gdb/findcmd.c

   1 /* The find command.
   2
   3    Copyright (C) 2008-2020 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 "arch-utils.h"
  22 #include <ctype.h>
  23 #include "gdbcmd.h"
  24 #include "value.h"
  25 #include "target.h"
  26 #include "cli/cli-utils.h"
  27 #include <algorithm>
  28 #include "gdbsupport/byte-vector.h"
  29
  30 /* Copied from bfd_put_bits.  */
  31
  32 static void
  33 put_bits (bfd_uint64_t data, gdb::byte_vector &buf, int bits, bfd_boolean big_p)
  34 {
  35   int i;
  36   int bytes;
  37
  38   gdb_assert (bits % 8 == 0);
  39
  40   bytes = bits / 8;
  41   size_t last = buf.size ();
  42   buf.resize (last + bytes);
  43   for (i = 0; i < bytes; i++)
  44     {
  45       int index = big_p ? bytes - i - 1 : i;
  46
  47       buf[last + index] = data & 0xff;
  48       data >>= 8;
  49     }
  50 }
  51
  52 /* Subroutine of find_command to simplify it.
  53    Parse the arguments of the "find" command.  */
  54
  55 static gdb::byte_vector
  56 parse_find_args (const char *args, ULONGEST *max_countp,
  57                  CORE_ADDR *start_addrp, ULONGEST *search_space_lenp,
  58                  bfd_boolean big_p)
  59 {
  60   /* Default to using the specified type.  */
  61   char size = '\0';
  62   ULONGEST max_count = ~(ULONGEST) 0;
  63   /* Buffer to hold the search pattern.  */
  64   gdb::byte_vector pattern_buf;
  65   CORE_ADDR start_addr;
  66   ULONGEST search_space_len;
  67   const char *s = args;
  68   struct value *v;
  69
  70   if (args == NULL)
  71     error (_("Missing search parameters."));
  72
  73   /* Get search granularity and/or max count if specified.
  74      They may be specified in either order, together or separately.  */
  75
  76   while (*s == '/')
  77     {
  78       ++s;
  79
  80       while (*s != '\0' && *s != '/' && !isspace (*s))
  81         {
  82           if (isdigit (*s))
  83             {
  84               max_count = atoi (s);
  85               while (isdigit (*s))
  86                 ++s;
  87               continue;
  88             }
  89
  90           switch (*s)
  91             {
  92             case 'b':
  93             case 'h':
  94             case 'w':
  95             case 'g':
  96               size = *s++;
  97               break;
  98             default:
  99               error (_("Invalid size granularity."));
 100             }
 101         }
 102
 103       s = skip_spaces (s);
 104     }
 105
 106   /* Get the search range.  */
 107
 108   v = parse_to_comma_and_eval (&s);
 109   start_addr = value_as_address (v);
 110
 111   if (*s == ',')
 112     ++s;
 113   s = skip_spaces (s);
 114
 115   if (*s == '+')
 116     {
 117       LONGEST len;
 118
 119       ++s;
 120       v = parse_to_comma_and_eval (&s);
 121       len = value_as_long (v);
 122       if (len == 0)
 123         {
 124           printf_filtered (_("Empty search range.\n"));
 125           return pattern_buf;
 126         }
 127       if (len < 0)
 128         error (_("Invalid length."));
 129       /* Watch for overflows.  */
 130       if (len > CORE_ADDR_MAX
 131           || (start_addr + len - 1) < start_addr)
 132         error (_("Search space too large."));
 133       search_space_len = len;
 134     }
 135   else
 136     {
 137       CORE_ADDR end_addr;
 138
 139       v = parse_to_comma_and_eval (&s);
 140       end_addr = value_as_address (v);
 141       if (start_addr > end_addr)
 142         error (_("Invalid search space, end precedes start."));
 143       search_space_len = end_addr - start_addr + 1;
 144       /* We don't support searching all of memory
 145          (i.e. start=0, end = 0xff..ff).
 146          Bail to avoid overflows later on.  */
 147       if (search_space_len == 0)
 148         error (_("Overflow in address range "
 149                  "computation, choose smaller range."));
 150     }
 151
 152   if (*s == ',')
 153     ++s;
 154
 155   /* Fetch the search string.  */
 156
 157   while (*s != '\0')
 158     {
 159       LONGEST x;
 160       struct type *t;
 161
 162       s = skip_spaces (s);
 163
 164       v = parse_to_comma_and_eval (&s);
 165       t = value_type (v);
 166
 167       if (size != '\0')
 168         {
 169           x = value_as_long (v);
 170           switch (size)
 171             {
 172             case 'b':
 173               pattern_buf.push_back (x);
 174               break;
 175             case 'h':
 176               put_bits (x, pattern_buf, 16, big_p);
 177               break;
 178             case 'w':
 179               put_bits (x, pattern_buf, 32, big_p);
 180               break;
 181             case 'g':
 182               put_bits (x, pattern_buf, 64, big_p);
 183               break;
 184             }
 185         }
 186       else
 187         {
 188           const gdb_byte *contents = value_contents (v);
 189           pattern_buf.insert (pattern_buf.end (), contents,
 190                               contents + TYPE_LENGTH (t));
 191         }
 192
 193       if (*s == ',')
 194         ++s;
 195       s = skip_spaces (s);
 196     }
 197
 198   if (pattern_buf.empty ())
 199     error (_("Missing search pattern."));
 200
 201   if (search_space_len < pattern_buf.size ())
 202     error (_("Search space too small to contain pattern."));
 203
 204   *max_countp = max_count;
 205   *start_addrp = start_addr;
 206   *search_space_lenp = search_space_len;
 207
 208   return pattern_buf;
 209 }
 210
 211 static void
 212 find_command (const char *args, int from_tty)
 213 {
 214   struct gdbarch *gdbarch = get_current_arch ();
 215   bfd_boolean big_p = gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG;
 216   /* Command line parameters.
 217      These are initialized to avoid uninitialized warnings from -Wall.  */
 218   ULONGEST max_count = 0;
 219   CORE_ADDR start_addr = 0;
 220   ULONGEST search_space_len = 0;
 221   /* End of command line parameters.  */
 222   unsigned int found_count;
 223   CORE_ADDR last_found_addr;
 224
 225   gdb::byte_vector pattern_buf = parse_find_args (args, &max_count,
 226                                                   &start_addr,
 227                                                   &search_space_len,
 228                                                   big_p);
 229
 230   /* Perform the search.  */
 231
 232   found_count = 0;
 233   last_found_addr = 0;
 234
 235   while (search_space_len >= pattern_buf.size ()
 236          && found_count < max_count)
 237     {
 238       /* Offset from start of this iteration to the next iteration.  */
 239       ULONGEST next_iter_incr;
 240       CORE_ADDR found_addr;
 241       int found = target_search_memory (start_addr, search_space_len,
 242                                         pattern_buf.data (),
 243                                         pattern_buf.size (),
 244                                         &found_addr);
 245
 246       if (found <= 0)
 247         break;
 248
 249       print_address (gdbarch, found_addr, gdb_stdout);
 250       printf_filtered ("\n");
 251       ++found_count;
 252       last_found_addr = found_addr;
 253
 254       /* Begin next iteration at one byte past this match.  */
 255       next_iter_incr = (found_addr - start_addr) + 1;
 256
 257       /* For robustness, we don't let search_space_len go -ve here.  */
 258       if (search_space_len >= next_iter_incr)
 259         search_space_len -= next_iter_incr;
 260       else
 261         search_space_len = 0;
 262       start_addr += next_iter_incr;
 263     }
 264
 265   /* Record and print the results.  */
 266
 267   set_internalvar_integer (lookup_internalvar ("numfound"), found_count);
 268   if (found_count > 0)
 269     {
 270       struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
 271
 272       set_internalvar (lookup_internalvar ("_"),
 273                        value_from_pointer (ptr_type, last_found_addr));
 274     }
 275
 276   if (found_count == 0)
 277     printf_filtered ("Pattern not found.\n");
 278   else
 279     printf_filtered ("%d pattern%s found.\n", found_count,
 280                      found_count > 1 ? "s" : "");
 281 }
 282
 283 void _initialize_mem_search ();
 284 void
 285 _initialize_mem_search ()
 286 {
 287   add_cmd ("find", class_vars, find_command, _("\
 288 Search memory for a sequence of bytes.\n\
 289 Usage:\nfind \
 290 [/SIZE-CHAR] [/MAX-COUNT] START-ADDRESS, END-ADDRESS, EXPR1 [, EXPR2 ...]\n\
 291 find [/SIZE-CHAR] [/MAX-COUNT] START-ADDRESS, +LENGTH, EXPR1 [, EXPR2 ...]\n\
 292 SIZE-CHAR is one of b,h,w,g for 8,16,32,64 bit values respectively,\n\
 293 and if not specified the size is taken from the type of the expression\n\
 294 in the current language.\n\
 295 Note that this means for example that in the case of C-like languages\n\
 296 a search for an untyped 0x42 will search for \"(int) 0x42\"\n\
 297 which is typically four bytes, and a search for a string \"hello\" will\n\
 298 include the trailing '\\0'.  The null terminator can be removed from\n\
 299 searching by using casts, e.g.: {char[5]}\"hello\".\n\
 300 \n\
 301 The address of the last match is stored as the value of \"$_\".\n\
 302 Convenience variable \"$numfound\" is set to the number of matches."),
 303            &cmdlist);
 304 }