Introduce a new set of helper macros for mocking symbols

Introduce virmock.h which provides some macros to assist in
creation of LD_PRELOAD overrides. When these are used, the
LD_PRELOAD code simply has some stubs which forward to a
wrapper function inside the main test case. This means that
logic for the test no longer has to be split between the
virXXXtest.c and virXXXmock.c files. It will also make it
possible to provide some common reusable modules for mocking
code like DBus.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

tests/Makefile.am

@@ -129,7 +129,8 @@ EXTRA_DIST =		\
 	xml2sexprdata \
 	xml2vmxdata \
 	vmwareverdata \
-	.valgrind.supp
+	.valgrind.supp \
+	virmock.h
 
 test_helpers = commandhelper ssh test_conf
 test_programs = virshtest sockettest \

tests/virmock.h

+/*
+ * virmock.h: helper for mocking C functions
+ *
+ * Copyright (C) 2014 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_MOCK_H__
+# define __VIR_MOCK_H__
+
+# include <dlfcn.h>
+# include <stdlib.h>
+# include <stdio.h>
+
+# include "internal.h"
+
+# define VIR_MOCK_COUNT_ARGS(...) VIR_MOCK_ARG21(__VA_ARGS__, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
+# define VIR_MOCK_ARG21(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, ...) _21
+# define VIR_MOCK_ARG_PASTE(a, b, ...) a##b(__VA_ARGS__)
+
+# define VIR_MOCK_ARGNAME(a, b) b
+# define VIR_MOCK_ARGTYPE(a, b) a
+# define VIR_MOCK_ARGTYPENAME(a, b) a b
+# define VIR_MOCK_ARGTYPENAME_UNUSED(a, b) a b ATTRIBUTE_UNUSED
+
+# define VIR_MOCK_GET_ARG2(z, a, b) z(a, b)
+# define VIR_MOCK_GET_ARG3(z, a, b, c) z(a, b)
+# define VIR_MOCK_GET_ARG4(z, a, b, c, d) z(a, b),  z(c, d)
+# define VIR_MOCK_GET_ARG5(z, a, b, c, d, e) z(a, b),  z(c, d)
+# define VIR_MOCK_GET_ARG6(z, a, b, c, d, e, f) z(a, b),  z(c, d), z(e, f)
+# define VIR_MOCK_GET_ARG7(z, a, b, c, d, e, f, g) z(a, b),  z(c, d), z(e, f)
+# define VIR_MOCK_GET_ARG8(z, a, b, c, d, e, f, g, h) z(a, b),  z(c, d), z(e, f), z(g, h)
+# define VIR_MOCK_GET_ARG9(z, a, b, c, d, e, f, g, h, i) z(a, b),  z(c, d), z(e, f), z(g, h)
+# define VIR_MOCK_GET_ARG10(z, a, b, c, d, e, f, g, h, i, j) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j)
+# define VIR_MOCK_GET_ARG11(z, a, b, c, d, e, f, g, h, i, j, k) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j)
+# define VIR_MOCK_GET_ARG12(z, a, b, c, d, e, f, g, h, i, j, k, l) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l)
+# define VIR_MOCK_GET_ARG13(z, a, b, c, d, e, f, g, h, i, j, k, l, m) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l)
+# define VIR_MOCK_GET_ARG14(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n)
+# define VIR_MOCK_GET_ARG15(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n)
+# define VIR_MOCK_GET_ARG16(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n), z(o, p)
+# define VIR_MOCK_GET_ARG17(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n), z(o, p)
+# define VIR_MOCK_GET_ARG18(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n), z(o, p), z(q, r)
+# define VIR_MOCK_GET_ARG19(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n), z(o, p), z(q, r)
+# define VIR_MOCK_GET_ARG20(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n), z(o, p), z(q, r), z(s, t)
+# define VIR_MOCK_GET_ARG21(z, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) z(a, b),  z(c, d), z(e, f), z(g, h), z(i, j), z(k, l), z(m, n), z(o, p), z(q, r), z(s, t)
+
+
+# define VIR_MOCK_ARGNAMES_EXPAND(a, b, ...) VIR_MOCK_ARG_PASTE(a, b, __VA_ARGS__)
+# define VIR_MOCK_ARGNAMES(...)                                         \
+    VIR_MOCK_ARGNAMES_EXPAND(VIR_MOCK_GET_ARG, VIR_MOCK_COUNT_ARGS(__VA_ARGS__), VIR_MOCK_ARGNAME, __VA_ARGS__)
+
+# define VIR_MOCK_ARGTYPES_EXPAND(a, b, ...) VIR_MOCK_ARG_PASTE(a, b, __VA_ARGS__)
+# define VIR_MOCK_ARGTYPES(...)                                         \
+    VIR_MOCK_ARGTYPES_EXPAND(VIR_MOCK_GET_ARG, VIR_MOCK_COUNT_ARGS(__VA_ARGS__), VIR_MOCK_ARGTYPE, __VA_ARGS__)
+
+# define VIR_MOCK_ARGTYPENAMES_EXPAND(a, b, ...) VIR_MOCK_ARG_PASTE(a, b, __VA_ARGS__)
+# define VIR_MOCK_ARGTYPENAMES(...)                                     \
+    VIR_MOCK_ARGTYPENAMES_EXPAND(VIR_MOCK_GET_ARG, VIR_MOCK_COUNT_ARGS(__VA_ARGS__), VIR_MOCK_ARGTYPENAME, __VA_ARGS__)
+
+# define VIR_MOCK_ARGTYPENAMES_UNUSED_EXPAND(a, b, ...) VIR_MOCK_ARG_PASTE(a, b, __VA_ARGS__)
+# define VIR_MOCK_ARGTYPENAMES_UNUSED(...)                              \
+    VIR_MOCK_ARGTYPENAMES_UNUSED_EXPAND(VIR_MOCK_GET_ARG, VIR_MOCK_COUNT_ARGS(__VA_ARGS__), VIR_MOCK_ARGTYPENAME_UNUSED, __VA_ARGS__)
+
+
+/*
+ * The VIR_MOCK_LINK_NNN_MMM() macros are intended for use in
+ * LD_PRELOAD based wrappers. They provide a replacement for
+ * for an existing shared library symbol export. They will
+ * then lookup the same symbol name but with 'wrap_' prefixed
+ * on it, and call that.
+ *
+ * The actual test suite should provide the implemention of
+ * the wrap_XXXX symbol, using the VIR_MOCK_WRAP_NNN_MMM
+ * macros.
+ */
+
+
+/**
+ * VIR_MOCK_LINK_RET_ARGS:
+ * @name: the symbol name to replace
+ * @rettype: the return type
+ * @...: pairs of parameter type and parameter name
+ *
+ * Define a replacement for @name which invokes wrap_@name
+ * forwarding on all args, and passing back the return value.
+ */
+# define VIR_MOCK_LINK_RET_ARGS(name, rettype, ...)                     \
+    rettype name(VIR_MOCK_ARGTYPENAMES(__VA_ARGS__))                    \
+    {                                                                   \
+        static rettype (*wrap_##name)(VIR_MOCK_ARGTYPES(__VA_ARGS__));  \
+        if (wrap_##name == NULL &&                                      \
+            !(wrap_##name = dlsym(RTLD_DEFAULT,                         \
+                                  "wrap_" #name))) {                    \
+            fprintf(stderr, "Missing symbol 'wrap_" #name "'\n");       \
+            abort();                                                    \
+        }                                                               \
+                                                                        \
+        return wrap_##name(VIR_MOCK_ARGNAMES(__VA_ARGS__));             \
+    }
+
+/**
+ * VIR_MOCK_LINK_RET_VOID:
+ * @name: the symbol name to replace
+ * @rettype: the return type
+ *
+ * Define a replacement for @name which invokes wrap_@name
+ * with no arguments, and passing back the return value.
+ */
+# define VIR_MOCK_LINK_RET_VOID(name, rettype)                      \
+    rettype name(void)                                              \
+    {                                                               \
+        static rettype (*wrap_##name)(void);                        \
+        if (wrap_##name == NULL &&                                  \
+            !(wrap_##name = dlsym(RTLD_DEFAULT,                     \
+                                  "wrap_" #name))) {                \
+            fprintf(stderr, "Missing symbol 'wrap_" #name "'\n");   \
+            abort();                                                \
+        }                                                           \
+                                                                    \
+        return wrap_##name();                                       \
+    }
+
+/**
+ * VIR_MOCK_LINK_VOID_ARGS:
+ * @name: the symbol name to replace
+ * @...: pairs of parameter type and parameter name
+ *
+ * Define a replacement for @name which invokes wrap_@name
+ * forwarding on all args, but with no return value.
+ */
+# define VIR_MOCK_LINK_VOID_ARGS(name, ...)                         \
+    void name(VIR_MOCK_ARGTYPENAMES(__VA_ARGS__))                   \
+    {                                                               \
+        static void (*wrap_##name)(VIR_MOCK_ARGTYPES(__VA_ARGS__)); \
+        if (wrap_##name == NULL &&                                  \
+            !(wrap_##name = dlsym(RTLD_DEFAULT,                     \
+                                  "wrap_" #name))) {                \
+            fprintf(stderr, "Missing symbol 'wrap_" #name "'\n");   \
+            abort();                                                \
+        }                                                           \
+                                                                    \
+        wrap_##name(VIR_MOCK_ARGNAMES(__VA_ARGS__));                \
+    }
+
+
+
+/*
+ * The VIR_MOCK_STUB_NNN_MMM() macros are intended for use in
+ * LD_PRELOAD based wrappers. They provide a replacement for
+ * for an existing shared library symbol export. They will
+ * be a pure no-op, optionally returning a dummy value.
+ */
+
+
+/**
+ * VIR_MOCK_STUB_RET_ARGS:
+ * @name: the symbol name to replace
+ * @rettype: the return type
+ * @retval: the return value
+ * @...: pairs of parameter type and parameter name
+ *
+ * Define a replacement for @name which invokes wrap_@name
+ * forwarding on all args, and passing back the return value.
+ */
+# define VIR_MOCK_STUB_RET_ARGS(name, rettype, retval, ...)             \
+    rettype name(VIR_MOCK_ARGTYPENAMES_UNUSED(__VA_ARGS__))             \
+    {                                                                   \
+        return retval;                                                  \
+    }
+
+/**
+ * VIR_MOCK_STUB_RET_VOID:
+ * @name: the symbol name to replace
+ * @rettype: the return type
+ *
+ * Define a replacement for @name which invokes wrap_@name
+ * with no arguments, and passing back the return value.
+ */
+# define VIR_MOCK_STUB_RET_VOID(name, rettype, retval)              \
+    rettype name(void)                                              \
+    {                                                               \
+        return retval;                                              \
+    }
+
+/**
+ * VIR_MOCK_STUB_VOID_ARGS:
+ * @name: the symbol name to replace
+ * @...: pairs of parameter type and parameter name
+ *
+ * Define a replacement for @name which invokes wrap_@name
+ * forwarding on all args, but with no return value.
+ */
+# define VIR_MOCK_STUB_VOID_ARGS(name, ...)                         \
+    void name(VIR_MOCK_ARGTYPENAMES_UNUSED(__VA_ARGS__))            \
+    {                                                               \
+    }
+
+
+
+/**
+ * VIR_MOCK_STUB_VOID_VOID:
+ * @name: the symbol name to replace
+ *
+ * Define a replacement for @name which invokes wrap_@name
+ * with no arguments and with no return value
+ */
+# define VIR_MOCK_STUB_VOID_VOID(name)                              \
+    void name(void)                                                 \
+    {                                                               \
+    }
+
+
+/*
+ * The VIR_MOCK_IMPL_NNN_MMM() macros are intended for use in the
+ * individual test suites. The define a stub implementation of
+ * the wrapped method and insert the caller provided code snippet
+ * as the body of the method.
+ */
+
+# define VIR_MOCK_IMPL_RET_ARGS(name, rettype, ...)                     \
+    rettype wrap_##name(VIR_MOCK_ARGTYPENAMES(__VA_ARGS__));            \
+    static rettype (*real_##name)(VIR_MOCK_ARGTYPES(__VA_ARGS__));      \
+    rettype wrap_##name(VIR_MOCK_ARGTYPENAMES_UNUSED(__VA_ARGS__))
+
+# define VIR_MOCK_IMPL_INIT_REAL(name)                                  \
+    do {                                                                \
+        if (real_##name == NULL &&                                      \
+            !(real_##name = dlsym(RTLD_NEXT,                            \
+                                  #name))) {                            \
+            fprintf(stderr, "Missing symbol '" #name "'\n");            \
+            abort();                                                    \
+        }                                                               \
+    } while (0)
+
+# define VIR_MOCK_IMPL_RET_VOID(name, rettype)                          \
+    rettype wrap_##name(void);                                          \
+    static rettype (*real_##name)(void);                                \
+    rettype wrap_##name(void)
+
+# define VIR_MOCK_IMPL_VOID_ARGS(name, ...)                             \
+    void wrap_##name(VIR_MOCK_ARGTYPENAMES(__VA_ARGS__));               \
+    static void (*real_##name)(VIR_MOCK_ARGTYPES(__VA_ARGS__));         \
+    void wrap_##name(VIR_MOCK_ARGTYPENAMES_UNUSED(__VA_ARGS__))
+
+# define VIR_MOCK_IMPL_VOID_VOID(name)                                  \
+    void wrap_##name(void);                                             \
+    static void (*real_##name)(void);                                   \
+    void wrap_##name(void)
+
+#endif /* __VIR_MOCK_H__ */