src/unexcw.c

   1 /* unexec() support for Cygwin;
   2    complete rewrite of xemacs Cygwin unexec() code
   3
   4    Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Emacs.
   7
   8 GNU Emacs is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GNU Emacs is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GNU Emacs; see the file COPYING.  If not, write to
  20 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21 Boston, MA 02110-1301, USA.  */
  22
  23 #include <config.h>
  24 #include <lisp.h>
  25 #include <stdio.h>
  26 #include <fcntl.h>
  27 #include <a.out.h>
  28 #include <unistd.h>
  29 #include <assert.h>
  30
  31 #define DOTEXE ".exe"
  32
  33 extern int bss_sbrk_did_unexec;
  34
  35 /* emacs symbols that indicate where bss and data end for emacs internals */
  36 extern char my_endbss[];
  37 extern char my_edata[];
  38
  39 /*
  40 ** header for Windows executable files
  41 */
  42 typedef struct
  43 {
  44   FILHDR file_header;
  45   PEAOUTHDR file_optional_header;
  46   SCNHDR section_header[32];
  47 } exe_header_t;
  48
  49 int debug_unexcw = 0;
  50
  51 /*
  52 ** Read the header from the executable into memory so we can more easily access it.
  53 */
  54 static exe_header_t *
  55 read_exe_header (int fd, exe_header_t * exe_header_buffer)
  56 {
  57   int i;
  58   int ret;
  59
  60   assert (fd >= 0);
  61   assert (exe_header_buffer != 0);
  62
  63   ret = lseek (fd, 0L, SEEK_SET);
  64   assert (ret != -1);
  65
  66   ret =
  67     read (fd, &exe_header_buffer->file_header,
  68           sizeof (exe_header_buffer->file_header));
  69   assert (ret == sizeof (exe_header_buffer->file_header));
  70
  71   assert (exe_header_buffer->file_header.e_magic == 0x5a4d);
  72   assert (exe_header_buffer->file_header.nt_signature == 0x4550);
  73   assert (exe_header_buffer->file_header.f_magic == 0x014c);
  74   assert (exe_header_buffer->file_header.f_nscns > 0);
  75   assert (exe_header_buffer->file_header.f_nscns <=
  76           sizeof (exe_header_buffer->section_header) /
  77           sizeof (exe_header_buffer->section_header[0]));
  78   assert (exe_header_buffer->file_header.f_opthdr > 0);
  79
  80   ret =
  81     read (fd, &exe_header_buffer->file_optional_header,
  82           sizeof (exe_header_buffer->file_optional_header));
  83   assert (ret == sizeof (exe_header_buffer->file_optional_header));
  84
  85   assert (exe_header_buffer->file_optional_header.magic == 0x010b);
  86
  87   for (i = 0; i < exe_header_buffer->file_header.f_nscns; ++i)
  88     {
  89       ret =
  90         read (fd, &exe_header_buffer->section_header[i],
  91               sizeof (exe_header_buffer->section_header[i]));
  92       assert (ret == sizeof (exe_header_buffer->section_header[i]));
  93     }
  94
  95   return (exe_header_buffer);
  96 }
  97
  98 /*
  99 ** Fix the dumped emacs executable:
 100 **
 101 ** - copy .data section data of interest from running executable into
 102 **   output .exe file
 103 **
 104 ** - convert .bss section into an initialized data section (like
 105 **   .data) and copy .bss section data of interest from running
 106 **   executable into output .exe file
 107 */
 108 static void
 109 fixup_executable (int fd)
 110 {
 111   exe_header_t exe_header_buffer;
 112   exe_header_t *exe_header;
 113   int i;
 114   int ret;
 115   int found_data = 0;
 116   int found_bss = 0;
 117
 118   exe_header = read_exe_header (fd, &exe_header_buffer);
 119   assert (exe_header != 0);
 120
 121   assert (exe_header->file_header.f_nscns > 0);
 122   for (i = 0; i < exe_header->file_header.f_nscns; ++i)
 123     {
 124       unsigned long start_address =
 125         exe_header->section_header[i].s_vaddr +
 126         exe_header->file_optional_header.ImageBase;
 127       unsigned long end_address =
 128         exe_header->section_header[i].s_vaddr +
 129         exe_header->file_optional_header.ImageBase +
 130         exe_header->section_header[i].s_paddr;
 131       if (debug_unexcw)
 132         printf ("%8s start 0x%08x end 0x%08x\n",
 133                 exe_header->section_header[i].s_name,
 134                 start_address, end_address);
 135       if (my_edata >= (char *) start_address
 136           && my_edata < (char *) end_address)
 137         {
 138           /* data section */
 139           ret =
 140             lseek (fd, (long) (exe_header->section_header[i].s_scnptr),
 141                    SEEK_SET);
 142           assert (ret != -1);
 143           ret =
 144             write (fd, (char *) start_address,
 145                    my_edata - (char *) start_address);
 146           assert (ret == my_edata - (char *) start_address);
 147           ++found_data;
 148           if (debug_unexcw)
 149             printf ("         .data, mem start 0x%08x mem length %d\n",
 150                     start_address, my_edata - (char *) start_address);
 151           if (debug_unexcw)
 152             printf ("         .data, file start %d file length %d\n",
 153                     (int) exe_header->section_header[i].s_scnptr,
 154                     (int) exe_header->section_header[i].s_paddr);
 155         }
 156       else if (my_endbss >= (char *) start_address
 157                && my_endbss < (char *) end_address)
 158         {
 159           /* bss section */
 160           ++found_bss;
 161           if (exe_header->section_header[i].s_flags & 0x00000080)
 162             {
 163               /* convert uninitialized data section to initialized data section */
 164               struct stat statbuf;
 165               ret = fstat (fd, &statbuf);
 166               assert (ret != -1);
 167
 168               exe_header->section_header[i].s_flags &= ~0x00000080;
 169               exe_header->section_header[i].s_flags |= 0x00000040;
 170
 171               exe_header->section_header[i].s_scnptr =
 172                 (statbuf.st_size +
 173                  exe_header->file_optional_header.FileAlignment) /
 174                 exe_header->file_optional_header.FileAlignment *
 175                 exe_header->file_optional_header.FileAlignment;
 176
 177               exe_header->section_header[i].s_size =
 178                 (exe_header->section_header[i].s_paddr +
 179                  exe_header->file_optional_header.FileAlignment) /
 180                 exe_header->file_optional_header.FileAlignment *
 181                 exe_header->file_optional_header.FileAlignment;
 182
 183               ret =
 184                 lseek (fd,
 185                        (long) (exe_header->section_header[i].s_scnptr +
 186                                exe_header->section_header[i].s_size - 1),
 187                        SEEK_SET);
 188               assert (ret != -1);
 189               ret = write (fd, "", 1);
 190               assert (ret == 1);
 191
 192               ret =
 193                 lseek (fd,
 194                        (long) ((char *) &exe_header->section_header[i] -
 195                                (char *) exe_header), SEEK_SET);
 196               assert (ret != -1);
 197               ret =
 198                 write (fd, &exe_header->section_header[i],
 199                        sizeof (exe_header->section_header[i]));
 200               assert (ret == sizeof (exe_header->section_header[i]));
 201               if (debug_unexcw)
 202                 printf ("         seek to %ld, write %d\n",
 203                         (long) ((char *) &exe_header->section_header[i] -
 204                                 (char *) exe_header),
 205                         sizeof (exe_header->section_header[i]));
 206             }
 207           /* write initialized data section */
 208           ret =
 209             lseek (fd, (long) (exe_header->section_header[i].s_scnptr),
 210                    SEEK_SET);
 211           assert (ret != -1);
 212           ret =
 213             write (fd, (char *) start_address,
 214                    my_endbss - (char *) start_address);
 215           assert (ret == (my_endbss - (char *) start_address));
 216           if (debug_unexcw)
 217             printf ("         .bss, mem start 0x%08x mem length %d\n",
 218                     start_address, my_endbss - (char *) start_address);
 219           if (debug_unexcw)
 220             printf ("         .bss, file start %d file length %d\n",
 221                     (int) exe_header->section_header[i].s_scnptr,
 222                     (int) exe_header->section_header[i].s_paddr);
 223         }
 224     }
 225   assert (found_bss == 1);
 226   assert (found_data == 1);
 227 }
 228
 229 /*
 230 ** Windows likes .exe suffixes on executables.
 231 */
 232 static char *
 233 add_exe_suffix_if_necessary (const char *name, char *modified)
 234 {
 235   int i = strlen (name);
 236   if (i <= (sizeof (DOTEXE) - 1))
 237     {
 238       sprintf (modified, "%s%s", name, DOTEXE);
 239     }
 240   else if (!strcasecmp (name + i - (sizeof (DOTEXE) - 1), DOTEXE))
 241     {
 242       strcpy (modified, name);
 243     }
 244   else
 245     {
 246       sprintf (modified, "%s%s", name, DOTEXE);
 247     }
 248   return (modified);
 249 }
 250
 251 int
 252 unexec (char *outfile, char *infile, unsigned start_data, unsigned d1,
 253         unsigned d2)
 254 {
 255   char infile_buffer[FILENAME_MAX];
 256   char outfile_buffer[FILENAME_MAX];
 257   int fd_in;
 258   int fd_out;
 259   int ret;
 260   int ret2;
 261
 262   if (bss_sbrk_did_unexec)
 263     {
 264       /* can only dump once */
 265       printf ("You can only dump Emacs once on this platform.\n");
 266       return (1);
 267     }
 268
 269   report_sheap_usage (1);
 270
 271   infile = add_exe_suffix_if_necessary (infile, infile_buffer);
 272   outfile = add_exe_suffix_if_necessary (outfile, outfile_buffer);
 273
 274   fd_in = open (infile, O_RDONLY | O_BINARY);
 275   assert (fd_in >= 0);
 276   fd_out = open (outfile, O_RDWR | O_TRUNC | O_CREAT | O_BINARY, 0755);
 277   assert (fd_out >= 0);
 278   for (;;)
 279     {
 280       char buffer[4096];
 281       ret = read (fd_in, buffer, sizeof (buffer));
 282       if (ret == 0)
 283         {
 284           /* eof */
 285           break;
 286         }
 287       assert (ret > 0);
 288       /* data */
 289       ret2 = write (fd_out, buffer, ret);
 290       assert (ret2 == ret);
 291     }
 292   ret = close (fd_in);
 293   assert (ret == 0);
 294
 295   bss_sbrk_did_unexec = 1;
 296   fixup_executable (fd_out);
 297   bss_sbrk_did_unexec = 0;
 298
 299   ret = close (fd_out);
 300   assert (ret == 0);
 301
 302   return (0);
 303 }
 304
 305 /* arch-tag: fc44f6c3-ca0a-45e0-a5a2-58b6101b1e65
 306    (do not change this comment) */