gdb/auxv.c

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