From 33e1b3f8f7af981256bf26c7eb6285f0d550f520 Mon Sep 17 00:00:00 2001
From: Fred Wright <fw@fwright.net>
Date: Fri, 18 Oct 2024 20:12:10 -0700
Subject: [PATCH] Rewrite symbol aliases test.
The old symbol aliases test relied on looking up symbols with dlsym(),
which doesn't work with a statically-linked library. This rewrites it
to use ordinary external references, which will fail if the referenced
symbols are missing.
This means that any errors are build-time errors rather than runtime
errors. As noted in the comment, there's theoretically a way to avoid
that by using weak references, but we don't bother to wrestle with the
added complications of that approach.
TESTED:
This version passes with both static and dynamic libraries.
---
test/test_symbol_aliases.c | 81 +++++++++++++++++++++++++++++---------
1 file changed, 63 insertions(+), 18 deletions(-)
diff --git a/test/test_symbol_aliases.c b/test/test_symbol_aliases.c
index 5d88b96..a6e0084 100644
--- a/test/test_symbol_aliases.c
+++ b/test/test_symbol_aliases.c
@@ -1,26 +1,71 @@
-#include <dlfcn.h>
-#include <assert.h>
-#include <stdio.h>
+/*
+ * Copyright (c) 2024 Frederick H. G. Wright II <fw@fwright.net>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
-int main()
-{
- void (*fptr)();
+/*
+ * This provides tests to verify that certain symbol aliases are present.
+ *
+ * Although there is probably a way to exploit weak references to defer
+ * errors until runtime, there are some complications with that approach,
+ * so we settle for simple external references, where failures are build
+ * errors rather than runtime errors.
+ */
- // void __bzero(void *s, size_t n);
- fptr = dlsym(RTLD_DEFAULT, "__bzero");
- assert( fptr!=0 && "__bzero symbol does not exist");
+#include <stdio.h>
+#include <string.h>
+
+/* Macro to avoid warnings converting pointer to ULL */
+#if defined(__LP64__) && __LP64__
+#define PTR2ULL(x) ((unsigned long long) (x))
+#else
+#define PTR2ULL(x) ((unsigned long long) (unsigned int) (x))
+#endif
- // int dirfd(DIR *dirp);
- fptr = dlsym(RTLD_DEFAULT, "dirfd");
- assert( fptr!=0 && "dirfd symbol does not exist");
+#define BASE_SYMS \
+ SYM_MAC(__bzero) \
+ SYM_MAC(dirfd)
-#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050 && !defined(__arm64__)
- // int fstatat$INODE64(int dirfd, const char *pathname, struct stat64 *buf, int flags);
- fptr = dlsym(RTLD_DEFAULT, "fstatat$INODE64");
- assert( fptr!=0 && "fstatat$INODE64 symbol does not exist");
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) \
+ && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050 \
+ && !defined(__arm64__)
+ #define CHECK_SYMS BASE_SYMS \
+ SYM_MAC(fstatat$INODE64)
+#else
+ #define CHECK_SYMS BASE_SYMS
#endif
- printf("All symbol aliases found\n");
+#define SYM_MAC(name) \
+ extern void name(); \
+ void *name##_adr = &name;
+CHECK_SYMS
+#undef SYM_MAC
+
+int
+main(int argc, char *argv[])
+{
+ int verbose = 0;
+
+ if (argc > 1 && !strcmp(argv[1], "-v")) verbose = 1;
+
+ if (verbose) {
+ #define SYM_MAC(name) \
+ printf(" " #name " = %llX\n", PTR2ULL(name##_adr));
+ CHECK_SYMS
+ #undef SYM_MAC
+ }
- return 0;
+ printf("symbol aliases test passed.\n");
+ return 0;
}
--
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