include/gdb/callback.h

   1 /* Remote target system call callback support.
   2    Copyright 1997-2013 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 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 /* This interface isn't intended to be specific to any particular kind
  21    of remote (hardware, simulator, whatever).  As such, support for it
  22    (e.g. sim/common/callback.c) should *not* live in the simulator source
  23    tree, nor should it live in the gdb source tree.  */
  24
  25 /* There are various ways to handle system calls:
  26
  27    1) Have a simulator intercept the appropriate trap instruction and
  28    directly perform the system call on behalf of the target program.
  29    This is the typical way of handling system calls for embedded targets.
  30    [Handling system calls for embedded targets isn't that much of an
  31    oxymoron as running compiler testsuites make use of the capability.]
  32
  33    This method of system call handling is done when STATE_ENVIRONMENT
  34    is ENVIRONMENT_USER.
  35
  36    2) Have a simulator emulate the hardware as much as possible.
  37    If the program running on the real hardware communicates with some sort
  38    of target manager, one would want to be able to run this program on the
  39    simulator as well.
  40
  41    This method of system call handling is done when STATE_ENVIRONMENT
  42    is ENVIRONMENT_OPERATING.
  43 */
  44
  45 #ifndef CALLBACK_H
  46 #define CALLBACK_H
  47
  48 /* ??? The reason why we check for va_start here should be documented.  */
  49
  50 #ifndef va_start
  51 #include <ansidecl.h>
  52 #include <stdarg.h>
  53 #endif
  54 /* Needed for enum bfd_endian.  */
  55 #include "bfd.h"
  56 \f
  57 /* Mapping of host/target values.  */
  58 /* ??? For debugging purposes, one might want to add a string of the
  59    name of the symbol.  */
  60
  61 typedef struct {
  62   int host_val;
  63   int target_val;
  64 } CB_TARGET_DEFS_MAP;
  65
  66 #define MAX_CALLBACK_FDS 10
  67
  68 /* Forward decl for stat/fstat.  */
  69 struct stat;
  70
  71 typedef struct host_callback_struct host_callback;
  72
  73 struct host_callback_struct
  74 {
  75   int (*close) (host_callback *,int);
  76   int (*get_errno) (host_callback *);
  77   int (*isatty) (host_callback *, int);
  78   int (*lseek) (host_callback *, int, long , int);
  79   int (*open) (host_callback *, const char*, int mode);
  80   int (*read) (host_callback *,int,  char *, int);
  81   int (*read_stdin) ( host_callback *, char *, int);
  82   int (*rename) (host_callback *, const char *, const char *);
  83   int (*system) (host_callback *, const char *);
  84   long (*time) (host_callback *, long *);
  85   int (*unlink) (host_callback *, const char *);
  86   int (*write) (host_callback *,int, const char *, int);
  87   int (*write_stdout) (host_callback *, const char *, int);
  88   void (*flush_stdout) (host_callback *);
  89   int (*write_stderr) (host_callback *, const char *, int);
  90   void (*flush_stderr) (host_callback *);
  91   int (*stat) (host_callback *, const char *, struct stat *);
  92   int (*fstat) (host_callback *, int, struct stat *);
  93   int (*lstat) (host_callback *, const char *, struct stat *);
  94   int (*ftruncate) (host_callback *, int, long);
  95   int (*truncate) (host_callback *, const char *, long);
  96   int (*pipe) (host_callback *, int *);
  97
  98   /* Called by the framework when a read call has emptied a pipe buffer.  */
  99   void (*pipe_empty) (host_callback *, int read_fd, int write_fd);
 100
 101   /* Called by the framework when a write call makes a pipe buffer
 102      non-empty.  */
 103   void (*pipe_nonempty) (host_callback *, int read_fd, int write_fd);
 104
 105   /* When present, call to the client to give it the oportunity to
 106      poll any io devices for a request to quit (indicated by a nonzero
 107      return value). */
 108   int (*poll_quit) (host_callback *);
 109
 110   /* Used when the target has gone away, so we can close open
 111      handles and free memory etc etc.  */
 112   int (*shutdown) (host_callback *);
 113   int (*init)     (host_callback *);
 114
 115   /* depreciated, use vprintf_filtered - Talk to the user on a console.  */
 116   void (*printf_filtered) (host_callback *, const char *, ...);
 117
 118   /* Talk to the user on a console.  */
 119   void (*vprintf_filtered) (host_callback *, const char *, va_list);
 120
 121   /* Same as vprintf_filtered but to stderr.  */
 122   void (*evprintf_filtered) (host_callback *, const char *, va_list);
 123
 124   /* Print an error message and "exit".
 125      In the case of gdb "exiting" means doing a longjmp back to the main
 126      command loop.  */
 127   void (*error) (host_callback *, const char *, ...)
 128 #ifdef __GNUC__
 129     __attribute__ ((__noreturn__))
 130 #endif
 131     ;
 132
 133   int last_errno;               /* host format */
 134
 135   int fdmap[MAX_CALLBACK_FDS];
 136   /* fd_buddy is used to contruct circular lists of target fds that point to
 137      the same host fd.  A uniquely mapped fd points to itself; for a closed
 138      one, fd_buddy has the value -1.  The host file descriptors for stdin /
 139      stdout / stderr are never closed by the simulators, so they are put
 140      in a special fd_buddy circular list which also has MAX_CALLBACK_FDS
 141      as a member.  */
 142   /* ??? We don't have a callback entry for dup, although it is trival to
 143      implement now.  */
 144   short fd_buddy[MAX_CALLBACK_FDS+1];
 145
 146   /* 0 = none, >0 = reader (index of writer),
 147      <0 = writer (negative index of reader).
 148      If abs (ispipe[N]) == N, then N is an end of a pipe whose other
 149      end is closed.  */
 150   short ispipe[MAX_CALLBACK_FDS];
 151
 152   /* A writer stores the buffer at its index.  Consecutive writes
 153      realloc the buffer and add to the size.  The reader indicates the
 154      read part in its .size, until it has consumed it all, at which
 155      point it deallocates the buffer and zeroes out both sizes.  */
 156   struct pipe_write_buffer
 157   {
 158     int size;
 159     char *buffer;
 160   } pipe_buffer[MAX_CALLBACK_FDS];
 161
 162   /* System call numbers.  */
 163   CB_TARGET_DEFS_MAP *syscall_map;
 164   /* Errno values.  */
 165   CB_TARGET_DEFS_MAP *errno_map;
 166   /* Flags to the open system call.  */
 167   CB_TARGET_DEFS_MAP *open_map;
 168   /* Signal numbers.  */
 169   CB_TARGET_DEFS_MAP *signal_map;
 170   /* Layout of `stat' struct.
 171      The format is a series of "name,length" pairs separated by colons.
 172      Empty space is indicated with a `name' of "space".
 173      All padding must be explicitly mentioned.
 174      Lengths are in bytes.  If this needs to be extended to bits,
 175      use "name.bits".
 176      Example: "st_dev,4:st_ino,4:st_mode,4:..."  */
 177   const char *stat_map;
 178
 179   enum bfd_endian target_endian;
 180
 181   /* Size of an "int" on the target (for syscalls whose ABI uses "int").
 182      This must include padding, and only padding-at-higher-address is
 183      supported.  For example, a 64-bit target with 32-bit int:s which
 184      are padded to 64 bits when in an array, should supposedly set this
 185      to 8.  The default is 4 which matches ILP32 targets and 64-bit
 186      targets with 32-bit ints and no padding.  */
 187   int target_sizeof_int;
 188
 189   /* Marker for those wanting to do sanity checks.
 190      This should remain the last member of this struct to help catch
 191      miscompilation errors. */
 192 #define HOST_CALLBACK_MAGIC 4705 /* teds constant */
 193   int magic;
 194 };
 195
 196 extern host_callback default_callback;
 197 \f
 198 /* Canonical versions of system call numbers.
 199    It's not intended to willy-nilly throw every system call ever heard
 200    of in here.  Only include those that have an important use.
 201    ??? One can certainly start a discussion over the ones that are currently
 202    here, but that will always be true.  */
 203
 204 /* These are used by the ANSI C support of libc.  */
 205 #define CB_SYS_exit     1
 206 #define CB_SYS_open     2
 207 #define CB_SYS_close    3
 208 #define CB_SYS_read     4
 209 #define CB_SYS_write    5
 210 #define CB_SYS_lseek    6
 211 #define CB_SYS_unlink   7
 212 #define CB_SYS_getpid   8
 213 #define CB_SYS_kill     9
 214 #define CB_SYS_fstat    10
 215 /*#define CB_SYS_sbrk   11 - not currently a system call, but reserved.  */
 216
 217 /* ARGV support.  */
 218 #define CB_SYS_argvlen  12
 219 #define CB_SYS_argv     13
 220
 221 /* These are extras added for one reason or another.  */
 222 #define CB_SYS_chdir    14
 223 #define CB_SYS_stat     15
 224 #define CB_SYS_chmod    16
 225 #define CB_SYS_utime    17
 226 #define CB_SYS_time     18
 227
 228 /* More standard syscalls.  */
 229 #define CB_SYS_lstat    19
 230 #define CB_SYS_rename   20
 231 #define CB_SYS_truncate 21
 232 #define CB_SYS_ftruncate 22
 233 #define CB_SYS_pipe     23
 234
 235 /* New ARGV support.  */
 236 #define CB_SYS_argc     24
 237 #define CB_SYS_argnlen  25
 238 #define CB_SYS_argn     26
 239 \f
 240 /* Struct use to pass and return information necessary to perform a
 241    system call.  */
 242 /* FIXME: Need to consider target word size.  */
 243
 244 typedef struct cb_syscall {
 245   /* The target's value of what system call to perform.  */
 246   int func;
 247   /* The arguments to the syscall.  */
 248   long arg1, arg2, arg3, arg4;
 249
 250   /* The result.  */
 251   long result;
 252   /* Some system calls have two results.  */
 253   long result2;
 254   /* The target's errno value, or 0 if success.
 255      This is converted to the target's value with host_to_target_errno.  */
 256   int errcode;
 257
 258   /* Working space to be used by memory read/write callbacks.  */
 259   PTR p1;
 260   PTR p2;
 261   long x1,x2;
 262
 263   /* Callbacks for reading/writing memory (e.g. for read/write syscalls).
 264      ??? long or unsigned long might be better to use for the `count'
 265      argument here.  We mimic sim_{read,write} for now.  Be careful to
 266      test any changes with -Wall -Werror, mixed signed comparisons
 267      will get you.  */
 268   int (*read_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 269                    unsigned long /*taddr*/, char * /*buf*/,
 270                    int /*bytes*/);
 271   int (*write_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 272                     unsigned long /*taddr*/, const char * /*buf*/,
 273                     int /*bytes*/);
 274
 275   /* For sanity checking, should be last entry.  */
 276   int magic;
 277 } CB_SYSCALL;
 278
 279 /* Magic number sanity checker.  */
 280 #define CB_SYSCALL_MAGIC 0x12344321
 281
 282 /* Macro to initialize CB_SYSCALL.  Called first, before filling in
 283    any fields.  */
 284 #define CB_SYSCALL_INIT(sc) \
 285 do { \
 286   memset ((sc), 0, sizeof (*(sc))); \
 287   (sc)->magic = CB_SYSCALL_MAGIC; \
 288 } while (0)
 289 \f
 290 /* Return codes for various interface routines.  */
 291
 292 typedef enum {
 293   CB_RC_OK = 0,
 294   /* generic error */
 295   CB_RC_ERR,
 296   /* either file not found or no read access */
 297   CB_RC_ACCESS,
 298   CB_RC_NO_MEM
 299 } CB_RC;
 300
 301 /* Read in target values for system call numbers, errno values, signals.  */
 302 CB_RC cb_read_target_syscall_maps (host_callback *, const char *);
 303
 304 /* Translate target to host syscall function numbers.  */
 305 int cb_target_to_host_syscall (host_callback *, int);
 306
 307 /* Translate host to target errno value.  */
 308 int cb_host_to_target_errno (host_callback *, int);
 309
 310 /* Translate target to host open flags.  */
 311 int cb_target_to_host_open (host_callback *, int);
 312
 313 /* Translate target signal number to host.  */
 314 int cb_target_to_host_signal (host_callback *, int);
 315
 316 /* Translate host signal number to target.  */
 317 int cb_host_to_gdb_signal (host_callback *, int);
 318
 319 /* Translate host stat struct to target.
 320    If stat struct ptr is NULL, just compute target stat struct size.
 321    Result is size of target stat struct or 0 if error.  */
 322 int cb_host_to_target_stat (host_callback *, const struct stat *, PTR);
 323
 324 /* Translate a value to target endian.  */
 325 void cb_store_target_endian (host_callback *, char *, int, long);
 326
 327 /* Tests for special fds.  */
 328 int cb_is_stdin (host_callback *, int);
 329 int cb_is_stdout (host_callback *, int);
 330 int cb_is_stderr (host_callback *, int);
 331
 332 /* Read a string out of the target.  */
 333 int cb_get_string (host_callback *, CB_SYSCALL *, char *, int, unsigned long);
 334
 335 /* Perform a system call.  */
 336 CB_RC cb_syscall (host_callback *, CB_SYSCALL *);
 337
 338 #endif