1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- G N A T . D E B U G _ P O O L S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2011, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26-- -- 27-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32-- This packages provides a special implementation of the Ada 95 storage pools 33 34-- The goal of this debug pool is to detect incorrect uses of memory 35-- (multiple deallocations, access to invalid memory,...). Errors are reported 36-- in one of two ways: either by immediately raising an exception, or by 37-- printing a message on standard output or standard error. 38 39-- You need to instrument your code to use this package: for each access type 40-- you want to monitor, you need to add a clause similar to: 41 42-- type Integer_Access is access Integer; 43-- for Integer_Access'Storage_Pool use Pool; 44 45-- where Pool is a tagged object declared with 46-- 47-- Pool : GNAT.Debug_Pools.Debug_Pool; 48 49-- This package was designed to be as efficient as possible, but still has an 50-- impact on the performance of your code, which depends on the number of 51-- allocations, deallocations and, somewhat less, dereferences that your 52-- application performs. 53 54-- For each faulty memory use, this debug pool will print several lines 55-- of information, including things like the location where the memory 56-- was initially allocated, the location where it was freed etc. 57 58-- Physical allocations and deallocations are done through the usual system 59-- calls. However, in order to provide proper checks, the debug pool will not 60-- release the memory immediately. It keeps released memory around (the amount 61-- kept around is configurable) so that it can distinguish between memory that 62-- has not been allocated and memory that has been allocated but freed. This 63-- also means that this memory cannot be reallocated, preventing what would 64-- otherwise be a false indication that freed memory is now allocated. 65 66-- In addition, this package presents several subprograms that help analyze 67-- the behavior of your program, by reporting memory leaks, the total amount 68-- of memory that was allocated. The pool is also designed to work correctly 69-- in conjunction with gnatmem. 70 71-- Finally, a subprogram Print_Pool is provided for use from the debugger 72 73-- Limitations 74-- =========== 75 76-- Current limitation of this debug pool: if you use this debug pool for a 77-- general access type ("access all"), the pool might report invalid 78-- dereferences if the access object is pointing to another object on the 79-- stack which was not allocated through a call to "new". 80 81-- This debug pool will respect all alignments specified in your code, but 82-- it does that by aligning all objects using Standard'Maximum_Alignment. 83-- This allows faster checks, and limits the performance impact of using 84-- this pool. 85 86with System; use System; 87with System.Storage_Elements; use System.Storage_Elements; 88with System.Checked_Pools; 89 90package GNAT.Debug_Pools is 91 92 type Debug_Pool is new System.Checked_Pools.Checked_Pool with private; 93 -- The new debug pool 94 95 subtype SSC is System.Storage_Elements.Storage_Count; 96 97 Default_Max_Freed : constant SSC := 50_000_000; 98 Default_Stack_Trace_Depth : constant Natural := 20; 99 Default_Reset_Content : constant Boolean := False; 100 Default_Raise_Exceptions : constant Boolean := True; 101 Default_Advanced_Scanning : constant Boolean := False; 102 Default_Min_Freed : constant SSC := 0; 103 Default_Errors_To_Stdout : constant Boolean := True; 104 Default_Low_Level_Traces : constant Boolean := False; 105 -- The above values are constants used for the parameters to Configure 106 -- if not overridden in the call. See description of Configure for full 107 -- details on these parameters. If these defaults are not satisfactory, 108 -- then you need to call Configure to change the default values. 109 110 procedure Configure 111 (Pool : in out Debug_Pool; 112 Stack_Trace_Depth : Natural := Default_Stack_Trace_Depth; 113 Maximum_Logically_Freed_Memory : SSC := Default_Max_Freed; 114 Minimum_To_Free : SSC := Default_Min_Freed; 115 Reset_Content_On_Free : Boolean := Default_Reset_Content; 116 Raise_Exceptions : Boolean := Default_Raise_Exceptions; 117 Advanced_Scanning : Boolean := Default_Advanced_Scanning; 118 Errors_To_Stdout : Boolean := Default_Errors_To_Stdout; 119 Low_Level_Traces : Boolean := Default_Low_Level_Traces); 120 -- Subprogram used to configure the debug pool. 121 -- 122 -- Stack_Trace_Depth. This parameter controls the maximum depth of stack 123 -- traces that are output to indicate locations of actions for error 124 -- conditions such as bad allocations. If set to zero, the debug pool 125 -- will not try to compute backtraces. This is more efficient but gives 126 -- less information on problem locations 127 -- 128 -- Maximum_Logically_Freed_Memory: maximum amount of memory (bytes) 129 -- that should be kept before starting to physically deallocate some. 130 -- This value should be non-zero, since having memory that is logically 131 -- but not physically freed helps to detect invalid memory accesses. 132 -- 133 -- Minimum_To_Free is the minimum amount of memory that should be freed 134 -- every time the pool starts physically releasing memory. The algorithm 135 -- to compute which block should be physically released needs some 136 -- expensive initialization (see Advanced_Scanning below), and this 137 -- parameter can be used to limit the performance impact by ensuring 138 -- that a reasonable amount of memory is freed each time. Even in the 139 -- advanced scanning mode, marked blocks may be released to match this 140 -- Minimum_To_Free parameter. 141 -- 142 -- Reset_Content_On_Free: If true, then the contents of the freed memory 143 -- is reset to the pattern 16#DEADBEEF#, following an old IBM convention. 144 -- This helps in detecting invalid memory references from the debugger. 145 -- 146 -- Raise_Exceptions: If true, the exceptions below will be raised every 147 -- time an error is detected. If you set this to False, then the action 148 -- is to generate output on standard error or standard output, depending 149 -- on Errors_To_Stdout, noting the errors, but to 150 -- keep running if possible (of course if storage is badly damaged, this 151 -- attempt may fail. This helps to detect more than one error in a run. 152 -- 153 -- Advanced_Scanning: If true, the pool will check the contents of all 154 -- allocated blocks before physically releasing memory. Any possible 155 -- reference to a logically free block will prevent its deallocation. 156 -- Note that this algorithm is approximate, and it is recommended 157 -- that you set Minimum_To_Free to a non-zero value to save time. 158 -- 159 -- Errors_To_Stdout: Errors messages will be displayed on stdout if 160 -- this parameter is True, or to stderr otherwise. 161 -- 162 -- Low_Level_Traces: Traces all allocation and deallocations on the 163 -- stream specified by Errors_To_Stdout. This can be used for 164 -- post-processing by your own application, or to debug the 165 -- debug_pool itself. The output indicates the size of the allocated 166 -- block both as requested by the application and as physically 167 -- allocated to fit the additional information needed by the debug 168 -- pool. 169 -- 170 -- All instantiations of this pool use the same internal tables. However, 171 -- they do not store the same amount of information for the tracebacks, 172 -- and they have different counters for maximum logically freed memory. 173 174 Accessing_Not_Allocated_Storage : exception; 175 -- Exception raised if Raise_Exception is True, and an attempt is made 176 -- to access storage that was never allocated. 177 178 Accessing_Deallocated_Storage : exception; 179 -- Exception raised if Raise_Exception is True, and an attempt is made 180 -- to access storage that was allocated but has been deallocated. 181 182 Freeing_Not_Allocated_Storage : exception; 183 -- Exception raised if Raise_Exception is True, and an attempt is made 184 -- to free storage that had not been previously allocated. 185 186 Freeing_Deallocated_Storage : exception; 187 -- Exception raised if Raise_Exception is True, and an attempt is made 188 -- to free storage that had already been freed. 189 190 -- Note on the above exceptions. The distinction between not allocated 191 -- and deallocated storage is not guaranteed to be accurate in the case 192 -- where storage is allocated, and then physically freed. Larger values 193 -- of the parameter Maximum_Logically_Freed_Memory will help to guarantee 194 -- that this distinction is made more accurately. 195 196 generic 197 with procedure Put_Line (S : String) is <>; 198 with procedure Put (S : String) is <>; 199 procedure Print_Info 200 (Pool : Debug_Pool; 201 Cumulate : Boolean := False; 202 Display_Slots : Boolean := False; 203 Display_Leaks : Boolean := False); 204 -- Print out information about the High Water Mark, the current and 205 -- total number of bytes allocated and the total number of bytes 206 -- deallocated. 207 -- 208 -- If Display_Slots is true, this subprogram prints a list of all the 209 -- locations in the application that have done at least one allocation or 210 -- deallocation. The result might be used to detect places in the program 211 -- where lots of allocations are taking place. This output is not in any 212 -- defined order. 213 -- 214 -- If Cumulate if True, then each stack trace will display the number of 215 -- allocations that were done either directly, or by the subprograms called 216 -- at that location (e.g: if there were two physical allocations at a->b->c 217 -- and a->b->d, then a->b would be reported as performing two allocations). 218 -- 219 -- If Display_Leaks is true, then each block that has not been deallocated 220 -- (often called a "memory leak") will be listed, along with the traceback 221 -- showing where it was allocated. Not that no grouping of the blocks is 222 -- done, you should use the Dump_Gnatmem procedure below in conjunction 223 -- with the gnatmem utility. 224 225 procedure Print_Info_Stdout 226 (Pool : Debug_Pool; 227 Cumulate : Boolean := False; 228 Display_Slots : Boolean := False; 229 Display_Leaks : Boolean := False); 230 -- Standard instantiation of Print_Info to print on standard_output. More 231 -- convenient to use where this is the intended location, and in particular 232 -- easier to use from the debugger. 233 234 procedure Dump_Gnatmem (Pool : Debug_Pool; File_Name : String); 235 -- Create an external file on the disk, which can be processed by gnatmem 236 -- to display the location of memory leaks. 237 -- 238 -- This provides a nicer output that Print_Info above, and groups similar 239 -- stack traces together. This also provides an easy way to save the memory 240 -- status of your program for post-mortem analysis. 241 -- 242 -- To use this file, use the following command line: 243 -- gnatmem 5 -i <File_Name> <Executable_Name> 244 -- If you want all the stack traces to be displayed with 5 levels. 245 246 procedure Print_Pool (A : System.Address); 247 pragma Export (C, Print_Pool, "print_pool"); 248 -- This subprogram is meant to be used from a debugger. Given an address in 249 -- memory, it will print on standard output the known information about 250 -- this address (provided, of course, the matching pointer is handled by 251 -- the Debug_Pool). 252 -- 253 -- The information includes the stacktrace for the allocation or 254 -- deallocation of that memory chunk, its current status (allocated or 255 -- logically freed), etc. 256 257private 258 -- The following are the standard primitive subprograms for a pool 259 260 procedure Allocate 261 (Pool : in out Debug_Pool; 262 Storage_Address : out Address; 263 Size_In_Storage_Elements : Storage_Count; 264 Alignment : Storage_Count); 265 -- Allocate a new chunk of memory, and set it up so that the debug pool 266 -- can check accesses to its data, and report incorrect access later on. 267 -- The parameters have the same semantics as defined in the ARM95. 268 269 procedure Deallocate 270 (Pool : in out Debug_Pool; 271 Storage_Address : Address; 272 Size_In_Storage_Elements : Storage_Count; 273 Alignment : Storage_Count); 274 -- Mark a block of memory as invalid. It might not be physically removed 275 -- immediately, depending on the setup of the debug pool, so that checks 276 -- are still possible. The parameters have the same semantics as defined 277 -- in the RM. 278 279 function Storage_Size (Pool : Debug_Pool) return SSC; 280 -- Return the maximal size of data that can be allocated through Pool. 281 -- Since Pool uses the malloc() system call, all the memory is accessible 282 -- through the pool 283 284 procedure Dereference 285 (Pool : in out Debug_Pool; 286 Storage_Address : System.Address; 287 Size_In_Storage_Elements : Storage_Count; 288 Alignment : Storage_Count); 289 -- Check whether a dereference statement is valid, i.e. whether the pointer 290 -- was allocated through Pool. As documented above, errors will be 291 -- reported either by a special error message or an exception, depending 292 -- on the setup of the storage pool. 293 -- The parameters have the same semantics as defined in the ARM95. 294 295 type Byte_Count is mod System.Max_Binary_Modulus; 296 -- Type used for maintaining byte counts, needs to be large enough 297 -- to accommodate counts allowing for repeated use of the same memory. 298 299 type Debug_Pool is new System.Checked_Pools.Checked_Pool with record 300 Stack_Trace_Depth : Natural := Default_Stack_Trace_Depth; 301 Maximum_Logically_Freed_Memory : SSC := Default_Max_Freed; 302 Reset_Content_On_Free : Boolean := Default_Reset_Content; 303 Raise_Exceptions : Boolean := Default_Raise_Exceptions; 304 Minimum_To_Free : SSC := Default_Min_Freed; 305 Advanced_Scanning : Boolean := Default_Advanced_Scanning; 306 Errors_To_Stdout : Boolean := Default_Errors_To_Stdout; 307 Low_Level_Traces : Boolean := Default_Low_Level_Traces; 308 309 Allocated : Byte_Count := 0; 310 -- Total number of bytes allocated in this pool 311 312 Logically_Deallocated : Byte_Count := 0; 313 -- Total number of bytes logically deallocated in this pool. This is the 314 -- memory that the application has released, but that the pool has not 315 -- yet physically released through a call to free(), to detect later 316 -- accessed to deallocated memory. 317 318 Physically_Deallocated : Byte_Count := 0; 319 -- Total number of bytes that were free()-ed 320 321 Marked_Blocks_Deallocated : Boolean := False; 322 -- Set to true if some mark blocks had to be deallocated in the advanced 323 -- scanning scheme. Since this is potentially dangerous, this is 324 -- reported to the user, who might want to rerun his program with a 325 -- lower Minimum_To_Free value. 326 327 High_Water : Byte_Count := 0; 328 -- Maximum of Allocated - Logically_Deallocated - Physically_Deallocated 329 330 First_Free_Block : System.Address := System.Null_Address; 331 Last_Free_Block : System.Address := System.Null_Address; 332 -- Pointers to the first and last logically freed blocks 333 334 First_Used_Block : System.Address := System.Null_Address; 335 -- Pointer to the list of currently allocated blocks. This list is 336 -- used to list the memory leaks in the application on exit, as well as 337 -- for the advanced freeing algorithms that needs to traverse all these 338 -- blocks to find possible references to the block being physically 339 -- freed. 340 end record; 341end GNAT.Debug_Pools; 342