ash: [MEMALLOC] Add pushstackmark

Upstream commit:

    Author: Herbert Xu <herbert@gondor.apana.org.au>
    Date:   Sat Oct 6 00:45:52 2007 +0800

    [MEMALLOC] Add pushstackmark

    This patch gets rid of the stack mark tracking hack by allocating a little
    bit of stack memory if we're at risk of planting a stack mark which may be
    grown later.  To do this a new function pushstackmark is added which lets
    the user pick a bigger amount to allocate since some users do that anyway
    after setting a stack mark.

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

diff --git a/shell/ash.c b/shell/ash.c
index 97f8d9377759fa5bdb8cec0541925d790f7d5ca7..f7ce698a38c9d9d7bdc55bc3922e9781b55b435b 100644 (file)
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -1371,13 +1371,11 @@ struct stackmark {
        struct stack_block *stackp;
        char *stacknxt;
        size_t stacknleft;
-       struct stackmark *marknext;
 };
 
 
 struct globals_memstack {
        struct stack_block *g_stackp; // = &stackbase;
-       struct stackmark *markp;
        char *g_stacknxt; // = stackbase.space;
        char *sstrend; // = stackbase.space + MINSIZE;
        size_t g_stacknleft; // = MINSIZE;
@@ -1387,7 +1385,6 @@ struct globals_memstack {
 extern struct globals_memstack *const ash_ptr_to_globals_memstack;
 #define G_memstack (*ash_ptr_to_globals_memstack)
 #define g_stackp     (G_memstack.g_stackp    )
-#define markp        (G_memstack.markp       )
 #define g_stacknxt   (G_memstack.g_stacknxt  )
 #define sstrend      (G_memstack.sstrend     )
 #define g_stacknleft (G_memstack.g_stacknleft)
@@ -1478,13 +1475,26 @@ sstrdup(const char *p)
 }
 
 static void
-setstackmark(struct stackmark *mark)
+grabstackblock(size_t len)
+{
+       len = SHELL_ALIGN(len);
+       g_stacknxt += len;
+       g_stacknleft -= len;
+}
+
+static void
+pushstackmark(struct stackmark *mark, size_t len)
 {
        mark->stackp = g_stackp;
        mark->stacknxt = g_stacknxt;
        mark->stacknleft = g_stacknleft;
-       mark->marknext = markp;
-       markp = mark;
+       grabstackblock(len);
+}
+
+static void
+setstackmark(struct stackmark *mark)
+{
+       pushstackmark(mark, g_stacknxt == g_stackp->space && g_stackp != &stackbase);
 }
 
 static void
@@ -1496,7 +1506,6 @@ popstackmark(struct stackmark *mark)
                return;
 
        INT_OFF;
-       markp = mark->marknext;
        while (g_stackp != mark->stackp) {
                sp = g_stackp;
                g_stackp = sp->prev;
@@ -1530,7 +1539,6 @@ growstackblock(void)
 
        if (g_stacknxt == g_stackp->space && g_stackp != &stackbase) {
                struct stack_block *oldstackp;
-               struct stackmark *xmark;
                struct stack_block *sp;
                struct stack_block *prevstackp;
                size_t grosslen;
@@ -1546,18 +1554,6 @@ growstackblock(void)
                g_stacknxt = sp->space;
                g_stacknleft = newlen;
                sstrend = sp->space + newlen;
-
-               /*
-                * 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 = g_stackp;
-                       xmark->stacknxt = g_stacknxt;
-                       xmark->stacknleft = g_stacknleft;
-                       xmark = xmark->marknext;
-               }
                INT_ON;
        } else {
                char *oldspace = g_stacknxt;
@@ -1570,14 +1566,6 @@ growstackblock(void)
        }
 }
 
-static void
-grabstackblock(size_t len)
-{
-       len = SHELL_ALIGN(len);
-       g_stacknxt += len;
-       g_stacknleft -= len;
-}
-
 /*
  * The following routines are somewhat easier to use than the above.
  * The user declares a variable of type STACKSTR, which may be declared
@@ -2482,8 +2470,7 @@ setprompt_if(smallint do_set, int whichprompt)
                prompt = nullstr;
        }
 #if ENABLE_ASH_EXPAND_PRMT
-       setstackmark(&smark);
-       stalloc(stackblocksize());
+       pushstackmark(&smark, stackblocksize());
 #endif
        putprompt(expandstr(prompt));
 #if ENABLE_ASH_EXPAND_PRMT
@@ -5938,10 +5925,8 @@ expbackq(union node *cmd, int flag)
        struct stackmark smark;
 
        INT_OFF;
-       setstackmark(&smark);
-       dest = expdest;
-       startloc = dest - (char *)stackblock();
-       grabstackstr(dest);
+       startloc = expdest - (char *)stackblock();
+       pushstackmark(&smark, startloc);
        evalbackcmd(cmd, &in);
        popstackmark(&smark);