svn commit: r194128 - head/bin/sh

[Jilles Tjoelker]

Author: jilles
Date: Sat Jun 13 21:17:45 2009
New Revision: 194128
URL: http://svn.freebsd.org/changeset/base/194128

Log:
  Avoid leaving unnecessary waiting shells in many forms of sh -c COMMAND.
  
  This change only affects strings passed to -c, when the -s
  option is not used.
  
  The approach is to check if there may be additional data
  in the string after parsing each command. If there is none,
  use the EV_EXIT flag so that a fork may be omitted in
  specific cases.
  
  If there are empty lines after the command, the check will
  not see the end and forks will not be omitted. The same
  thing seems to happen in bash.
  
  Example:
    sh -c 'ps lT'
  No longer shows a shell process waiting for ps to finish.
  
  PR:		bin/113860
  Reviewed by:	stefanf
  Approved by:	ed (mentor)

Modified:
  head/bin/sh/eval.c
  head/bin/sh/eval.h
  head/bin/sh/input.c
  head/bin/sh/input.h
  head/bin/sh/main.c

Modified: head/bin/sh/eval.c
==============================================================================
--- head/bin/sh/eval.c	Sat Jun 13 21:10:41 2009	(r194127)
+++ head/bin/sh/eval.c	Sat Jun 13 21:17:45 2009	(r194128)
@@ -74,11 +74,6 @@ __FBSDID("$FreeBSD$");
 #endif
 
 
-/* flags in argument to evaltree */
-#define EV_EXIT 01		/* exit after evaluating tree */
-#define EV_TESTED 02		/* exit status is checked; ignore -e flag */
-#define EV_BACKCMD 04		/* command executing within back quotes */
-
 MKINIT int evalskip;		/* set if we are skipping commands */
 STATIC int skipcount;		/* number of levels to skip */
 MKINIT int loopnest;		/* current loop nesting level */
@@ -163,20 +158,28 @@ evalstring(char *s, int flags)
 {
 	union node *n;
 	struct stackmark smark;
+	int flags_exit;
 
+	flags_exit = flags & EV_EXIT;
+	flags &= ~EV_EXIT;
 	setstackmark(&smark);
 	setinputstring(s, 1);
 	while ((n = parsecmd(0)) != NEOF) {
-		if (n != NULL)
-			evaltree(n, flags);
+		if (n != NULL) {
+			if (flags_exit && preadateof())
+				evaltree(n, flags | EV_EXIT);
+			else
+				evaltree(n, flags);
+		}
 		popstackmark(&smark);
 	}
 	popfile();
 	popstackmark(&smark);
+	if (flags_exit)
+		exitshell(exitstatus);
 }
 
 
-
 /*
  * Evaluate a parse tree.  The value is left in the global variable
  * exitstatus.

Modified: head/bin/sh/eval.h
==============================================================================
--- head/bin/sh/eval.h	Sat Jun 13 21:10:41 2009	(r194127)
+++ head/bin/sh/eval.h	Sat Jun 13 21:17:45 2009	(r194128)
@@ -45,6 +45,11 @@ struct backcmd {		/* result of evalbackc
 	struct job *jp;		/* job structure for command */
 };
 
+/* flags in argument to evaltree/evalstring */
+#define EV_EXIT 01		/* exit after evaluating tree */
+#define EV_TESTED 02		/* exit status is checked; ignore -e flag */
+#define EV_BACKCMD 04		/* command executing within back quotes */
+
 int evalcmd(int, char **);
 void evalstring(char *, int);
 union node;	/* BLETCH for ansi C */

Modified: head/bin/sh/input.c
==============================================================================
--- head/bin/sh/input.c	Sat Jun 13 21:10:41 2009	(r194127)
+++ head/bin/sh/input.c	Sat Jun 13 21:17:45 2009	(r194128)
@@ -321,6 +321,23 @@ check:
 }
 
 /*
+ * Returns if we are certain we are at EOF. Does not cause any more input
+ * to be read from the outside world.
+ */
+
+int
+preadateof(void)
+{
+	if (parsenleft > 0)
+		return 0;
+	if (parsefile->strpush)
+		return 0;
+	if (parsenleft == EOF_NLEFT || parsefile->buf == NULL)
+		return 1;
+	return 0;
+}
+
+/*
  * Undo the last call to pgetc.  Only one character may be pushed back.
  * PEOF may be pushed back.
  */

Modified: head/bin/sh/input.h
==============================================================================
--- head/bin/sh/input.h	Sat Jun 13 21:10:41 2009	(r194127)
+++ head/bin/sh/input.h	Sat Jun 13 21:17:45 2009	(r194128)
@@ -48,6 +48,7 @@ extern int init_editline;	/* 0 == not se
 char *pfgets(char *, int);
 int pgetc(void);
 int preadbuffer(void);
+int preadateof(void);
 void pungetc(void);
 void pushstring(char *, int, void *);
 void popstring(void);

Modified: head/bin/sh/main.c
==============================================================================
--- head/bin/sh/main.c	Sat Jun 13 21:10:41 2009	(r194127)
+++ head/bin/sh/main.c	Sat Jun 13 21:17:45 2009	(r194128)
@@ -178,7 +178,7 @@ state2:
 state3:
 	state = 4;
 	if (minusc) {
-		evalstring(minusc, 0);
+		evalstring(minusc, sflag ? 0 : EV_EXIT);
 	}
 	if (sflag || minusc == NULL) {
 state4:	/* XXX ??? - why isn't this before the "if" statement */