libc: add poolisoverlap() and definitions for Pool *secrmem

sys/include/pool.h

@@ -35,6 +35,7 @@ extern void*	poolalloc(Pool*, ulong);
 extern void*	poolallocalign(Pool*, ulong, ulong, long, ulong);
 extern void	poolfree(Pool*, void*);
 extern ulong	poolmsize(Pool*, void*);
+extern int	poolisoverlap(Pool*, void*, ulong);
 extern void*	poolrealloc(Pool*, void*, ulong);
 extern void	poolcheck(Pool*);
 extern int	poolcompact(Pool*);
@@ -43,6 +44,7 @@ extern void	pooldump(Pool*);
 
 extern Pool*	mainmem;
 extern Pool*	imagmem;
+extern Pool*	secrmem;
 
 enum {	/* flags */
 	POOL_ANTAGONISM	= 1<<0,

sys/man/2/pool

@@ -1,6 +1,6 @@
 .TH POOL 2
 .SH NAME
-poolalloc, poolallocalign, poolfree, poolmsize, poolrealloc, poolcompact, poolcheck, poolblockcheck,
+poolalloc, poolallocalign, poolfree, poolmsize, poolisoverlap, poolrealloc, poolcompact, poolcheck, poolblockcheck,
 pooldump \- general memory management routines
 .SH SYNOPSIS
 .B #include <u.h>
@@ -25,6 +25,9 @@ void	poolfree(Pool* pool, void* ptr)
 ulong	poolmsize(Pool* pool, void* ptr)
 .PP
 .B
+int	poolisoverlap(Pool* pool, void* ptr, ulong len)
+.PP
+.B
 void*	poolrealloc(Pool* pool, void* ptr, ulong size)
 .PP
 .B
@@ -109,6 +112,13 @@ that would usually go unused.
 .IR Poolmsize
 grows the block to encompass this extra space and returns the new size.
 .PP
+.I Poolisoverlap
+checks if the byte span
+.BR [ptr , ptr + len)
+overlaps the arenas of the specified
+.BR pool ,
+returning non-zero when there is overlap or zero if none.
+.PP
 The 
 .I poolblockcheck
 and

sys/src/libc/port/pool.c

@@ -1332,6 +1332,19 @@ poolmsize(Pool *p, void *v)
 	return dsize;
 }
 
+int
+poolisoverlap(Pool *p, void *v, ulong n)
+{
+	Arena *a;
+
+	p->lock(p);
+	for(a = p->arenalist; a != nil; a = a->down)
+		if((uchar*)v+n > (uchar*)a && (uchar*)v < (uchar*)a+a->asize)
+			break;
+	p->unlock(p);
+	return a != nil;
+}
+
 /*
  * Debugging
  */