binutils-gdb/gdb/windows-tdep.h
Simon Marchi 8db5243724 gdb: select "Cygwin" OS ABI for Cygwin binaries
Before this patch, the "Windows" OS ABI is selected for all Windows
executables, including Cygwin ones.  This patch makes GDB differentiate
Cygwin binaries from non-Cygwin ones, and selects the "Cygwin" OS ABI
for the Cygwin ones.

To check whether a Windows PE executable is a Cygwin one, we check the
library list in the .idata section, see if it contains "cygwin1.dll".

I had to add code to parse the .idata section, because BFD doesn't seem
to expose this information.  BFD does parse this information, but only
to print it in textual form (function pe_print_idata):

  https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=bfd/peXXigen.c;h=e42d646552a0ca1e856e082256cd3d943b54ddf0;hb=HEAD#l1261

Here's the relevant portion of the PE format documentation:

  https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#the-idata-section

This page was also useful:

  https://blog.kowalczyk.info/articles/pefileformat.html#9ccef823-67e7-4372-9172-045d7b1fb006

With this patch applied, this is what I get:

    (gdb) file some_mingw_x86_64_binary.exe
    Reading symbols from some_mingw_x86_64_binary.exe...
    (gdb) show osabi
    The current OS ABI is "auto" (currently "Windows").
    The default OS ABI is "GNU/Linux".

    (gdb) file some_mingw_i386_binary.exe
    Reading symbols from some_mingw_i386_binary.exe...
    (gdb) show osabi
    The current OS ABI is "auto" (currently "Windows").
    The default OS ABI is "GNU/Linux".

    (gdb) file some_cygwin_x86_64_binary.exe
    Reading symbols from some_cygwin_x86_64_binary.exe...
    (gdb) show osabi
    The current OS ABI is "auto" (currently "Cygwin").
    The default OS ABI is "GNU/Linux".

gdb/ChangeLog:

	* windows-tdep.h (is_linked_with_cygwin_dll): New declaration.
	* windows-tdep.c (CYGWIN_DLL_NAME): New.
	(pe_import_directory_entry): New struct type.
	(is_linked_with_cygwin_dll): New function.
	* amd64-windows-tdep.c (amd64_windows_osabi_sniffer): Select
	GDB_OSABI_CYGWIN if the BFD is linked with the Cygwin DLL.
	* i386-windows-tdep.c (i386_windows_osabi_sniffer): Likewise.
2020-03-16 16:56:36 -04:00

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C

/* Copyright (C) 2008-2020 Free Software Foundation, Inc.
This file is part of GDB.
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, see <http://www.gnu.org/licenses/>. */
#ifndef WINDOWS_TDEP_H
#define WINDOWS_TDEP_H
struct obstack;
struct gdbarch;
extern struct cmd_list_element *info_w32_cmdlist;
extern void init_w32_command_list (void);
extern void windows_xfer_shared_library (const char* so_name,
CORE_ADDR load_addr,
CORE_ADDR *text_offset_cached,
struct gdbarch *gdbarch,
struct obstack *obstack);
extern void windows_init_abi (struct gdbarch_info info,
struct gdbarch *gdbarch);
/* Return true if the Portable Executable behind ABFD uses the Cygwin dll
(cygwin1.dll). */
extern bool is_linked_with_cygwin_dll (bfd *abfd);
#endif