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- /* BFD back-end for Intel 386 COFF files (DJGPP variant with a stub).
- Copyright (C) 1997-2022 Free Software Foundation, Inc.
- Written by Robert Hoehne.
- This file is part of BFD, the Binary File Descriptor library.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
- MA 02110-1301, USA. */
- /* This file handles now also stubbed coff images. The stub is a small
- DOS executable program before the coff image to load it in memory
- and execute it. This is needed, because DOS cannot run coff files.
- The COFF image is loaded in memory without the stub attached, so
- all offsets are relative to the beginning of the image, not the
- actual file. We handle this in bfd by setting bfd->origin to where
- the COFF image starts. */
- #define TARGET_SYM i386_coff_go32stubbed_vec
- #define TARGET_NAME "coff-go32-exe"
- #define TARGET_UNDERSCORE '_'
- #define COFF_GO32_EXE
- #define COFF_LONG_SECTION_NAMES
- #define COFF_SUPPORT_GNU_LINKONCE
- #define COFF_LONG_FILENAMES
- #define COFF_SECTION_ALIGNMENT_ENTRIES \
- { COFF_SECTION_NAME_EXACT_MATCH (".data"), \
- COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
- { COFF_SECTION_NAME_EXACT_MATCH (".text"), \
- COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
- { COFF_SECTION_NAME_PARTIAL_MATCH (".debug"), \
- COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }, \
- { COFF_SECTION_NAME_PARTIAL_MATCH (".gnu.linkonce.wi"), \
- COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }
- /* Section contains extended relocations. */
- #define IMAGE_SCN_LNK_NRELOC_OVFL (0x01000000)
- #include "sysdep.h"
- #include "bfd.h"
- #include "coff/msdos.h"
- static bfd_cleanup go32exe_check_format (bfd *);
- static bool go32exe_write_object_contents (bfd *);
- static bool go32exe_mkobject (bfd *);
- static bool go32exe_copy_private_bfd_data (bfd *, bfd *);
- /* Defined in coff-go32.c. */
- bool _bfd_go32_mkobject (bfd *);
- void _bfd_go32_swap_scnhdr_in (bfd *, void *, void *);
- unsigned int _bfd_go32_swap_scnhdr_out (bfd *, void *, void *);
- #define COFF_CHECK_FORMAT go32exe_check_format
- #define COFF_WRITE_CONTENTS go32exe_write_object_contents
- #define coff_mkobject go32exe_mkobject
- #define coff_bfd_copy_private_bfd_data go32exe_copy_private_bfd_data
- #define coff_SWAP_scnhdr_in _bfd_go32_swap_scnhdr_in
- #define coff_SWAP_scnhdr_out _bfd_go32_swap_scnhdr_out
- #include "coff-i386.c"
- /* This macro is used, because I cannot assume the endianness of the
- host system. */
- #define _H(index) (H_GET_16 (abfd, (header + index * 2)))
- /* These bytes are a 2048-byte DOS executable, which loads the COFF
- image into memory and then runs it. It is called 'stub'. */
- #define GO32EXE_DEFAULT_STUB_SIZE 2048
- static const unsigned char go32exe_default_stub[GO32EXE_DEFAULT_STUB_SIZE] =
- {
- #include "go32stub.h"
- };
- /* Temporary location for stub read from input file. */
- static char * go32exe_temp_stub = NULL;
- static bfd_size_type go32exe_temp_stub_size = 0;
- /* That's the function, which creates the stub. There are
- different cases from where the stub is taken.
- At first the environment variable $(GO32STUB) is checked and then
- $(STUB) if it was not set.
- If it exists and points to a valid stub the stub is taken from
- that file. This file can be also a whole executable file, because
- the stub is computed from the exe information at the start of that
- file.
- If there was any error, the standard stub (compiled in this file)
- is taken.
- Ideally this function should exec '$(TARGET)-stubify' to generate
- a stub, like gcc does. */
- static void
- go32exe_create_stub (bfd *abfd)
- {
- /* Do it only once. */
- if (coff_data (abfd)->stub == NULL)
- {
- char *stub;
- struct stat st;
- int f;
- unsigned char header[10];
- char magic[8];
- unsigned long coff_start;
- long exe_start;
- /* If we read a stub from an input file, use that one. */
- if (go32exe_temp_stub != NULL)
- {
- coff_data (abfd)->stub = bfd_alloc (abfd,
- go32exe_temp_stub_size);
- if (coff_data (abfd)->stub == NULL)
- return;
- memcpy (coff_data (abfd)->stub, go32exe_temp_stub,
- go32exe_temp_stub_size);
- coff_data (abfd)->stub_size = go32exe_temp_stub_size;
- free (go32exe_temp_stub);
- go32exe_temp_stub = NULL;
- go32exe_temp_stub_size = 0;
- return;
- }
- /* Check at first the environment variable $(GO32STUB). */
- stub = getenv ("GO32STUB");
- /* Now check the environment variable $(STUB). */
- if (stub == NULL)
- stub = getenv ("STUB");
- if (stub == NULL)
- goto stub_end;
- if (stat (stub, &st) != 0)
- goto stub_end;
- #ifdef O_BINARY
- f = open (stub, O_RDONLY | O_BINARY);
- #else
- f = open (stub, O_RDONLY);
- #endif
- if (f < 0)
- goto stub_end;
- if (read (f, &header, sizeof (header)) < 0)
- {
- close (f);
- goto stub_end;
- }
- if (_H (0) != 0x5a4d) /* It is not an exe file. */
- {
- close (f);
- goto stub_end;
- }
- /* Compute the size of the stub (it is every thing up
- to the beginning of the coff image). */
- coff_start = (long) _H (2) * 512L;
- if (_H (1))
- coff_start += (long) _H (1) - 512L;
- exe_start = _H (4) * 16;
- if ((long) lseek (f, exe_start, SEEK_SET) != exe_start)
- {
- close (f);
- goto stub_end;
- }
- if (read (f, &magic, 8) != 8)
- {
- close (f);
- goto stub_end;
- }
- if (! startswith (magic, "go32stub"))
- {
- close (f);
- goto stub_end;
- }
- /* Now we found a correct stub (hopefully). */
- coff_data (abfd)->stub = bfd_alloc (abfd, (bfd_size_type) coff_start);
- if (coff_data (abfd)->stub == NULL)
- {
- close (f);
- return;
- }
- lseek (f, 0L, SEEK_SET);
- if ((unsigned long) read (f, coff_data (abfd)->stub, coff_start)
- != coff_start)
- {
- bfd_release (abfd, coff_data (abfd)->stub);
- coff_data (abfd)->stub = NULL;
- }
- else
- coff_data (abfd)->stub_size = coff_start;
- close (f);
- }
- stub_end:
- /* There was something wrong above, so use now the standard builtin
- stub. */
- if (coff_data (abfd)->stub == NULL)
- {
- coff_data (abfd)->stub
- = bfd_alloc (abfd, (bfd_size_type) GO32EXE_DEFAULT_STUB_SIZE);
- if (coff_data (abfd)->stub == NULL)
- return;
- memcpy (coff_data (abfd)->stub, go32exe_default_stub,
- GO32EXE_DEFAULT_STUB_SIZE);
- coff_data (abfd)->stub_size = GO32EXE_DEFAULT_STUB_SIZE;
- }
- }
- /* If ibfd was a stubbed coff image, copy the stub from that bfd
- to the new obfd. */
- static bool
- go32exe_copy_private_bfd_data (bfd *ibfd, bfd *obfd)
- {
- /* Check if both are the same targets. */
- if (ibfd->xvec != obfd->xvec)
- return true;
- /* Make sure we have a source stub. */
- BFD_ASSERT (coff_data (ibfd)->stub != NULL);
- /* Reallocate the output stub if necessary. */
- if (coff_data (ibfd)->stub_size > coff_data (obfd)->stub_size)
- coff_data (obfd)->stub = bfd_alloc (obfd, coff_data (ibfd)->stub_size);
- if (coff_data (obfd)->stub == NULL)
- return false;
- /* Now copy the stub. */
- memcpy (coff_data (obfd)->stub, coff_data (ibfd)->stub,
- coff_data (ibfd)->stub_size);
- coff_data (obfd)->stub_size = coff_data (ibfd)->stub_size;
- obfd->origin = coff_data (obfd)->stub_size;
- return true;
- }
- /* Cleanup function, returned from check_format hook. */
- static void
- go32exe_cleanup (bfd *abfd)
- {
- abfd->origin = 0;
- free (go32exe_temp_stub);
- go32exe_temp_stub = NULL;
- go32exe_temp_stub_size = 0;
- }
- /* Check that there is a GO32 stub and read it to go32exe_temp_stub.
- Then set abfd->origin so that the COFF image is read at the correct
- file offset. */
- static bfd_cleanup
- go32exe_check_format (bfd *abfd)
- {
- struct external_DOS_hdr filehdr_dos;
- uint16_t num_pages;
- uint16_t last_page_size;
- uint32_t header_end;
- bfd_size_type stubsize;
- /* This format can not appear in an archive. */
- if (abfd->origin != 0)
- {
- bfd_set_error (bfd_error_wrong_format);
- return NULL;
- }
- bfd_set_error (bfd_error_system_call);
- /* Read in the stub file header, which is a DOS MZ executable. */
- if (bfd_bread (&filehdr_dos, DOS_HDR_SIZE, abfd) != DOS_HDR_SIZE)
- goto fail;
- /* Make sure that this is an MZ executable. */
- if (H_GET_16 (abfd, filehdr_dos.e_magic) != IMAGE_DOS_SIGNATURE)
- goto fail_format;
- /* Determine the size of the stub */
- num_pages = H_GET_16 (abfd, filehdr_dos.e_cp);
- last_page_size = H_GET_16 (abfd, filehdr_dos.e_cblp);
- stubsize = num_pages * 512;
- if (last_page_size != 0)
- stubsize += last_page_size - 512;
- /* Save now the stub to be used later. Put the stub data to a temporary
- location first as tdata still does not exist. It may not even
- be ever created if we are just checking the file format of ABFD. */
- bfd_seek (abfd, 0, SEEK_SET);
- go32exe_temp_stub = bfd_malloc (stubsize);
- if (go32exe_temp_stub == NULL)
- goto fail;
- if (bfd_bread (go32exe_temp_stub, stubsize, abfd) != stubsize)
- goto fail;
- go32exe_temp_stub_size = stubsize;
- /* Confirm that this is a go32stub. */
- header_end = H_GET_16 (abfd, filehdr_dos.e_cparhdr) * 16UL;
- if (go32exe_temp_stub_size < header_end
- || go32exe_temp_stub_size - header_end < sizeof "go32stub" - 1
- || !startswith (go32exe_temp_stub + header_end, "go32stub"))
- goto fail_format;
- /* Set origin to where the COFF header starts and seek there. */
- abfd->origin = stubsize;
- if (bfd_seek (abfd, 0, SEEK_SET) != 0)
- goto fail;
- /* Call coff_object_p to read the COFF image. If this fails then the file
- must be just a stub with no COFF data attached. */
- bfd_cleanup cleanup = coff_object_p (abfd);
- if (cleanup == NULL)
- goto fail;
- BFD_ASSERT (cleanup == _bfd_no_cleanup);
- return go32exe_cleanup;
- fail_format:
- bfd_set_error (bfd_error_wrong_format);
- fail:
- go32exe_cleanup (abfd);
- return NULL;
- }
- /* Write the stub to the output file, then call coff_write_object_contents. */
- static bool
- go32exe_write_object_contents (bfd *abfd)
- {
- const bfd_size_type pos = bfd_tell (abfd);
- const bfd_size_type stubsize = coff_data (abfd)->stub_size;
- BFD_ASSERT (stubsize != 0);
- bfd_set_error (bfd_error_system_call);
- /* Write the stub. */
- abfd->origin = 0;
- if (bfd_seek (abfd, 0, SEEK_SET) != 0)
- return false;
- if (bfd_bwrite (coff_data (abfd)->stub, stubsize, abfd) != stubsize)
- return false;
- /* Seek back to where we were. */
- abfd->origin = stubsize;
- if (bfd_seek (abfd, pos, SEEK_SET) != 0)
- return false;
- return coff_write_object_contents (abfd);
- }
- /* mkobject hook. Called directly through bfd_set_format or via
- coff_mkobject_hook etc from bfd_check_format. */
- static bool
- go32exe_mkobject (bfd *abfd)
- {
- /* Don't output to an archive. */
- if (abfd->my_archive != NULL)
- return false;
- if (!_bfd_go32_mkobject (abfd))
- return false;
- go32exe_create_stub (abfd);
- if (coff_data (abfd)->stub == NULL)
- {
- bfd_release (abfd, coff_data (abfd));
- return false;
- }
- abfd->origin = coff_data (abfd)->stub_size;
- return true;
- }
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