src/unexcw.c

   1 /* unexec() support for Cygwin;
   2    complete rewrite of xemacs Cygwin unexec() code
   3
   4    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 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 of the License, or
  11 (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include <config.h>
  22 #include <setjmp.h>
  23 #include <lisp.h>
  24 #include <stdio.h>
  25 #include <fcntl.h>
  26 #include <a.out.h>
  27 #include <unistd.h>
  28 #include <assert.h>
  29
  30 #define DOTEXE ".exe"
  31
  32 extern int bss_sbrk_did_unexec;
  33
  34 /* emacs symbols that indicate where bss and data end for emacs internals */
  35 extern char my_endbss[];
  36 extern char my_edata[];
  37
  38 /*
  39 ** header for Windows executable files
  40 */
  41 typedef struct
  42 {
  43   FILHDR file_header;
  44   PEAOUTHDR file_optional_header;
  45   SCNHDR section_header[32];
  46 } exe_header_t;
  47
  48 int debug_unexcw = 0;
  49
  50 /*
  51 ** Read the header from the executable into memory so we can more easily access it.
  52 */
  53 static exe_header_t *
  54 read_exe_header (int fd, exe_header_t * exe_header_buffer)
  55 {
  56   int i;
  57   int ret;
  58
  59   assert (fd >= 0);
  60   assert (exe_header_buffer != 0);
  61
  62   ret = lseek (fd, 0L, SEEK_SET);
  63   assert (ret != -1);
  64
  65   ret =
  66     read (fd, &exe_header_buffer->file_header,
  67           sizeof (exe_header_buffer->file_header));
  68   assert (ret == sizeof (exe_header_buffer->file_header));
  69
  70   assert (exe_header_buffer->file_header.e_magic == 0x5a4d);
  71   assert (exe_header_buffer->file_header.nt_signature == 0x4550);
  72   assert (exe_header_buffer->file_header.f_magic == 0x014c);
  73   assert (exe_header_buffer->file_header.f_nscns > 0);
  74   assert (exe_header_buffer->file_header.f_nscns <=
  75           sizeof (exe_header_buffer->section_header) /
  76           sizeof (exe_header_buffer->section_header[0]));
  77   assert (exe_header_buffer->file_header.f_opthdr > 0);
  78
  79   ret =
  80     read (fd, &exe_header_buffer->file_optional_header,
  81           sizeof (exe_header_buffer->file_optional_header));
  82   assert (ret == sizeof (exe_header_buffer->file_optional_header));
  83
  84   assert (exe_header_buffer->file_optional_header.magic == 0x010b);
  85
  86   for (i = 0; i < exe_header_buffer->file_header.f_nscns; ++i)
  87     {
  88       ret =
  89         read (fd, &exe_header_buffer->section_header[i],
  90               sizeof (exe_header_buffer->section_header[i]));
  91       assert (ret == sizeof (exe_header_buffer->section_header[i]));
  92     }
  93
  94   return (exe_header_buffer);
  95 }
  96
  97 /*
  98 ** Fix the dumped emacs executable:
  99 **
 100 ** - copy .data section data of interest from running executable into
 101 **   output .exe file
 102 **
 103 ** - convert .bss section into an initialized data section (like
 104 **   .data) and copy .bss section data of interest from running
 105 **   executable into output .exe file
 106 */
 107 static void
 108 fixup_executable (int fd)
 109 {
 110   exe_header_t exe_header_buffer;
 111   exe_header_t *exe_header;
 112   int i;
 113   int ret;
 114   int found_data = 0;
 115   int found_bss = 0;
 116
 117   exe_header = read_exe_header (fd, &exe_header_buffer);
 118   assert (exe_header != 0);
 119
 120   assert (exe_header->file_header.f_nscns > 0);
 121   for (i = 0; i < exe_header->file_header.f_nscns; ++i)
 122     {
 123       unsigned long start_address =
 124         exe_header->section_header[i].s_vaddr +
 125         exe_header->file_optional_header.ImageBase;
 126       unsigned long end_address =
 127         exe_header->section_header[i].s_vaddr +
 128         exe_header->file_optional_header.ImageBase +
 129         exe_header->section_header[i].s_paddr;
 130       if (debug_unexcw)
 131         printf ("%8s start 0x%08x end 0x%08x\n",
 132                 exe_header->section_header[i].s_name,
 133                 start_address, end_address);
 134       if (my_edata >= (char *) start_address
 135           && my_edata < (char *) end_address)
 136         {
 137           /* data section */
 138           ret =
 139             lseek (fd, (long) (exe_header->section_header[i].s_scnptr),
 140                    SEEK_SET);
 141           assert (ret != -1);
 142           ret =
 143             write (fd, (char *) start_address,
 144                    my_edata - (char *) start_address);
 145           assert (ret == my_edata - (char *) start_address);
 146           ++found_data;
 147           if (debug_unexcw)
 148             printf ("         .data, mem start 0x%08x mem length %d\n",
 149                     start_address, my_edata - (char *) start_address);
 150           if (debug_unexcw)
 151             printf ("         .data, file start %d file length %d\n",
 152                     (int) exe_header->section_header[i].s_scnptr,
 153                     (int) exe_header->section_header[i].s_paddr);
 154         }
 155       else if (my_endbss >= (char *) start_address
 156                && my_endbss < (char *) end_address)
 157         {
 158           /* bss section */
 159           ++found_bss;
 160           if (exe_header->section_header[i].s_flags & 0x00000080)
 161             {
 162               /* convert uninitialized data section to initialized data section */
 163               struct stat statbuf;
 164               ret = fstat (fd, &statbuf);
 165               assert (ret != -1);
 166
 167               exe_header->section_header[i].s_flags &= ~0x00000080;
 168               exe_header->section_header[i].s_flags |= 0x00000040;
 169
 170               exe_header->section_header[i].s_scnptr =
 171                 (statbuf.st_size +
 172                  exe_header->file_optional_header.FileAlignment) /
 173                 exe_header->file_optional_header.FileAlignment *
 174                 exe_header->file_optional_header.FileAlignment;
 175
 176               exe_header->section_header[i].s_size =
 177                 (exe_header->section_header[i].s_paddr +
 178                  exe_header->file_optional_header.FileAlignment) /
 179                 exe_header->file_optional_header.FileAlignment *
 180                 exe_header->file_optional_header.FileAlignment;
 181
 182               ret =
 183                 lseek (fd,
 184                        (long) (exe_header->section_header[i].s_scnptr +
 185                                exe_header->section_header[i].s_size - 1),
 186                        SEEK_SET);
 187               assert (ret != -1);
 188               ret = write (fd, "", 1);
 189               assert (ret == 1);
 190
 191               ret =
 192                 lseek (fd,
 193                        (long) ((char *) &exe_header->section_header[i] -
 194                                (char *) exe_header), SEEK_SET);
 195               assert (ret != -1);
 196               ret =
 197                 write (fd, &exe_header->section_header[i],
 198                        sizeof (exe_header->section_header[i]));
 199               assert (ret == sizeof (exe_header->section_header[i]));
 200               if (debug_unexcw)
 201                 printf ("         seek to %ld, write %d\n",
 202                         (long) ((char *) &exe_header->section_header[i] -
 203                                 (char *) exe_header),
 204                         sizeof (exe_header->section_header[i]));
 205             }
 206           /* write initialized data section */
 207           ret =
 208             lseek (fd, (long) (exe_header->section_header[i].s_scnptr),
 209                    SEEK_SET);
 210           assert (ret != -1);
 211           ret =
 212             write (fd, (char *) start_address,
 213                    my_endbss - (char *) start_address);
 214           assert (ret == (my_endbss - (char *) start_address));
 215           if (debug_unexcw)
 216             printf ("         .bss, mem start 0x%08x mem length %d\n",
 217                     start_address, my_endbss - (char *) start_address);
 218           if (debug_unexcw)
 219             printf ("         .bss, file start %d file length %d\n",
 220                     (int) exe_header->section_header[i].s_scnptr,
 221                     (int) exe_header->section_header[i].s_paddr);
 222         }
 223     }
 224   assert (found_bss == 1);
 225   assert (found_data == 1);
 226 }
 227
 228 /*
 229 ** Windows likes .exe suffixes on executables.
 230 */
 231 static char *
 232 add_exe_suffix_if_necessary (const char *name, char *modified)
 233 {
 234   int i = strlen (name);
 235   if (i <= (sizeof (DOTEXE) - 1))
 236     {
 237       sprintf (modified, "%s%s", name, DOTEXE);
 238     }
 239   else if (!strcasecmp (name + i - (sizeof (DOTEXE) - 1), DOTEXE))
 240     {
 241       strcpy (modified, name);
 242     }
 243   else
 244     {
 245       sprintf (modified, "%s%s", name, DOTEXE);
 246     }
 247   return (modified);
 248 }
 249
 250 int
 251 unexec (const char *outfile, const char *infile)
 252 {
 253   char infile_buffer[FILENAME_MAX];
 254   char outfile_buffer[FILENAME_MAX];
 255   int fd_in;
 256   int fd_out;
 257   int ret;
 258   int ret2;
 259
 260   if (bss_sbrk_did_unexec)
 261     {
 262       /* can only dump once */
 263       printf ("You can only dump Emacs once on this platform.\n");
 264       return (1);
 265     }
 266
 267   report_sheap_usage (1);
 268
 269   infile = add_exe_suffix_if_necessary (infile, infile_buffer);
 270   outfile = add_exe_suffix_if_necessary (outfile, outfile_buffer);
 271
 272   fd_in = open (infile, O_RDONLY | O_BINARY);
 273   assert (fd_in >= 0);
 274   fd_out = open (outfile, O_RDWR | O_TRUNC | O_CREAT | O_BINARY, 0755);
 275   assert (fd_out >= 0);
 276   for (;;)
 277     {
 278       char buffer[4096];
 279       ret = read (fd_in, buffer, sizeof (buffer));
 280       if (ret == 0)
 281         {
 282           /* eof */
 283           break;
 284         }
 285       assert (ret > 0);
 286       /* data */
 287       ret2 = write (fd_out, buffer, ret);
 288       assert (ret2 == ret);
 289     }
 290   ret = close (fd_in);
 291   assert (ret == 0);
 292
 293   bss_sbrk_did_unexec = 1;
 294   fixup_executable (fd_out);
 295   bss_sbrk_did_unexec = 0;
 296
 297   ret = close (fd_out);
 298   assert (ret == 0);
 299
 300   return (0);
 301 }
 302