Fix dladdr behaviour

* If dladdr can't find an exact match, it returns the nearest symbol
  less than the given address.
* If no suitable symbol can be found, but the address is within a
  loaded library, dladdr returns the library name and base address.

Signed-off-by: Ingo Weinhold <[email protected]>

headers/private/runtime_loader/runtime_loader.h

@@ -36,8 +36,9 @@ struct rld_export {
 	status_t (*get_nth_image_symbol)(image_id imageID, int32 num,
 		char *symbolName, int32 *nameLength, int32 *symbolType,
 		void **_location);
-	status_t (*get_symbol_at_address)(void* address, image_id* _imageID,
+	status_t (*get_nearest_symbol_at_address)(void* address,
-		char* nameBuffer, int32* _nameLength, int32* _type, void** _location);
+		image_id* _imageID,	char** _imagePath, char** _symbolName,
+		int32* _type, void** _location);
 	status_t (*test_executable)(const char *path, char *interpreter);
 	status_t (*get_next_image_dependency)(image_id id, uint32 *cookie,
 		const char **_name);

src/system/libroot/posix/dlfcn.c

@@ -74,15 +74,14 @@ dlerror(void)
 int
 dladdr(void *address, Dl_info *info)
 {
-	static char sImageName[MAXPATHLEN];
-	static char sSymbolName[NAME_MAX];
-
 	image_id image;
-	int32 nameLength = sizeof(sSymbolName);
+	char* imagePath;
+	char* symbolName;
 	void* location;
 	image_info imageInfo;
-	sStatus = __gRuntimeLoader->get_symbol_at_address(address, &image,
+
-		sSymbolName, &nameLength, NULL, &location);
+	sStatus = __gRuntimeLoader->get_nearest_symbol_at_address(address, &image,
+		&imagePath, &symbolName, NULL, &location);
 	if (sStatus != B_OK)
 		return 0;
 
@@ -90,10 +89,9 @@ dladdr(void *address, Dl_info *info)
 	if (sStatus != B_OK)
 		return 0;
 
-	strlcpy(sImageName, imageInfo.name, MAXPATHLEN);
+	info->dli_fname = imagePath;
-	info->dli_fname = sImageName;
 	info->dli_fbase = imageInfo.text;
-	info->dli_sname = sSymbolName;
+	info->dli_sname = symbolName;
 	info->dli_saddr = location;
 
 	return 1;

src/system/runtime_loader/elf.cpp

@@ -710,8 +710,8 @@ out:
 
 
 status_t
-get_symbol_at_address(void* address, image_id* _imageID, char* nameBuffer,
+get_nearest_symbol_at_address(void* address, image_id* _imageID,
-	int32* _nameLength, int32* _type, void** _location)
+	char** _imagePath, char** _symbolName, int32* _type, void** _location)
 {
 	rld_lock();
 
@@ -721,42 +721,57 @@ get_symbol_at_address(void* address, image_id* _imageID, char* nameBuffer,
 		return B_BAD_VALUE;
 	}
 
-	for (uint32 i = 0; i < HASHTABSIZE(image); i++) {
+	struct Elf32_Sym* foundSymbol = NULL;
+	addr_t foundLocation = (addr_t)NULL;
+
+	bool found = false;
+	for (uint32 i = 0; i < HASHTABSIZE(image) && !found; i++) {
 		for (int32 j = HASHBUCKETS(image)[i]; j != STN_UNDEF;
 				j = HASHCHAINS(image)[j]) {
 			struct Elf32_Sym *symbol = &image->syms[j];
 			addr_t location = symbol->st_value + image->regions[0].delta;
 
-			if (location <= (addr_t)address
+			if (location <= (addr_t)address	&& location >= foundLocation) {
-				&& location - 1 + symbol->st_size >= (addr_t)address) {
+				foundSymbol = symbol;
-				const char* symbolName = SYMNAME(image, symbol);
+				foundLocation = location;
-				strlcpy(nameBuffer, symbolName, *_nameLength);
-				*_nameLength = strlen(symbolName);
 
-				int32 type;
+				// jump out if we have an exact match
-				if (ELF32_ST_TYPE(symbol->st_info) == STT_FUNC)
+				if (foundLocation == (addr_t)address) {
-					type = B_SYMBOL_TYPE_TEXT;
+					found = true;
-				else if (ELF32_ST_TYPE(symbol->st_info) == STT_OBJECT)
+					break;
-					type = B_SYMBOL_TYPE_DATA;
+				}
-				else
-					type = B_SYMBOL_TYPE_ANY;
-					// TODO: check with the return types of that BeOS function
-
-				if (_imageID != NULL)
-					*_imageID = image->id;
-				if (_type != NULL)
-					*_type = type;
-				if (_location != NULL)
-					*_location = (void*)location;
-
-				rld_unlock();
-				return B_OK;
 			}
 		}
 	}
 
+	if (_imageID != NULL)
+		*_imageID = image->id;
+	if (_imagePath != NULL)
+		*_imagePath = image->path;
+
+	if (foundSymbol != NULL) {
+		*_symbolName = SYMNAME(image, foundSymbol);
+
+		if (_type != NULL) {
+			if (ELF32_ST_TYPE(foundSymbol->st_info) == STT_FUNC)
+				*_type = B_SYMBOL_TYPE_TEXT;
+			else if (ELF32_ST_TYPE(foundSymbol->st_info) == STT_OBJECT)
+				*_type = B_SYMBOL_TYPE_DATA;
+			else
+				*_type = B_SYMBOL_TYPE_ANY;
+			// TODO: check with the return types of that BeOS function
+		}
+
+		if (_location != NULL)
+			*_location = (void*)foundLocation;
+	} else {
+		*_symbolName = NULL;
+		if (_location != NULL)
+			*_location = NULL;
+	}
+
 	rld_unlock();
-	return B_BAD_VALUE;
+	return B_OK;
 }
 
 

src/system/runtime_loader/export.cpp

@@ -51,7 +51,7 @@ struct rld_export gRuntimeLoader = {
 	get_symbol,
 	get_library_symbol,
 	get_nth_symbol,
-	get_symbol_at_address,
+	get_nearest_symbol_at_address,
 	test_executable,
 	get_next_image_dependency,
 

src/system/runtime_loader/runtime_loader_private.h

@@ -65,8 +65,8 @@ image_id load_library(char const* path, uint32 flags, bool addOn,
 status_t unload_library(void* handle, image_id imageID, bool addOn);
 status_t get_nth_symbol(image_id imageID, int32 num, char* nameBuffer,
 	int32* _nameLength, int32* _type, void** _location);
-status_t get_symbol_at_address(void* address, image_id* _imageID,
+status_t get_nearest_symbol_at_address(void* address, image_id* _imageID,
-	char* nameBuffer, int32* _nameLength, int32* _type, void** _location);
+	char** _imagePath, char** _symbolName, int32* _type, void** _location);
 status_t get_symbol(image_id imageID, char const* symbolName, int32 symbolType,
 	bool recursive, image_id* _inImage, void** _location);
 status_t get_library_symbol(void* handle, void* caller, const char* symbolName,