From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Tue, 25 Oct 2016 19:10:20 +0000 (+0200)
Subject: ash: [EXPAND] Removed herefd hack
X-Git-Tag: 1_26_0~129
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=579ad107a69690efc17401c487b06e89d9e8a91d;p=oweals%2Fbusybox.git

ash: [EXPAND] Removed herefd hack

Upstream commit:

    Date: Sun, 11 Nov 2007 15:00:06 +0800
    [EXPAND] Removed herefd hack

    The herefd hack goes back more than a decade.  it limits the amount of
    memory we have to allocate when expanding here-documents by writing the
    result out from time to time.  However, it's no longer safe because the
    stack is used to place intermediate results too and there we certainly
    don't want to write them out should we be short on memory.

    In any case, with today's computers we can afford to keep the entire
    result in memory and write them out at the end.

function                                             old     new   delta
redirect                                            1268    1264      -4
ash_main                                            1485    1478      -7
subevalvar                                          1157    1132     -25
growstackstr                                          54      24     -30
argstr                                              1192    1154     -38
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/5 up/down: 0/-104)           Total: -104 bytes

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

diff --git a/shell/ash.c b/shell/ash.c
index 3f1405d81..527abc7b1 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -1399,7 +1399,6 @@ struct globals_memstack {
 	char *g_stacknxt; // = stackbase.space;
 	char *sstrend; // = stackbase.space + MINSIZE;
 	size_t g_stacknleft; // = MINSIZE;
-	int    herefd; // = -1;
 	struct stack_block stackbase;
 };
 extern struct globals_memstack *const ash_ptr_to_globals_memstack;
@@ -1408,7 +1407,6 @@ extern struct globals_memstack *const ash_ptr_to_globals_memstack;
 #define g_stacknxt   (G_memstack.g_stacknxt  )
 #define sstrend      (G_memstack.sstrend     )
 #define g_stacknleft (G_memstack.g_stacknleft)
-#define herefd       (G_memstack.herefd      )
 #define stackbase    (G_memstack.stackbase   )
 #define INIT_G_memstack() do { \
 	(*(struct globals_memstack**)&ash_ptr_to_globals_memstack) = xzalloc(sizeof(G_memstack)); \
@@ -1417,7 +1415,6 @@ extern struct globals_memstack *const ash_ptr_to_globals_memstack;
 	g_stacknxt = stackbase.space; \
 	g_stacknleft = MINSIZE; \
 	sstrend = stackbase.space + MINSIZE; \
-	herefd = -1; \
 } while (0)
 
 
@@ -1605,10 +1602,6 @@ static void *
 growstackstr(void)
 {
 	size_t len = stackblocksize();
-	if (herefd >= 0 && len >= 1024) {
-		full_write(herefd, stackblock(), len);
-		return stackblock();
-	}
 	growstackblock();
 	return (char *)stackblock() + len;
 }
@@ -5893,33 +5886,28 @@ static int evaltree(union node *, int);
 static void FAST_FUNC
 evalbackcmd(union node *n, struct backcmd *result)
 {
-	int saveherefd;
+	int pip[2];
+	struct job *jp;
 
 	result->fd = -1;
 	result->buf = NULL;
 	result->nleft = 0;
 	result->jp = NULL;
-	if (n == NULL)
+	if (n == NULL) {
 		goto out;
+	}
 
-	saveherefd = herefd;
-	herefd = -1;
-
-	{
-		int pip[2];
-		struct job *jp;
-
-		if (pipe(pip) < 0)
-			ash_msg_and_raise_error("pipe call failed");
-		jp = makejob(/*n,*/ 1);
-		if (forkshell(jp, n, FORK_NOJOB) == 0) {
-			FORCE_INT_ON;
-			close(pip[0]);
-			if (pip[1] != 1) {
-				/*close(1);*/
-				copyfd(pip[1], 1 | COPYFD_EXACT);
-				close(pip[1]);
-			}
+	if (pipe(pip) < 0)
+		ash_msg_and_raise_error("pipe call failed");
+	jp = makejob(/*n,*/ 1);
+	if (forkshell(jp, n, FORK_NOJOB) == 0) {
+		FORCE_INT_ON;
+		close(pip[0]);
+		if (pip[1] != 1) {
+			/*close(1);*/
+			copyfd(pip[1], 1 | COPYFD_EXACT);
+			close(pip[1]);
+		}
 /* TODO: eflag clearing makes the following not abort:
  *  ash -c 'set -e; z=$(false;echo foo); echo $z'
  * which is what bash does (unless it is in POSIX mode).
@@ -5928,15 +5916,14 @@ evalbackcmd(union node *n, struct backcmd *result)
  *  [EVAL] Don't clear eflag in evalbackcmd
  * For now, preserve bash-like behavior, it seems to be somewhat more useful:
  */
-			eflag = 0;
-			evaltree(n, EV_EXIT); /* actually evaltreenr... */
-			/* NOTREACHED */
-		}
-		close(pip[1]);
-		result->fd = pip[0];
-		result->jp = jp;
+		eflag = 0;
+		evaltree(n, EV_EXIT); /* actually evaltreenr... */
+		/* NOTREACHED */
 	}
-	herefd = saveherefd;
+	close(pip[1]);
+	result->fd = pip[0];
+	result->jp = jp;
+
  out:
 	TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
 		result->fd, result->buf, result->nleft, result->jp));
@@ -6343,7 +6330,6 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
 	char *str;
 	IF_ASH_BASH_COMPAT(char *repl = NULL;)
 	IF_ASH_BASH_COMPAT(int pos, len, orig_len;)
-	int saveherefd = herefd;
 	int amount, resetloc;
 	IF_ASH_BASH_COMPAT(int workloc;)
 	int zero;
@@ -6352,12 +6338,10 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
 	//bb_error_msg("subevalvar(p:'%s',varname:'%s',strloc:%d,subtype:%d,startloc:%d,varflags:%x,quotes:%d)",
 	//		p, varname, strloc, subtype, startloc, varflags, quotes);
 
-	herefd = -1;
 	argstr(p, EXP_TILDE | (subtype != VSASSIGN && subtype != VSQUESTION ?
 			(flag & (EXP_QUOTED | EXP_QPAT) ? EXP_QPAT : EXP_CASE) : 0),
 			var_str_list);
 	STPUTC('\0', expdest);
-	herefd = saveherefd;
 	argbackq = saveargbackq;
 	startp = (char *)stackblock() + startloc;
 
@@ -7391,7 +7375,6 @@ expandarg(union node *arg, struct arglist *arglist, int flag)
 static void
 expandhere(union node *arg, int fd)
 {
-	herefd = fd;
 	expandarg(arg, (struct arglist *)NULL, EXP_QUOTED);
 	full_write(fd, stackblock(), expdest - (char *)stackblock());
 }