gdbsupport/rsp-low.cc

   1 /* Low-level RSP routines for GDB, the GNU debugger.
   2
   3    Copyright (C) 1988-2022 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 "common-defs.h"
  21 #include "rsp-low.h"
  22
  23 /* See rsp-low.h.  */
  24
  25 int
  26 tohex (int nib)
  27 {
  28   if (nib < 10)
  29     return '0' + nib;
  30   else
  31     return 'a' + nib - 10;
  32 }
  33
  34 /* Encode 64 bits in 16 chars of hex.  */
  35
  36 static const char hexchars[] = "0123456789abcdef";
  37
  38 static int
  39 ishex (int ch, int *val)
  40 {
  41   if ((ch >= 'a') && (ch <= 'f'))
  42     {
  43       *val = ch - 'a' + 10;
  44       return 1;
  45     }
  46   if ((ch >= 'A') && (ch <= 'F'))
  47     {
  48       *val = ch - 'A' + 10;
  49       return 1;
  50     }
  51   if ((ch >= '0') && (ch <= '9'))
  52     {
  53       *val = ch - '0';
  54       return 1;
  55     }
  56   return 0;
  57 }
  58
  59 /* See rsp-low.h.  */
  60
  61 char *
  62 pack_nibble (char *buf, int nibble)
  63 {
  64   *buf++ = hexchars[(nibble & 0x0f)];
  65   return buf;
  66 }
  67
  68 /* See rsp-low.h.  */
  69
  70 char *
  71 pack_hex_byte (char *pkt, int byte)
  72 {
  73   *pkt++ = hexchars[(byte >> 4) & 0xf];
  74   *pkt++ = hexchars[(byte & 0xf)];
  75   return pkt;
  76 }
  77
  78 /* See rsp-low.h.  */
  79
  80 const char *
  81 unpack_varlen_hex (const char *buff,    /* packet to parse */
  82                    ULONGEST *result)
  83 {
  84   int nibble;
  85   ULONGEST retval = 0;
  86
  87   while (ishex (*buff, &nibble))
  88     {
  89       buff++;
  90       retval = retval << 4;
  91       retval |= nibble & 0x0f;
  92     }
  93   *result = retval;
  94   return buff;
  95 }
  96
  97 /* See rsp-low.h.  */
  98
  99 std::string
 100 hex2str (const char *hex)
 101 {
 102   return hex2str (hex, strlen (hex));
 103 }
 104
 105 /* See rsp-low.h.  */
 106
 107 std::string
 108 hex2str (const char *hex, int count)
 109 {
 110   std::string ret;
 111
 112   ret.reserve (count);
 113   for (size_t i = 0; i < count; ++i)
 114     {
 115       if (hex[0] == '\0' || hex[1] == '\0')
 116         {
 117           /* Hex string is short, or of uneven length.  Return what we
 118              have so far.  */
 119           return ret;
 120         }
 121       ret += fromhex (hex[0]) * 16 + fromhex (hex[1]);
 122       hex += 2;
 123     }
 124
 125   return ret;
 126 }
 127
 128 /* See rsp-low.h.  */
 129
 130 int
 131 bin2hex (const gdb_byte *bin, char *hex, int count)
 132 {
 133   int i;
 134
 135   for (i = 0; i < count; i++)
 136     {
 137       *hex++ = tohex ((*bin >> 4) & 0xf);
 138       *hex++ = tohex (*bin++ & 0xf);
 139     }
 140   *hex = 0;
 141   return i;
 142 }
 143
 144 /* See rsp-low.h.  */
 145
 146 std::string
 147 bin2hex (const gdb_byte *bin, int count)
 148 {
 149   std::string ret;
 150
 151   ret.reserve (count * 2);
 152   for (int i = 0; i < count; ++i)
 153     {
 154       ret += tohex ((*bin >> 4) & 0xf);
 155       ret += tohex (*bin++ & 0xf);
 156     }
 157
 158   return ret;
 159 }
 160
 161 /* Return whether byte B needs escaping when sent as part of binary data.  */
 162
 163 static int
 164 needs_escaping (gdb_byte b)
 165 {
 166   return b == '$' || b == '#' || b == '}' || b == '*';
 167 }
 168
 169 /* See rsp-low.h.  */
 170
 171 int
 172 remote_escape_output (const gdb_byte *buffer, int len_units, int unit_size,
 173                       gdb_byte *out_buf, int *out_len_units,
 174                       int out_maxlen_bytes)
 175 {
 176   int input_unit_index, output_byte_index = 0, byte_index_in_unit;
 177   int number_escape_bytes_needed;
 178
 179   /* Try to copy integral addressable memory units until
 180      (1) we run out of space or
 181      (2) we copied all of them.  */
 182   for (input_unit_index = 0;
 183        input_unit_index < len_units;
 184        input_unit_index++)
 185     {
 186       /* Find out how many escape bytes we need for this unit.  */
 187       number_escape_bytes_needed = 0;
 188       for (byte_index_in_unit = 0;
 189            byte_index_in_unit < unit_size;
 190            byte_index_in_unit++)
 191         {
 192           int idx = input_unit_index * unit_size + byte_index_in_unit;
 193           gdb_byte b = buffer[idx];
 194           if (needs_escaping (b))
 195             number_escape_bytes_needed++;
 196         }
 197
 198       /* Check if we have room to fit this escaped unit.  */
 199       if (output_byte_index + unit_size + number_escape_bytes_needed >
 200             out_maxlen_bytes)
 201           break;
 202
 203       /* Copy the unit byte per byte, adding escapes.  */
 204       for (byte_index_in_unit = 0;
 205            byte_index_in_unit < unit_size;
 206            byte_index_in_unit++)
 207         {
 208           int idx = input_unit_index * unit_size + byte_index_in_unit;
 209           gdb_byte b = buffer[idx];
 210           if (needs_escaping (b))
 211             {
 212               out_buf[output_byte_index++] = '}';
 213               out_buf[output_byte_index++] = b ^ 0x20;
 214             }
 215           else
 216             out_buf[output_byte_index++] = b;
 217         }
 218     }
 219
 220   *out_len_units = input_unit_index;
 221   return output_byte_index;
 222 }
 223
 224 /* See rsp-low.h.  */
 225
 226 int
 227 remote_unescape_input (const gdb_byte *buffer, int len,
 228                        gdb_byte *out_buf, int out_maxlen)
 229 {
 230   int input_index, output_index;
 231   int escaped;
 232
 233   output_index = 0;
 234   escaped = 0;
 235   for (input_index = 0; input_index < len; input_index++)
 236     {
 237       gdb_byte b = buffer[input_index];
 238
 239       if (output_index + 1 > out_maxlen)
 240         error (_("Received too much data from the target."));
 241
 242       if (escaped)
 243         {
 244           out_buf[output_index++] = b ^ 0x20;
 245           escaped = 0;
 246         }
 247       else if (b == '}')
 248         escaped = 1;
 249       else
 250         out_buf[output_index++] = b;
 251     }
 252
 253   if (escaped)
 254     error (_("Unmatched escape character in target response."));
 255
 256   return output_index;
 257 }
 258