Added IMemoryUtils::ResolveSymbol() for resolving symbols hidden via GCC's -fvisibility=hidden (bug 4091, r=dvander,pred).

Right now, this is only used on L4D2 where it is needed.

core/GameConfigs.cpp

@@ -1,8 +1,8 @@
 /**
- * vim: set ts=4 :
+ * vim: set ts=4 sw=4 tw=99 noet :
  * =============================================================================
  * SourceMod
- * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
+ * Copyright (C) 2004-2009 AlliedModders LLC.  All rights reserved.
  * =============================================================================
  *
  * This program is free software; you can redistribute it and/or modify it under
@@ -25,8 +25,6 @@
  * this exception to all derivative works.  AlliedModders LLC defines further
  * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
  * or <http://www.sourcemod.net/license.php>.
- *
- * Version: $Id$
  */
 
 #include <string.h>
@@ -506,7 +504,11 @@ SMCResult CGameConfig::ReadSMC_LeavingSection(const SMCStates *states)
 						void *handle = dlopen(info.dli_fname, RTLD_NOW);
 						if (handle)
 						{
+#if SOURCE_ENGINE == SE_LEFT4DEAD2
+							final_addr = g_MemUtils.ResolveSymbol(handle, &s_TempSig.sig[1]);
+#else
 							final_addr = dlsym(handle, &s_TempSig.sig[1]);
+#endif
 							dlclose(handle);
 						} else {
 							g_Logger.LogError("[SM] Unable to load library \"%s\" (gameconf \"%s\")",

core/MemoryUtils.cpp

@@ -1,8 +1,8 @@
 /**
- * vim: set ts=4 :
+ * vim: set ts=4 sw=4 tw=99 noet :
  * =============================================================================
  * SourceMod
- * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
+ * Copyright (C) 2004-2009 AlliedModders LLC.  All rights reserved.
  * =============================================================================
  *
  * This program is free software; you can redistribute it and/or modify it under
@@ -25,15 +25,14 @@
  * this exception to all derivative works.  AlliedModders LLC defines further
  * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
  * or <http://www.sourcemod.net/license.php>.
- *
- * Version: $Id$
  */
 
 #include "MemoryUtils.h"
 #include "ShareSys.h"
 #ifdef PLATFORM_LINUX
-#include <string.h>
+#include <fcntl.h>
-#include <elf.h>
+#include <link.h>
+#include <sys/mman.h>
 #endif
 
 MemoryUtils g_MemUtils;
@@ -56,6 +55,17 @@ MemoryUtils::MemoryUtils()
 }
 #endif
 
+MemoryUtils::~MemoryUtils()
+{
+#ifdef PLATFORM_LINUX
+	for (size_t i = 0; i < m_SymTables.size(); i++)
+	{
+		delete m_SymTables[i];
+	}
+	m_SymTables.clear();
+#endif
+}
+
 void MemoryUtils::OnSourceModAllInitialized()
 {
 	g_ShareSys.AddInterface(NULL, this);
@@ -98,6 +108,149 @@ void *MemoryUtils::FindPattern(const void *libPtr, const char *pattern, size_t l
 	return NULL;
 }
 
+void *MemoryUtils::ResolveSymbol(void *handle, const char *symbol)
+{
+#ifdef PLATFORM_WINDOWS
+
+	return GetProcAddress((HMODULE)handle, symbol);
+
+#elif defined PLATFORM_LINUX
+
+	struct link_map *dlmap;
+	struct stat dlstat;
+	int dlfile;
+	uintptr_t map_base;
+	Elf32_Ehdr *file_hdr;
+	Elf32_Shdr *sections, *shstrtab_hdr, *symtab_hdr, *strtab_hdr;
+	Elf32_Sym *symtab;
+	const char *shstrtab, *strtab;
+	uint16_t section_count;
+	uint32_t symbol_count;
+	LibSymbolTable *libtable;
+	SymbolTable *table;
+	Symbol *symbol_entry;
+
+	dlmap = (struct link_map *)handle;
+	symtab_hdr = NULL;
+	strtab_hdr = NULL;
+	table = NULL;
+	
+	/* See if we already have a symbol table for this library */
+	for (size_t i = 0; i < m_SymTables.size(); i++)
+	{
+		libtable = m_SymTables[i];
+		if (libtable->lib_base == dlmap->l_addr)
+		{
+			table = &libtable->table;
+			break;
+		}
+	}
+
+	/* If we don't have a symbol table for this library, then create one */
+	if (table == NULL)
+	{
+		libtable = new LibSymbolTable();
+		libtable->table.Initialize();
+		libtable->lib_base = dlmap->l_addr;
+		libtable->last_pos = 0;
+		table = &libtable->table;
+		m_SymTables.push_back(libtable);
+	}
+
+	/* See if the symbol is already cached in our table */
+	symbol_entry = table->FindSymbol(symbol, strlen(symbol));
+	if (symbol_entry != NULL)
+	{
+		return symbol_entry->address;
+	}
+
+	/* If symbol isn't in our table, then we have open the actual library */
+	dlfile = open(dlmap->l_name, O_RDONLY);
+	if (dlfile == -1 || fstat(dlfile, &dlstat) == -1)
+	{
+		close(dlfile);
+		return NULL;
+	}
+
+	/* Map library file into memory */
+	file_hdr = (Elf32_Ehdr *)mmap(NULL, dlstat.st_size, PROT_READ, MAP_PRIVATE, dlfile, 0);
+	map_base = (uintptr_t)file_hdr;
+	if (file_hdr == MAP_FAILED)
+	{
+		close(dlfile);
+		return NULL;
+	}
+	close(dlfile);
+
+	if (file_hdr->e_shoff == 0 || file_hdr->e_shstrndx == SHN_UNDEF)
+	{
+		munmap(file_hdr, dlstat.st_size);
+		return NULL;
+	}
+
+	sections = (Elf32_Shdr *)(map_base + file_hdr->e_shoff);
+	section_count = file_hdr->e_shnum;
+	/* Get ELF section header string table */
+	shstrtab_hdr = &sections[file_hdr->e_shstrndx];
+	shstrtab = (const char *)(map_base + shstrtab_hdr->sh_offset);
+
+	/* Iterate sections while looking for ELF symbol table and string table */
+	for (uint16_t i = 0; i < section_count; i++)
+	{
+		Elf32_Shdr &hdr = sections[i];
+		const char *section_name = shstrtab + hdr.sh_name;
+
+		if (strcmp(section_name, ".symtab") == 0)
+		{
+			symtab_hdr = &hdr;
+		}
+		else if (strcmp(section_name, ".strtab") == 0)
+		{
+			strtab_hdr = &hdr;
+		}
+	}
+
+	/* Uh oh, we don't have a symbol table or a string table */
+	if (symtab_hdr == NULL || strtab_hdr == NULL)
+	{
+		munmap(file_hdr, dlstat.st_size);
+		return NULL;
+	}
+
+	symtab = (Elf32_Sym *)(map_base + symtab_hdr->sh_offset);
+	strtab = (const char *)(map_base + strtab_hdr->sh_offset);
+	symbol_count = symtab_hdr->sh_size / symtab_hdr->sh_entsize;
+
+	/* Iterate symbol table starting from the position we were at last time */
+	for (uint32_t i = libtable->last_pos; i < symbol_count; i++)
+	{
+		Elf32_Sym &sym = symtab[i];
+		unsigned char sym_type = ELF32_ST_TYPE(sym.st_info);
+		const char *sym_name = strtab + sym.st_name;
+		Symbol *cur_sym;
+
+		/* Skip symbols that are undefined or do not refer to functions or objects */
+		if (sym.st_shndx == SHN_UNDEF || (sym_type != STT_FUNC && sym_type != STT_OBJECT))
+		{
+			continue;
+		}
+
+		/* Caching symbols as we go along */
+		cur_sym = table->InternSymbol(sym_name, strlen(sym_name), (void *)(dlmap->l_addr + sym.st_value));
+		if (strcmp(symbol, sym_name) == 0)
+		{
+			symbol_entry = cur_sym;
+			libtable->last_pos = ++i;
+			break;
+		}
+	}
+
+	munmap(file_hdr, dlstat.st_size);
+	return symbol_entry ? symbol_entry->address : NULL;
+
+#endif
+}
+
 bool MemoryUtils::GetLibraryInfo(const void *libPtr, DynLibInfo &lib)
 {
 	unsigned long baseAddr;

core/MemoryUtils.h

@@ -1,8 +1,8 @@
 /**
- * vim: set ts=4 :
+ * vim: set ts=4 sw=4 tw=99 noet :
  * =============================================================================
  * SourceMod
- * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
+ * Copyright (C) 2004-2000 AlliedModders LLC.  All rights reserved.
  * =============================================================================
  *
  * This program is free software; you can redistribute it and/or modify it under
@@ -25,8 +25,6 @@
  * this exception to all derivative works.  AlliedModders LLC defines further
  * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
  * or <http://www.sourcemod.net/license.php>.
- *
- * Version: $Id$
  */
 
 #ifndef _INCLUDE_SOURCEMOD_MEMORYUTILS_H_
@@ -34,6 +32,12 @@
 
 #include <IMemoryUtils.h>
 #include "sm_globals.h"
+#ifdef PLATFORM_LINUX
+#include <sh_vector.h>
+#include "sm_symtable.h"
+
+using namespace SourceHook;
+#endif
 
 using namespace SourceMod;
 
@@ -43,16 +47,34 @@ struct DynLibInfo
 	size_t memorySize;
 };
 
+#ifdef PLATFORM_LINUX
+typedef uint32_t Elf32_Addr;
+
+struct LibSymbolTable
+{
+	SymbolTable table;
+	Elf32_Addr lib_base;
+	uint32_t last_pos;
+};
+#endif
+
 class MemoryUtils : 
 	public IMemoryUtils,
 	public SMGlobalClass
 {
+public:
+	~MemoryUtils();
 public: // SMGlobalClass
 	void OnSourceModAllInitialized();
 public: // IMemoryUtils
 	void *FindPattern(const void *libPtr, const char *pattern, size_t len);
+	void *ResolveSymbol(void *handle, const char *symbol);
 public:
 	bool GetLibraryInfo(const void *libPtr, DynLibInfo &lib);
+#ifdef PLATFORM_LINUX
+private:
+	CVector<LibSymbolTable *> m_SymTables;
+#endif
 };
 
 extern MemoryUtils g_MemUtils;

core/msvc9/sourcemod_mm.vcproj

@@ -60,6 +60,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -224,6 +225,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -308,6 +310,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -472,6 +475,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -556,6 +560,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -638,6 +643,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -719,6 +725,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -803,6 +810,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -885,6 +893,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -966,6 +975,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -1050,6 +1060,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -1214,6 +1225,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -1298,6 +1310,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -1548,6 +1561,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -1712,6 +1726,7 @@
 			<Tool
 				Name="VCResourceCompilerTool"
 				PreprocessorDefinitions="BINARY_NAME=\&quot;$(TargetFileName)\&quot;"
+				AdditionalIncludeDirectories="..\..\public"
 			/>
 			<Tool
 				Name="VCPreLinkEventTool"
@@ -2263,6 +2278,10 @@
 				RelativePath="..\sm_stringutil.h"
 				>
 			</File>
+			<File
+				RelativePath="..\sm_symtable.h"
+				>
+			</File>
 			<File
 				RelativePath="..\sm_trie.h"
 				>

core/sm_symtable.h

@@ -0,0 +1,231 @@
+/**
+ * vim: set ts=4 sw=4 tw=99 noet :
+ * =============================================================================
+ * SourceMod
+ * Copyright (C) 2004-2009 AlliedModders LLC.  All rights reserved.
+ * =============================================================================
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, version 3.0, as published by the
+ * Free Software Foundation.
+ * 
+ * This program 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 General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As a special exception, AlliedModders LLC gives you permission to link the
+ * code of this program (as well as its derivative works) to "Half-Life 2," the
+ * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software
+ * by the Valve Corporation.  You must obey the GNU General Public License in
+ * all respects for all other code used.  Additionally, AlliedModders LLC grants
+ * this exception to all derivative works.  AlliedModders LLC defines further
+ * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
+ * or <http://www.sourcemod.net/license.php>.
+ */
+
+#ifndef _INCLUDE_SOURCEMOD_CORE_SYMBOLTABLE_H_
+#define _INCLUDE_SOURCEMOD_CORE_SYMBOLTABLE_H_
+
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+#define KESTRING_TABLE_START_SIZE 65536
+
+struct Symbol
+{
+	size_t length;
+	uint32_t hash;
+	void *address;
+	Symbol *tbl_next;
+
+	inline char *buffer()
+	{
+		return reinterpret_cast<char *>(this + 1);
+	}
+};
+
+class SymbolTable
+{
+public:
+	~SymbolTable()
+	{
+		for (uint32_t i = 0; i < nbuckets; i++)
+		{
+			Symbol *sym = buckets[i];
+			while (sym != NULL)
+			{
+				Symbol *next = sym->tbl_next;
+				free(sym);
+				sym = next;
+			}
+		}
+		free(buckets);
+	}
+
+	bool Initialize()
+	{
+		buckets = (Symbol **)malloc(sizeof(Symbol *) * KESTRING_TABLE_START_SIZE);
+		if (buckets == NULL)
+		{
+			return false;
+		}
+		memset(buckets, 0, sizeof(Symbol *) * KESTRING_TABLE_START_SIZE);
+
+		nbuckets = KESTRING_TABLE_START_SIZE;
+		nused = 0;
+		bucketmask = KESTRING_TABLE_START_SIZE - 1;
+		return true;
+	}
+
+	static inline uint32_t HashString(const char *data, size_t len)
+	{
+		#undef get16bits
+		#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
+				|| defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
+			#define get16bits(d) (*((const uint16_t *) (d)))
+		#endif
+		#if !defined (get16bits)
+			#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
+											 +(uint32_t)(((const uint8_t *)(d))[0]) )
+		#endif
+		uint32_t hash = len, tmp;
+		int rem;
+
+		if (len <= 0 || data == NULL)
+		{
+			return 0;
+		}
+
+		rem = len & 3;
+		len >>= 2;
+
+		/* Main loop */
+		for (;len > 0; len--) {
+				hash	+= get16bits (data);
+				tmp		= (get16bits (data+2) << 11) ^ hash;
+				hash	 = (hash << 16) ^ tmp;
+				data	+= 2 * sizeof (uint16_t);
+				hash	+= hash >> 11;
+		}
+
+		/* Handle end cases */
+		switch (rem) {
+				case 3: hash += get16bits (data);
+								hash ^= hash << 16;
+								hash ^= data[sizeof (uint16_t)] << 18;
+								hash += hash >> 11;
+								break;
+				case 2: hash += get16bits (data);
+								hash ^= hash << 11;
+								hash += hash >> 17;
+								break;
+				case 1: hash += *data;
+								hash ^= hash << 10;
+								hash += hash >> 1;
+		}
+
+		/* Force "avalanching" of final 127 bits */
+		hash ^= hash << 3;
+		hash += hash >> 5;
+		hash ^= hash << 4;
+		hash += hash >> 17;
+		hash ^= hash << 25;
+		hash += hash >> 6;
+
+		return hash;
+
+		#undef get16bits
+	}
+
+	Symbol **FindSymbolBucket(const char *str, size_t len, uint32_t hash)
+	{
+		uint32_t bucket = hash & bucketmask;
+		Symbol **pkvs = &buckets[bucket];
+
+		Symbol *kvs = *pkvs;
+		while (kvs != NULL)
+		{
+			if (len == kvs->length && memcmp(str, kvs->buffer(), len * sizeof(char)) == 0)
+			{
+				return pkvs;
+			}
+			pkvs = &kvs->tbl_next;
+			kvs = *pkvs;
+		}
+
+		return pkvs;
+	}
+
+	void ResizeSymbolTable()
+	{
+		uint32_t xnbuckets = nbuckets * 2;
+		Symbol **xbuckets = (Symbol **)malloc(sizeof(Symbol *) * xnbuckets);
+		if (xbuckets == NULL)
+		{
+			return;
+		}
+		memset(xbuckets, 0, sizeof(Symbol *) * xnbuckets);
+		uint32_t xbucketmask = xnbuckets - 1;
+		for (uint32_t i = 0; i < nbuckets; i++)
+		{
+			Symbol *sym = buckets[i];
+			while (sym != NULL)
+			{
+				Symbol *next = sym->tbl_next;
+				uint32_t bucket = sym->hash & xbucketmask;
+				sym->tbl_next = xbuckets[bucket];
+				xbuckets[bucket] = sym;
+				sym = next;
+			}
+		}
+		free(buckets);
+		buckets = xbuckets;
+		nbuckets = xnbuckets;
+		bucketmask = xbucketmask;
+	}
+
+	Symbol *FindSymbol(const char *str, size_t len)
+	{
+		uint32_t hash = HashString(str, len);
+		Symbol **pkvs = FindSymbolBucket(str, len, hash);
+		return *pkvs;
+	}
+
+	Symbol *InternSymbol(const char* str, size_t len, void *address)
+	{
+		uint32_t hash = HashString(str, len);
+		Symbol **pkvs = FindSymbolBucket(str, len, hash);
+		if (*pkvs != NULL)
+		{
+			return *pkvs;
+		}
+
+		Symbol *kvs = (Symbol *)malloc(sizeof(Symbol) + sizeof(char) * (len + 1));
+		kvs->length = len;
+		kvs->hash = hash;
+		kvs->address = address;
+		kvs->tbl_next = NULL;
+		memcpy(kvs + 1, str, sizeof(char) * (len + 1));
+		*pkvs = kvs;
+		nused++;
+
+		if (nused > nbuckets && nbuckets <= INT_MAX / 2)
+		{
+			ResizeSymbolTable();
+		}
+
+		return kvs;
+	}
+private:
+	uint32_t nbuckets;
+	uint32_t nused;
+	uint32_t bucketmask;
+	Symbol **buckets;
+};
+
+#endif //_INCLUDE_SOURCEMOD_CORE_SYMBOLTABLE_H_

extensions/sdktools/vcaller.cpp

@@ -1,8 +1,8 @@
 /**
- * vim: set ts=4 :
+ * vim: set ts=4 sw=4 tw=99 noet :
  * =============================================================================
  * SourceMod SDKTools Extension
- * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
+ * Copyright (C) 2004-2009 AlliedModders LLC.  All rights reserved.
  * =============================================================================
  *
  * This program is free software; you can redistribute it and/or modify it under
@@ -25,8 +25,6 @@
  * this exception to all derivative works.  AlliedModders LLC defines further
  * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
  * or <http://www.sourcemod.net/license.php>.
- *
- * Version: $Id$
  */
 
 #include "extension.h"
@@ -131,7 +129,11 @@ static cell_t PrepSDKCall_SetSignature(IPluginContext *pContext, const cell_t *p
 		{
 			return 0;
 		}
+#if SOURCE_ENGINE == SE_LEFT4DEAD2
+		s_call_addr = memutils->ResolveSymbol(handle, &sig[1]);
+#else
 		s_call_addr = dlsym(handle, &sig[1]);
+#endif
 		dlclose(handle);
 
 		return (s_call_addr != NULL) ? 1 : 0;

public/IMemoryUtils.h

@@ -1,8 +1,8 @@
 /**
- * vim: set ts=4 :
+ * vim: set ts=4 sw=4 tw=99 noet :
  * =============================================================================
  * SourceMod
- * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
+ * Copyright (C) 2004-2009 AlliedModders LLC.  All rights reserved.
  * =============================================================================
  *
  * This program is free software; you can redistribute it and/or modify it under
@@ -25,8 +25,6 @@
  * this exception to all derivative works.  AlliedModders LLC defines further
  * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
  * or <http://www.sourcemod.net/license.php>.
- *
- * Version: $Id$
  */
 
 #ifndef _INCLUDE_SOURCEMOD_INTERFACE_BINARYUTILS_H_
@@ -35,7 +33,7 @@
 #include <IShareSys.h>
 
 #define SMINTERFACE_MEMORYUTILS_NAME		"IMemoryUtils"
-#define SMINTERFACE_MEMORYUTILS_VERSION		1
+#define SMINTERFACE_MEMORYUTILS_VERSION		2
 
 /**
  * @file IMemoryUtils.h
@@ -65,6 +63,19 @@ namespace SourceMod
 		 * @return			Pointer to pattern found in memory, NULL if not found.
 		 */
 		virtual void *FindPattern(const void *libPtr, const char *pattern, size_t len) =0;
+
+		/**
+		 * @brief Retrieves a symbol pointer from a dynamic library.
+		 *
+		 * Note: On Linux, this function is able to resolve symbols that are hidden via GCC's
+		 * -fvisibility=hidden option.
+		 *
+		 * @param handle	Operating system specific handle that points to dynamic library.
+		 *					This comes from dlopen() on Linux or LoadLibrary() on Windows.
+		 * @param symbol	Symbol name.
+		 * @return			Symbol pointer, or NULL if not found.
+		 */
+		virtual void *ResolveSymbol(void *handle, const char *symbol) =0;
 	};
 }