gcc/ada/libgnat/s-objrea.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                 S Y S T E M . O B J E C T _ R E A D E R                  --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2009-2017, 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 package implements a simple, minimal overhead reader for object files
  33 --  composed of sections of untyped heterogeneous binary data.
  34
  35 with Interfaces;
  36 with System.Mmap;
  37
  38 package System.Object_Reader is
  39
  40    --------------
  41    --  Limits  --
  42    --------------
  43
  44    BUFFER_SIZE : constant := 8 * 1024;
  45
  46    ------------------
  47    -- Object files --
  48    ------------------
  49
  50    type Object_File (<>) is private;
  51
  52    type Object_File_Access is access Object_File;
  53
  54    ---------------------
  55    -- Object sections --
  56    ----------------------
  57
  58    type Object_Section is private;
  59
  60    Null_Section : constant Object_Section;
  61
  62    --------------------
  63    -- Object symbols --
  64    --------------------
  65
  66    type Object_Symbol is private;
  67
  68    ------------------------
  69    -- Object format type --
  70    ------------------------
  71
  72    type Object_Format is
  73      (ELF32,
  74       --  Object format is 32-bit ELF
  75
  76       ELF64,
  77       --  Object format is 64-bit ELF
  78
  79       PECOFF,
  80       --  Object format is Microsoft PECOFF
  81
  82       PECOFF_PLUS,
  83       --  Object format is Microsoft PECOFF+
  84
  85       XCOFF32);
  86       --  Object format is AIX 32-bit XCOFF
  87
  88    --  PECOFF | PECOFF_PLUS appears so often as a case choice, would
  89    --  seem a good idea to have a subtype name covering these two choices ???
  90
  91    ------------------------------
  92    -- Object architecture type --
  93    ------------------------------
  94
  95    type Object_Arch is
  96      (Unknown,
  97       --  The target architecture has not yet been determined
  98
  99       SPARC,
 100       --  32-bit SPARC
 101
 102       SPARC64,
 103       --  64-bit SPARC
 104
 105       i386,
 106       --  Intel IA32
 107
 108       MIPS,
 109       --  MIPS Technologies MIPS
 110
 111       x86_64,
 112       --  x86-64 (64-bit AMD/Intel)
 113
 114       IA64,
 115       --  Intel IA64
 116
 117       PPC,
 118       --  32-bit PowerPC
 119
 120       PPC64);
 121       --  64-bit PowerPC
 122
 123    ------------------
 124    -- Target types --
 125    ------------------
 126
 127    subtype Offset is Interfaces.Integer_64;
 128
 129    subtype uint8  is Interfaces.Unsigned_8;
 130    subtype uint16 is Interfaces.Unsigned_16;
 131    subtype uint32 is Interfaces.Unsigned_32;
 132    subtype uint64 is Interfaces.Unsigned_64;
 133
 134    subtype int8  is Interfaces.Integer_8;
 135    subtype int16 is Interfaces.Integer_16;
 136    subtype int32 is Interfaces.Integer_32;
 137    subtype int64 is Interfaces.Integer_64;
 138
 139    type Buffer is array (0 .. BUFFER_SIZE - 1) of uint8;
 140
 141    type String_Ptr_Len is record
 142       Ptr : Mmap.Str_Access;
 143       Len : Natural;
 144    end record;
 145    --  A string made from a pointer and a length. Not all strings for name
 146    --  are C strings: COFF inlined symbol names have a max length of 8.
 147
 148    -------------------------------------------
 149    -- Operations on buffers of untyped data --
 150    -------------------------------------------
 151
 152    function To_String (Buf : Buffer) return String;
 153    --  Construct string from C style null-terminated string stored in a buffer
 154
 155    function To_String_Ptr_Len
 156      (Ptr : Mmap.Str_Access;
 157       Max_Len : Natural := Natural'Last) return String_Ptr_Len;
 158    --  Convert PTR to a String_Ptr_Len.
 159
 160    function Strlen (Buf : Buffer) return int32;
 161    --  Return the length of a C style null-terminated string
 162
 163    -------------------------
 164    -- Opening and closing --
 165    -------------------------
 166
 167    function Open
 168      (File_Name    : String;
 169       In_Exception : Boolean := False) return Object_File_Access;
 170    --  Open the object file and initialize the reader. In_Exception is true
 171    --  when the parsing is done as part of an exception handler decorator. In
 172    --  this mode we do not want to raise an exception.
 173
 174    procedure Close (Obj : in out Object_File);
 175    --  Close the object file
 176
 177    -----------------------
 178    -- Sequential access --
 179    -----------------------
 180
 181    type Mapped_Stream is private;
 182    --  Provide an abstraction of a stream on a memory mapped file
 183
 184    function Create_Stream (Mf : System.Mmap.Mapped_File;
 185                            File_Offset : System.Mmap.File_Size;
 186                            File_Length : System.Mmap.File_Size)
 187                           return Mapped_Stream;
 188    --  Create a stream from Mf
 189
 190    procedure Close (S : in out Mapped_Stream);
 191    --  Close the stream (deallocate memory)
 192
 193    procedure Read_Raw
 194      (S   : in out Mapped_Stream;
 195       Addr  : Address;
 196       Size  : uint32);
 197    pragma Inline (Read_Raw);
 198    --  Read a number of fixed sized records
 199
 200    procedure Seek (S : in out Mapped_Stream; Off : Offset);
 201    --  Seek to an absolute offset in bytes
 202
 203    procedure Tell (Obj : in out Mapped_Stream; Off : out Offset)
 204      with Inline;
 205    function Tell (Obj : Mapped_Stream) return Offset
 206      with Inline;
 207    --  Fetch the current offset
 208
 209    function Length (Obj : Mapped_Stream) return Offset
 210      with Inline;
 211    --  Length of the stream
 212
 213    function Read (S : in out Mapped_Stream) return Mmap.Str_Access;
 214    --  Provide a pointer in memory at the current offset
 215
 216    function Read (S : in out Mapped_Stream) return String_Ptr_Len;
 217    --  Provide a pointer in memory at the current offset
 218
 219    function Read (S : in out Mapped_Stream) return uint8;
 220    function Read (S : in out Mapped_Stream) return uint16;
 221    function Read (S : in out Mapped_Stream) return uint32;
 222    function Read (S : in out Mapped_Stream) return uint64;
 223    function Read (S : in out Mapped_Stream) return int8;
 224    function Read (S : in out Mapped_Stream) return int16;
 225    function Read (S : in out Mapped_Stream) return int32;
 226    function Read (S : in out Mapped_Stream) return int64;
 227    --  Read a scalar
 228
 229    function Read_Address
 230      (Obj : Object_File; S : in out Mapped_Stream) return uint64;
 231    --  Read either a 64 or 32 bit address from the file stream depending on the
 232    --  address size of the target architecture and promote it to a 64 bit type.
 233
 234    function Read_LEB128 (S : in out Mapped_Stream) return uint32;
 235    function Read_LEB128 (S : in out Mapped_Stream) return int32;
 236    --  Read a value encoding in Little-Endian Base 128 format
 237
 238    procedure Read_C_String (S : in out Mapped_Stream; B : out Buffer);
 239    function Read_C_String (S : in out Mapped_Stream) return Mmap.Str_Access;
 240    --  Read a C style NULL terminated string
 241
 242    function Offset_To_String
 243      (S : in out Mapped_Stream;
 244       Off : Offset) return String;
 245    --  Construct a string from a C style NULL terminated string located at an
 246    --  offset into the object file.
 247
 248    ------------------------
 249    -- Object information --
 250    ------------------------
 251
 252    function Arch (Obj : Object_File) return Object_Arch;
 253    --  Return the object architecture
 254
 255    function Format (Obj : Object_File) return Object_Format;
 256    --  Return the object file format
 257
 258    function Get_Load_Address (Obj : Object_File) return uint64;
 259    --  Return the load address defined in Obj. May raise Format_Error if not
 260    --  implemented
 261
 262    function Num_Sections (Obj : Object_File) return uint32;
 263    --  Return the number of sections composing the object file
 264
 265    function Get_Section
 266      (Obj   : in out Object_File;
 267       Shnum : uint32) return Object_Section;
 268    --  Return the Nth section (numbered from zero)
 269
 270    function Get_Section
 271      (Obj      : in out Object_File;
 272       Sec_Name : String) return Object_Section;
 273    --  Return a section by name
 274
 275    function Create_Stream
 276      (Obj : Object_File;
 277       Sec : Object_Section) return Mapped_Stream;
 278    --  Create a stream for section Sec
 279
 280    procedure Get_Memory_Bounds
 281      (Obj   : in out Object_File;
 282       Low, High : out uint64);
 283    --  Return the low and high addresses of the code for the object file. Can
 284    --  be used to check if an address in within this object file. This
 285    --  procedure is not efficient and the result should be saved to avoid
 286    --  recomputation.
 287
 288    -------------------------
 289    -- Section information --
 290    -------------------------
 291
 292    function Name
 293      (Obj : in out Object_File;
 294       Sec : Object_Section) return String;
 295    --  Return the name of a section as a string
 296
 297    function Size (Sec : Object_Section) return uint64;
 298    --  Return the size of a section in bytes
 299
 300    function Num (Sec : Object_Section) return uint32;
 301    --  Return the index of a section from zero
 302
 303    function Off (Sec : Object_Section) return Offset;
 304    --  Return the byte offset of the section within the object
 305
 306    ------------------------------
 307    -- Symbol table information --
 308    ------------------------------
 309
 310    Null_Symbol : constant Object_Symbol;
 311    --  An empty symbol table entry.
 312
 313    function First_Symbol (Obj : in out Object_File) return Object_Symbol;
 314    --  Return the first element in the symbol table or Null_Symbol if the
 315    --  symbol table is empty.
 316
 317    function Next_Symbol
 318      (Obj  : in out Object_File;
 319       Prev : Object_Symbol) return Object_Symbol;
 320    --  Return the element following Prev in the symbol table, or Null_Symbol if
 321    --  Prev is the last symbol in the table.
 322
 323    function Read_Symbol
 324      (Obj : in out Object_File;
 325       Off : Offset) return Object_Symbol;
 326    --  Read symbol at Off
 327
 328    function Name
 329      (Obj : in out Object_File;
 330       Sym : Object_Symbol) return String_Ptr_Len;
 331    --  Return the name of the symbol
 332
 333    function Decoded_Ada_Name
 334      (Obj : in out Object_File;
 335       Sym : String_Ptr_Len) return String;
 336    --  Return the decoded name of a symbol encoded as per exp_dbug.ads
 337
 338    function Strip_Leading_Char
 339      (Obj : in out Object_File;
 340       Sym : String_Ptr_Len) return Positive;
 341    --  Return the index of the first character to decode the name. This can
 342    --  strip one character for ABI with a prefix (like x86 for PECOFF).
 343
 344    function Value (Sym : Object_Symbol) return uint64;
 345    --  Return the name of the symbol
 346
 347    function Size (Sym : Object_Symbol) return uint64;
 348    --  Return the size of the symbol in bytes
 349
 350    function Spans (Sym : Object_Symbol; Addr : uint64) return Boolean;
 351    --  Determine whether a particular address corresponds to the range
 352    --  referenced by this symbol.
 353
 354    function Off (Sym : Object_Symbol) return Offset;
 355    --  Return the offset of the symbol.
 356
 357    ----------------
 358    -- Exceptions --
 359    ----------------
 360
 361    IO_Error : exception;
 362    --  Input/Output error reading file
 363
 364    Format_Error : exception;
 365    --  Encountered a problem parsing the object
 366
 367 private
 368    type Mapped_Stream is record
 369       Region : System.Mmap.Mapped_Region;
 370       Off    : Offset;
 371       Len    : Offset;
 372    end record;
 373
 374    subtype ELF is Object_Format range ELF32 .. ELF64;
 375    subtype Any_PECOFF is Object_Format range PECOFF .. PECOFF_PLUS;
 376
 377    type Object_File (Format : Object_Format) is record
 378       Mf           : System.Mmap.Mapped_File :=
 379                         System.Mmap.Invalid_Mapped_File;
 380       Arch         : Object_Arch := Unknown;
 381
 382       Num_Sections : uint32 := 0;
 383       --  Number of sections
 384
 385       Symtab_Last : Offset;       --  Last offset of symbol table
 386
 387       In_Exception : Boolean := False;
 388       --  True if the parsing is done as part of an exception handler
 389
 390       Sectab_Stream : Mapped_Stream;
 391       --  Section table
 392
 393       Symtab_Stream : Mapped_Stream;
 394       --  Symbol table
 395
 396       Symstr_Stream : Mapped_Stream;
 397       --  Symbol strings
 398
 399       case Format is
 400          when ELF =>
 401             Secstr_Stream : Mapped_Stream;
 402             --  Section strings
 403          when Any_PECOFF =>
 404             ImageBase   : uint64;       --  ImageBase value from header
 405
 406             --  Cache for latest result of Get_Section_Virtual_Address
 407
 408             GSVA_Sec  : uint32 := uint32'Last;
 409             GSVA_Addr : uint64;
 410          when XCOFF32 =>
 411             null;
 412       end case;
 413    end record;
 414
 415    subtype ELF_Object_File is Object_File; -- with
 416    --  Predicate => ELF_Object_File.Format in ELF;
 417    subtype PECOFF_Object_File is Object_File; -- with
 418    --  Predicate => PECOFF_Object_File.Format in Any_PECOFF;
 419    subtype XCOFF32_Object_File is Object_File; -- with
 420    --  Predicate => XCOFF32_Object_File.Format in XCOFF32;
 421    --  ???Above predicates cause the compiler to crash when instantiating
 422    --  ELF64_Ops (see package body).
 423
 424    type Object_Section is record
 425       Num        : uint32 := 0;
 426       --  Section index in the section table
 427
 428       Off        : Offset := 0;
 429       --  First byte of the section in the object file
 430
 431       Addr       : uint64 := 0;
 432       --  Load address of the section. Valid only when Flag_Alloc is true.
 433
 434       Size       : uint64 := 0;
 435       --  Length of the section in bytes
 436
 437       Flag_Alloc : Boolean := False;
 438       --  True if the section is mapped in memory by the OS loader
 439    end record;
 440
 441    Null_Section : constant Object_Section := (0, 0, 0, 0, False);
 442
 443    type Object_Symbol is record
 444       Off   : Offset := 0;  --  Offset of underlying symbol on disk
 445       Next  : Offset := 0;  --  Offset of the following symbol
 446       Value : uint64 := 0;  --  Value associated with this symbol
 447       Size  : uint64 := 0;  --  Size of the referenced entity
 448    end record;
 449
 450    Null_Symbol : constant Object_Symbol := (0, 0, 0, 0);
 451 end System.Object_Reader;