gdb/exec.c

   1 /* Work with executable files, for GDB.
   2    Copyright 1988, 1989, 1991, 1992 Free Software Foundation, Inc.
   3
   4 This file is part of GDB.
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 #include "defs.h"
  21 #include "frame.h"
  22 #include "inferior.h"
  23 #include "target.h"
  24 #include "gdbcmd.h"
  25
  26 #ifdef USG
  27 #include <sys/types.h>
  28 #endif
  29
  30 #include <sys/param.h>
  31 #include <fcntl.h>
  32 #include <string.h>
  33
  34 #include "gdbcore.h"
  35
  36 #include <ctype.h>
  37 #include <sys/stat.h>
  38 #ifndef O_BINARY
  39 #define O_BINARY 0
  40 #endif
  41
  42 /* Prototypes for local functions */
  43
  44 static void
  45 add_to_section_table PARAMS ((bfd *, sec_ptr, PTR));
  46
  47 static void
  48 exec_close PARAMS ((int));
  49
  50 static void
  51 file_command PARAMS ((char *, int));
  52
  53 static void
  54 set_section_command PARAMS ((char *, int));
  55
  56 static void
  57 exec_files_info PARAMS ((struct target_ops *));
  58
  59 extern int info_verbose;
  60
  61 /* The Binary File Descriptor handle for the executable file.  */
  62
  63 bfd *exec_bfd = NULL;
  64
  65 /* Whether to open exec and core files read-only or read-write.  */
  66
  67 int write_files = 0;
  68
  69 /* Text start and end addresses (KLUDGE) if needed */
  70
  71 #ifdef NEED_TEXT_START_END
  72 CORE_ADDR text_start = 0;
  73 CORE_ADDR text_end   = 0;
  74 #endif
  75
  76 /* Forward decl */
  77
  78 extern struct target_ops exec_ops;
  79
  80 /* ARGSUSED */
  81 static void
  82 exec_close (quitting)
  83      int quitting;
  84 {
  85   if (exec_bfd) {
  86     bfd_close (exec_bfd);
  87     exec_bfd = NULL;
  88   }
  89   if (exec_ops.to_sections) {
  90     free ((PTR)exec_ops.to_sections);
  91     exec_ops.to_sections = NULL;
  92     exec_ops.to_sections_end = NULL;
  93   }
  94 }
  95
  96 /*  Process the first arg in ARGS as the new exec file.
  97
  98     Note that we have to explicitly ignore additional args, since we can
  99     be called from file_command(), which also calls symbol_file_command()
 100     which can take multiple args. */
 101
 102 void
 103 exec_file_command (args, from_tty)
 104      char *args;
 105      int from_tty;
 106 {
 107   char **argv;
 108   char *filename;
 109
 110   target_preopen (from_tty);
 111
 112   /* Remove any previous exec file.  */
 113   unpush_target (&exec_ops);
 114
 115   /* Now open and digest the file the user requested, if any.  */
 116
 117   if (args)
 118     {
 119       char *scratch_pathname;
 120       int scratch_chan;
 121
 122       /* Scan through the args and pick up the first non option arg
 123          as the filename. */
 124
 125       if ((argv = buildargv (args)) == NULL)
 126         {
 127           nomem (0);
 128         }
 129       make_cleanup (freeargv, (char *) argv);
 130
 131       for (; (*argv != NULL) && (**argv == '-'); argv++) {;}
 132       if (*argv == NULL)
 133         {
 134           error ("no exec file name was specified");
 135         }
 136
 137       filename = tilde_expand (*argv);
 138       make_cleanup (free, filename);
 139
 140       scratch_chan = openp (getenv ("PATH"), 1, filename,
 141                             write_files? O_RDWR|O_BINARY: O_RDONLY|O_BINARY, 0,
 142                             &scratch_pathname);
 143       if (scratch_chan < 0)
 144         perror_with_name (filename);
 145
 146       exec_bfd = bfd_fdopenr (scratch_pathname, NULL, scratch_chan);
 147       if (!exec_bfd)
 148         error ("Could not open `%s' as an executable file: %s",
 149                scratch_pathname, bfd_errmsg (bfd_error));
 150       if (!bfd_check_format (exec_bfd, bfd_object))
 151         error ("\"%s\": not in executable format: %s.",
 152                scratch_pathname, bfd_errmsg (bfd_error));
 153
 154       if (build_section_table (exec_bfd, &exec_ops.to_sections,
 155                                 &exec_ops.to_sections_end))
 156         error ("Can't find the file sections in `%s': %s",
 157                 exec_bfd->filename, bfd_errmsg (bfd_error));
 158
 159 #ifdef NEED_TEXT_START_END
 160       /* This is a KLUDGE (FIXME) because a few places in a few ports
 161          (29K springs to mind) need this info for now.  */
 162       {
 163         struct section_table *p;
 164         for (p = exec_ops.to_sections; p < exec_ops.to_sections_end; p++)
 165           if (!strcmp (".text", bfd_section_name (p->bfd, p->sec_ptr)))
 166             {
 167               text_start = p->addr;
 168               text_end   = p->endaddr;
 169               break;
 170             }
 171       }
 172 #endif
 173
 174       validate_files ();
 175
 176       push_target (&exec_ops);
 177
 178       /* Tell display code (if any) about the changed file name.  */
 179       if (exec_file_display_hook)
 180         (*exec_file_display_hook) (filename);
 181     }
 182   else if (from_tty)
 183     printf ("No exec file now.\n");
 184 }
 185
 186 /* Set both the exec file and the symbol file, in one command.
 187    What a novelty.  Why did GDB go through four major releases before this
 188    command was added?  */
 189
 190 static void
 191 file_command (arg, from_tty)
 192      char *arg;
 193      int from_tty;
 194 {
 195   /* FIXME, if we lose on reading the symbol file, we should revert
 196      the exec file, but that's rough.  */
 197   exec_file_command (arg, from_tty);
 198   symbol_file_command (arg, from_tty);
 199 }
 200
 201 \f
 202 /* Locate all mappable sections of a BFD file.
 203    table_pp_char is a char * to get it through bfd_map_over_sections;
 204    we cast it back to its proper type.  */
 205
 206 static void
 207 add_to_section_table (abfd, asect, table_pp_char)
 208      bfd *abfd;
 209      sec_ptr asect;
 210      PTR table_pp_char;
 211 {
 212   struct section_table **table_pp = (struct section_table **)table_pp_char;
 213   flagword aflag;
 214
 215   aflag = bfd_get_section_flags (abfd, asect);
 216   /* FIXME, we need to handle BSS segment here...it alloc's but doesn't load */
 217   if (!(aflag & SEC_LOAD))
 218     return;
 219   if (0 == bfd_section_size (abfd, asect))
 220     return;
 221   (*table_pp)->bfd = abfd;
 222   (*table_pp)->sec_ptr = asect;
 223   (*table_pp)->addr = bfd_section_vma (abfd, asect);
 224   (*table_pp)->endaddr = (*table_pp)->addr + bfd_section_size (abfd, asect);
 225   (*table_pp)++;
 226 }
 227
 228 /* Builds a section table, given args BFD, SECTABLE_PTR, SECEND_PTR.
 229    Returns 0 if OK, 1 on error.  */
 230
 231 int
 232 build_section_table (some_bfd, start, end)
 233      bfd *some_bfd;
 234      struct section_table **start, **end;
 235 {
 236   unsigned count;
 237
 238   count = bfd_count_sections (some_bfd);
 239   if (*start)
 240     free ((PTR)*start);
 241   *start = (struct section_table *) xmalloc (count * sizeof (**start));
 242   *end = *start;
 243   bfd_map_over_sections (some_bfd, add_to_section_table, (char *)end);
 244   if (*end > *start + count)
 245     abort();
 246   /* We could realloc the table, but it probably loses for most files.  */
 247   return 0;
 248 }
 249 \f
 250 /* Read or write the exec file.
 251
 252    Args are address within a BFD file, address within gdb address-space,
 253    length, and a flag indicating whether to read or write.
 254
 255    Result is a length:
 256
 257         0:    We cannot handle this address and length.
 258         > 0:  We have handled N bytes starting at this address.
 259               (If N == length, we did it all.)  We might be able
 260               to handle more bytes beyond this length, but no
 261               promises.
 262         < 0:  We cannot handle this address, but if somebody
 263               else handles (-N) bytes, we can start from there.
 264
 265     The same routine is used to handle both core and exec files;
 266     we just tail-call it with more arguments to select between them.  */
 267
 268 int
 269 xfer_memory (memaddr, myaddr, len, write, target)
 270      CORE_ADDR memaddr;
 271      char *myaddr;
 272      int len;
 273      int write;
 274      struct target_ops *target;
 275 {
 276   boolean res;
 277   struct section_table *p;
 278   CORE_ADDR nextsectaddr, memend;
 279   boolean (*xfer_fn) PARAMS ((bfd *, sec_ptr, PTR, file_ptr, bfd_size_type));
 280
 281   if (len <= 0)
 282     abort();
 283
 284   memend = memaddr + len;
 285   xfer_fn = write? bfd_set_section_contents: bfd_get_section_contents;
 286   nextsectaddr = memend;
 287
 288   for (p = target->to_sections; p < target->to_sections_end; p++)
 289     {
 290       if (p->addr <= memaddr)
 291         if (p->endaddr >= memend)
 292           {
 293             /* Entire transfer is within this section.  */
 294             res = xfer_fn (p->bfd, p->sec_ptr, myaddr, memaddr - p->addr, len);
 295             return (res != false)? len: 0;
 296           }
 297         else if (p->endaddr <= memaddr)
 298           {
 299             /* This section ends before the transfer starts.  */
 300             continue;
 301           }
 302         else
 303           {
 304             /* This section overlaps the transfer.  Just do half.  */
 305             len = p->endaddr - memaddr;
 306             res = xfer_fn (p->bfd, p->sec_ptr, myaddr, memaddr - p->addr, len);
 307             return (res != false)? len: 0;
 308           }
 309       else if (p->addr < nextsectaddr)
 310         nextsectaddr = p->addr;
 311     }
 312
 313   if (nextsectaddr >= memend)
 314     return 0;                           /* We can't help */
 315   else
 316     return - (nextsectaddr - memaddr);  /* Next boundary where we can help */
 317 }
 318
 319 #ifdef FIXME
 320 #ifdef REG_STACK_SEGMENT
 321 /* MOVE TO BFD... */
 322     /* Pyramids and AM29000s have an extra segment in the virtual address space
 323        for the (control) stack of register-window frames.  The AM29000 folk
 324        call it the "register stack" rather than the "memory stack".  */
 325     else if (memaddr >= reg_stack_start && memaddr < reg_stack_end)
 326       {
 327         i = min (len, reg_stack_end - memaddr);
 328         fileptr = memaddr - reg_stack_start + reg_stack_offset;
 329         wanna_xfer = coredata;
 330       }
 331 #endif                          /* REG_STACK_SEGMENT */
 332 #endif /* FIXME */
 333 \f
 334 void
 335 print_section_info (t, abfd)
 336   struct target_ops *t;
 337   bfd *abfd;
 338 {
 339   struct section_table *p;
 340
 341   printf_filtered ("\t`%s', ", bfd_get_filename(abfd));
 342   wrap_here ("        ");
 343   printf_filtered ("file type %s.\n", bfd_get_target(abfd));
 344
 345   for (p = t->to_sections; p < t->to_sections_end; p++) {
 346     printf_filtered ("\t%s", local_hex_string_custom (p->addr, "08"));
 347     printf_filtered (" - %s", local_hex_string_custom (p->endaddr, "08"));
 348     if (info_verbose)
 349       printf_filtered (" @ %s",
 350                        local_hex_string_custom (p->sec_ptr->filepos, "08"));
 351     printf_filtered (" is %s", bfd_section_name (p->bfd, p->sec_ptr));
 352     if (p->bfd != abfd) {
 353       printf_filtered (" in %s", bfd_get_filename (p->bfd));
 354     }
 355     printf_filtered ("\n");
 356   }
 357 }
 358
 359 static void
 360 exec_files_info (t)
 361   struct target_ops *t;
 362 {
 363   print_section_info (t, exec_bfd);
 364 }
 365
 366 static void
 367 set_section_command (args, from_tty)
 368      char *args;
 369      int from_tty;
 370 {
 371   struct section_table *p;
 372   char *secname;
 373   unsigned seclen;
 374   unsigned long secaddr;
 375   char secprint[100];
 376   long offset;
 377
 378   if (args == 0)
 379     error ("Must specify section name and its virtual address");
 380
 381   /* Parse out section name */
 382   for (secname = args; !isspace(*args); args++) ;
 383   seclen = args - secname;
 384
 385   /* Parse out new virtual address */
 386   secaddr = parse_and_eval_address (args);
 387
 388   for (p = exec_ops.to_sections; p < exec_ops.to_sections_end; p++) {
 389     if (!strncmp (secname, bfd_section_name (exec_bfd, p->sec_ptr), seclen)
 390         && bfd_section_name (exec_bfd, p->sec_ptr)[seclen] == '\0') {
 391       offset = secaddr - p->addr;
 392       p->addr += offset;
 393       p->endaddr += offset;
 394       if (from_tty)
 395         exec_files_info(&exec_ops);
 396       return;
 397     }
 398   }
 399   if (seclen >= sizeof (secprint))
 400     seclen = sizeof (secprint) - 1;
 401   strncpy (secprint, secname, seclen);
 402   secprint[seclen] = '\0';
 403   error ("Section %s not found", secprint);
 404 }
 405
 406 struct target_ops exec_ops = {
 407         "exec", "Local exec file",
 408         "Use an executable file as a target.\n\
 409 Specify the filename of the executable file.",
 410         exec_file_command, exec_close, /* open, close */
 411         find_default_attach, 0, 0, 0, /* attach, detach, resume, wait, */
 412         0, 0, /* fetch_registers, store_registers, */
 413         0, /* prepare_to_store, */
 414         xfer_memory, exec_files_info,
 415         0, 0, /* insert_breakpoint, remove_breakpoint, */
 416         0, 0, 0, 0, 0, /* terminal stuff */
 417         0, 0, /* kill, load */
 418         0, /* lookup sym */
 419         find_default_create_inferior,
 420         0, /* mourn_inferior */
 421         0, /* can_run */
 422         0, /* notice_signals */
 423         file_stratum, 0, /* next */
 424         0, 1, 0, 0, 0,  /* all mem, mem, stack, regs, exec */
 425         0, 0,                   /* section pointers */
 426         OPS_MAGIC,              /* Always the last thing */
 427 };
 428
 429 void
 430 _initialize_exec()
 431 {
 432
 433   add_com ("file", class_files, file_command,
 434            "Use FILE as program to be debugged.\n\
 435 It is read for its symbols, for getting the contents of pure memory,\n\
 436 and it is the program executed when you use the `run' command.\n\
 437 If FILE cannot be found as specified, your execution directory path\n\
 438 ($PATH) is searched for a command of that name.\n\
 439 No arg means to have no executable file and no symbols.");
 440
 441   add_com ("exec-file", class_files, exec_file_command,
 442            "Use FILE as program for getting contents of pure memory.\n\
 443 If FILE cannot be found as specified, your execution directory path\n\
 444 is searched for a command of that name.\n\
 445 No arg means have no executable file.");
 446
 447   add_com ("section", class_files, set_section_command,
 448    "Change the base address of section SECTION of the exec file to ADDR.\n\
 449 This can be used if the exec file does not contain section addresses,\n\
 450 (such as in the a.out format), or when the addresses specified in the\n\
 451 file itself are wrong.  Each section must be changed separately.  The\n\
 452 ``info files'' command lists all the sections and their addresses.");
 453
 454   add_show_from_set
 455     (add_set_cmd ("write", class_support, var_boolean, (char *)&write_files,
 456                   "Set writing into executable and core files.",
 457                   &setlist),
 458      &showlist);
 459
 460   add_target (&exec_ops);
 461 }