gdb/auxv.c

   1 /* Auxiliary vector support for GDB, the GNU debugger.
   2
   3    Copyright 2004 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 2 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, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "target.h"
  24 #include "gdbtypes.h"
  25 #include "command.h"
  26 #include "inferior.h"
  27 #include "valprint.h"
  28 #include "gdb_assert.h"
  29
  30 #include "auxv.h"
  31 #include "elf/common.h"
  32
  33 #include <unistd.h>
  34 #include <fcntl.h>
  35
  36
  37 /* This function is called like a to_xfer_partial hook,
  38    but must be called with TARGET_OBJECT_AUXV.
  39    It handles access via /proc/PID/auxv, which is the common method.
  40    This function is appropriate for doing:
  41            #define NATIVE_XFER_AUXV     procfs_xfer_auxv
  42    for a native target that uses inftarg.c's child_xfer_partial hook.  */
  43
  44 LONGEST
  45 procfs_xfer_auxv (struct target_ops *ops,
  46                   int /* enum target_object */ object,
  47                   const char *annex,
  48                   void *readbuf,
  49                   const void *writebuf,
  50                   ULONGEST offset,
  51                   LONGEST len)
  52 {
  53   char *pathname;
  54   int fd;
  55   LONGEST n;
  56
  57   gdb_assert (object == TARGET_OBJECT_AUXV);
  58   gdb_assert (readbuf || writebuf);
  59
  60   pathname = xstrprintf ("/proc/%d/auxv", PIDGET (inferior_ptid));
  61   fd = open (pathname, writebuf != NULL ? O_WRONLY : O_RDONLY);
  62   xfree (pathname);
  63   if (fd < 0)
  64     return -1;
  65
  66   if (offset != (ULONGEST) 0
  67       && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
  68     n = -1;
  69   else if (readbuf != NULL)
  70     n = read (fd, readbuf, len);
  71   else
  72     n = write (fd, writebuf, len);
  73
  74   (void) close (fd);
  75
  76   return n;
  77 }
  78
  79 /* Read all the auxv data into a contiguous xmalloc'd buffer,
  80    stored in *DATA.  Return the size in bytes of this data.
  81    If zero, there is no data and *DATA is null.
  82    if < 0, there was an error and *DATA is null.  */
  83 LONGEST
  84 target_auxv_read (struct target_ops *ops, char **data)
  85 {
  86   size_t auxv_alloc = 512, auxv_pos = 0;
  87   char *auxv = xmalloc (auxv_alloc);
  88   int n;
  89
  90   while (1)
  91     {
  92       n = target_read_partial (ops, TARGET_OBJECT_AUXV,
  93                                NULL, &auxv[auxv_pos], 0,
  94                                auxv_alloc - auxv_pos);
  95       if (n <= 0)
  96         break;
  97       auxv_pos += n;
  98       if (auxv_pos < auxv_alloc) /* Read all there was.  */
  99         break;
 100       gdb_assert (auxv_pos == auxv_alloc);
 101       auxv_alloc *= 2;
 102       auxv = xrealloc (auxv, auxv_alloc);
 103     }
 104
 105   if (auxv_pos == 0)
 106     {
 107       xfree (auxv);
 108       *data = NULL;
 109       return n;
 110     }
 111
 112   *data = auxv;
 113   return auxv_pos;
 114 }
 115
 116 /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
 117    Return 0 if *READPTR is already at the end of the buffer.
 118    Return -1 if there is insufficient buffer for a whole entry.
 119    Return 1 if an entry was read into *TYPEP and *VALP.  */
 120 int
 121 target_auxv_parse (struct target_ops *ops, char **readptr, char *endptr,
 122                    CORE_ADDR *typep, CORE_ADDR *valp)
 123 {
 124   const int sizeof_auxv_field = TYPE_LENGTH (builtin_type_void_data_ptr);
 125   char *ptr = *readptr;
 126
 127   if (endptr == ptr)
 128     return 0;
 129
 130   if (endptr - ptr < sizeof_auxv_field * 2)
 131     return -1;
 132
 133   *typep = extract_unsigned_integer (ptr, sizeof_auxv_field);
 134   ptr += sizeof_auxv_field;
 135   *valp = extract_unsigned_integer (ptr, sizeof_auxv_field);
 136   ptr += sizeof_auxv_field;
 137
 138   *readptr = ptr;
 139   return 1;
 140 }
 141
 142 /* Extract the auxiliary vector entry with a_type matching MATCH.
 143    Return zero if no such entry was found, or -1 if there was
 144    an error getting the information.  On success, return 1 after
 145    storing the entry's value field in *VALP.  */
 146 int
 147 target_auxv_search (struct target_ops *ops, CORE_ADDR match, CORE_ADDR *valp)
 148 {
 149   CORE_ADDR type, val;
 150   char *data;
 151   int n = target_auxv_read (ops, &data);
 152   char *ptr = data;
 153   int ents = 0;
 154
 155   if (n <= 0)
 156     return n;
 157
 158   while (1)
 159     switch (target_auxv_parse (ops, &ptr, data + n, &type, &val))
 160       {
 161       case 1:                   /* Here's an entry, check it.  */
 162         if (type == match)
 163           {
 164             xfree (data);
 165             *valp = val;
 166             return 1;
 167           }
 168         break;
 169       case 0:                   /* End of the vector.  */
 170         xfree (data);
 171         return 0;
 172       default:                  /* Bogosity.  */
 173         xfree (data);
 174         return -1;
 175       }
 176
 177   /*NOTREACHED*/
 178 }
 179
 180
 181 /* Print the contents of the target's AUXV on the specified file. */
 182 int
 183 fprint_target_auxv (struct ui_file *file, struct target_ops *ops)
 184 {
 185   CORE_ADDR type, val;
 186   char *data;
 187   int len = target_auxv_read (ops, &data);
 188   char *ptr = data;
 189   int ents = 0;
 190
 191   if (len <= 0)
 192     return len;
 193
 194   while (target_auxv_parse (ops, &ptr, data + len, &type, &val) > 0)
 195     {
 196       extern int addressprint;
 197       const char *name = "???";
 198       const char *description = "";
 199       enum { dec, hex, str } flavor = hex;
 200
 201       switch (type)
 202         {
 203 #define TAG(tag, text, kind) \
 204         case tag: name = #tag; description = text; flavor = kind; break
 205           TAG (AT_NULL, _("End of vector"), hex);
 206           TAG (AT_IGNORE, _("Entry should be ignored"), hex);
 207           TAG (AT_EXECFD, _("File descriptor of program"), dec);
 208           TAG (AT_PHDR, _("Program headers for program"), hex);
 209           TAG (AT_PHENT, _("Size of program header entry"), dec);
 210           TAG (AT_PHNUM, _("Number of program headers"), dec);
 211           TAG (AT_PAGESZ, _("System page size"), dec);
 212           TAG (AT_BASE, _("Base address of interpreter"), hex);
 213           TAG (AT_FLAGS, _("Flags"), hex);
 214           TAG (AT_ENTRY, _("Entry point of program"), hex);
 215           TAG (AT_NOTELF, _("Program is not ELF"), dec);
 216           TAG (AT_UID, _("Real user ID"), dec);
 217           TAG (AT_EUID, _("Effective user ID"), dec);
 218           TAG (AT_GID, _("Real group ID"), dec);
 219           TAG (AT_EGID, _("Effective group ID"), dec);
 220           TAG (AT_CLKTCK, _("Frequency of times()"), dec);
 221           TAG (AT_PLATFORM, _("String identifying platform"), str);
 222           TAG (AT_HWCAP, _("Machine-dependent CPU capability hints"), hex);
 223           TAG (AT_FPUCW, _("Used FPU control word"), dec);
 224           TAG (AT_DCACHEBSIZE, _("Data cache block size"), dec);
 225           TAG (AT_ICACHEBSIZE, _("Instruction cache block size"), dec);
 226           TAG (AT_UCACHEBSIZE, _("Unified cache block size"), dec);
 227           TAG (AT_IGNOREPPC, _("Entry should be ignored"), dec);
 228           TAG (AT_SYSINFO, _("Special system info/entry points"), hex);
 229           TAG (AT_SYSINFO_EHDR, _("System-supplied DSO's ELF header"), hex);
 230           TAG (AT_SECURE, _("Boolean, was exec setuid-like?"), dec);
 231           TAG (AT_SUN_UID, _("Effective user ID"), dec);
 232           TAG (AT_SUN_RUID, _("Real user ID"), dec);
 233           TAG (AT_SUN_GID, _("Effective group ID"), dec);
 234           TAG (AT_SUN_RGID, _("Real group ID"), dec);
 235           TAG (AT_SUN_LDELF, _("Dynamic linker's ELF header"), hex);
 236           TAG (AT_SUN_LDSHDR, _("Dynamic linker's section headers"), hex);
 237           TAG (AT_SUN_LDNAME, _("String giving name of dynamic linker"), str);
 238           TAG (AT_SUN_LPAGESZ, _("Large pagesize"), dec);
 239           TAG (AT_SUN_PLATFORM, _("Platform name string"), str);
 240           TAG (AT_SUN_HWCAP, _("Machine-dependent CPU capability hints"), hex);
 241           TAG (AT_SUN_IFLUSH, _("Should flush icache?"), dec);
 242           TAG (AT_SUN_CPU, _("CPU name string"), str);
 243           TAG (AT_SUN_EMUL_ENTRY, _("COFF entry point address"), hex);
 244           TAG (AT_SUN_EMUL_EXECFD, _("COFF executable file descriptor"), dec);
 245           TAG (AT_SUN_EXECNAME,
 246                _("Canonicalized file name given to execve"), str);
 247           TAG (AT_SUN_MMU, _("String for name of MMU module"), str);
 248           TAG (AT_SUN_LDDATA, _("Dynamic linker's data segment address"), hex);
 249         }
 250
 251       fprintf_filtered (file, "%-4s %-20s %-30s ",
 252                         paddr_d (type), name, description);
 253       switch (flavor)
 254         {
 255         case dec:
 256           fprintf_filtered (file, "%s\n", paddr_d (val));
 257           break;
 258         case hex:
 259           fprintf_filtered (file, "0x%s\n", paddr_nz (val));
 260           break;
 261         case str:
 262           if (addressprint)
 263             fprintf_filtered (file, "0x%s", paddr_nz (val));
 264           val_print_string (val, -1, 1, file);
 265           fprintf_filtered (file, "\n");
 266           break;
 267         }
 268       ++ents;
 269     }
 270
 271   xfree (data);
 272
 273   return ents;
 274 }
 275
 276 static void
 277 info_auxv_command (char *cmd, int from_tty)
 278 {
 279   if (! target_has_stack)
 280     error (_("The program has no auxiliary information now."));
 281   else
 282     {
 283       int ents = fprint_target_auxv (gdb_stdout, &current_target);
 284       if (ents < 0)
 285         error (_("No auxiliary vector found, or failed reading it."));
 286       else if (ents == 0)
 287         error (_("Auxiliary vector is empty."));
 288     }
 289 }
 290
 291
 292 extern initialize_file_ftype _initialize_auxv; /* -Wmissing-prototypes; */
 293
 294 void
 295 _initialize_auxv (void)
 296 {
 297   add_info ("auxv", info_auxv_command,
 298             _("Display the inferior's auxiliary vector.\n\
 299 This is information provided by the operating system at program startup."));
 300 }