From ada909acfa49fa59bbd8005e5b118c32447dfad0 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Sat, 31 Mar 2018 10:23:59 +0100
Subject: ash: revise handling of builtin environment variables during fork

Commit db03ff5ea made some improvements to the handling of builtin
environment variables during forkshell.  However, more can be done.

Currently the calculated size of varinit doesn't match what's actually
copied.  It overestimates the amount of string space and the number
of pointers.  The text of each builtin environment variable is also
copied twice:  once as part of vartab and again from varinit.

Remove the code to copy varinit via the forkshell block.  Instead
use information from vartab and varinit_data to reinitialise varinit
and fix the links in vartab.

In addition, ensure that the LINENO variable is properly initialised
in the child.
---
 shell/ash.c | 56 ++++++++++++++++++++++++--------------------------------
 1 file changed, 24 insertions(+), 32 deletions(-)

diff --git a/shell/ash.c b/shell/ash.c
index 2d51b48f9..57f87f0e1 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -14946,27 +14946,31 @@ forkshell_child(struct forkshell *fs)
 }
 
 /*
- * Reset the pointers to the builtin environment variables in the hash
- * table to point to varinit rather than the bogus copy created during
- * forkshell_prepare.
+ * Reinitialise the builtin environment variables in varinit.  Their
+ * current settings have been copied from the parent in vartab.  Look
+ * these up using the names from varinit_data, copy the details from
+ * vartab to varinit and replace the old copy in vartab with the new
+ * one in varinit.
+ *
+ * Also reinitialise the function pointers and line number variable.
  */
 static void
 reinitvar(void)
 {
-	struct var *vp;
-	struct var *end;
-	struct var **vpp;
-	struct var **old;
+	int i;
+	const char *name;
+	struct var **vpp, **old;
 
-	vp = varinit;
-	end = vp + ARRAY_SIZE(varinit);
-	do {
-		vpp = hashvar(vp->var_text);
-		if ( (old=findvar(vpp, vp->var_text)) != NULL ) {
-			vp->next = (*old)->next;
-			*old = vp;
+	for (i=0; i<ARRAY_SIZE(varinit); ++i) {
+		name = varinit_data[i].var_text ? varinit_data[i].var_text : "LINENO=";
+		vpp = hashvar(name);
+		if ( (old=findvar(vpp, name)) != NULL ) {
+			varinit[i] = **old;
+			*old = varinit+i;
 		}
-	} while (++vp < end);
+		varinit[i].var_func = varinit_data[i].var_func;
+	}
+	vlineno.var_text = linenovar;
 }
 
 /* FIXME: should consider running forkparent() and forkchild() */
@@ -15049,10 +15053,6 @@ SLIST_SIZE_END()
 SLIST_COPY_BEGIN(var_copy,struct var)
 (*vpp)->var_text = nodeckstrdup(vp->var_text);
 (*vpp)->flags = vp->flags;
-/*
- * The only place that can set struct var#func is varinit[],
- * which will be fixed by forkshell_init()
- */
 (*vpp)->var_func = NULL;
 SAVE_PTR((*vpp)->var_text);
 SLIST_COPY_END()
@@ -15230,12 +15230,12 @@ globals_var_size(struct globals_var *gvp)
 	redirtab_size(gvp->redirlist);
 	for (i = 0; i < VTABSIZE; i++)
 		var_size(gvp->vartab[i]);
-	for (i = 0; i < ARRAY_SIZE(varinit_data); i++)
-		var_size(gvp->varinit+i);
-	nodeptrsize += 2 + VTABSIZE; /* gvp->redirlist, gvp->shellparam.p, vartab  */
+	nodeptrsize += 2 + VTABSIZE; /* gvp->redirlist, gvp->shellparam.p, vartab */
 }
 
 #undef preverrout_fd
+#undef lineno
+#undef linenovar
 static struct globals_var *
 globals_var_copy(struct globals_var *gvp)
 {
@@ -15260,14 +15260,8 @@ globals_var_copy(struct globals_var *gvp)
 		SAVE_PTR(new->vartab[i]);
 	}
 
-	/* Can't use var_copy because varinit is already allocated */
-	for (i = 0; i < ARRAY_SIZE(varinit_data); i++) {
-		new->varinit[i].next = NULL;
-		new->varinit[i].var_text = nodeckstrdup(gvp->varinit[i].var_text);
-		SAVE_PTR(new->varinit[i].var_text);
-		new->varinit[i].flags = gvp->varinit[i].flags;
-		new->varinit[i].var_func = gvp->varinit[i].var_func;
-	}
+	new->lineno = gvp->lineno;
+	strcpy(new->linenovar, gvp->linenovar);
 	return new;
 }
 
@@ -15425,8 +15419,6 @@ forkshell_init(const char *idstr)
 	}
 
 	/* Now fix up stuff that can't be transferred */
-	for (i = 0; i < ARRAY_SIZE(varinit_data); i++)
-		fs->gvp->varinit[i].var_func = varinit_data[i].var_func;
 	for (i = 0; i < CMDTABLESIZE; i++) {
 		struct tblentry *e = fs->cmdtable[i];
 		while (e) {
-- 
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