include/gdb/callback.h

   1 /* Remote target system call callback support.
   2    Copyright 1997, 2007 Free Software Foundation, Inc.
   3    Contributed by Cygnus Solutions.
   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, Boston, MA 02111-1307, USA.  */
  20
  21 /* This interface isn't intended to be specific to any particular kind
  22    of remote (hardware, simulator, whatever).  As such, support for it
  23    (e.g. sim/common/callback.c) should *not* live in the simulator source
  24    tree, nor should it live in the gdb source tree.  */
  25
  26 /* There are various ways to handle system calls:
  27
  28    1) Have a simulator intercept the appropriate trap instruction and
  29    directly perform the system call on behalf of the target program.
  30    This is the typical way of handling system calls for embedded targets.
  31    [Handling system calls for embedded targets isn't that much of an
  32    oxymoron as running compiler testsuites make use of the capability.]
  33
  34    This method of system call handling is done when STATE_ENVIRONMENT
  35    is ENVIRONMENT_USER.
  36
  37    2) Have a simulator emulate the hardware as much as possible.
  38    If the program running on the real hardware communicates with some sort
  39    of target manager, one would want to be able to run this program on the
  40    simulator as well.
  41
  42    This method of system call handling is done when STATE_ENVIRONMENT
  43    is ENVIRONMENT_OPERATING.
  44 */
  45
  46 #ifndef CALLBACK_H
  47 #define CALLBACK_H
  48
  49 /* ??? The reason why we check for va_start here should be documented.  */
  50
  51 #ifndef va_start
  52 #include <ansidecl.h>
  53 #include <stdarg.h>
  54 #endif
  55 /* Needed for enum bfd_endian.  */
  56 #include "bfd.h"
  57 \f
  58 /* Mapping of host/target values.  */
  59 /* ??? For debugging purposes, one might want to add a string of the
  60    name of the symbol.  */
  61
  62 typedef struct {
  63   int host_val;
  64   int target_val;
  65 } CB_TARGET_DEFS_MAP;
  66
  67 #define MAX_CALLBACK_FDS 10
  68
  69 /* Forward decl for stat/fstat.  */
  70 struct stat;
  71
  72 typedef struct host_callback_struct host_callback;
  73
  74 struct host_callback_struct
  75 {
  76   int (*close) PARAMS ((host_callback *,int));
  77   int (*get_errno) PARAMS ((host_callback *));
  78   int (*isatty) PARAMS ((host_callback *, int));
  79   int (*lseek) PARAMS ((host_callback *, int, long , int));
  80   int (*open) PARAMS ((host_callback *, const char*, int mode));
  81   int (*read) PARAMS ((host_callback *,int,  char *, int));
  82   int (*read_stdin) PARAMS (( host_callback *, char *, int));
  83   int (*rename) PARAMS ((host_callback *, const char *, const char *));
  84   int (*system) PARAMS ((host_callback *, const char *));
  85   long (*time) PARAMS ((host_callback *, long *));
  86   int (*unlink) PARAMS ((host_callback *, const char *));
  87   int (*write) PARAMS ((host_callback *,int, const char *, int));
  88   int (*write_stdout) PARAMS ((host_callback *, const char *, int));
  89   void (*flush_stdout) PARAMS ((host_callback *));
  90   int (*write_stderr) PARAMS ((host_callback *, const char *, int));
  91   void (*flush_stderr) PARAMS ((host_callback *));
  92   int (*stat) PARAMS ((host_callback *, const char *, struct stat *));
  93   int (*fstat) PARAMS ((host_callback *, int, struct stat *));
  94   int (*lstat) PARAMS ((host_callback *, const char *, struct stat *));
  95   int (*ftruncate) PARAMS ((host_callback *, int, long));
  96   int (*truncate) PARAMS ((host_callback *, const char *, long));
  97   int (*pipe) PARAMS ((host_callback *, int *));
  98
  99   /* Called by the framework when a read call has emptied a pipe buffer.  */
 100   void (*pipe_empty) PARAMS ((host_callback *, int read_fd, int write_fd));
 101
 102   /* Called by the framework when a write call makes a pipe buffer
 103      non-empty.  */
 104   void (*pipe_nonempty) PARAMS ((host_callback *, int read_fd, int write_fd));
 105
 106   /* When present, call to the client to give it the oportunity to
 107      poll any io devices for a request to quit (indicated by a nonzero
 108      return value). */
 109   int (*poll_quit) PARAMS ((host_callback *));
 110
 111   /* Used when the target has gone away, so we can close open
 112      handles and free memory etc etc.  */
 113   int (*shutdown) PARAMS ((host_callback *));
 114   int (*init)     PARAMS ((host_callback *));
 115
 116   /* depreciated, use vprintf_filtered - Talk to the user on a console.  */
 117   void (*printf_filtered) PARAMS ((host_callback *, const char *, ...));
 118
 119   /* Talk to the user on a console.  */
 120   void (*vprintf_filtered) PARAMS ((host_callback *, const char *, va_list));
 121
 122   /* Same as vprintf_filtered but to stderr.  */
 123   void (*evprintf_filtered) PARAMS ((host_callback *, const char *, va_list));
 124
 125   /* Print an error message and "exit".
 126      In the case of gdb "exiting" means doing a longjmp back to the main
 127      command loop.  */
 128   void (*error) PARAMS ((host_callback *, const char *, ...));
 129
 130   int last_errno;               /* host format */
 131
 132   int fdmap[MAX_CALLBACK_FDS];
 133   /* fd_buddy is used to contruct circular lists of target fds that point to
 134      the same host fd.  A uniquely mapped fd points to itself; for a closed
 135      one, fd_buddy has the value -1.  The host file descriptors for stdin /
 136      stdout / stderr are never closed by the simulators, so they are put
 137      in a special fd_buddy circular list which also has MAX_CALLBACK_FDS
 138      as a member.  */
 139   /* ??? We don't have a callback entry for dup, although it is trival to
 140      implement now.  */
 141   short fd_buddy[MAX_CALLBACK_FDS+1];
 142
 143   /* 0 = none, >0 = reader (index of writer),
 144      <0 = writer (negative index of reader).
 145      If abs (ispipe[N]) == N, then N is an end of a pipe whose other
 146      end is closed.  */
 147   short ispipe[MAX_CALLBACK_FDS];
 148
 149   /* A writer stores the buffer at its index.  Consecutive writes
 150      realloc the buffer and add to the size.  The reader indicates the
 151      read part in its .size, until it has consumed it all, at which
 152      point it deallocates the buffer and zeroes out both sizes.  */
 153   struct pipe_write_buffer
 154   {
 155     int size;
 156     char *buffer;
 157   } pipe_buffer[MAX_CALLBACK_FDS];
 158
 159   /* System call numbers.  */
 160   CB_TARGET_DEFS_MAP *syscall_map;
 161   /* Errno values.  */
 162   CB_TARGET_DEFS_MAP *errno_map;
 163   /* Flags to the open system call.  */
 164   CB_TARGET_DEFS_MAP *open_map;
 165   /* Signal numbers.  */
 166   CB_TARGET_DEFS_MAP *signal_map;
 167   /* Layout of `stat' struct.
 168      The format is a series of "name,length" pairs separated by colons.
 169      Empty space is indicated with a `name' of "space".
 170      All padding must be explicitly mentioned.
 171      Lengths are in bytes.  If this needs to be extended to bits,
 172      use "name.bits".
 173      Example: "st_dev,4:st_ino,4:st_mode,4:..."  */
 174   const char *stat_map;
 175
 176   enum bfd_endian target_endian;
 177
 178   /* Size of an "int" on the target (for syscalls whose ABI uses "int").
 179      This must include padding, and only padding-at-higher-address is
 180      supported.  For example, a 64-bit target with 32-bit int:s which
 181      are padded to 64 bits when in an array, should supposedly set this
 182      to 8.  The default is 4 which matches ILP32 targets and 64-bit
 183      targets with 32-bit ints and no padding.  */
 184   int target_sizeof_int;
 185
 186   /* Marker for those wanting to do sanity checks.
 187      This should remain the last member of this struct to help catch
 188      miscompilation errors. */
 189 #define HOST_CALLBACK_MAGIC 4705 /* teds constant */
 190   int magic;
 191 };
 192
 193 extern host_callback default_callback;
 194 \f
 195 /* Canonical versions of system call numbers.
 196    It's not intended to willy-nilly throw every system call ever heard
 197    of in here.  Only include those that have an important use.
 198    ??? One can certainly start a discussion over the ones that are currently
 199    here, but that will always be true.  */
 200
 201 /* These are used by the ANSI C support of libc.  */
 202 #define CB_SYS_exit     1
 203 #define CB_SYS_open     2
 204 #define CB_SYS_close    3
 205 #define CB_SYS_read     4
 206 #define CB_SYS_write    5
 207 #define CB_SYS_lseek    6
 208 #define CB_SYS_unlink   7
 209 #define CB_SYS_getpid   8
 210 #define CB_SYS_kill     9
 211 #define CB_SYS_fstat    10
 212 /*#define CB_SYS_sbrk   11 - not currently a system call, but reserved.  */
 213
 214 /* ARGV support.  */
 215 #define CB_SYS_argvlen  12
 216 #define CB_SYS_argv     13
 217
 218 /* These are extras added for one reason or another.  */
 219 #define CB_SYS_chdir    14
 220 #define CB_SYS_stat     15
 221 #define CB_SYS_chmod    16
 222 #define CB_SYS_utime    17
 223 #define CB_SYS_time     18
 224
 225 /* More standard syscalls.  */
 226 #define CB_SYS_lstat    19
 227 #define CB_SYS_rename   20
 228 #define CB_SYS_truncate 21
 229 #define CB_SYS_ftruncate 22
 230 #define CB_SYS_pipe     23
 231 \f
 232 /* Struct use to pass and return information necessary to perform a
 233    system call.  */
 234 /* FIXME: Need to consider target word size.  */
 235
 236 typedef struct cb_syscall {
 237   /* The target's value of what system call to perform.  */
 238   int func;
 239   /* The arguments to the syscall.  */
 240   long arg1, arg2, arg3, arg4;
 241
 242   /* The result.  */
 243   long result;
 244   /* Some system calls have two results.  */
 245   long result2;
 246   /* The target's errno value, or 0 if success.
 247      This is converted to the target's value with host_to_target_errno.  */
 248   int errcode;
 249
 250   /* Working space to be used by memory read/write callbacks.  */
 251   PTR p1;
 252   PTR p2;
 253   long x1,x2;
 254
 255   /* Callbacks for reading/writing memory (e.g. for read/write syscalls).
 256      ??? long or unsigned long might be better to use for the `count'
 257      argument here.  We mimic sim_{read,write} for now.  Be careful to
 258      test any changes with -Wall -Werror, mixed signed comparisons
 259      will get you.  */
 260   int (*read_mem) PARAMS ((host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 261                            unsigned long /*taddr*/, char * /*buf*/,
 262                            int /*bytes*/));
 263   int (*write_mem) PARAMS ((host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 264                             unsigned long /*taddr*/, const char * /*buf*/,
 265                             int /*bytes*/));
 266
 267   /* For sanity checking, should be last entry.  */
 268   int magic;
 269 } CB_SYSCALL;
 270
 271 /* Magic number sanity checker.  */
 272 #define CB_SYSCALL_MAGIC 0x12344321
 273
 274 /* Macro to initialize CB_SYSCALL.  Called first, before filling in
 275    any fields.  */
 276 #define CB_SYSCALL_INIT(sc) \
 277 do { \
 278   memset ((sc), 0, sizeof (*(sc))); \
 279   (sc)->magic = CB_SYSCALL_MAGIC; \
 280 } while (0)
 281 \f
 282 /* Return codes for various interface routines.  */
 283
 284 typedef enum {
 285   CB_RC_OK = 0,
 286   /* generic error */
 287   CB_RC_ERR,
 288   /* either file not found or no read access */
 289   CB_RC_ACCESS,
 290   CB_RC_NO_MEM
 291 } CB_RC;
 292
 293 /* Read in target values for system call numbers, errno values, signals.  */
 294 CB_RC cb_read_target_syscall_maps PARAMS ((host_callback *, const char *));
 295
 296 /* Translate target to host syscall function numbers.  */
 297 int cb_target_to_host_syscall PARAMS ((host_callback *, int));
 298
 299 /* Translate host to target errno value.  */
 300 int cb_host_to_target_errno PARAMS ((host_callback *, int));
 301
 302 /* Translate target to host open flags.  */
 303 int cb_target_to_host_open PARAMS ((host_callback *, int));
 304
 305 /* Translate target signal number to host.  */
 306 int cb_target_to_host_signal PARAMS ((host_callback *, int));
 307
 308 /* Translate host signal number to target.  */
 309 int cb_host_to_target_signal PARAMS ((host_callback *, int));
 310
 311 /* Translate host stat struct to target.
 312    If stat struct ptr is NULL, just compute target stat struct size.
 313    Result is size of target stat struct or 0 if error.  */
 314 int cb_host_to_target_stat PARAMS ((host_callback *, const struct stat *, PTR));
 315
 316 /* Translate a value to target endian.  */
 317 void cb_store_target_endian PARAMS ((host_callback *, char *, int, long));
 318
 319 /* Perform a system call.  */
 320 CB_RC cb_syscall PARAMS ((host_callback *, CB_SYSCALL *));
 321
 322 #endif