gdb/auxv.c

   1 /* Auxiliary vector support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "target.h"
  23 #include "gdbtypes.h"
  24 #include "command.h"
  25 #include "inferior.h"
  26 #include "valprint.h"
  27 #include "gdb_assert.h"
  28
  29 #include "auxv.h"
  30 #include "elf/common.h"
  31
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34
  35
  36 /* This function is called like a to_xfer_partial hook, but must be
  37    called with TARGET_OBJECT_AUXV.  It handles access via
  38    /proc/PID/auxv, which is a common method for native targets.  */
  39
  40 LONGEST
  41 procfs_xfer_auxv (struct target_ops *ops,
  42                   enum target_object object,
  43                   const char *annex,
  44                   gdb_byte *readbuf,
  45                   const gdb_byte *writebuf,
  46                   ULONGEST offset,
  47                   LONGEST len)
  48 {
  49   char *pathname;
  50   int fd;
  51   LONGEST n;
  52
  53   gdb_assert (object == TARGET_OBJECT_AUXV);
  54   gdb_assert (readbuf || writebuf);
  55
  56   pathname = xstrprintf ("/proc/%d/auxv", PIDGET (inferior_ptid));
  57   fd = open (pathname, writebuf != NULL ? O_WRONLY : O_RDONLY);
  58   xfree (pathname);
  59   if (fd < 0)
  60     return -1;
  61
  62   if (offset != (ULONGEST) 0
  63       && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
  64     n = -1;
  65   else if (readbuf != NULL)
  66     n = read (fd, readbuf, len);
  67   else
  68     n = write (fd, writebuf, len);
  69
  70   (void) close (fd);
  71
  72   return n;
  73 }
  74
  75 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
  76    Return 0 if *READPTR is already at the end of the buffer.
  77    Return -1 if there is insufficient buffer for a whole entry.
  78    Return 1 if an entry was read into *TYPEP and *VALP.  */
  79 static int
  80 default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
  81                    gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
  82 {
  83   const int sizeof_auxv_field = gdbarch_ptr_bit (target_gdbarch)
  84                                 / TARGET_CHAR_BIT;
  85   const enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
  86   gdb_byte *ptr = *readptr;
  87
  88   if (endptr == ptr)
  89     return 0;
  90
  91   if (endptr - ptr < sizeof_auxv_field * 2)
  92     return -1;
  93
  94   *typep = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
  95   ptr += sizeof_auxv_field;
  96   *valp = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
  97   ptr += sizeof_auxv_field;
  98
  99   *readptr = ptr;
 100   return 1;
 101 }
 102
 103 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
 104    Return 0 if *READPTR is already at the end of the buffer.
 105    Return -1 if there is insufficient buffer for a whole entry.
 106    Return 1 if an entry was read into *TYPEP and *VALP.  */
 107 int
 108 target_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
 109                   gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
 110 {
 111   struct target_ops *t;
 112   for (t = ops; t != NULL; t = t->beneath)
 113     if (t->to_auxv_parse != NULL)
 114       return t->to_auxv_parse (t, readptr, endptr, typep, valp);
 115
 116   return default_auxv_parse (ops, readptr, endptr, typep, valp);
 117 }
 118
 119 /* Extract the auxiliary vector entry with a_type matching MATCH.
 120    Return zero if no such entry was found, or -1 if there was
 121    an error getting the information.  On success, return 1 after
 122    storing the entry's value field in *VALP.  */
 123 int
 124 target_auxv_search (struct target_ops *ops, CORE_ADDR match, CORE_ADDR *valp)
 125 {
 126   CORE_ADDR type, val;
 127   gdb_byte *data;
 128   LONGEST n = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL, &data);
 129   gdb_byte *ptr = data;
 130   int ents = 0;
 131
 132   if (n <= 0)
 133     return n;
 134
 135   while (1)
 136     switch (target_auxv_parse (ops, &ptr, data + n, &type, &val))
 137       {
 138       case 1:                   /* Here's an entry, check it.  */
 139         if (type == match)
 140           {
 141             xfree (data);
 142             *valp = val;
 143             return 1;
 144           }
 145         break;
 146       case 0:                   /* End of the vector.  */
 147         xfree (data);
 148         return 0;
 149       default:                  /* Bogosity.  */
 150         xfree (data);
 151         return -1;
 152       }
 153
 154   /*NOTREACHED*/
 155 }
 156
 157
 158 /* Print the contents of the target's AUXV on the specified file. */
 159 int
 160 fprint_target_auxv (struct ui_file *file, struct target_ops *ops)
 161 {
 162   CORE_ADDR type, val;
 163   gdb_byte *data;
 164   LONGEST len = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL,
 165                                    &data);
 166   gdb_byte *ptr = data;
 167   int ents = 0;
 168
 169   if (len <= 0)
 170     return len;
 171
 172   while (target_auxv_parse (ops, &ptr, data + len, &type, &val) > 0)
 173     {
 174       const char *name = "???";
 175       const char *description = "";
 176       enum { dec, hex, str } flavor = hex;
 177
 178       switch (type)
 179         {
 180 #define TAG(tag, text, kind) \
 181         case tag: name = #tag; description = text; flavor = kind; break
 182           TAG (AT_NULL, _("End of vector"), hex);
 183           TAG (AT_IGNORE, _("Entry should be ignored"), hex);
 184           TAG (AT_EXECFD, _("File descriptor of program"), dec);
 185           TAG (AT_PHDR, _("Program headers for program"), hex);
 186           TAG (AT_PHENT, _("Size of program header entry"), dec);
 187           TAG (AT_PHNUM, _("Number of program headers"), dec);
 188           TAG (AT_PAGESZ, _("System page size"), dec);
 189           TAG (AT_BASE, _("Base address of interpreter"), hex);
 190           TAG (AT_FLAGS, _("Flags"), hex);
 191           TAG (AT_ENTRY, _("Entry point of program"), hex);
 192           TAG (AT_NOTELF, _("Program is not ELF"), dec);
 193           TAG (AT_UID, _("Real user ID"), dec);
 194           TAG (AT_EUID, _("Effective user ID"), dec);
 195           TAG (AT_GID, _("Real group ID"), dec);
 196           TAG (AT_EGID, _("Effective group ID"), dec);
 197           TAG (AT_CLKTCK, _("Frequency of times()"), dec);
 198           TAG (AT_PLATFORM, _("String identifying platform"), str);
 199           TAG (AT_HWCAP, _("Machine-dependent CPU capability hints"), hex);
 200           TAG (AT_FPUCW, _("Used FPU control word"), dec);
 201           TAG (AT_DCACHEBSIZE, _("Data cache block size"), dec);
 202           TAG (AT_ICACHEBSIZE, _("Instruction cache block size"), dec);
 203           TAG (AT_UCACHEBSIZE, _("Unified cache block size"), dec);
 204           TAG (AT_IGNOREPPC, _("Entry should be ignored"), dec);
 205           TAG (AT_BASE_PLATFORM, _("String identifying base platform"), str);
 206           TAG (AT_RANDOM, _("Address of 16 random bytes"), hex);
 207           TAG (AT_EXECFN, _("File name of executable"), str);
 208           TAG (AT_SECURE, _("Boolean, was exec setuid-like?"), dec);
 209           TAG (AT_SYSINFO, _("Special system info/entry points"), hex);
 210           TAG (AT_SYSINFO_EHDR, _("System-supplied DSO's ELF header"), hex);
 211           TAG (AT_SUN_UID, _("Effective user ID"), dec);
 212           TAG (AT_SUN_RUID, _("Real user ID"), dec);
 213           TAG (AT_SUN_GID, _("Effective group ID"), dec);
 214           TAG (AT_SUN_RGID, _("Real group ID"), dec);
 215           TAG (AT_SUN_LDELF, _("Dynamic linker's ELF header"), hex);
 216           TAG (AT_SUN_LDSHDR, _("Dynamic linker's section headers"), hex);
 217           TAG (AT_SUN_LDNAME, _("String giving name of dynamic linker"), str);
 218           TAG (AT_SUN_LPAGESZ, _("Large pagesize"), dec);
 219           TAG (AT_SUN_PLATFORM, _("Platform name string"), str);
 220           TAG (AT_SUN_HWCAP, _("Machine-dependent CPU capability hints"), hex);
 221           TAG (AT_SUN_IFLUSH, _("Should flush icache?"), dec);
 222           TAG (AT_SUN_CPU, _("CPU name string"), str);
 223           TAG (AT_SUN_EMUL_ENTRY, _("COFF entry point address"), hex);
 224           TAG (AT_SUN_EMUL_EXECFD, _("COFF executable file descriptor"), dec);
 225           TAG (AT_SUN_EXECNAME,
 226                _("Canonicalized file name given to execve"), str);
 227           TAG (AT_SUN_MMU, _("String for name of MMU module"), str);
 228           TAG (AT_SUN_LDDATA, _("Dynamic linker's data segment address"), hex);
 229           TAG (AT_SUN_AUXFLAGS,
 230                _("AF_SUN_ flags passed from the kernel"), hex);
 231         }
 232
 233       fprintf_filtered (file, "%-4s %-20s %-30s ",
 234                         plongest (type), name, description);
 235       switch (flavor)
 236         {
 237         case dec:
 238           fprintf_filtered (file, "%s\n", plongest (val));
 239           break;
 240         case hex:
 241           fprintf_filtered (file, "%s\n", paddress (target_gdbarch, val));
 242           break;
 243         case str:
 244           {
 245             struct value_print_options opts;
 246             get_user_print_options (&opts);
 247             if (opts.addressprint)
 248               fprintf_filtered (file, "%s", paddress (target_gdbarch, val));
 249             val_print_string (builtin_type (target_gdbarch)->builtin_char,
 250                               val, -1, file, &opts);
 251             fprintf_filtered (file, "\n");
 252           }
 253           break;
 254         }
 255       ++ents;
 256       if (type == AT_NULL)
 257         break;
 258     }
 259
 260   xfree (data);
 261
 262   return ents;
 263 }
 264
 265 static void
 266 info_auxv_command (char *cmd, int from_tty)
 267 {
 268   if (! target_has_stack)
 269     error (_("The program has no auxiliary information now."));
 270   else
 271     {
 272       int ents = fprint_target_auxv (gdb_stdout, &current_target);
 273       if (ents < 0)
 274         error (_("No auxiliary vector found, or failed reading it."));
 275       else if (ents == 0)
 276         error (_("Auxiliary vector is empty."));
 277     }
 278 }
 279
 280
 281 extern initialize_file_ftype _initialize_auxv; /* -Wmissing-prototypes; */
 282
 283 void
 284 _initialize_auxv (void)
 285 {
 286   add_info ("auxv", info_auxv_command,
 287             _("Display the inferior's auxiliary vector.\n\
 288 This is information provided by the operating system at program startup."));
 289 }