util: add virendian.h macros

We have several cases where we need to read endian-dependent
data regardless of host endianness; rather than open-coding
these call sites, it will be nicer to funnel things through
a macro.

The virendian.h file can be expanded to add writer functions,
and/or 16-bit access patterns, if needed.  Also, if we need
to turn things into a function to avoid multiple evaluations
of buf, that can be done later.  But for now, a macro worked.

* src/util/virendian.h: New file.
* src/Makefile.am (UTIL_SOURCES): Ship it.
* tests/virendiantest.c: New test.
* tests/Makefile.am (test_programs, virendiantest_SOURCES): Run
the test.
* .gitignore: Ignore built file.

.gitignore

@@ -177,6 +177,7 @@
 /tests/virbitmaptest
 /tests/virbuftest
 /tests/virdrivermoduletest
+/tests/virendiantest
 /tests/virhashtest
 /tests/virkeyfiletest
 /tests/virlockspacetest

src/Makefile.am

@@ -67,6 +67,7 @@ UTIL_SOURCES =							\
 		util/virdbus.c util/virdbus.h			\
 		util/virdnsmasq.c util/virdnsmasq.h		\
 		util/virebtables.c util/virebtables.h		\
+		util/virendian.h				\
 		util/virerror.c util/virerror.h			\
 		util/virevent.c util/virevent.h			\
 		util/vireventpoll.c util/vireventpoll.h		\

src/util/virendian.h

@@ -0,0 +1,93 @@
+/*
+ * virendian.h: aid for reading endian-specific data
+ *
+ * Copyright (C) 2013 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef __VIR_ENDIAN_H__
+# define __VIR_ENDIAN_H__
+
+# include "internal.h"
+
+/* The interfaces in this file are provided as macros for speed.  */
+
+/**
+ * virReadBufInt64BE:
+ * @buf: byte to start reading at (can be 'char*' or 'unsigned char*');
+ *       evaluating buf must not have any side effects
+ *
+ * Read 8 bytes at BUF as a big-endian 64-bit number.  Caller is
+ * responsible to avoid reading beyond array bounds.
+ */
+# define virReadBufInt64BE(buf)                          \
+    (((uint64_t)(uint8_t)((buf)[0]) << 56) |             \
+     ((uint64_t)(uint8_t)((buf)[1]) << 48) |             \
+     ((uint64_t)(uint8_t)((buf)[2]) << 40) |             \
+     ((uint64_t)(uint8_t)((buf)[3]) << 32) |             \
+     ((uint64_t)(uint8_t)((buf)[4]) << 24) |             \
+     ((uint64_t)(uint8_t)((buf)[5]) << 16) |             \
+     ((uint64_t)(uint8_t)((buf)[6]) << 8) |              \
+     (uint64_t)(uint8_t)((buf)[7]))
+
+/**
+ * virReadBufInt64LE:
+ * @buf: byte to start reading at (can be 'char*' or 'unsigned char*');
+ *       evaluating buf must not have any side effects
+ *
+ * Read 8 bytes at BUF as a little-endian 64-bit number.  Caller is
+ * responsible to avoid reading beyond array bounds.
+ */
+# define virReadBufInt64LE(buf)                          \
+    ((uint64_t)(uint8_t)((buf)[0]) |                     \
+     ((uint64_t)(uint8_t)((buf)[1]) << 8) |              \
+     ((uint64_t)(uint8_t)((buf)[2]) << 16) |             \
+     ((uint64_t)(uint8_t)((buf)[3]) << 24) |             \
+     ((uint64_t)(uint8_t)((buf)[4]) << 32) |             \
+     ((uint64_t)(uint8_t)((buf)[5]) << 40) |             \
+     ((uint64_t)(uint8_t)((buf)[6]) << 48) |             \
+     ((uint64_t)(uint8_t)((buf)[7]) << 56))
+
+/**
+ * virReadBufInt32BE:
+ * @buf: byte to start reading at (can be 'char*' or 'unsigned char*');
+ *       evaluating buf must not have any side effects
+ *
+ * Read 4 bytes at BUF as a big-endian 32-bit number.  Caller is
+ * responsible to avoid reading beyond array bounds.
+ */
+# define virReadBufInt32BE(buf)                          \
+    (((uint32_t)(uint8_t)((buf)[0]) << 24) |             \
+     ((uint32_t)(uint8_t)((buf)[1]) << 16) |             \
+     ((uint32_t)(uint8_t)((buf)[2]) << 8) |              \
+     (uint32_t)(uint8_t)((buf)[3]))
+
+/**
+ * virReadBufInt32LE:
+ * @buf: byte to start reading at (can be 'char*' or 'unsigned char*');
+ *       evaluating buf must not have any side effects
+ *
+ * Read 4 bytes at BUF as a little-endian 32-bit number.  Caller is
+ * responsible to avoid reading beyond array bounds.
+ */
+# define virReadBufInt32LE(buf)                          \
+    ((uint32_t)(uint8_t)((buf)[0]) |                     \
+     ((uint32_t)(uint8_t)((buf)[1]) << 8) |              \
+     ((uint32_t)(uint8_t)((buf)[2]) << 16) |             \
+     ((uint32_t)(uint8_t)((buf)[3]) << 24))
+
+#endif /* __VIR_ENDIAN_H__ */

tests/Makefile.am

@@ -1,6 +1,6 @@
 ## Process this file with automake to produce Makefile.in
 
-## Copyright (C) 2005-2012 Red Hat, Inc.
+## Copyright (C) 2005-2013 Red Hat, Inc.
 ## See COPYING.LIB for the License of this software
 
 SHELL = $(PREFERABLY_POSIX_SHELL)
@@ -95,7 +95,7 @@ test_programs = virshtest sockettest \
 	utiltest shunloadtest \
 	virtimetest viruritest virkeyfiletest \
 	virauthconfigtest \
-	virbitmaptest \
+	virbitmaptest virendiantest \
 	virlockspacetest \
 	virstringtest \
         virportallocatortest \
@@ -649,6 +649,10 @@ virbitmaptest_SOURCES = \
 	virbitmaptest.c testutils.h testutils.c
 virbitmaptest_LDADD = $(LDADDS)
 
+virendiantest_SOURCES = \
+	virendiantest.c testutils.h testutils.c
+virendiantest_LDADD = $(LDADDS)
+
 jsontest_SOURCES = \
 	jsontest.c testutils.h testutils.c
 jsontest_LDADD = $(LDADDS)

tests/virendiantest.c

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2013 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <config.h>
+
+#include "testutils.h"
+
+#include "virendian.h"
+
+static int
+test1(const void *data ATTRIBUTE_UNUSED)
+{
+    /* Regular char should work, even if signed, and even with
+     * unaligned access.  */
+    char array[] = { 1, 2, 3, 4, 5, 6, 7, 8,
+                     0x89, 0x8a, 0x8b, 0x8c, 0x8d };
+    int ret = -1;
+
+    if (virReadBufInt64BE(array) != 0x0102030405060708ULL)
+        goto cleanup;
+    if (virReadBufInt64BE(array + 5) != 0x060708898a8b8c8dULL)
+        goto cleanup;
+    if (virReadBufInt64LE(array) != 0x0807060504030201ULL)
+        goto cleanup;
+    if (virReadBufInt64LE(array + 5) != 0x8d8c8b8a89080706ULL)
+        goto cleanup;
+
+    if (virReadBufInt32BE(array) != 0x01020304U)
+        goto cleanup;
+    if (virReadBufInt32BE(array + 9) != 0x8a8b8c8dU)
+        goto cleanup;
+    if (virReadBufInt32LE(array) != 0x04030201U)
+        goto cleanup;
+    if (virReadBufInt32LE(array + 9) != 0x8d8c8b8aU)
+        goto cleanup;
+
+    ret = 0;
+cleanup:
+    return ret;
+}
+
+static int
+test2(const void *data ATTRIBUTE_UNUSED)
+{
+    /* Unsigned char should work without cast, even if unaligned access.  */
+    unsigned char array[] = { 1, 2, 3, 4, 5, 6, 7, 8,
+                              0x89, 0x8a, 0x8b, 0x8c, 0x8d };
+    int ret = -1;
+
+    if (virReadBufInt64BE(array) != 0x0102030405060708ULL)
+        goto cleanup;
+    if (virReadBufInt64BE(array + 5) != 0x060708898a8b8c8dULL)
+        goto cleanup;
+    if (virReadBufInt64LE(array) != 0x0807060504030201ULL)
+        goto cleanup;
+    if (virReadBufInt64LE(array + 5) != 0x8d8c8b8a89080706ULL)
+        goto cleanup;
+
+    if (virReadBufInt32BE(array) != 0x01020304U)
+        goto cleanup;
+    if (virReadBufInt32BE(array + 9) != 0x8a8b8c8dU)
+        goto cleanup;
+    if (virReadBufInt32LE(array) != 0x04030201U)
+        goto cleanup;
+    if (virReadBufInt32LE(array + 9) != 0x8d8c8b8aU)
+        goto cleanup;
+
+    ret = 0;
+cleanup:
+    return ret;
+}
+
+static int
+mymain(void)
+{
+    int ret = 0;
+
+    if (virtTestRun("test1", 1, test1, NULL) < 0)
+        ret = -1;
+    if (virtTestRun("test2", 1, test2, NULL) < 0)
+        ret = -1;
+
+    return ret;
+}
+
+VIRT_TEST_MAIN(mymain)