engine: platform: android: reformat dlsym-weak and make it C only

engine/platform/android/dlsym-weak.c

@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2008, 2009 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if defined __ANDROID__ && !defined XASH_64BIT
+#include <string.h>
+#include <android/log.h>
+#include "linker.h"
+
+static Elf_Sym *soinfo_elf_lookup( const soinfo *si, unsigned hash, const char *name )
+{
+	const Elf_Sym *symtab = si->symtab;
+	const char *strtab = si->strtab;
+	unsigned n;
+
+	if( si->nbucket == 0 )
+		return NULL;
+
+	for( n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n] )
+	{
+		const Elf_Sym *s = symtab + n;
+
+		if( strcmp( strtab + s->st_name, name ))
+			continue;
+
+		/* only concern ourselves with global and weak symbol definitions */
+		switch( ELF_ST_BIND( s->st_info ))
+		{
+		case STB_GLOBAL:
+		case STB_WEAK:
+			if( s->st_shndx == SHN_UNDEF )
+				continue;
+			return s;
+		}
+	}
+
+	return NULL;
+}
+
+static unsigned elfhash( const unsigned char *name )
+{
+	unsigned h = 0;
+
+	while( *name )
+	{
+		unsigned g;
+
+		h = ( h << 4 ) + *name++;
+		g = h & 0xf0000000;
+		h ^= g;
+		h ^= g >> 24;
+	}
+	return h;
+}
+
+/* This is used by dlsym(3).  It performs symbol lookup only within the
+   specified soinfo object and not in any of its dependencies.
+
+   TODO: Only looking in the specified soinfo seems wrong. dlsym(3) says
+   that it should do a breadth first search through the dependency
+   tree. This agrees with the ELF spec (aka System V Application
+   Binary Interface) where in Chapter 5 it discuss resolving "Shared
+   Object Dependencies" in breadth first search order.
+ */
+static Elf_Sym *dlsym_handle_lookup( const soinfo *si, const char *name )
+{
+	return soinfo_elf_lookup( si, elfhash((const unsigned char *)name ), name );
+}
+
+void *dlsym_weak( void *handle, const char *symbol )
+{
+	soinfo *found = (soinfo *)handle;
+	Elf_Sym *sym = dlsym_handle_lookup( found, symbol );
+
+	if( sym != NULL )
+		return (void*)( sym->st_value + found->base/*load_bias*/ );
+
+	__android_log_print( ANDROID_LOG_ERROR, "dlsym-weak", "Failed when looking up %s\n", symbol );
+	return NULL;
+}
+#endif