gdb/auxv.c

   1 /* Auxiliary vector support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
   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,
  37    but must be called with TARGET_OBJECT_AUXV.
  38    It handles access via /proc/PID/auxv, which is the common method.
  39    This function is appropriate for doing:
  40            #define NATIVE_XFER_AUXV     procfs_xfer_auxv
  41    for a native target that uses inftarg.c's child_xfer_partial hook.  */
  42
  43 LONGEST
  44 procfs_xfer_auxv (struct target_ops *ops,
  45                   int /* enum target_object */ object,
  46                   const char *annex,
  47                   gdb_byte *readbuf,
  48                   const gdb_byte *writebuf,
  49                   ULONGEST offset,
  50                   LONGEST len)
  51 {
  52   char *pathname;
  53   int fd;
  54   LONGEST n;
  55
  56   gdb_assert (object == TARGET_OBJECT_AUXV);
  57   gdb_assert (readbuf || writebuf);
  58
  59   pathname = xstrprintf ("/proc/%d/auxv", PIDGET (inferior_ptid));
  60   fd = open (pathname, writebuf != NULL ? O_WRONLY : O_RDONLY);
  61   xfree (pathname);
  62   if (fd < 0)
  63     return -1;
  64
  65   if (offset != (ULONGEST) 0
  66       && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
  67     n = -1;
  68   else if (readbuf != NULL)
  69     n = read (fd, readbuf, len);
  70   else
  71     n = write (fd, writebuf, len);
  72
  73   (void) close (fd);
  74
  75   return n;
  76 }
  77
  78 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
  79    Return 0 if *READPTR is already at the end of the buffer.
  80    Return -1 if there is insufficient buffer for a whole entry.
  81    Return 1 if an entry was read into *TYPEP and *VALP.  */
  82 static int
  83 default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
  84                    gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
  85 {
  86   const int sizeof_auxv_field = gdbarch_ptr_bit (target_gdbarch)
  87                                 / TARGET_CHAR_BIT;
  88   gdb_byte *ptr = *readptr;
  89
  90   if (endptr == ptr)
  91     return 0;
  92
  93   if (endptr - ptr < sizeof_auxv_field * 2)
  94     return -1;
  95
  96   *typep = extract_unsigned_integer (ptr, sizeof_auxv_field);
  97   ptr += sizeof_auxv_field;
  98   *valp = extract_unsigned_integer (ptr, sizeof_auxv_field);
  99   ptr += sizeof_auxv_field;
 100
 101   *readptr = ptr;
 102   return 1;
 103 }
 104
 105 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
 106    Return 0 if *READPTR is already at the end of the buffer.
 107    Return -1 if there is insufficient buffer for a whole entry.
 108    Return 1 if an entry was read into *TYPEP and *VALP.  */
 109 int
 110 target_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
 111                   gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
 112 {
 113   struct target_ops *t;
 114   for (t = ops; t != NULL; t = t->beneath)
 115     if (t->to_auxv_parse != NULL)
 116       return t->to_auxv_parse (t, readptr, endptr, typep, valp);
 117
 118   return default_auxv_parse (ops, readptr, endptr, typep, valp);
 119 }
 120
 121 /* Extract the auxiliary vector entry with a_type matching MATCH.
 122    Return zero if no such entry was found, or -1 if there was
 123    an error getting the information.  On success, return 1 after
 124    storing the entry's value field in *VALP.  */
 125 int
 126 target_auxv_search (struct target_ops *ops, CORE_ADDR match, CORE_ADDR *valp)
 127 {
 128   CORE_ADDR type, val;
 129   gdb_byte *data;
 130   LONGEST n = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL, &data);
 131   gdb_byte *ptr = data;
 132   int ents = 0;
 133
 134   if (n <= 0)
 135     return n;
 136
 137   while (1)
 138     switch (target_auxv_parse (ops, &ptr, data + n, &type, &val))
 139       {
 140       case 1:                   /* Here's an entry, check it.  */
 141         if (type == match)
 142           {
 143             xfree (data);
 144             *valp = val;
 145             return 1;
 146           }
 147         break;
 148       case 0:                   /* End of the vector.  */
 149         xfree (data);
 150         return 0;
 151       default:                  /* Bogosity.  */
 152         xfree (data);
 153         return -1;
 154       }
 155
 156   /*NOTREACHED*/
 157 }
 158
 159
 160 /* Print the contents of the target's AUXV on the specified file. */
 161 int
 162 fprint_target_auxv (struct ui_file *file, struct target_ops *ops)
 163 {
 164   CORE_ADDR type, val;
 165   gdb_byte *data;
 166   LONGEST len = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL,
 167                                    &data);
 168   gdb_byte *ptr = data;
 169   int ents = 0;
 170
 171   if (len <= 0)
 172     return len;
 173
 174   while (target_auxv_parse (ops, &ptr, data + len, &type, &val) > 0)
 175     {
 176       const char *name = "???";
 177       const char *description = "";
 178       enum { dec, hex, str } flavor = hex;
 179
 180       switch (type)
 181         {
 182 #define TAG(tag, text, kind) \
 183         case tag: name = #tag; description = text; flavor = kind; break
 184           TAG (AT_NULL, _("End of vector"), hex);
 185           TAG (AT_IGNORE, _("Entry should be ignored"), hex);
 186           TAG (AT_EXECFD, _("File descriptor of program"), dec);
 187           TAG (AT_PHDR, _("Program headers for program"), hex);
 188           TAG (AT_PHENT, _("Size of program header entry"), dec);
 189           TAG (AT_PHNUM, _("Number of program headers"), dec);
 190           TAG (AT_PAGESZ, _("System page size"), dec);
 191           TAG (AT_BASE, _("Base address of interpreter"), hex);
 192           TAG (AT_FLAGS, _("Flags"), hex);
 193           TAG (AT_ENTRY, _("Entry point of program"), hex);
 194           TAG (AT_NOTELF, _("Program is not ELF"), dec);
 195           TAG (AT_UID, _("Real user ID"), dec);
 196           TAG (AT_EUID, _("Effective user ID"), dec);
 197           TAG (AT_GID, _("Real group ID"), dec);
 198           TAG (AT_EGID, _("Effective group ID"), dec);
 199           TAG (AT_CLKTCK, _("Frequency of times()"), dec);
 200           TAG (AT_PLATFORM, _("String identifying platform"), str);
 201           TAG (AT_HWCAP, _("Machine-dependent CPU capability hints"), hex);
 202           TAG (AT_FPUCW, _("Used FPU control word"), dec);
 203           TAG (AT_DCACHEBSIZE, _("Data cache block size"), dec);
 204           TAG (AT_ICACHEBSIZE, _("Instruction cache block size"), dec);
 205           TAG (AT_UCACHEBSIZE, _("Unified cache block size"), dec);
 206           TAG (AT_IGNOREPPC, _("Entry should be ignored"), dec);
 207           TAG (AT_BASE_PLATFORM, _("String identifying base platform"), str);
 208           TAG (AT_RANDOM, _("Address of 16 random bytes"), hex);
 209           TAG (AT_EXECFN, _("File name of executable"), str);
 210           TAG (AT_SECURE, _("Boolean, was exec setuid-like?"), dec);
 211           TAG (AT_SYSINFO, _("Special system info/entry points"), hex);
 212           TAG (AT_SYSINFO_EHDR, _("System-supplied DSO's ELF header"), hex);
 213           TAG (AT_SUN_UID, _("Effective user ID"), dec);
 214           TAG (AT_SUN_RUID, _("Real user ID"), dec);
 215           TAG (AT_SUN_GID, _("Effective group ID"), dec);
 216           TAG (AT_SUN_RGID, _("Real group ID"), dec);
 217           TAG (AT_SUN_LDELF, _("Dynamic linker's ELF header"), hex);
 218           TAG (AT_SUN_LDSHDR, _("Dynamic linker's section headers"), hex);
 219           TAG (AT_SUN_LDNAME, _("String giving name of dynamic linker"), str);
 220           TAG (AT_SUN_LPAGESZ, _("Large pagesize"), dec);
 221           TAG (AT_SUN_PLATFORM, _("Platform name string"), str);
 222           TAG (AT_SUN_HWCAP, _("Machine-dependent CPU capability hints"), hex);
 223           TAG (AT_SUN_IFLUSH, _("Should flush icache?"), dec);
 224           TAG (AT_SUN_CPU, _("CPU name string"), str);
 225           TAG (AT_SUN_EMUL_ENTRY, _("COFF entry point address"), hex);
 226           TAG (AT_SUN_EMUL_EXECFD, _("COFF executable file descriptor"), dec);
 227           TAG (AT_SUN_EXECNAME,
 228                _("Canonicalized file name given to execve"), str);
 229           TAG (AT_SUN_MMU, _("String for name of MMU module"), str);
 230           TAG (AT_SUN_LDDATA, _("Dynamic linker's data segment address"), hex);
 231           TAG (AT_SUN_AUXFLAGS,
 232                _("AF_SUN_ flags passed from the kernel"), hex);
 233         }
 234
 235       fprintf_filtered (file, "%-4s %-20s %-30s ",
 236                         plongest (type), name, description);
 237       switch (flavor)
 238         {
 239         case dec:
 240           fprintf_filtered (file, "%s\n", plongest (val));
 241           break;
 242         case hex:
 243           fprintf_filtered (file, "0x%s\n", paddr_nz (val));
 244           break;
 245         case str:
 246           {
 247             struct value_print_options opts;
 248             get_user_print_options (&opts);
 249             if (opts.addressprint)
 250               fprintf_filtered (file, "0x%s", paddr_nz (val));
 251             val_print_string (builtin_type (target_gdbarch)->builtin_char,
 252                               val, -1, file, &opts);
 253             fprintf_filtered (file, "\n");
 254           }
 255           break;
 256         }
 257       ++ents;
 258       if (type == AT_NULL)
 259         break;
 260     }
 261
 262   xfree (data);
 263
 264   return ents;
 265 }
 266
 267 static void
 268 info_auxv_command (char *cmd, int from_tty)
 269 {
 270   if (! target_has_stack)
 271     error (_("The program has no auxiliary information now."));
 272   else
 273     {
 274       int ents = fprint_target_auxv (gdb_stdout, &current_target);
 275       if (ents < 0)
 276         error (_("No auxiliary vector found, or failed reading it."));
 277       else if (ents == 0)
 278         error (_("Auxiliary vector is empty."));
 279     }
 280 }
 281
 282
 283 extern initialize_file_ftype _initialize_auxv; /* -Wmissing-prototypes; */
 284
 285 void
 286 _initialize_auxv (void)
 287 {
 288   add_info ("auxv", info_auxv_command,
 289             _("Display the inferior's auxiliary vector.\n\
 290 This is information provided by the operating system at program startup."));
 291 }