PATCH: redirection and xtrace output

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxxxxxxxxx>]

This patch introduces a global FILE *xtrerr which is used for (hopefully)
all xtrace output.  Normally it just points to stderr, but during execcmd()
it's fdopened on a dup of fileno(stderr) before redirections are performed,
then restored before returning.

There's probably some test that I haven't figured out yet that would permit
changing xtrerr only if fd 2 is actually being redirected.  Or maybe there
isn't any reason to reclaim the file descriptor, and we should just open
xtrerr once in init_io() and leave it open forever?

There is still one problem with this:  The xtrace output of ( ... ) and
{ ... } constructs is NOT redirected with stderr, which it should be. I
suspect that's a matter of restoring xtrerr = stderr in entersubsh(), but
I wasn't sure exactly where.

Index: Src/builtin.c
===================================================================
@@ -351,13 +351,13 @@
     /* display execution trace information, if required */
     if (xtr) {
 	printprompt4();
-	fprintf(stderr, "%s", name);
+	fprintf(xtrerr, "%s", name);
 	if (xarg)
-	    fprintf(stderr, " %s", xarg);
+	    fprintf(xtrerr, " %s", xarg);
 	while (*oargv)
-	    fprintf(stderr, " %s", *oargv++);
-	fputc('\n', stderr);
-	fflush(stderr);
+	    fprintf(xtrerr, " %s", *oargv++);
+	fputc('\n', xtrerr);
+	fflush(xtrerr);
     }
     /* call the handler function, and return its return value */
     return (*(bn->handlerfunc)) (name, argv, ops, bn->funcid);
Index: Src/cond.c
===================================================================
@@ -50,12 +50,12 @@
     switch (ctype) {
     case COND_NOT:
 	if (tracingcond)
-	    fprintf(stderr, " %s", condstr[ctype]);
+	    fprintf(xtrerr, " %s", condstr[ctype]);
 	return !evalcond(state);
     case COND_AND:
 	if (evalcond(state)) {
 	    if (tracingcond)
-		fprintf(stderr, " %s", condstr[ctype]);
+		fprintf(xtrerr, " %s", condstr[ctype]);
 	    return evalcond(state);
 	} else {
 	    state->pc = pcode + (WC_COND_SKIP(code) + 1);
@@ -64,7 +64,7 @@
     case COND_OR:
 	if (!evalcond(state)) {
 	    if (tracingcond)
-		fprintf(stderr, " %s", condstr[ctype]);
+		fprintf(xtrerr, " %s", condstr[ctype]);
 	    return evalcond(state);
 	} else {
 	    state->pc = pcode + (WC_COND_SKIP(code) + 1);
@@ -136,9 +136,9 @@
 		singsub(&rt);
 		untokenize(rt);
 	    }
-	    fprintf(stderr, " %s %s %s", left, condstr[ctype], rt);
+	    fprintf(xtrerr, " %s %s %s", left, condstr[ctype], rt);
 	} else
-	    fprintf(stderr, " -%c %s", ctype, left);
+	    fprintf(xtrerr, " -%c %s", ctype, left);
     }
 
     if (ctype >= COND_EQ && ctype <= COND_GE) {
@@ -410,10 +410,10 @@
     for (aptr = args; *aptr; aptr++)
 	untokenize(*aptr);
     if (inf) {
-	fprintf(stderr, " %s %s %s", args[0], name, args[1]);
+	fprintf(xtrerr, " %s %s %s", args[0], name, args[1]);
     } else {
-	fprintf(stderr, " %s", name);
+	fprintf(xtrerr, " %s", name);
 	while (*args)
-	    fprintf(stderr, " %s", *args++);
+	    fprintf(xtrerr, " %s", *args++);
     }
 }
Index: Src/exec.c
===================================================================
@@ -1195,12 +1195,12 @@
 
 	for (node = firstnode(list); node; incnode(node)) {
 	    *ptr++ = (char *)getdata(node);
-	    zputs(getdata(node), stderr);
+	    zputs(getdata(node), xtrerr);
 	    if (nextnode(node))
-		fputc(' ', stderr);
+		fputc(' ', xtrerr);
 	}
-	fputc('\n', stderr);
-	fflush(stderr);
+	fputc('\n', xtrerr);
+	fflush(xtrerr);
     } else {
 	for (node = firstnode(list); node; incnode(node))
 	    *ptr++ = (char *)getdata(node);
@@ -1404,7 +1404,7 @@
 	name = ecgetstr(state, 1);
 	untokenize(name);
 	if (xtr)
-	    fprintf(stderr, "%s=", name);
+	    fprintf(xtrerr, "%s=", name);
 	if ((isstr = (WC_ASSIGN_TYPE(ac) == WC_ASSIGN_SCALAR))) {
 	    vl = newlinklist();
 	    addlinknode(vl, ecgetstr(state, 1));
@@ -1437,7 +1437,7 @@
 		val = ztrdup(ugetnode(vl));
 	    }
 	    if (xtr)
-		fprintf(stderr, "%s ", val);
+		fprintf(xtrerr, "%s ", val);
 	    if (export && !strchr(name, '[')) {
 		if (export < 0 && isset(RESTRICTED) &&
 		    (pm = (Param) paramtab->removenode(paramtab, name)) &&
@@ -1470,10 +1470,10 @@
 
 	*ptr = NULL;
 	if (xtr) {
-	    fprintf(stderr, "( ");
+	    fprintf(xtrerr, "( ");
 	    for (ptr = arr; *ptr; ptr++)
-		fprintf(stderr, "%s ", *ptr);
-	    fprintf(stderr, ") ");
+		fprintf(xtrerr, "%s ", *ptr);
+	    fprintf(xtrerr, ") ");
 	}
 	setaparam(name, arr);
 	if (errflag) {
@@ -1698,8 +1698,8 @@
 		    else
 			lastval = cmdoutval;
 		    if (isset(XTRACE)) {
-			fputc('\n', stderr);
-			fflush(stderr);
+			fputc('\n', xtrerr);
+			fflush(xtrerr);
 		    }
 		    return;
 		}
@@ -1935,6 +1935,12 @@
 	goto err;
     }
 
+    /* Make a copy of stderr for xtrace output before redirecting */
+    fflush(xtrerr);
+    if (xtrerr == stderr &&
+	!(xtrerr = fdopen(movefd(dup(fileno(stderr))), "w")))
+	xtrerr = stderr;
+
     /* Add pipeline input/output to mnodes */
     if (input)
 	addfd(forked, save, mfds, 0, input, 0);
@@ -2088,7 +2094,7 @@
 	    for (i = 0; i < 10; i++)
 		if (save[i] != -2)
 		    zclose(save[i]);
-	    return;
+	    goto done;
 	}
 	/*
 	 * If nullexec is 2, we have variables to add with the redirections
@@ -2098,8 +2104,8 @@
 	    addvars(state, varspc, 0);
 	lastval = errflag ? errflag : cmdoutval;
 	if (isset(XTRACE)) {
-	    fputc('\n', stderr);
-	    fflush(stderr);
+	    fputc('\n', xtrerr);
+	    fflush(xtrerr);
 	}
     } else if (isset(EXECOPT) && !errflag) {
 	/*
@@ -2138,7 +2144,7 @@
 		    restore_params(restorelist, removelist);
 		    lastval = 1;
 		    fixfds(save);
-		    return;
+		    goto done;
 		}
 	    }
 
@@ -2239,6 +2245,14 @@
     if (forked)
 	_exit(lastval);
     fixfds(save);
+
+ done:
+    if (xtrerr != stderr) {
+	fil = fileno(xtrerr);
+	fclose(xtrerr);
+	zclose(fil);
+	xtrerr = stderr;
+    }
 }
 
 /* Arrange to have variables restored. */
@@ -2870,13 +2884,13 @@
     state->pc--;
     if (isset(XTRACE)) {
 	printprompt4();
-	fprintf(stderr, "[[");
+	fprintf(xtrerr, "[[");
 	tracingcond++;
     }
     stat = !evalcond(state);
     if (isset(XTRACE)) {
-	fprintf(stderr, " ]]\n");
-	fflush(stderr);
+	fprintf(xtrerr, " ]]\n");
+	fflush(xtrerr);
 	tracingcond--;
     }
     return stat;
@@ -2893,18 +2907,18 @@
 
     if (isset(XTRACE)) {
 	printprompt4();
-	fprintf(stderr, "((");
+	fprintf(xtrerr, "((");
     }
     e = ecgetstr(state, 1);
     singsub(&e);
     if (isset(XTRACE))
-	fprintf(stderr, " %s", e);
+	fprintf(xtrerr, " %s", e);
 
     val = mathevali(e);
 
     if (isset(XTRACE)) {
-	fprintf(stderr, " ))\n");
-	fflush(stderr);
+	fprintf(xtrerr, " ))\n");
+	fflush(xtrerr);
     }
     errflag = 0;
     return !val;
@@ -3017,11 +3031,11 @@
 	if (args)
 	    for (lptr = firstnode(args); lptr; incnode(lptr)) {
 		if (lptr != firstnode(args))
-		    fputc(' ', stderr);
-		fprintf(stderr, "%s", (char *)getdata(lptr));
+		    fputc(' ', xtrerr);
+		fprintf(xtrerr, "%s", (char *)getdata(lptr));
 	    }
-	fputc('\n', stderr);
-	fflush(stderr);
+	fputc('\n', xtrerr);
+	fflush(xtrerr);
     }
     ocs = cmdstack;
     ocsp = cmdsp;
Index: Src/init.c
===================================================================
@@ -331,6 +331,9 @@
 	SHTTY = -1;
     }
 
+    /* Send xtrace output to stderr -- see execcmd() */
+    xtrerr = stderr;
+
     /* Make sure the tty is opened read/write. */
     if (isatty(0)) {
 	zsfree(ttystrname);
Index: Src/loop.c
===================================================================
RCS file: /extra/cvsroot/zsh/zsh-3.1/Src/loop.c,v
retrieving revision 1.21
diff -u -r1.21 loop.c
--- loop.c	2000/02/06 18:42:31	1.21
+++ loop.c	2000/02/19 18:53:58
@@ -66,8 +66,8 @@
 	    char *str2 = dupstring(str);
 	    untokenize(str2);
 	    printprompt4();
-	    fprintf(stderr, "%s\n", str2);
-	    fflush(stderr);
+	    fprintf(xtrerr, "%s\n", str2);
+	    fflush(xtrerr);
 	}
 	if (!errflag)
 	    matheval(str);
@@ -105,8 +105,8 @@
 		if (*str) {
 		    if (isset(XTRACE)) {
 			printprompt4();
-			fprintf(stderr, "%s\n", str);
-			fflush(stderr);
+			fprintf(xtrerr, "%s\n", str);
+			fflush(xtrerr);
 		    }
 		    val = mathevali(str);
 		} else
@@ -125,8 +125,8 @@
 		break;
 	    if (isset(XTRACE)) {
 		printprompt4();
-		fprintf(stderr, "%s=%s\n", name, str);
-		fflush(stderr);
+		fprintf(xtrerr, "%s=%s\n", name, str);
+		fflush(xtrerr);
 	    }
 	    setsparam(name, ztrdup(str));
 	}
@@ -144,8 +144,8 @@
 	    str = dupstring(advance);
 	    if (isset(XTRACE)) {
 		printprompt4();
-		fprintf(stderr, "%s\n", str);
-		fflush(stderr);
+		fprintf(xtrerr, "%s\n", str);
+		fflush(xtrerr);
 	    }
 	    singsub(&str);
 	    if (!errflag)
@@ -517,8 +517,8 @@
 	    pat2 = dupstring(pat);
 	    untokenize(pat2);
 	    printprompt4();
-	    fprintf(stderr, "case %s (%s)\n", word, pat2);
-	    fflush(stderr);
+	    fprintf(xtrerr, "case %s (%s)\n", word, pat2);
+	    fflush(xtrerr);
 	    state->pc++;
 	} else
 	    state->pc += 2;
Index: Src/utils.c
===================================================================
@@ -791,9 +791,14 @@
 /* This prints the XTRACE prompt. */
 
 /**/
+FILE *xtrerr = 0;
+
+/**/
 void
 printprompt4(void)
 {
+    if (!xtrerr)
+	xtrerr = stderr;
     if (prompt4) {
 	int l;
 	char *s = dupstring(prompt4);
@@ -801,7 +806,7 @@
 	unmetafy(s, &l);
 	s = unmetafy(promptexpand(metafy(s, l, META_NOALLOC), 0, NULL, NULL), &l);
 
-	fprintf(stderr, "%s", s);
+	fprintf(xtrerr, "%s", s);
     }
 }
 

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com