implement fixed-size array stack data structure

lib/isc/Makefile.in

@@ -46,7 +46,7 @@ WIN32OBJS = 	win32/condition.@O@ win32/dir.@O@ win32/errno.@O@ \
 
 # Alphabetically
 OBJS =		pk11.@O@ pk11_result.@O@ \
-		aes.@O@ app.@O@ assertions.@O@ \
+		aes.@O@ app.@O@ assertions.@O@ astack.@O@ \
 		backtrace.@O@ base32.@O@ base64.@O@ \
 		bind9.@O@ buffer.@O@ bufferlist.@O@ \
 		commandline.@O@ counter.@O@ crc64.@O@ error.@O@ entropy.@O@ \
@@ -66,7 +66,7 @@ SYMTBLOBJS =	backtrace-emptytbl.@O@
 
 # Alphabetically
 SRCS =		pk11.c pk11_result.c \
-		aes.c app.c assertions.c \
+		aes.c app.c assertions.c astack.c \
 		backtrace.c base32.c base64.c bind9.c \
 		buffer.c bufferlist.c commandline.c counter.c crc64.c \
 		entropy.c error.c event.c hash.c ht.c heap.c \

lib/isc/astack.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <inttypes.h>
+#include <string.h>
+
+#include <isc/astack.h>
+#include <isc/atomic.h>
+#include <isc/mem.h>
+#include <isc/mutex.h>
+#include <isc/types.h>
+#include <isc/util.h>
+
+struct isc_astack {
+	isc_mem_t *mctx;
+	size_t size;
+	size_t pos;
+	isc_mutex_t lock;
+	uintptr_t nodes[];
+};
+
+isc_astack_t *
+isc_astack_new(isc_mem_t *mctx, size_t size) {
+	isc_astack_t *stack =
+		isc_mem_get(mctx,
+			    sizeof(isc_astack_t) + size * sizeof(uintptr_t));
+
+	stack->mctx = NULL;
+	isc_mem_attach(mctx, &stack->mctx);
+	stack->size = size;
+	stack->pos = 0;
+	memset(stack->nodes, 0, size * sizeof(uintptr_t));
+	isc_mutex_init(&stack->lock);
+	return (stack);
+}
+
+bool
+isc_astack_trypush(isc_astack_t *stack, void *obj) {
+	if (isc_mutex_trylock(&stack->lock) == false) {
+		if (stack->pos >= stack->size) {
+			isc_mutex_unlock(&stack->lock);
+			return (false);
+		}
+		stack->nodes[stack->pos++] = (uintptr_t) obj;
+		isc_mutex_unlock(&stack->lock);
+		return (true);
+	} else {
+		return (false);
+	}
+}
+
+void *
+isc_astack_pop(isc_astack_t *stack) {
+	isc_mutex_lock(&stack->lock);
+	uintptr_t rv;
+	if (stack->pos == 0) {
+		rv = 0;
+	} else {
+		rv = stack->nodes[--stack->pos];
+	}
+	isc_mutex_unlock(&stack->lock);
+	return ((void*) rv);
+}
+
+void
+isc_astack_destroy(isc_astack_t *stack) {
+	REQUIRE(stack->pos == 0);
+
+	isc_mem_putanddetach(&stack->mctx, stack,
+			     sizeof(struct isc_astack) +
+			      stack->size * sizeof(uintptr_t));
+}

lib/isc/include/isc/Makefile.in

@@ -18,7 +18,7 @@ VERSION=@BIND9_VERSION@
 # machine generated.  The latter are handled specially in the
 # install target below.
 #
-HEADERS =	aes.h app.h assertions.h atomic.h backtrace.h \
+HEADERS =	aes.h app.h assertions.h astack.h atomic.h backtrace.h \
 		base32.h base64.h bind9.h buffer.h bufferlist.h \
 		commandline.h counter.h crc64.h deprecated.h \
 		endian.h errno.h error.h event.h eventclass.h \

lib/isc/include/isc/astack.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <inttypes.h>
+#include <isc/mem.h>
+#include <isc/types.h>
+
+isc_astack_t *
+isc_astack_new(isc_mem_t *mctx, size_t size);
+/*%<
+ * Allocate and initialize a new array stack of size 'size'.
+ */
+
+void
+isc_astack_destroy(isc_astack_t *stack);
+/*%<
+ * Free an array stack 'stack'.
+ *
+ * Requires:
+ * \li	'stack' is empty.
+ */
+
+bool
+isc_astack_trypush(isc_astack_t *stack, void *obj);
+/*%<
+ * Try to push 'obj' onto array stack 'astack'. On failure, either
+ * because the stack size limit has been reached or because another
+ * thread has already changed the stack pointer, return 'false'.
+ */
+
+void *
+isc_astack_pop(isc_astack_t *stack);
+/*%<
+ * Pop an object off of array stack 'stack'. If the stack is empty,
+ * return NULL.
+ */

lib/isc/include/isc/types.h

@@ -31,6 +31,7 @@
  */
 #define ISC_LIST(type) struct { type *head, *tail; }
 
+typedef struct isc_astack		isc_astack_t;		/*%< Array-based fast stack */
 typedef struct isc_appctx		isc_appctx_t;	 	/*%< Application context */
 typedef struct isc_backtrace_symmap	isc_backtrace_symmap_t; /*%< Symbol Table Entry */
 typedef struct isc_buffer		isc_buffer_t;		/*%< Buffer */

lib/isc/win32/libisc.def.in

@@ -24,6 +24,10 @@ isc_app_start
 isc_app_unblock
 isc_appctx_create
 isc_appctx_destroy
+isc_astack_destroy
+isc_astack_new
+isc_astack_pop
+isc_astack_trypush
 isc__buffer_activeregion
 isc__buffer_add
 isc__buffer_availableregion

lib/isc/win32/libisc.vcxproj.filters.in

@@ -35,6 +35,9 @@
     <ClInclude Include="..\include\isc\assertions.h">
       <Filter>Library Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="..\include\isc\astack.h">
+      <Filter>Library Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="..\include\isc\atomic.h">
       <Filter>Library Header Files</Filter>
     </ClInclude>
@@ -452,6 +455,9 @@
     <ClCompile Include="..\assertions.c">
       <Filter>Library Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\astack.c">
+      <Filter>Library Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="..\backtrace.c">
       <Filter>Library Source Files</Filter>
     </ClCompile>

lib/isc/win32/libisc.vcxproj.in

@@ -288,6 +288,7 @@ copy InstallFiles ..\Build\Release\
     <ClInclude Include="..\include\isc\aes.h" />
     <ClInclude Include="..\include\isc\app.h" />
     <ClInclude Include="..\include\isc\assertions.h" />
+    <ClInclude Include="..\include\isc\astack.h" />
     <ClInclude Include="..\include\isc\atomic.h" />
     <ClInclude Include="..\include\isc\backtrace.h" />
     <ClInclude Include="..\include\isc\base32.h" />
@@ -405,6 +406,7 @@ copy InstallFiles ..\Build\Release\
     <ClCompile Include="..\aes.c" />
     <ClCompile Include="..\app.c" />
     <ClCompile Include="..\assertions.c" />
+    <ClCompile Include="..\astack.c" />
     <ClCompile Include="..\backtrace-emptytbl.c" />
     <ClCompile Include="..\backtrace.c" />
     <ClCompile Include="..\base32.c" />

util/copyrights

@@ -2129,6 +2129,7 @@
 ./lib/isc/api					X	1999,2000,2001,2006,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019
 ./lib/isc/app.c					C	1999,2000,2001,2002,2003,2004,2005,2007,2008,2009,2013,2014,2015,2016,2017,2018,2019
 ./lib/isc/assertions.c				C	1997,1998,1999,2000,2001,2004,2005,2007,2008,2009,2015,2016,2018,2019
+./lib/isc/astack.c				C	2019
 ./lib/isc/backtrace-emptytbl.c			C	2009,2016,2018,2019
 ./lib/isc/backtrace.c				C	2009,2013,2014,2015,2016,2018,2019
 ./lib/isc/base32.c				C	2008,2009,2013,2014,2015,2016,2018,2019
@@ -2156,6 +2157,7 @@
 ./lib/isc/include/isc/aes.h			C	2014,2016,2018,2019
 ./lib/isc/include/isc/app.h			C	1999,2000,2001,2004,2005,2006,2007,2009,2013,2014,2015,2016,2018,2019
 ./lib/isc/include/isc/assertions.h		C	1997,1998,1999,2000,2001,2004,2005,2006,2007,2008,2009,2016,2017,2018,2019
+./lib/isc/include/isc/astack.h			C	2019
 ./lib/isc/include/isc/atomic.h			C	2018,2019
 ./lib/isc/include/isc/backtrace.h		C	2009,2016,2018,2019
 ./lib/isc/include/isc/base32.h			C	2008,2014,2016,2018,2019