[git commit] ash: [REDIR] Move null redirect checks into caller

[Denys Vlasenko]

commit: https://git.busybox.net/busybox/commit/?id=eaf9436b08f68be8b96730307fe1da1faf374ee0
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

Upstream commit:

    Date: Thu, 27 May 2010 14:21:17 +0800
    [REDIR] Move null redirect checks into caller

    The null redirect checks were added as an optimisation to avoid
    unnecessary memory allocations.  However, we could avoid this
    completely by simply making the caller avoid making a redirection
    unless it is not null.

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

function                                             old     new   delta
evaltree                                             784     809     +25
evalcommand                                         1251    1261     +10
hashvar                                               59      62      +3
dotcmd                                               321     319      -2
clearredir                                            37      30      -7
popredir                                             183     162     -21
redirect                                            1264    1233     -31
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/4 up/down: 63/-61)            Total: -23 bytes

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 shell/ash.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/shell/ash.c b/shell/ash.c
index dc0f607..dc26bc1 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -1951,7 +1951,6 @@ struct redirtab;
 struct globals_var {
 	struct shparam shellparam;      /* $@ current positional parameters */
 	struct redirtab *redirlist;
-	int g_nullredirs;
 	int preverrout_fd;   /* save fd2 before print debug if xflag is set. */
 	struct var *vartab[VTABSIZE];
 	struct var varinit[ARRAY_SIZE(varinit_data)];
@@ -1960,7 +1959,6 @@ extern struct globals_var *const ash_ptr_to_globals_var;
 #define G_var (*ash_ptr_to_globals_var)
 #define shellparam    (G_var.shellparam   )
 //#define redirlist     (G_var.redirlist    )
-#define g_nullredirs  (G_var.g_nullredirs )
 #define preverrout_fd (G_var.preverrout_fd)
 #define vartab        (G_var.vartab       )
 #define varinit       (G_var.varinit      )
@@ -5216,7 +5214,6 @@ struct two_fd_t {
 };
 struct redirtab {
 	struct redirtab *next;
-	int nullredirs;
 	int pair_count;
 	struct two_fd_t two_fd[];
 };
@@ -5295,7 +5292,6 @@ redirect(union node *redir, int flags)
 	int newfd;
 	int copied_fd2 = -1;
 
-	g_nullredirs++;
 	if (!redir) {
 		return;
 	}
@@ -5317,8 +5313,6 @@ redirect(union node *redir, int flags)
 		sv->next = redirlist;
 		sv->pair_count = sv_pos;
 		redirlist = sv;
-		sv->nullredirs = g_nullredirs - 1;
-		g_nullredirs = 0;
 		while (sv_pos > 0) {
 			sv_pos--;
 			sv->two_fd[sv_pos].orig = sv->two_fd[sv_pos].copy = EMPTY;
@@ -5430,7 +5424,7 @@ popredir(int drop, int restore)
 	struct redirtab *rp;
 	int i;
 
-	if (--g_nullredirs >= 0 || redirlist == NULL)
+	if (redirlist == NULL)
 		return;
 	INT_OFF;
 	rp = redirlist;
@@ -5452,7 +5446,6 @@ popredir(int drop, int restore)
 		}
 	}
 	redirlist = rp->next;
-	g_nullredirs = rp->nullredirs;
 	free(rp);
 	INT_ON;
 }
@@ -5467,12 +5460,8 @@ popredir(int drop, int restore)
 static void
 clearredir(int drop)
 {
-	for (;;) {
-		g_nullredirs = 0;
-		if (!redirlist)
-			break;
+	while (redirlist)
 		popredir(drop, /*restore:*/ 0);
-	}
 }
 
 static int
@@ -8573,7 +8562,8 @@ evaltree(union node *n, int flags)
 		if (!status) {
 			status = evaltree(n->nredir.n, flags & EV_TESTED);
 		}
-		popredir(/*drop:*/ 0, /*restore:*/ 0 /* not sure */);
+		if (n->nredir.redirect)
+			popredir(/*drop:*/ 0, /*restore:*/ 0 /* not sure */);
 		goto setstatus;
 	case NCMD:
 		evalfn = evalcommand;
@@ -9645,7 +9635,8 @@ evalcommand(union node *cmd, int flags)
 	} /* switch */
 
  out:
-	popredir(/*drop:*/ cmd_is_exec, /*restore:*/ cmd_is_exec);
+	if (cmd->ncmd.redirect)
+		popredir(/*drop:*/ cmd_is_exec, /*restore:*/ cmd_is_exec);
 	if (lastarg) {
 		/* dsl: I think this is intended to be used to support
 		 * '_' in 'vi' command mode during line editing...