
 		if (cmdentry.u.index != EXECCMD)

bin/sh/input.c

@@ -508,6 +508,32 @@ popfile(void)
 }
 
 
+/*
+ * Return current file (to go back to it later using popfilesupto()).
+ */
+
+struct parsefile *
+getcurrentfile(void)
+{
+	return parsefile;
+}
+
+
+/*
+ * Pop files until the given file is on top again. Useful for regular
+ * builtins that read shell commands from files or strings.
+ * If the given file is not an active file, an error is raised.
+ */
+
+void
+popfilesupto(struct parsefile *file)
+{
+	while (parsefile != file && parsefile != &basepf)
+		popfile();
+	if (parsefile != file)
+		error("popfilesupto() misused");
+}
+
 /*
  * Return to top level.
  */

bin/sh/input.h

@@ -45,6 +45,8 @@ extern int parsenleft;		/* number of characters left in input buffer */
 extern char *parsenextc;	/* next character in input buffer */
 extern int init_editline;	/* 0 == not setup, 1 == OK, -1 == failed */
 
+struct parsefile;
+
 char *pfgets(char *, int);
 int pgetc(void);
 int preadbuffer(void);
@@ -56,6 +58,8 @@ void setinputfile(char *, int);
 void setinputfd(int, int);
 void setinputstring(char *, int);
 void popfile(void);
+struct parsefile *getcurrentfile(void);
+void popfilesupto(struct parsefile *);
 void popallfiles(void);
 void closescript(void);
 

tools/regression/bin/sh/builtins/fc1.0

@@ -0,0 +1,27 @@
+# $FreeBSD$
+set -e
+trap 'echo Broken pipe -- test failed' pipe
+
+P=${TMPDIR:-/tmp}
+cd $P
+T=$(mktemp -d sh-test.XXXXXX)
+cd $T
+
+mkfifo input output error
+HISTFILE=/dev/null sh -i <input >output 2>error &
+{
+	# Syntax error
+	echo ')' >&3
+	# Read error message, shell will read new input now
+	read dummy <&5
+	# Execute bad command again
+	echo 'fc -e true' >&3
+	# Verify that the shell is still running
+	echo 'echo continued' >&3 || rc=3
+	echo 'exit' >&3 || rc=3
+	read line <&4 && [ "$line" = continued ] && : ${rc:=0}
+} 3>input 4<output 5<error
+
+rm input output error
+rmdir ${P}/${T}
+exit ${rc:-3}