Author: jilles
Date: Sat May 11 20:51:00 2013
New Revision: 250527
URL: http://svnweb.freebsd.org/changeset/base/250527
Log:
sh: Remove linked list of stack marks.
The linked list of stack marks may cause problems if the allocation stack is
used between an exception and a higher-level popstackmark(), as it may then
touch a stack mark that is local to a function which has returned.
Also, the adjustment compares to a pointer passed to realloc(), which is
undefined behaviour.
Instead of adjusting stack marks when reallocating stack blocks, ensure that
such an adjustment is never necessary by fixing a small piece of memory in
place at a stack mark. This also simplifies the code.
To avoid the problems reported in bin/175922, it remains necessary to call
setstackmark() after popstackmark() if the stack mark remains in use.
Modified:
head/bin/sh/memalloc.c
head/bin/sh/memalloc.h
Modified: head/bin/sh/memalloc.c
==============================================================================
--- head/bin/sh/memalloc.c Sat May 11 19:46:15 2013 (r250526)
+++ head/bin/sh/memalloc.c Sat May 11 20:51:00 2013 (r250527)
@@ -124,7 +124,6 @@ struct stack_block {
#define SPACE(sp) ((char*)(sp) + ALIGN(sizeof(struct stack_block)))
static struct stack_block *stackp;
-static struct stackmark *markp;
char *stacknxt;
int stacknleft;
char *sstrend;
@@ -186,8 +185,9 @@ setstackmark(struct stackmark *mark)
mark->stackp = stackp;
mark->stacknxt = stacknxt;
mark->stacknleft = stacknleft;
- mark->marknext = markp;
- markp = mark;
+ /* Ensure this block stays in place. */
+ if (stackp != NULL && stacknxt == SPACE(stackp))
+ stalloc(1);
}
@@ -197,7 +197,6 @@ popstackmark(struct stackmark *mark)
struct stack_block *sp;
INTOFF;
- markp = mark->marknext;
while (stackp != mark->stackp) {
sp = stackp;
stackp = sp->prev;
@@ -229,7 +228,6 @@ growstackblock(int min)
int oldlen;
struct stack_block *sp;
struct stack_block *oldstackp;
- struct stackmark *xmark;
if (min < stacknleft)
min = stacknleft;
@@ -254,18 +252,6 @@ growstackblock(int min)
stacknxt = SPACE(sp);
stacknleft = newlen - (stacknxt - (char*)sp);
sstrend = stacknxt + stacknleft;
-
- /*
- * Stack marks pointing to the start of the old block
- * must be relocated to point to the new block
- */
- xmark = markp;
- while (xmark != NULL && xmark->stackp == oldstackp) {
- xmark->stackp = stackp;
- xmark->stacknxt = stacknxt;
- xmark->stacknleft = stacknleft;
- xmark = xmark->marknext;
- }
INTON;
} else {
newlen -= ALIGN(sizeof(struct stack_block));
Modified: head/bin/sh/memalloc.h
==============================================================================
--- head/bin/sh/memalloc.h Sat May 11 19:46:15 2013 (r250526)
+++ head/bin/sh/memalloc.h Sat May 11 20:51:00 2013 (r250527)
@@ -39,7 +39,6 @@ struct stackmark {
struct stack_block *stackp;
char *stacknxt;
int stacknleft;
- struct stackmark *marknext;
};
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