Changed the POOL_QALIGN flag to POOL_NO_QALIGN, reversing the setting

(making pools aligned by default).  Added the missing code to make the
documented behavior of pool_free() with a NULL addr work.  Updated the
pool_alloc.3 manpage.

flist.c

@@ -2432,7 +2432,7 @@ struct file_list *flist_new(int flags, char *msg)
 	if (flags & FLIST_TEMP) {
 		if (!(flist->file_pool = pool_create(SMALL_EXTENT, 0,
 						     out_of_memory,
-						     POOL_INTERN|POOL_QALIGN)))
+						     POOL_INTERN)))
 			out_of_memory(msg);
 	} else {
 		/* This is a doubly linked list with prev looping back to
@@ -2440,7 +2440,7 @@ struct file_list *flist_new(int flags, char *msg)
 		if (!first_flist) {
 			flist->file_pool = pool_create(NORMAL_EXTENT, 0,
 						       out_of_memory,
-						       POOL_INTERN|POOL_QALIGN);
+						       POOL_INTERN);
 			if (!flist->file_pool)
 				out_of_memory(msg);
 

lib/pool_alloc.3

@@ -95,25 +95,39 @@ for
 .I quantum
 will produce a quantum that should meet maximal alignment
 on most platforms.
-If
-.B POOL_QALIGN
+Unless
+.B POOL_NO_QALIGN
 is set in the
 .IR flags ,
 allocations will be aligned to addresses that are a
 multiple of
 .IR quantum .
+A
+.B NULL
+may be specified for the
+.I bomb
+function pointer if it is not needed.  (See the
+.B pool_alloc()
+function for how it is used.)
 If
 .B POOL_CLEAR
 is set in the
 .IR flags ,
 all allocations from the pool will be initialized to zeros.
-You may specify a
-.B NULL
-for the
-.I bomb
-function pointer if you don't wish to use it.  (See the
-.B pool_alloc()
-function for how it is used.)
+If either
+.B POOL_PREPEND
+or
+.B POOL_INTERN
+is specified in the
+.IR flags ,
+each extent's data structure will be allocated at the start of the
+.IR size -length
+buffer (rather than as a separate, non-pool allocation), with the
+former extending the
+.I size
+to hold the structure, and the latter subtracting the structure's
+length from the indicated
+.IR size .
 .P
 .B pool_destroy()
 destroys an allocation
@@ -131,8 +145,8 @@ is
 .BR 0 ,
 .I quantum
 bytes will be allocated.
-If the pool has been created with
-.BR POOL_QALIGN ,
+If the pool has been created without
+.BR POOL_NO_QALIGN ,
 every chunk of memory that is returned will be suitably aligned.
 You can use this with the default
 .I quantum
@@ -169,7 +183,7 @@ an extent), its memory will be completely freed back to the system.
 If
 .I addr
 is
-.BR 0 ,
+.BR NULL ,
 no memory will be freed, but subsequent allocations will come
 from a new extent.
 .P

lib/pool_alloc.c

@@ -2,7 +2,7 @@
 
 #define POOL_DEF_EXTENT	(32 * 1024)
 
-#define POOL_QALIGN_P2	(1<<16)
+#define POOL_QALIGN_P2		(1<<16)		/* power-of-2 qalign	*/
 
 struct alloc_pool
 {
@@ -72,8 +72,8 @@ pool_create(size_t size, size_t quantum, void (*bomb)(const char *), int flags)
 	}
 
 	if (quantum <= 1)
-		flags &= ~(POOL_QALIGN | POOL_QALIGN_P2);
-	else if (flags & POOL_QALIGN) {
+		flags = (flags | POOL_NO_QALIGN) & ~POOL_QALIGN_P2;
+	else if (!(flags & POOL_NO_QALIGN)) {
 		if (size % quantum)
 			size += quantum - size % quantum;
 		/* If quantum is a power of 2, we'll avoid using modulus. */
@@ -123,7 +123,7 @@ pool_alloc(alloc_pool_t p, size_t len, const char *bomb_msg)
 	else if (pool->flags & POOL_QALIGN_P2) {
 		if (len & (pool->quantum - 1))
 			len += pool->quantum - (len & (pool->quantum - 1));
-	} else if (pool->flags & POOL_QALIGN) {
+	} else if (!(pool->flags & POOL_NO_QALIGN)) {
 		if (len % pool->quantum)
 			len += pool->quantum - len % pool->quantum;
 	}
@@ -185,12 +185,21 @@ pool_free(alloc_pool_t p, size_t len, void *addr)
 	if (!pool)
 		return;
 
+	if (!addr) {
+		/* A NULL addr starts a fresh extent for new allocations. */
+		if ((cur = pool->extents) != NULL && cur->free != pool->size) {
+			cur->bound += cur->free;
+			cur->free = 0;
+		}
+		return;
+	}
+
 	if (!len)
 		len = pool->quantum;
 	else if (pool->flags & POOL_QALIGN_P2) {
 		if (len & (pool->quantum - 1))
 			len += pool->quantum - (len & (pool->quantum - 1));
-	} else if (pool->flags & POOL_QALIGN) {
+	} else if (!(pool->flags & POOL_NO_QALIGN)) {
 		if (len % pool->quantum)
 			len += pool->quantum - len % pool->quantum;
 	}

lib/pool_alloc.h

 #include <stddef.h>
 
 #define POOL_CLEAR	(1<<0)		/* zero fill allocations	*/
-#define POOL_QALIGN	(1<<1)		/* align data to quanta		*/
+#define POOL_NO_QALIGN	(1<<1)		/* don't align data to quanta	*/
 #define POOL_INTERN	(1<<2)		/* Allocate extent structures	*/
 #define POOL_PREPEND	(1<<3)		/*   or prepend to extent data	*/