ash: [VAR] Replace cmdenviron with localvars

Upstream commit:

    Date: Wed, 26 May 2010 18:54:19 +0800
    [VAR] Replace cmdenviron with localvars

    This patch replaces the cmdenviron mechanism for temporary command
    variables with the localvars mechanism used by functions.

    This reduces code size, and more importantly, makes the variable
    assignment take effect immediately as required by POSIX.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

shell/ash.c

@@ -1250,7 +1250,6 @@ static struct parsefile basepf;        /* top level input file */
 static struct parsefile *g_parsefile = &basepf;  /* current input file */
 static int startlinno;                 /* line # where last token started */
 static char *commandname;              /* currently executing command */
-static struct strlist *cmdenviron;     /* environment for builtin command */
 
 
 /* ============ Message printing */
@@ -2225,15 +2224,9 @@ reinit_unicode_for_ash(void)
 /*
  * Search the environment of a builtin command.
  */
-static const char *
+static inline const char *
 bltinlookup(const char *name)
 {
-	struct strlist *sp;
-
-	for (sp = cmdenviron; sp; sp = sp->next) {
-		if (varcmp(sp->text, name) == 0)
-			return var_end(sp->text);
-	}
 	return lookupvar(name);
 }
 
@@ -9179,7 +9172,7 @@ static struct localvar_list *localvar_stack;
  * Interrupts must be off.
  */
 static void
-poplocalvars(void)
+poplocalvars(int keep)
 {
 	struct localvar_list *ll;
 	struct localvar *lvp, *next;
@@ -9196,7 +9189,23 @@ poplocalvars(void)
 		next = lvp->next;
 		vp = lvp->vp;
 		TRACE(("poplocalvar %s\n", vp ? vp->var_text : "-"));
-		if (vp == NULL) {       /* $- saved */
+		if (keep) {
+			int bits = VSTRFIXED;
+
+			if (lvp->flags != VUNSET) {
+				if (vp->var_text == lvp->text)
+					bits |= VTEXTFIXED;
+				else if (!(lvp->flags & (VTEXTFIXED|VSTACK)))
+					free((char*)lvp->text);
+			}
+
+			vp->flags &= ~bits;
+			vp->flags |= (lvp->flags & bits);
+
+			if ((vp->flags &
+			     (VEXPORT|VREADONLY|VSTRFIXED|VUNSET)) == VUNSET)
+				unsetvar(vp->var_text);
+		} else if (vp == NULL) {	/* $- saved */
 			memcpy(optlist, lvp->text, sizeof(optlist));
 			free((char*)lvp->text);
 			optschanged();
@@ -9260,7 +9269,7 @@ evalfun(struct funcnode *func, int argc, char **argv, int flags)
 #endif
 	pushlocalvars();
 	evaltree(func->n.narg.next, flags & EV_TESTED);
-	poplocalvars();
+	poplocalvars(0);
  funcdone:
 	INT_OFF;
 	funcnest--;
@@ -9631,6 +9640,7 @@ evalcommand(union node *cmd, int flags)
 	/* First expand the arguments. */
 	TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
 	setstackmark(&smark);
+	pushlocalvars();
 	back_exitstatus = 0;
 
 	cmdentry.cmdtype = CMDBUILTIN;
@@ -9684,6 +9694,8 @@ evalcommand(union node *cmd, int flags)
 		spp = varlist.lastp;
 		expandarg(argp, &varlist, EXP_VARTILDE);
 
+		mklocal((*spp)->text);
+
 		/*
 		 * Modify the command lookup path, if a PATH= assignment
 		 * is present
@@ -9815,6 +9827,7 @@ evalcommand(union node *cmd, int flags)
 				/* parent */
 				status = waitforjob(jp);
 				INT_ON;
+				poplocalvars(0);
 				TRACE(("forked child exited with %d\n", status));
 				break;
 			}
@@ -9827,17 +9840,10 @@ evalcommand(union node *cmd, int flags)
 		/* NOTREACHED */
 	} /* default */
 	case CMDBUILTIN:
-		cmdenviron = varlist.list;
+		poplocalvars(spclbltin > 0 || argc == 0);
-		if (cmdenviron) {
+		if (cmd_is_exec && argc > 1)
-			struct strlist *list = cmdenviron;
+			listsetvar(varlist.list, VEXPORT);
-			int i = VNOSET;
+
-			if (spclbltin > 0 || argc == 0) {
-				i = 0;
-				if (cmd_is_exec && argc > 1)
-					i = VEXPORT;
-			}
-			listsetvar(list, i);
-		}
 		/* Tight loop with builtins only:
 		 * "while kill -0 $child; do true; done"
 		 * will never exit even if $child died, unless we do this
@@ -9855,7 +9861,7 @@ evalcommand(union node *cmd, int flags)
 		goto readstatus;
 
 	case CMDFUNCTION:
-		listsetvar(varlist.list, 0);
+		poplocalvars(1);
 		/* See above for the rationale */
 		dowait(DOWAIT_NONBLOCK, NULL);
 		if (evalfun(cmdentry.u.func, argc, argv, flags))
@@ -12714,11 +12720,12 @@ dotcmd(int argc_ UNUSED_PARAM, char **argv_ UNUSED_PARAM)
 	char *fullname;
 	char **argv;
 	char *args_need_save;
-	struct strlist *sp;
 	volatile struct shparam saveparam;
 
-	for (sp = cmdenviron; sp; sp = sp->next)
+//???
-		setvareq(ckstrdup(sp->text), VSTRFIXED | VTEXTFIXED);
+//	struct strlist *sp;
+//	for (sp = cmdenviron; sp; sp = sp->next)
+//		setvareq(ckstrdup(sp->text), VSTRFIXED | VTEXTFIXED);
 
 	nextopt(nullstr); /* handle possible "--" */
 	argv = argptr;
@@ -13601,7 +13608,7 @@ reset(void)
 
 	/* from var.c: */
 	while (localvar_stack)
-		poplocalvars();
+		poplocalvars(0);
 }
 
 #if PROFILE