Refactor dynamic linker API, fix system/dynlink example

3 files changed, 85 insertions, 75 deletions

diff --git a/libpsn00b/include/dlfcn.h b/libpsn00b/include/dlfcn.h
index b3a5cec..6874d06 100644
--- a/libpsn00b/include/dlfcn.h
+++ b/libpsn00b/include/dlfcn.h
@@ -21,39 +21,39 @@
 #define RTLD_DEFAULT ((DLL *) 0)
 
 typedef enum _DL_Error {
-	RTLD_E_NONE        =  0, // No error
-	RTLD_E_FILE_OPEN   =  1, // Unable to find or open file
-	RTLD_E_FILE_ALLOC  =  2, // Unable to allocate buffer to load file into
-	RTLD_E_FILE_READ   =  3, // Failed to read file
-	RTLD_E_NO_MAP      =  4, // No symbol map has been loaded yet
-	RTLD_E_MAP_ALLOC   =  5, // Unable to allocate symbol map structures
-	RTLD_E_NO_SYMBOLS  =  6, // No symbols found in symbol map
-	RTLD_E_DLL_NULL    =  7, // Unable to initialize DLL from null pointer
-	RTLD_E_DLL_ALLOC   =  8, // Unable to allocate DLL metadata structures
-	RTLD_E_DLL_FORMAT  =  9, // Unsupported DLL type or format
-	RTLD_E_NO_FILE_API = 10, // psxetc has been built without file support
-	RTLD_E_MAP_SYMBOL  = 11, // Symbol not found in symbol map
-	RTLD_E_DLL_SYMBOL  = 12, // Symbol not found in DLL
-	RTLD_E_HASH_LOOKUP = 13  // Hash table lookup failed due to internal error
+	RTLD_E_NONE			=  0, // No error
+	RTLD_E_FILE_OPEN	=  1, // Unable to find or open file
+	RTLD_E_FILE_ALLOC	=  2, // Unable to allocate buffer to load file into
+	RTLD_E_FILE_READ	=  3, // Failed to read file
+	RTLD_E_NO_MAP		=  4, // No symbol map has been loaded yet
+	RTLD_E_MAP_ALLOC	=  5, // Unable to allocate symbol map structures
+	RTLD_E_NO_SYMBOLS	=  6, // No symbols found in symbol map
+	RTLD_E_DLL_NULL		=  7, // Unable to initialize DLL from null pointer
+	RTLD_E_DLL_ALLOC	=  8, // Unable to allocate DLL metadata structures
+	RTLD_E_DLL_FORMAT	=  9, // Unsupported DLL type or format
+	RTLD_E_MAP_SYMBOL	= 10, // Symbol not found in symbol map
+	RTLD_E_DLL_SYMBOL	= 11, // Symbol not found in DLL
+	RTLD_E_HASH_LOOKUP	= 12  // Hash table lookup failed due to internal error
 } DL_Error;
 
 typedef enum _DL_ResolveMode {
-	RTLD_LAZY = 1, // Resolve functions when they are first called (default)
-	RTLD_NOW  = 2  // Resolve all symbols immediately on load
+	RTLD_LAZY				= 1, // Resolve functions when they are first called (default)
+	RTLD_NOW				= 2, // Resolve all symbols immediately on load
+	RTLD_FREE_ON_DESTROY	= 4  // Automatically free DLL buffer when closing DLL
 } DL_ResolveMode;
 
 // Members of this struct should not be accessed directly in most cases, but
 // they are intentionally exposed for easier expandability.
 typedef struct _DLL {
-	void           *ptr;
-	void           *malloc_ptr;
-	size_t         size;
-	const uint32_t *hash;
-	uint32_t       *got;
-	Elf32_Sym      *symtab;
-	const char     *strtab;
-	uint16_t       symbol_count;
-	uint16_t       got_length;
+	void			*ptr;
+	void			*malloc_ptr;
+	size_t			size;
+	const uint32_t	*hash;
+	uint32_t		*got;
+	Elf32_Sym		*symtab;
+	const char		*strtab;
+	uint16_t		symbol_count;
+	uint16_t		got_length;
 } DLL;
 
 /* API */
@@ -62,8 +62,6 @@ typedef struct _DLL {
 extern "C" {
 #endif
 
-// TODO: rewrite these javadoc comments into proper documentation
-
 /**
  * @brief Reads the symbol table from the provided string buffer (which may or
  * may not be null-terminated), parses it and stores the parsed entries into a
@@ -80,13 +78,14 @@ extern "C" {
  * file in the appropriate format after building the executable, by using this
  * command:
  *
- *   mipsel-unknown-elf-nm -f posix -l -n executable.elf >executable.map
+ *   mipsel-none-elf-nm -f posix -l -n executable.elf >executable.map
  *
  * @param ptr
  * @param size
  * @return -1 or number of entries parsed
  */
 int32_t DL_ParseSymbolMap(const char *ptr, size_t size);
+
 /**
  * @brief File wrapper around DL_ParseSymbolMap(). Allocates a temporary buffer
  * then loads the specified map file into it (using BIOS APIs) and calls
@@ -96,14 +95,16 @@ int32_t DL_ParseSymbolMap(const char *ptr, size_t size);
  * @param filename Must always contain device name, e.g. "cdrom:MODULE.DLL;1"
  * @return -1 or number of entries parsed
  */
-int32_t DL_LoadSymbolMap(const char *filename);
+//int32_t DL_LoadSymbolMapFromFile(const char *filename);
+
 /**
  * @brief Frees internal buffers containing the currently loaded symbol map.
  * This is automatically done before loading a new symbol map so there is no
  * need to call this function in most cases, however it can still be useful to
  * free up space on the heap once the symbol map is no longer needed.
  */
-void    DL_UnloadSymbolMap(void);
+void DL_UnloadSymbolMap(void);
+
 /**
  * @brief Queries the currently loaded symbol map for the symbol with the given
  * name and returns a pointer to it, which can then be used to directly access
@@ -112,7 +113,8 @@ void    DL_UnloadSymbolMap(void);
  * @param name
  * @return NULL or pointer to symbol (any type)
  */
-void    *DL_GetSymbolByName(const char *name);
+void *DL_GetSymbolByName(const char *name);
+
 /**
  * @brief Sets a custom function to be called for resolving symbols in DLLs.
  * The function will be given a pointer to the current DLL and the unresolved
@@ -123,7 +125,7 @@ void    *DL_GetSymbolByName(const char *name);
  * 
  * @param callback NULL or pointer to callback function
  */
-void    DL_SetResolveCallback(void *(*callback)(DLL *, const char *));
+void DL_SetResolveCallback(void *(*callback)(DLL *, const char *));
 
 /**
  * @brief Initializes a buffer holding the contents of a dynamically-loaded
@@ -131,8 +133,8 @@ void    DL_SetResolveCallback(void *(*callback)(DLL *, const char *));
  * binary) *in-place*. A new DLL struct is allocated to store metadata but,
  * unlike DL_ParseSymbolMap(), the DLL's actual code, data and tables are
  * referenced directly from the provided buffer. The buffer must not be moved
- * or deallocated, at least not before calling dlclose() on the DLL struct
- * returned by this function.
+ * or deallocated, at least not before calling DL_DestroyDLL() on the DLL
+ * struct returned by this function.
  *
  * The third argument specifies when symbols in the DLL should be resolved.
  * Setting it to RTLD_LAZY defers resolution of undefined functions to when
@@ -145,7 +147,8 @@ void    DL_SetResolveCallback(void *(*callback)(DLL *, const char *));
  * @param mode RTLD_LAZY or RTLD_NOW
  * @return NULL or pointer to a new DLL struct
  */
-DLL  *dlinit(void *ptr, size_t size, DL_ResolveMode mode);
+DLL *DL_CreateDLL(void *ptr, size_t size, DL_ResolveMode mode);
+
 /**
  * @brief File wrapper around dlinit(). Allocates a new buffer, loads the
  * specified file into it (using BIOS APIs) and calls dlinit() on that. When
@@ -153,19 +156,22 @@ DLL  *dlinit(void *ptr, size_t size, DL_ResolveMode mode);
  * automatically destroyed.
  *
  * @param filename Must always contain device name, e.g. "cdrom:MODULE.DLL;1"
- * @param mode RTLD_LAZY or RTLD_NOW
+ * @param mode RTLD_LAZY or RTLD_NOW + optionally RTLD_FREE_ON_DESTROY
  * @return NULL or pointer to a new DLL struct
  */
-DLL  *dlopen(const char *filename, DL_ResolveMode mode);
+//DLL *DL_LoadDLLFromFile(const char *filename, DL_ResolveMode mode);
+
 /**
  * @brief Destroys a loaded DLL by calling its global destructors and freeing
- * the buffer it's loaded in. Any pointer passed to dlclose() should no longer
- * be used after the call. If the DLL was initialized in-place using dlinit(),
- * dlclose() will *NOT* free the buffer initially passed to dlinit().
+ * the buffer it's loaded in. Any pointer passed to DL_DestroyDLL() should no
+ * longer be used after the call. If the DLL was initialized in-place using
+ * DL_CreateDLL(), DL_DestroyDLL() will only free the buffer initially passed
+ * to DL_CreateDLL() if RTLD_FREE_ON_DESTROY was used.
  *
  * @param dll
  */
-void dlclose(DLL *dll);
+void DL_DestroyDLL(DLL *dll);
+
 /**
  * @brief Returns a pointer to the DLL symbol with the given name, or null if
  * it can't be found. If null or RTLD_DEFAULT is passed as first argument, the
@@ -176,7 +182,8 @@ void dlclose(DLL *dll);
  * @param name
  * @return NULL or pointer to symbol (any type)
  */
-void *dlsym(DLL *dll, const char *name);
+void *DL_GetDLLSymbol(const DLL *dll, const char *name);
+
 /**
  * @brief Returns a code describing the last error that occurred, or DL_E_NONE
  * if no error has occurred since the last call to dlerror() (i.e. calling this
@@ -184,7 +191,15 @@ void *dlsym(DLL *dll, const char *name);
  *
  * @return NULL or member of DL_Error enum
  */
-DL_Error dlerror(void);
+DL_Error DL_GetLastError(void);
+
+/* POSIX "compatibility" macros */
+
+#define dlinit(ptr, size, mode)	DL_CreateDLL(ptr, size, mode)
+//#define dlopen(filename, mode)	DL_LoadDLLFromFile(filename, mode)
+#define dlsym(dll, name)		DL_GetDLLSymbol(dll, name)
+#define dlclose(dll)			DL_DestroyDLL(dll)
+#define dlerror()				DL_GetLastError()
 
 #ifdef __cplusplus
 }
diff --git a/libpsn00b/psxetc/_dl_resolve_wrapper.s b/libpsn00b/psxetc/_dl_resolve_wrapper.s
index 069ee84..7f1132b 100644
--- a/libpsn00b/psxetc/_dl_resolve_wrapper.s
+++ b/libpsn00b/psxetc/_dl_resolve_wrapper.s
@@ -4,7 +4,7 @@
 # This function is called by the lazy loader stubs generated by GCC in the
 # .plt/.MIPS.stubs section when attempting to call a GOT entry whose address
 # hasn't yet been resolved. The generated stubs conform to the MIPS ABI and
-# uses the following registers to pass the following parameters:
+# uses the following registers:
 # - $t7 = address the resolved function should return to (i.e. $ra of the
 #   caller that triggered the stub)
 # - $t8 = index of the function in the .dynsym symbol table
@@ -25,13 +25,13 @@ _dl_resolve_wrapper:
 
 	# Figure out where the DLL's struct is. dlinit() places a pointer to the
 	# struct in the second GOT entry, so it's just a matter of indexing the GOT
-	# using GP. Then call _dl_resolve_helper with the struct and $t8 as
+	# using $gp. Then call _dl_resolve_helper with the struct and $t8 as
 	# arguments, and store the return value into $t0.
-	lw    $a0, -0x7fec($gp) # sizeof(uint32_t) - 0x7ff0 (see dll.ld)
+	lw    $a0, -0x7fec($gp) # (DLL *) sizeof(uint32_t) - 0x7ff0 [see dll.ld]
 	move  $a1, $t8
 
 	jal   _dl_resolve_helper
-	addiu $sp, -8 # (branch delay)
+	addiu $sp, -8
 	addiu $sp, 8
 
 	move  $t0, $v0
diff --git a/libpsn00b/psxetc/dl.c b/libpsn00b/psxetc/dl.c
index e43374f..cbdcb66 100644
--- a/libpsn00b/psxetc/dl.c
+++ b/libpsn00b/psxetc/dl.c
@@ -38,8 +38,9 @@
 //#define DEBUG
 
 // Comment before building to disable functions that rely on BIOS file APIs,
-// i.e. DL_LoadSymbolMap() and dlopen().
-#define USE_FILE_API
+// i.e. DL_LoadSymbolMapFromFile() and DL_LoadDLLFromFile().
+// FIXME: those seem to be broken currently, and shouldn't be used anyway
+//#define USE_FILE_API
 
 /* Private types */
 
@@ -132,7 +133,7 @@ static uint32_t _elf_hash(const char *str) {
 }
 
 #ifdef USE_FILE_API
-static uint8_t *_load_file(const char *filename, size_t *size_output) {
+static uint8_t *_dl_load_file(const char *filename, size_t *size_output) {
 	int32_t fd = open(filename, 1);
 	if (fd < 0) {
 		_LOG("psxetc: Can't open %s, error = %d\n", filename, fd);
@@ -286,10 +287,10 @@ int32_t DL_ParseSymbolMap(const char *ptr, size_t size) {
 	return entries;
 }
 
-int32_t DL_LoadSymbolMap(const char *filename) {
 #ifdef USE_FILE_API
+int32_t DL_LoadSymbolMapFromFile(const char *filename) {
 	size_t size;
-	char   *ptr = _load_file(filename, &size);
+	char   *ptr = _dl_load_file(filename, &size);
 	if (!ptr)
 		return -1;
 
@@ -297,10 +298,8 @@ int32_t DL_LoadSymbolMap(const char *filename) {
 	free(ptr);
 
 	return entries;
-#else
-	_ERROR(RTLD_E_NO_FILE_API, -1);
-#endif
 }
+#endif
 
 void DL_UnloadSymbolMap(void) {
 	if (!_symbol_map.entries)
@@ -354,7 +353,7 @@ void DL_SetResolveCallback(void *(*callback)(DLL *, const char *)) {
 
 /* Library loading and linking API */
 
-DLL *dlinit(void *ptr, size_t size, DL_ResolveMode mode) {
+DLL *DL_CreateDLL(void *ptr, size_t size, DL_ResolveMode mode) {
 	if (!ptr)
 		_ERROR(RTLD_E_DLL_NULL, 0);
 
@@ -365,7 +364,7 @@ DLL *dlinit(void *ptr, size_t size, DL_ResolveMode mode) {
 	}
 
 	dll->ptr        = ptr;
-	dll->malloc_ptr = 0;
+	dll->malloc_ptr = (mode & RTLD_FREE_ON_DESTROY) ? ptr : 0;
 	dll->size       = size;
 	_LOG("psxetc: Initializing DLL at %08x\n", ptr);
 
@@ -548,7 +547,7 @@ DLL *dlinit(void *ptr, size_t size, DL_ResolveMode mode) {
 
 		// If RTLD_NOW was passed, resolve GOT entries ahead of time by
 		// cross-referencing them with the symbol table.
-		if (mode != RTLD_NOW)
+		if (!(mode & RTLD_NOW))
 			continue;
 
 		for (uint32_t j = got_offset; j < dll->got_length; j++) {
@@ -584,7 +583,7 @@ DLL *dlinit(void *ptr, size_t size, DL_ResolveMode mode) {
 	// _start() for regular executables, but we have to do it outside of the
 	// DLL as there's no _start() or even a defined entry point within the
 	// DLL itself.
-	const uint32_t *ctor_list = dlsym(dll, "__CTOR_LIST__");
+	const uint32_t *ctor_list = DL_GetDLLSymbol(dll, "__CTOR_LIST__");
 	if (ctor_list) {
 		for (uint32_t i = ((uint32_t) ctor_list[0]); i >= 1; i--) {
 			void (*ctor)(void) = (void (*)(void)) ctor_list[i];
@@ -595,32 +594,28 @@ DLL *dlinit(void *ptr, size_t size, DL_ResolveMode mode) {
 	return dll;
 }
 
-DLL *dlopen(const char *filename, DL_ResolveMode mode) {
 #ifdef USE_FILE_API
+DLL *DL_LoadDLLFromFile(const char *filename, DL_ResolveMode mode) {
 	size_t size;
-	char   *ptr = _load_file(filename, &size);
+	char   *ptr = _dl_load_file(filename, &size);
 	if (!ptr)
 		return 0;
 
-	DLL *dll = dlinit(ptr, size, mode);
-	if (dll)
-		dll->malloc_ptr = dll->ptr;
-	else
+	DLL *dll = DL_CreateDLL(ptr, size, mode | RTLD_FREE_ON_DESTROY);
+	if (!dll)
 		free(ptr);
 
 	return dll;
-#else
-	_ERROR(RTLD_E_NO_FILE_API, 0);
-#endif
 }
+#endif
 
-void dlclose(DLL *dll) {
+void DL_DestroyDLL(DLL *dll) {
 	if (dll == RTLD_DEFAULT)
 		return;
 
 	if (dll->ptr) {
 		// Call the DLL's global destructors.
-		const uint32_t *dtor_list = dlsym(dll, "__DTOR_LIST__");
+		const uint32_t *dtor_list = DL_GetDLLSymbol(dll, "__DTOR_LIST__");
 		if (dtor_list) {
 			for (uint32_t i = 0; i < ((uint32_t) dtor_list[0]); i++) {
 				void (*dtor)(void) = (void (*)(void)) dtor_list[i + 1];
@@ -629,15 +624,15 @@ void dlclose(DLL *dll) {
 		}
 	}
 
-	// If the DLL is associated to a buffer allocated by dlopen(), free that
-	// buffer.
+	// If the DLL is associated to a buffer allocated by DL_LoadDLLFromFile(),
+	// free that buffer.
 	if (dll->malloc_ptr)
 		free(dll->malloc_ptr);
 
 	free(dll);
 }
 
-void *dlsym(DLL *dll, const char *name) {
+void *DL_GetDLLSymbol(const DLL *dll, const char *name) {
 	if (dll == RTLD_DEFAULT)
 		return DL_GetSymbolByName(name);
 		//return _dl_resolve_callback(RTLD_DEFAULT, name);
@@ -654,7 +649,7 @@ void *dlsym(DLL *dll, const char *name) {
 	// provided.
 	for (uint32_t i = bucket[hash_mod]; i != 0xffffffff;) {
 		if (i >= nchain) {
-			_LOG("psxetc: dlsym() index out of bounds (i = %d, n = %d)\n", i, nchain);
+			_LOG("psxetc: DL_GetDLLSymbol() index out of bounds (i = %d, n = %d)\n", i, nchain);
 			_ERROR(RTLD_E_HASH_LOOKUP, 0);
 		}
 
@@ -673,7 +668,7 @@ void *dlsym(DLL *dll, const char *name) {
 	_ERROR(RTLD_E_DLL_SYMBOL, 0);
 }
 
-DL_Error dlerror(void) {
+DL_Error DL_GetLastError(void) {
 	DL_Error last = _error_code;
 	_error_code   = RTLD_E_NONE;