From d43f4efe6075555041ceacb2a50e8a15ff8244f0 Mon Sep 17 00:00:00 2001
From: tg <tg@mirbsd.org>
Date: Tue, 7 Apr 2009 18:56:51 +0000
Subject: [PATCH] employ some "nice" constants and comment lalloc.c

---
 lalloc.c | 35 +++++++++++++++++++++++------------
 sh.h     | 16 +++++++++++++---
 2 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/lalloc.c b/lalloc.c
index 8803038..bc3b28e 100644
--- a/lalloc.c
+++ b/lalloc.c
@@ -1,6 +1,6 @@
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/lalloc.c,v 1.8 2009/04/07 18:46:07 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/lalloc.c,v 1.9 2009/04/07 18:56:51 tg Exp $");
 
 /* build with CPPFLAGS+= -DUSE_REALLOC_MALLOC=0 on ancient systems */
 #if defined(USE_REALLOC_MALLOC) && (USE_REALLOC_MALLOC == 0)
@@ -9,18 +9,21 @@ __RCSID("$MirOS: src/bin/mksh/lalloc.c,v 1.8 2009/04/07 18:46:07 tg Exp $");
 #define remalloc(p,n)	realloc((p), (n))
 #endif
 
-static struct lalloc *findptr(struct lalloc **, char *, Area *);
+static ALLOC_ITEM *findptr(ALLOC_ITEM **, char *, Area *);
 
 void
 ainit(Area *ap)
 {
+	/* area pointer is an ALLOC_ITEM, just the head of the list */
 	ap->next = NULL;
 }
 
-static struct lalloc *
-findptr(struct lalloc **lpp, char *ptr, Area *ap)
+static ALLOC_ITEM *
+findptr(ALLOC_ITEM **lpp, char *ptr, Area *ap)
 {
-	*lpp = (struct lalloc *)(ptr - sizeof (struct lalloc));
+	/* get address of ALLOC_ITEM from user item */
+	*lpp = (ALLOC_ITEM *)(ptr - ALLOC_SIZE);
+	/* search for allocation item in group list */
 	while (ap->next != *lpp)
 		if ((ap = ap->next) == NULL)
 			internal_errorf("rogue pointer %p", ptr);
@@ -30,32 +33,37 @@ findptr(struct lalloc **lpp, char *ptr, Area *ap)
 void *
 aresize(void *ptr, size_t numb, Area *ap)
 {
-	struct lalloc *lp = NULL;
+	ALLOC_ITEM *lp = NULL;
 
+	/* resizing (true) or newly allocating? */
 	if (ptr != NULL) {
-		struct lalloc *pp;
+		ALLOC_ITEM *pp;
 
 		pp = findptr(&lp, ptr, ap);
 		pp->next = lp->next;
 	}
 
-	if ((numb >= SIZE_MAX - sizeof (struct lalloc)) ||
-	    (lp = remalloc(lp, numb + sizeof (struct lalloc))) == NULL)
+	if ((numb >= SIZE_MAX - ALLOC_SIZE) ||
+	    (lp = remalloc(lp, numb + ALLOC_SIZE)) == NULL)
 		internal_errorf("cannot allocate %lu data bytes",
 		    (unsigned long)numb);
+	/* this only works because Area is an ALLOC_ITEM */
 	lp->next = ap->next;
 	ap->next = lp;
-	return ((char *)lp + sizeof (struct lalloc));
+	/* return user item address */
+	return ((char *)lp + ALLOC_SIZE);
 }
 
 void
 afree(void *ptr, Area *ap)
 {
 	if (ptr != NULL) {
-		struct lalloc *lp, *pp;
+		ALLOC_ITEM *lp, *pp;
 
 		pp = findptr(&lp, ptr, ap);
+		/* unhook */
 		pp->next = lp->next;
+		/* now free ALLOC_ITEM */
 		free(lp);
 	}
 }
@@ -63,10 +71,13 @@ afree(void *ptr, Area *ap)
 void
 afreeall(Area *ap)
 {
-	struct lalloc *lp;
+	ALLOC_ITEM *lp;
 
+	/* traverse group (linked list) */
 	while ((lp = ap->next) != NULL) {
+		/* make next ALLOC_ITEM head of list */
 		ap->next = lp->next;
+		/* free old head */
 		free(lp);
 	}
 }
diff --git a/sh.h b/sh.h
index 01b12e2..c9db78d 100644
--- a/sh.h
+++ b/sh.h
@@ -102,7 +102,7 @@
 #define __SCCSID(x)	__IDSTRING(sccsid,x)
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.291 2009/04/07 18:46:07 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.292 2009/04/07 18:56:51 tg Exp $");
 #endif
 #define MKSH_VERSION "R37 2009/04/05"
 
@@ -423,9 +423,19 @@ char *ucstrstr(char *, const char *);
 /*
  * simple grouping allocator
  */
-typedef struct lalloc {
+
+/* 1. internal structure */
+struct lalloc {
 	struct lalloc *next;
-} Area;
+};
+
+/* 2. sizes */
+#define ALLOC_ITEM	struct lalloc
+#define ALLOC_SIZE	(sizeof (ALLOC_ITEM))
+
+/* 3. group structure (only the same for lalloc.c) */
+typedef struct lalloc Area;
+
 
 EXTERN Area aperm;		/* permanent object space */
 #define APERM	&aperm