diff mbox

: libbacktrace - add support of PE/COFF

Message ID 2DD28AFE-AAB7-4B92-9ED0-A0F5763923CC@adacore.com
State New
Headers show

Commit Message

Tristan Gingold May 21, 2015, 12:41 p.m. UTC
Hello,

this patch adds basic support to libbacktrace for PE32 and PE32+ (Windows and Windows64 object formats).
Support is ‘basic’ because neither DLL nor PIE (if that exists) are handled.  Furthermore, there is no windows versions of mmapio.c and mmap.c
Finally, I have disabled the support of data symbols for PE because I wasn’t able to pass ‘make check’ with that: symbol ‘_global’ is at the same address as a symbol defined by the linker and I haven’t found any way to discard the latter.  As I think data symbol support isn’t a required feature, I have preferred to disable that feature on PE.

The new file, pecoff.c, mostly follows the structure of elf.c

Tested on both windows and windows64.
No regression on Gnu/Linux x86.

Tristan.


2015-05-21  Tristan Gingold  <gingold@adacore.com>

	* pecoff.c: New file.
	* Makefile.am (FORMAT_FILES): Add pecoff.c and dependencies.
	* Makefile.in: Regenerate.
	* filetype.awk: Detect pecoff.
	* configure.ac: Define BACKTRACE_SUPPORTS_DATA on elf platforms.
	Add pecoff.
	* btest.c (test5): Test enabled only if BACKTRACE_SUPPORTS_DATA is
	true.
	* backtrace-supported.h.in (BACKTRACE_SUPPORTS_DATA): Define.
	* configure: Regenerate.
	* pecoff.c: New file.


commit ac17f650356728fc07121c71213401e1e159df2f
Author: Tristan Gingold <gingold@adacore.com>
Date:   Thu May 21 14:29:44 2015 +0200

    Add support for PE/COFF to libbacktrace.

Comments

Ian Lance Taylor May 23, 2015, 12:46 a.m. UTC | #1
On Thu, May 21, 2015 at 5:41 AM, Tristan Gingold <gingold@adacore.com> wrote:
>
> 2015-05-21  Tristan Gingold  <gingold@adacore.com>
>
>         * pecoff.c: New file.
>         * Makefile.am (FORMAT_FILES): Add pecoff.c and dependencies.
>         * Makefile.in: Regenerate.
>         * filetype.awk: Detect pecoff.
>         * configure.ac: Define BACKTRACE_SUPPORTS_DATA on elf platforms.
>         Add pecoff.
>         * btest.c (test5): Test enabled only if BACKTRACE_SUPPORTS_DATA is
>         true.
>         * backtrace-supported.h.in (BACKTRACE_SUPPORTS_DATA): Define.
>         * configure: Regenerate.
>         * pecoff.c: New file.


Thanks for working on this.


> diff --git a/libbacktrace/backtrace-supported.h.in b/libbacktrace/backtrace-supported.h.in
> index 5115ce1..4574635 100644
> --- a/libbacktrace/backtrace-supported.h.in
> +++ b/libbacktrace/backtrace-supported.h.in
> @@ -59,3 +59,8 @@ POSSIBILITY OF SUCH DAMAGE.  */
>     as 0.  */
>
>  #define BACKTRACE_SUPPORTS_THREADS @BACKTRACE_SUPPORTS_THREADS@
> +
> +/* BACKTRACE_SUPPORTS_DATA will be #defined'd as 1 if the backtrace library
> +   also handles data symbols, 0 if not.  */
> +
> +#define BACKTRACE_SUPPORTS_DATA @BACKTRACE_SUPPORTS_DATA@

End users are expected to read and understand this file, so I think
this comment is too obscure.  I suggest:

BACKTRACE_SUPPORTS_DATA will be #define'd as 1 if backtrace_syminfo
will work for variables.  It will always work for functions.


I would have thought you could distinguish relevant symbols using the
storage class and type.  But perhaps not.



> diff --git a/libbacktrace/filetype.awk b/libbacktrace/filetype.awk
> index 0a656f7..37099ad 100644
> --- a/libbacktrace/filetype.awk
> +++ b/libbacktrace/filetype.awk
> @@ -1,3 +1,4 @@
>  # An awk script to determine the type of a file.
>  /\177ELF\001/ { if (NR == 1) { print "elf32"; exit } }
>  /\177ELF\002/ { if (NR == 1) { print "elf64"; exit } }
> +/\114\001/    { if (NR == 1) { print "pecoff"; exit } }

That works for 32-bit, but I think not for 64-bit.  For 64-bit I would
expect \144\206.


> +#include <windows.h>

Where is <windows.h> going to come from when building a
cross-compiler?  I think this needs to be removed.  I see that you
define the structs yourself, as you should, so why do you need
<windows.h>?



> +/* Read a potentially unaligned 2 byte word at P, using native endianness.  */

Is there really ever a case where a 2 byte word might be misaligned?


> +/* Return true iff SYM is a defined symbol for a function.  Data symbols
> +   are discarded because they aren't easily identified.  */
> +
> +static int
> +coff_is_symbol (const b_coff_internal_symbol *isym)
> +{
> +  return isym->type == 0x20 && isym->sec > 0;
> +}

Is this really right?  This seems to test for DT_FCN set, but won't a
function returning, say, int, have type 0x24 (DT_FCN << N_TBSHFT) | T_INT?

Also, the name isn't right--this is coff_is_function_symbol.


> +      if (coff_expand_symbol (&isym, asym, sects_num, strtab, strtab_size) < 0)
> +       {
> +         error_callback (data, "invalid coff symbol", 0);
> +         return 0;
> +       }

That's not a very useful error message--can you be more specific?


> +  /* Allocate memory for symbols are strings.  */

Comment looks wrong--omit "are"?


Ian
Jeff Law May 27, 2015, 1:36 p.m. UTC | #2
On 05/21/2015 06:41 AM, Tristan Gingold wrote:
> Hello,
>
> this patch adds basic support to libbacktrace for PE32 and PE32+ (Windows and Windows64 object formats).
> Support is ‘basic’ because neither DLL nor PIE (if that exists) are handled.  Furthermore, there is no windows versions of mmapio.c and mmap.c
> Finally, I have disabled the support of data symbols for PE because I wasn’t able to pass ‘make check’ with that: symbol ‘_global’ is at the same address as a symbol defined by the linker and I haven’t found any way to discard the latter.  As I think data symbol support isn’t a required feature, I have preferred to disable that feature on PE.
>
> The new file, pecoff.c, mostly follows the structure of elf.c
>
> Tested on both windows and windows64.
> No regression on Gnu/Linux x86.
>
> Tristan.
>
>
> 2015-05-21  Tristan Gingold  <gingold@adacore.com>
>
> 	* pecoff.c: New file.
> 	* Makefile.am (FORMAT_FILES): Add pecoff.c and dependencies.
> 	* Makefile.in: Regenerate.
> 	* filetype.awk: Detect pecoff.
> 	* configure.ac: Define BACKTRACE_SUPPORTS_DATA on elf platforms.
> 	Add pecoff.
> 	* btest.c (test5): Test enabled only if BACKTRACE_SUPPORTS_DATA is
> 	true.
> 	* backtrace-supported.h.in (BACKTRACE_SUPPORTS_DATA): Define.
> 	* configure: Regenerate.
> 	* pecoff.c: New file.
> +
> +/* Return true iff SYM is a defined symbol for a function.  Data symbols
> +   are discarded because they aren't easily identified.  */
> +
> +static int
> +coff_is_symbol (const b_coff_internal_symbol *isym)
> +{
> +  return isym->type == 0x20 && isym->sec > 0;
> +}
You probably want const or enum so that you can have a symbolic name 
rather than 0x20 here.  It also seems like the name ought to better 
indicate it's testing for function symbols.

It's a given  that you know COFF specifics better than I ever did, so 
I'm comfortable assuming you got the COFF specifics right.

The overall structure of elf.c & coff.c is the same with code templates 
that are very similar, except they work on different underlying types. 
  Presumably there wasn't a good way to factor any of the generic 
looking bits out?  And no, I'm not requesting you rewrite all this in 
BFD :-)


OK for the trunk.  Any future issues with the coff bits I'll send your way.

jeff
Ian Lance Taylor May 28, 2015, 12:26 a.m. UTC | #3
On Wed, May 27, 2015 at 6:36 AM, Jeff Law <law@redhat.com> wrote:
> On 05/21/2015 06:41 AM, Tristan Gingold wrote:
>>
>> Hello,
>>
>> this patch adds basic support to libbacktrace for PE32 and PE32+ (Windows
>> and Windows64 object formats).
>> Support is ‘basic’ because neither DLL nor PIE (if that exists) are
>> handled.  Furthermore, there is no windows versions of mmapio.c and mmap.c
>> Finally, I have disabled the support of data symbols for PE because I
>> wasn’t able to pass ‘make check’ with that: symbol ‘_global’ is at the same
>> address as a symbol defined by the linker and I haven’t found any way to
>> discard the latter.  As I think data symbol support isn’t a required
>> feature, I have preferred to disable that feature on PE.
>>
>> The new file, pecoff.c, mostly follows the structure of elf.c
>>
>> Tested on both windows and windows64.
>> No regression on Gnu/Linux x86.
>>
>> Tristan.
>>
>>
>> 2015-05-21  Tristan Gingold  <gingold@adacore.com>
>>
>>         * pecoff.c: New file.
>>         * Makefile.am (FORMAT_FILES): Add pecoff.c and dependencies.
>>         * Makefile.in: Regenerate.
>>         * filetype.awk: Detect pecoff.
>>         * configure.ac: Define BACKTRACE_SUPPORTS_DATA on elf platforms.
>>         Add pecoff.
>>         * btest.c (test5): Test enabled only if BACKTRACE_SUPPORTS_DATA is
>>         true.
>>         * backtrace-supported.h.in (BACKTRACE_SUPPORTS_DATA): Define.
>>         * configure: Regenerate.
>>         * pecoff.c: New file.
>> +
>> +/* Return true iff SYM is a defined symbol for a function.  Data symbols
>> +   are discarded because they aren't easily identified.  */
>> +
>> +static int
>> +coff_is_symbol (const b_coff_internal_symbol *isym)
>> +{
>> +  return isym->type == 0x20 && isym->sec > 0;
>> +}
>
> You probably want const or enum so that you can have a symbolic name rather
> than 0x20 here.  It also seems like the name ought to better indicate it's
> testing for function symbols.
>
> It's a given  that you know COFF specifics better than I ever did, so I'm
> comfortable assuming you got the COFF specifics right.
>
> The overall structure of elf.c & coff.c is the same with code templates that
> are very similar, except they work on different underlying types.
> Presumably there wasn't a good way to factor any of the generic looking bits
> out?  And no, I'm not requesting you rewrite all this in BFD :-)
>
>
> OK for the trunk.  Any future issues with the coff bits I'll send your way.

The #include <windows.h> will break cross-compilers.  It's not OK for
trunk until that is fixed.

Ian
Tristan Gingold May 29, 2015, 8:43 a.m. UTC | #4
> On 28 May 2015, at 17:14, Ian Lance Taylor <iant@google.com> wrote:
> 
> On Thu, May 28, 2015 at 5:01 AM, Tristan Gingold <gingold@adacore.com> wrote:
>> 
>>> On 28 May 2015, at 02:26, Ian Lance Taylor <iant@google.com> wrote:
>> 
>>> The #include <windows.h> will break cross-compilers.  It's not OK for
>>> trunk until that is fixed.
>> 
>> I am confused by this comment, for two reasons:
>> 
>> - I don’t see how that would break cross-compilers.  Cross compilers
>> hosted on windows are not impacted by this include when the library is
>> used for the tools.  When then backtrace library is used for the target,
>> pecoff is not used unless the target is windows.
>> So I don’t see a case where the include breaks cross-compilers.
> 
> The way you have written the code, I'm fairly sure that it will be
> compiled for an i386-coff target.

And the only coff target supported is djgpp, right ?

>> - If the case exists, I don’t see how to implement backtrace within
>> shared libraries: I need a windows specific function to get the list
>> of DLL.
> 
> I would be OK with a #include <windows.h> that is conditional on
> something that indicates that the host (from the point of view of
> libbacktrace) really is Windows.

Is it ok to test if the _WIN32 macro is defined (like in libiberty) ?

> The new version of the patch is OK.

Thanks, now committed.

Tristan.
Ian Lance Taylor May 29, 2015, 2:11 p.m. UTC | #5
On Fri, May 29, 2015 at 1:43 AM, Tristan Gingold <gingold@adacore.com> wrote:
>
>> On 28 May 2015, at 17:14, Ian Lance Taylor <iant@google.com> wrote:
>>
>> The way you have written the code, I'm fairly sure that it will be
>> compiled for an i386-coff target.
>
> And the only coff target supported is djgpp, right ?

Really?  I didn't know that we had dropped COFF support.  That is good
to hear.


>> I would be OK with a #include <windows.h> that is conditional on
>> something that indicates that the host (from the point of view of
>> libbacktrace) really is Windows.
>
> Is it ok to test if the _WIN32 macro is defined (like in libiberty) ?

Sure.

Ian
diff mbox

Patch

diff --git a/libbacktrace/ChangeLog b/libbacktrace/ChangeLog
index c6604d9..139521a 100644
--- a/libbacktrace/ChangeLog
+++ b/libbacktrace/ChangeLog
@@ -1,3 +1,17 @@ 
+2015-05-21  Tristan Gingold  <gingold@adacore.com>
+
+	* pecoff.c: New file.
+	* Makefile.am (FORMAT_FILES): Add pecoff.c and dependencies.
+	* Makefile.in: Regenerate.
+	* filetype.awk: Detect pecoff.
+	* configure.ac: Define BACKTRACE_SUPPORTS_DATA on elf platforms.
+	Add pecoff.
+	* btest.c (test5): Test enabled only if BACKTRACE_SUPPORTS_DATA is
+	true.
+	* backtrace-supported.h.in (BACKTRACE_SUPPORTS_DATA): Define.
+	* configure: Regenerate.
+	* pecoff.c: New file.
+
 2015-05-13  Michael Haubenwallner  <michael.haubenwallner@ssi-schaefer.com>
 
 	* Makefile.in: Regenerated with automake-1.11.6.
diff --git a/libbacktrace/Makefile.am b/libbacktrace/Makefile.am
index a93b82a..c5f0dcb 100644
--- a/libbacktrace/Makefile.am
+++ b/libbacktrace/Makefile.am
@@ -56,6 +56,7 @@  BACKTRACE_FILES = \
 
 FORMAT_FILES = \
 	elf.c \
+	pecoff.c \
 	unknown.c
 
 VIEW_FILES = \
@@ -124,6 +125,7 @@  fileline.lo: config.h backtrace.h internal.h
 mmap.lo: config.h backtrace.h internal.h
 mmapio.lo: config.h backtrace.h internal.h
 nounwind.lo: config.h internal.h
+pecoff.lo: config.h backtrace.h internal.h
 posix.lo: config.h backtrace.h internal.h
 print.lo: config.h backtrace.h internal.h
 read.lo: config.h backtrace.h internal.h
diff --git a/libbacktrace/Makefile.in b/libbacktrace/Makefile.in
index a949f29..b434d76e 100644
--- a/libbacktrace/Makefile.in
+++ b/libbacktrace/Makefile.in
@@ -299,6 +299,7 @@  BACKTRACE_FILES = \
 
 FORMAT_FILES = \
 	elf.c \
+	pecoff.c \
 	unknown.c
 
 VIEW_FILES = \
@@ -753,6 +754,7 @@  fileline.lo: config.h backtrace.h internal.h
 mmap.lo: config.h backtrace.h internal.h
 mmapio.lo: config.h backtrace.h internal.h
 nounwind.lo: config.h internal.h
+pecoff.lo: config.h backtrace.h internal.h
 posix.lo: config.h backtrace.h internal.h
 print.lo: config.h backtrace.h internal.h
 read.lo: config.h backtrace.h internal.h
diff --git a/libbacktrace/backtrace-supported.h.in b/libbacktrace/backtrace-supported.h.in
index 5115ce1..4574635 100644
--- a/libbacktrace/backtrace-supported.h.in
+++ b/libbacktrace/backtrace-supported.h.in
@@ -59,3 +59,8 @@  POSSIBILITY OF SUCH DAMAGE.  */
    as 0.  */
 
 #define BACKTRACE_SUPPORTS_THREADS @BACKTRACE_SUPPORTS_THREADS@
+
+/* BACKTRACE_SUPPORTS_DATA will be #defined'd as 1 if the backtrace library
+   also handles data symbols, 0 if not.  */
+
+#define BACKTRACE_SUPPORTS_DATA @BACKTRACE_SUPPORTS_DATA@
diff --git a/libbacktrace/btest.c b/libbacktrace/btest.c
index 9424a92..9821e34 100644
--- a/libbacktrace/btest.c
+++ b/libbacktrace/btest.c
@@ -616,6 +616,8 @@  f33 (int f1line, int f2line)
   return failures;
 }
 
+#if BACKTRACE_SUPPORTS_DATA
+
 int global = 1;
 
 static int
@@ -684,6 +686,8 @@  test5 (void)
   return failures;
 }
 
+#endif /* BACKTRACE_SUPPORTS_DATA  */
+
 static void
 error_callback_create (void *data ATTRIBUTE_UNUSED, const char *msg,
 		       int errnum)
@@ -708,8 +712,10 @@  main (int argc ATTRIBUTE_UNUSED, char **argv)
   test2 ();
   test3 ();
   test4 ();
+#if BACKTRACE_SUPPORTS_DATA
   test5 ();
 #endif
+#endif
 
   exit (failures ? EXIT_FAILURE : EXIT_SUCCESS);
 }
diff --git a/libbacktrace/configure b/libbacktrace/configure
index fa81659..19418c9 100755
--- a/libbacktrace/configure
+++ b/libbacktrace/configure
@@ -607,6 +607,7 @@  NATIVE_TRUE
 BACKTRACE_USES_MALLOC
 ALLOC_FILE
 VIEW_FILE
+BACKTRACE_SUPPORTS_DATA
 BACKTRACE_SUPPORTED
 FORMAT_FILE
 BACKTRACE_SUPPORTS_THREADS
@@ -11129,7 +11130,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11132 "configure"
+#line 11133 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11235,7 +11236,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11238 "configure"
+#line 11239 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11826,8 +11827,12 @@  $as_echo "$libbacktrace_cv_sys_filetype" >&6; }
 
 # Match the file type to decide what files to compile.
 FORMAT_FILE=
+backtrace_supports_data=yes
 case "$libbacktrace_cv_sys_filetype" in
 elf*) FORMAT_FILE="elf.lo" ;;
+pecoff) FORMAT_FILE="pecoff.lo"
+        backtrace_supports_data=no
+	;;
 *) { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: could not determine output file type" >&5
 $as_echo "$as_me: WARNING: could not determine output file type" >&2;}
    FORMAT_FILE="unknown.lo"
@@ -11841,6 +11846,7 @@  elfsize=
 case "$libbacktrace_cv_sys_filetype" in
 elf32) elfsize=32 ;;
 elf64) elfsize=64 ;;
+*)     elfsize=unused
 esac
 
 cat >>confdefs.h <<_ACEOF
@@ -11854,6 +11860,12 @@  if test "$backtrace_supported" = "yes"; then
 fi
 
 
+BACKTRACE_SUPPORTS_DATA=0
+if test "$backtrace_supports_data" = "yes"; then
+  BACKTRACE_SUPPORTS_DATA=1
+fi
+
+
 
 
 inttype_headers=`echo inttypes.h sys/inttypes.h  | sed -e 's/,/ /g'`
diff --git a/libbacktrace/configure.ac b/libbacktrace/configure.ac
index 9c37dac..2e5b9c7 100644
--- a/libbacktrace/configure.ac
+++ b/libbacktrace/configure.ac
@@ -229,8 +229,12 @@  libbacktrace_cv_sys_filetype=$filetype])
 
 # Match the file type to decide what files to compile.
 FORMAT_FILE=
+backtrace_supports_data=yes
 case "$libbacktrace_cv_sys_filetype" in
 elf*) FORMAT_FILE="elf.lo" ;;
+pecoff) FORMAT_FILE="pecoff.lo"
+        backtrace_supports_data=no
+	;;
 *) AC_MSG_WARN([could not determine output file type])
    FORMAT_FILE="unknown.lo"
    backtrace_supported=no
@@ -243,6 +247,7 @@  elfsize=
 case "$libbacktrace_cv_sys_filetype" in
 elf32) elfsize=32 ;;
 elf64) elfsize=64 ;;
+*)     elfsize=unused
 esac
 AC_DEFINE_UNQUOTED([BACKTRACE_ELF_SIZE], [$elfsize], [ELF size: 32 or 64])
 
@@ -252,6 +257,12 @@  if test "$backtrace_supported" = "yes"; then
 fi
 AC_SUBST(BACKTRACE_SUPPORTED)
 
+BACKTRACE_SUPPORTS_DATA=0
+if test "$backtrace_supports_data" = "yes"; then
+  BACKTRACE_SUPPORTS_DATA=1
+fi
+AC_SUBST(BACKTRACE_SUPPORTS_DATA)
+
 GCC_HEADER_STDINT(gstdint.h)
 
 AC_CHECK_HEADERS(sys/mman.h)
diff --git a/libbacktrace/filetype.awk b/libbacktrace/filetype.awk
index 0a656f7..37099ad 100644
--- a/libbacktrace/filetype.awk
+++ b/libbacktrace/filetype.awk
@@ -1,3 +1,4 @@ 
 # An awk script to determine the type of a file.
 /\177ELF\001/ { if (NR == 1) { print "elf32"; exit } }
 /\177ELF\002/ { if (NR == 1) { print "elf64"; exit } }
+/\114\001/    { if (NR == 1) { print "pecoff"; exit } }
diff --git a/libbacktrace/pecoff.c b/libbacktrace/pecoff.c
new file mode 100644
index 0000000..c67fa96
--- /dev/null
+++ b/libbacktrace/pecoff.c
@@ -0,0 +1,929 @@ 
+/* pecoff.c -- Get debug data from a PE/COFFF file for backtraces.
+   Copyright (C) 2015 Free Software Foundation, Inc.
+   Adapted from elf.c by Tristan Gingold, AdaCore.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include <windows.h>
+
+#include "backtrace.h"
+#include "internal.h"
+
+/* Coff file header.  */
+
+typedef struct {
+  uint16_t machine;
+  uint16_t number_of_sections;
+  uint32_t time_date_stamp;
+  uint32_t pointer_to_symbol_table;
+  uint32_t number_of_symbols;
+  uint16_t size_of_optional_header;
+  uint16_t characteristics;
+} b_coff_file_header;
+
+/* Coff optional header.  */
+
+typedef struct {
+  uint16_t magic;
+  uint8_t  major_linker_version;
+  uint8_t  minor_linker_version;
+  uint32_t size_of_code;
+  uint32_t size_of_initialized_data;
+  uint32_t size_of_uninitialized_data;
+  uint32_t address_of_entry_point;
+  uint32_t base_of_code;
+  union {
+    struct {
+      uint32_t base_of_data;
+      uint32_t image_base;
+    } pe;
+    struct {
+      uint64_t image_base;
+    } pep;
+  } u;
+} b_coff_optional_header;
+
+/* Values of magic in optional header.  */
+
+#define PE_MAGIC 0x10b		/* PE32 executable.  */
+#define PEP_MAGIC 0x20b		/* PE32+ executable (for 64bit targets).  */
+
+/* Coff section header.  */
+
+typedef struct {
+  char name[8];
+  uint32_t virtual_size;
+  uint32_t virtual_address;
+  uint32_t size_of_raw_data;
+  uint32_t pointer_to_raw_data;
+  uint32_t pointer_to_relocations;
+  uint32_t pointer_to_line_numbers;
+  uint16_t number_of_relocations;
+  uint16_t number_of_line_numbers;
+  uint32_t characteristics;
+} b_coff_section_header;
+
+/* Coff symbol name.  */
+
+typedef union {
+  char short_name[8];
+  struct {
+    unsigned char zeroes[4];
+    unsigned char off[4];
+  } long_name;
+} b_coff_name;
+
+/* Coff symbol (external representation which is unaligned).  */
+
+typedef struct {
+  b_coff_name name;
+  unsigned char value[4];
+  unsigned char section_number[2];
+  unsigned char type[2];
+  unsigned char storage_class;
+  unsigned char number_of_aux_symbols;
+} b_coff_external_symbol;
+
+/* Size of a coff symbol.  */
+
+#define SYM_SZ 18
+
+/* Coff symbol, internal representation (aligned).  */
+
+typedef struct {
+  const char *name;
+  uint32_t value;
+  int16_t sec;
+  uint16_t type;
+  uint16_t sc;
+} b_coff_internal_symbol;
+
+/* An index of sections we care about.  */
+
+enum debug_section
+{
+  DEBUG_INFO,
+  DEBUG_LINE,
+  DEBUG_ABBREV,
+  DEBUG_RANGES,
+  DEBUG_STR,
+  DEBUG_MAX
+};
+
+/* Names of sections, indexed by enum debug_section.  */
+
+static const char * const debug_section_names[DEBUG_MAX] =
+{
+  ".debug_info",
+  ".debug_line",
+  ".debug_abbrev",
+  ".debug_ranges",
+  ".debug_str"
+};
+
+/* Information we gather for the sections we care about.  */
+
+struct debug_section_info
+{
+  /* Section file offset.  */
+  off_t offset;
+  /* Section size.  */
+  size_t size;
+  /* Section contents, after read from file.  */
+  const unsigned char *data;
+};
+
+/* Information we keep for an coff symbol.  */
+
+struct coff_symbol
+{
+  /* The name of the symbol.  */
+  const char *name;
+  /* The address of the symbol.  */
+  uintptr_t address;
+};
+
+/* Information to pass to coff_syminfo.  */
+
+struct coff_syminfo_data
+{
+  /* Symbols for the next module.  */
+  struct coff_syminfo_data *next;
+  /* The COFF symbols, sorted by address.  */
+  struct coff_symbol *symbols;
+  /* The number of symbols.  */
+  size_t count;
+};
+
+/* A dummy callback function used when we can't find any debug info.  */
+
+static int
+coff_nodebug (struct backtrace_state *state ATTRIBUTE_UNUSED,
+	      uintptr_t pc ATTRIBUTE_UNUSED,
+	      backtrace_full_callback callback ATTRIBUTE_UNUSED,
+	      backtrace_error_callback error_callback, void *data)
+{
+  error_callback (data, "no debug info in PE/COFF executable", -1);
+  return 0;
+}
+
+/* A dummy callback function used when we can't find a symbol
+   table.  */
+
+static void
+coff_nosyms (struct backtrace_state *state ATTRIBUTE_UNUSED,
+	     uintptr_t addr ATTRIBUTE_UNUSED,
+	     backtrace_syminfo_callback callback ATTRIBUTE_UNUSED,
+	     backtrace_error_callback error_callback, void *data)
+{
+  error_callback (data, "no symbol table in PE/COFF executable", -1);
+}
+
+/* Read a potentially unaligned 4 byte word at P, using native endianness.  */
+
+static uint32_t
+coff_read4 (const unsigned char *p)
+{
+  uint32_t res;
+
+  memcpy (&res, p, 4);
+  return res;
+}
+
+/* Read a potentially unaligned 2 byte word at P, using native endianness.  */
+
+static uint16_t
+coff_read2 (const unsigned char *p)
+{
+  uint16_t res;
+
+  memcpy (&res, p, sizeof (res));
+  return res;
+}
+
+/* Return the length (without the trailing 0) of a COFF short name.  */
+
+static size_t
+coff_short_name_len (const char *name)
+{
+  int i;
+
+  for (i = 0; i < 8; i++)
+    if (name[i] == 0)
+      return i;
+  return 8;
+}
+
+/* Return true iff COFF short name CNAME is the same as NAME (a NUL-terminated
+   string).  */
+
+static int
+coff_short_name_eq (const char *name, const char *cname)
+{
+  int i;
+
+  for (i = 0; i < 8; i++)
+    {
+      if (name[i] != cname[i])
+	return 0;
+      if (name[i] == 0)
+	return 1;
+    }
+  return name[8] == 0;
+}
+
+/* Return true iff NAME is the same as string at offset OFF.  */
+
+static int
+coff_long_name_eq (const char *name, unsigned int off,
+		   struct backtrace_view *str_view)
+{
+  if (off >= str_view->len)
+    return 0;
+  return strcmp (name, (const char *)str_view->data + off) == 0;
+}
+
+/* Compare struct coff_symbol for qsort.  */
+
+static int
+coff_symbol_compare (const void *v1, const void *v2)
+{
+  const struct coff_symbol *e1 = (const struct coff_symbol *) v1;
+  const struct coff_symbol *e2 = (const struct coff_symbol *) v2;
+
+  if (e1->address < e2->address)
+    return -1;
+  else if (e1->address > e2->address)
+    return 1;
+  else
+    return 0;
+}
+
+/* Convert SYM to internal (and aligned) format ISYM, using string table
+   from STRTAB and STRTAB_SIZE, and number of sections SECTS_NUM.
+   Return -1 in case of error (invalid section number or string index).  */
+
+static int
+coff_expand_symbol (b_coff_internal_symbol *isym,
+		    const b_coff_external_symbol *sym,
+		    uint16_t sects_num,
+		    const unsigned char *strtab, size_t strtab_size)
+{
+  isym->type = coff_read2 (sym->type);
+  isym->sec = coff_read2 (sym->section_number);
+  isym->sc = sym->storage_class;
+
+  if (isym->sec > 0 && (uint16_t) isym->sec > sects_num)
+    return -1;
+  if (sym->name.short_name[0] != 0)
+    isym->name = sym->name.short_name;
+  else
+    {
+      uint32_t off = coff_read4 (sym->name.long_name.off);
+
+      if (off >= strtab_size)
+	return -1;
+      isym->name = (const char *) strtab + off;
+    }
+  return 0;
+}
+
+/* Return true iff SYM is a defined symbol for a function.  Data symbols
+   are discarded because they aren't easily identified.  */
+
+static int
+coff_is_symbol (const b_coff_internal_symbol *isym)
+{
+  return isym->type == 0x20 && isym->sec > 0;
+}
+
+/* Initialize the symbol table info for coff_syminfo.  */
+
+static int
+coff_initialize_syminfo (struct backtrace_state *state,
+			 uintptr_t base_address,
+			 const b_coff_section_header *sects, size_t sects_num,
+			 const b_coff_external_symbol *syms, size_t syms_size,
+			 const unsigned char *strtab, size_t strtab_size,
+			 backtrace_error_callback error_callback,
+			 void *data, struct coff_syminfo_data *sdata)
+{
+  size_t syms_count;
+  char *coff_symstr;
+  size_t coff_symstr_len;
+  size_t coff_symbol_count;
+  size_t coff_symbol_size;
+  struct coff_symbol *coff_symbols;
+  struct coff_symbol *coff_sym;
+  char *coff_str;
+  size_t i;
+
+  syms_count = syms_size / SYM_SZ;
+
+  /* We only care about function symbols.  Count them.  Also count size of
+     strings for in-symbol names.  */
+  coff_symbol_count = 0;
+  coff_symstr_len = 0;
+  for (i = 0; i < syms_count; ++i)
+    {
+      const b_coff_external_symbol *asym = &syms[i];
+      b_coff_internal_symbol isym;
+
+      if (coff_expand_symbol (&isym, asym, sects_num, strtab, strtab_size) < 0)
+	{
+	  error_callback (data, "invalid coff symbol", 0);
+	  return 0;
+	}
+      if (coff_is_symbol (&isym))
+	{
+	  ++coff_symbol_count;
+	  if (asym->name.short_name[0] != 0)
+	    coff_symstr_len += coff_short_name_len (asym->name.short_name) + 1;
+	}
+
+      i += asym->number_of_aux_symbols;
+    }
+
+  coff_symbol_size = (coff_symbol_count + 1) * sizeof (struct coff_symbol);
+  coff_symbols = ((struct coff_symbol *)
+		  backtrace_alloc (state, coff_symbol_size, error_callback,
+				   data));
+  if (coff_symbols == NULL)
+    return 0;
+
+  /* Allocate memory for symbols are strings.  */
+  if (coff_symstr_len > 0)
+    {
+      coff_symstr = ((char *)
+		     backtrace_alloc (state, coff_symstr_len, error_callback,
+				      data));
+      if (coff_symstr == NULL)
+	{
+	  backtrace_free (state, coff_symbols, coff_symbol_size,
+			  error_callback, data);
+	  return 0;
+	}
+    }
+  else
+    coff_symstr = NULL;
+
+  /* Copy symbols.  */
+  coff_sym = coff_symbols;
+  coff_str = coff_symstr;
+  for (i = 0; i < syms_count; ++i)
+    {
+      const b_coff_external_symbol *asym = &syms[i];
+      b_coff_internal_symbol isym;
+
+      if (coff_expand_symbol (&isym, asym, sects_num, strtab, strtab_size))
+	{
+	  /* Should not fail, as it was already tested in the previous
+	     loop.  */
+	  abort ();
+	}
+      if (coff_is_symbol (&isym))
+	{
+	  const char *name;
+	  int16_t secnum;
+
+	  if (asym->name.short_name[0] != 0)
+	    {
+	      size_t len = coff_short_name_len (isym.name);
+	      name = coff_str;
+	      memcpy (coff_str, isym.name, len);
+	      coff_str[len] = 0;
+	      coff_str += len + 1;
+	    }
+	  else
+	    name = isym.name;
+
+	  /* Strip leading '_'.  */
+	  if (name[0] == '_')
+	    name++;
+
+	  /* Symbol value is section relative, so we need to read the address
+	     of its section.  */
+	  secnum = coff_read2 (asym->section_number);
+
+	  coff_sym->name = name;
+	  coff_sym->address = (coff_read4 (asym->value)
+			       + sects[secnum - 1].virtual_address
+			       + base_address);
+	  coff_sym++;
+	}
+
+      i += asym->number_of_aux_symbols;
+    }
+
+  /* End of symbols marker.  */
+  coff_sym->name = NULL;
+  coff_sym->address = -1;
+
+  backtrace_qsort (coff_symbols, coff_symbol_count,
+		   sizeof (struct coff_symbol), coff_symbol_compare);
+
+  sdata->next = NULL;
+  sdata->symbols = coff_symbols;
+  sdata->count = coff_symbol_count;
+
+  return 1;
+}
+
+/* Add EDATA to the list in STATE.  */
+
+static void
+coff_add_syminfo_data (struct backtrace_state *state,
+		       struct coff_syminfo_data *sdata)
+{
+  if (!state->threaded)
+    {
+      struct coff_syminfo_data **pp;
+
+      for (pp = (struct coff_syminfo_data **) (void *) &state->syminfo_data;
+	   *pp != NULL;
+	   pp = &(*pp)->next)
+	;
+      *pp = sdata;
+    }
+  else
+    {
+      while (1)
+	{
+	  struct coff_syminfo_data **pp;
+
+	  pp = (struct coff_syminfo_data **) (void *) &state->syminfo_data;
+
+	  while (1)
+	    {
+	      struct coff_syminfo_data *p;
+
+	      p = backtrace_atomic_load_pointer (pp);
+
+	      if (p == NULL)
+		break;
+
+	      pp = &p->next;
+	    }
+
+	  if (__sync_bool_compare_and_swap (pp, NULL, sdata))
+	    break;
+	}
+    }
+}
+
+/* Compare an ADDR against an elf_symbol for bsearch.  We allocate one
+   extra entry in the array so that this can look safely at the next
+   entry.  */
+
+static int
+coff_symbol_search (const void *vkey, const void *ventry)
+{
+  const uintptr_t *key = (const uintptr_t *) vkey;
+  const struct coff_symbol *entry = (const struct coff_symbol *) ventry;
+  uintptr_t addr;
+
+  addr = *key;
+  if (addr < entry->address)
+    return -1;
+  else if (addr >= entry[1].address)
+    return 1;
+  else
+    return 0;
+}
+
+/* Return the symbol name and value for an ADDR.  */
+
+static void
+coff_syminfo (struct backtrace_state *state, uintptr_t addr,
+	      backtrace_syminfo_callback callback,
+	      backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
+	      void *data)
+{
+  struct coff_syminfo_data *sdata;
+  struct coff_symbol *sym = NULL;
+
+  if (!state->threaded)
+    {
+      for (sdata = (struct coff_syminfo_data *) state->syminfo_data;
+	   sdata != NULL;
+	   sdata = sdata->next)
+	{
+	  sym = ((struct coff_symbol *)
+		 bsearch (&addr, sdata->symbols, sdata->count,
+			  sizeof (struct coff_symbol), coff_symbol_search));
+	  if (sym != NULL)
+	    break;
+	}
+    }
+  else
+    {
+      struct coff_syminfo_data **pp;
+
+      pp = (struct coff_syminfo_data **) (void *) &state->syminfo_data;
+      while (1)
+	{
+	  sdata = backtrace_atomic_load_pointer (pp);
+	  if (sdata == NULL)
+	    break;
+
+	  sym = ((struct coff_symbol *)
+		 bsearch (&addr, sdata->symbols, sdata->count,
+			  sizeof (struct coff_symbol), coff_symbol_search));
+	  if (sym != NULL)
+	    break;
+
+	  pp = &sdata->next;
+	}
+    }
+
+  if (sym == NULL)
+    callback (data, addr, NULL, 0, 0);
+  else
+    callback (data, addr, sym->name, sym->address, 0);
+}
+
+/* Add the backtrace data for one PE/COFF file.  Returns 1 on success,
+   0 on failure (in both cases descriptor is closed).  */
+
+static int
+coff_add (struct backtrace_state *state, int descriptor,
+	  backtrace_error_callback error_callback, void *data,
+	  fileline *fileline_fn, int *found_sym, int *found_dwarf)
+{
+  struct backtrace_view fhdr_view;
+  off_t fhdr_off;
+  int magic_ok;
+  b_coff_file_header fhdr;
+  off_t opt_sects_off;
+  size_t opt_sects_size;
+  unsigned int sects_num;
+  struct backtrace_view sects_view;
+  int sects_view_valid;
+  const b_coff_optional_header *opt_hdr;
+  const b_coff_section_header *sects;
+  struct backtrace_view str_view;
+  int str_view_valid;
+  size_t str_size;
+  off_t str_off;
+  struct backtrace_view syms_view;
+  off_t syms_off;
+  size_t syms_size;
+  int syms_view_valid;
+  unsigned int syms_num;
+  unsigned int i;
+  struct debug_section_info sections[DEBUG_MAX];
+  off_t min_offset;
+  off_t max_offset;
+  struct backtrace_view debug_view;
+  int debug_view_valid;
+  uintptr_t image_base;
+
+  *found_sym = 0;
+  *found_dwarf = 0;
+
+  sects_view_valid = 0;
+  syms_view_valid = 0;
+  str_view_valid = 0;
+  debug_view_valid = 0;
+
+  /* Map the MS-DOS stub (if any) and extract file header offset.  */
+  if (!backtrace_get_view (state, descriptor, 0, 0x40, error_callback,
+			   data, &fhdr_view))
+    goto fail;
+
+  {
+    const char *vptr = (const char *)fhdr_view.data;
+
+    if (vptr[0] == 'M' && vptr[1] == 'Z')
+      memcpy (&fhdr_off, vptr + 0x3c, 4);
+    else
+      fhdr_off = 0;
+  }
+
+  backtrace_release_view (state, &fhdr_view, error_callback, data);
+
+  /* Map the coff file header.  */
+  if (!backtrace_get_view (state, descriptor, fhdr_off,
+			   sizeof (b_coff_file_header) + 4,
+			   error_callback, data, &fhdr_view))
+    goto fail;
+
+  if (fhdr_off != 0)
+    {
+      const char *magic = (const char *) fhdr_view.data;
+      magic_ok = memcmp (magic, "PE\0", 4) == 0;
+      fhdr_off += 4;
+
+      memcpy (&fhdr, fhdr_view.data + 4, sizeof fhdr);
+    }
+  else
+    {
+      memcpy (&fhdr, fhdr_view.data, sizeof fhdr);
+      /* TODO: test fhdr.machine for coff but non-PE platforms.  */
+      magic_ok = 0;
+    }
+  backtrace_release_view (state, &fhdr_view, error_callback, data);
+
+  if (!magic_ok)
+    {
+      error_callback (data, "executable file is not COFF", 0);
+      goto fail;
+    }
+
+  sects_num = fhdr.number_of_sections;
+  syms_num = fhdr.number_of_symbols;
+
+  opt_sects_off = fhdr_off + sizeof (fhdr);
+  opt_sects_size = (fhdr.size_of_optional_header
+		    + sects_num * sizeof (b_coff_section_header));
+
+  /* To translate PC to file/line when using DWARF, we need to find
+     the .debug_info and .debug_line sections.  */
+
+  /* Read the optional header and the section headers.  */
+
+  if (!backtrace_get_view (state, descriptor, opt_sects_off, opt_sects_size,
+			   error_callback, data, &sects_view))
+    goto fail;
+  sects_view_valid = 1;
+  opt_hdr = (const b_coff_optional_header *) sects_view.data;
+  sects = (const b_coff_section_header *)
+    (sects_view.data + fhdr.size_of_optional_header);
+
+  if (fhdr.size_of_optional_header > sizeof (*opt_hdr))
+    {
+      if (opt_hdr->magic == PE_MAGIC)
+	image_base = opt_hdr->u.pe.image_base;
+      else if (opt_hdr->magic == PEP_MAGIC)
+	image_base = opt_hdr->u.pep.image_base;
+      else
+	{
+	  error_callback (data, "bad magic in PE optional header", 0);
+	  goto fail;
+	}
+    }
+  else
+    image_base = 0;
+
+  /* Read the symbol table and the string table.  */
+
+  if (fhdr.pointer_to_symbol_table == 0)
+    {
+      /* No symbol table, no string table.  */
+      str_off = 0;
+      str_size = 0;
+      syms_num = 0;
+    }
+  else
+    {
+      /* Symbol table is followed by the string table.  The string table
+	 starts with its length (on 4 bytes).
+	 Map the symbol table and the length of the string table.  */
+      syms_off = fhdr.pointer_to_symbol_table;
+      syms_size = syms_num * SYM_SZ;
+
+      if (!backtrace_get_view (state, descriptor, syms_off, syms_size + 4,
+			       error_callback, data, &syms_view))
+	goto fail;
+      syms_view_valid = 1;
+
+      memcpy (&str_size, syms_view.data + syms_size, 4);
+
+      str_off = syms_off + syms_size;
+
+      if (str_size > 4)
+	{
+	  /* Map string table (including the length word).  */
+
+	  if (!backtrace_get_view (state, descriptor, str_off, str_size,
+				   error_callback, data, &str_view))
+	    goto fail;
+	  str_view_valid = 1;
+	}
+    }
+
+  memset (sections, 0, sizeof sections);
+
+  /* Look for the symbol table.  */
+  for (i = 0; i < sects_num; ++i)
+    {
+      const b_coff_section_header *s = sects + i;
+      unsigned int str_off;
+      int j;
+
+      if (s->name[0] == '/')
+	{
+	  /* Extended section name.  */
+	  str_off = atoi (s->name + 1);
+	}
+      else
+	str_off = 0;
+
+      for (j = 0; j < (int) DEBUG_MAX; ++j)
+	{
+	  const char *dbg_name = debug_section_names[j];
+	  int match;
+
+	  if (str_off != 0)
+	    match = coff_long_name_eq (dbg_name, str_off, &str_view);
+	  else
+	    match = coff_short_name_eq (dbg_name, s->name);
+	  if (match)
+	    {
+	      sections[j].offset = s->pointer_to_raw_data;
+	      sections[j].size = s->virtual_size <= s->size_of_raw_data ?
+		s->virtual_size : s->size_of_raw_data;
+	      break;
+	    }
+	}
+    }
+
+  if (syms_num != 0)
+    {
+      struct coff_syminfo_data *sdata;
+
+      sdata = ((struct coff_syminfo_data *)
+	       backtrace_alloc (state, sizeof *sdata, error_callback, data));
+      if (sdata == NULL)
+	goto fail;
+
+      if (!coff_initialize_syminfo (state, image_base,
+				    sects, sects_num,
+				    syms_view.data, syms_size,
+				    str_view.data, str_size,
+				    error_callback, data, sdata))
+	{
+	  backtrace_free (state, sdata, sizeof *sdata, error_callback, data);
+	  goto fail;
+	}
+
+      *found_sym = 1;
+
+      coff_add_syminfo_data (state, sdata);
+    }
+
+  backtrace_release_view (state, &sects_view, error_callback, data);
+  sects_view_valid = 0;
+  backtrace_release_view (state, &syms_view, error_callback, data);
+  syms_view_valid = 0;
+
+  /* Read all the debug sections in a single view, since they are
+     probably adjacent in the file.  We never release this view.  */
+
+  min_offset = 0;
+  max_offset = 0;
+  for (i = 0; i < (int) DEBUG_MAX; ++i)
+    {
+      off_t end;
+
+      if (sections[i].size == 0)
+	continue;
+      if (min_offset == 0 || sections[i].offset < min_offset)
+	min_offset = sections[i].offset;
+      end = sections[i].offset + sections[i].size;
+      if (end > max_offset)
+	max_offset = end;
+    }
+  if (min_offset == 0 || max_offset == 0)
+    {
+      if (!backtrace_close (descriptor, error_callback, data))
+	goto fail;
+      *fileline_fn = coff_nodebug;
+      return 1;
+    }
+
+  if (!backtrace_get_view (state, descriptor, min_offset,
+			   max_offset - min_offset,
+			   error_callback, data, &debug_view))
+    goto fail;
+  debug_view_valid = 1;
+
+  /* We've read all we need from the executable.  */
+  if (!backtrace_close (descriptor, error_callback, data))
+    goto fail;
+  descriptor = -1;
+
+  for (i = 0; i < (int) DEBUG_MAX; ++i)
+    {
+      if (sections[i].size == 0)
+	sections[i].data = NULL;
+      else
+	sections[i].data = ((const unsigned char *) debug_view.data
+			    + (sections[i].offset - min_offset));
+    }
+
+  if (!backtrace_dwarf_add (state, /* base_address */ 0,
+			    sections[DEBUG_INFO].data,
+			    sections[DEBUG_INFO].size,
+			    sections[DEBUG_LINE].data,
+			    sections[DEBUG_LINE].size,
+			    sections[DEBUG_ABBREV].data,
+			    sections[DEBUG_ABBREV].size,
+			    sections[DEBUG_RANGES].data,
+			    sections[DEBUG_RANGES].size,
+			    sections[DEBUG_STR].data,
+			    sections[DEBUG_STR].size,
+			    0, /* FIXME */
+			    error_callback, data, fileline_fn))
+    goto fail;
+
+  *found_dwarf = 1;
+
+  return 1;
+
+ fail:
+  if (sects_view_valid)
+    backtrace_release_view (state, &sects_view, error_callback, data);
+  if (str_view_valid)
+    backtrace_release_view (state, &str_view, error_callback, data);
+  if (syms_view_valid)
+    backtrace_release_view (state, &syms_view, error_callback, data);
+  if (debug_view_valid)
+    backtrace_release_view (state, &debug_view, error_callback, data);
+  if (descriptor != -1)
+    backtrace_close (descriptor, error_callback, data);
+  return 0;
+}
+
+/* Initialize the backtrace data we need from an ELF executable.  At
+   the ELF level, all we need to do is find the debug info
+   sections.  */
+
+int
+backtrace_initialize (struct backtrace_state *state, int descriptor,
+		      backtrace_error_callback error_callback,
+		      void *data, fileline *fileline_fn)
+{
+  int ret;
+  int found_sym;
+  int found_dwarf;
+  fileline coff_fileline_fn;
+
+  ret = coff_add (state, descriptor, error_callback, data,
+		  &coff_fileline_fn, &found_sym, &found_dwarf);
+  if (!ret)
+    return 0;
+
+  if (!state->threaded)
+    {
+      if (found_sym)
+	state->syminfo_fn = coff_syminfo;
+      else if (state->syminfo_fn == NULL)
+	state->syminfo_fn = coff_nosyms;
+    }
+  else
+    {
+      if (found_sym)
+	backtrace_atomic_store_pointer (&state->syminfo_fn, coff_syminfo);
+      else
+	__sync_bool_compare_and_swap (&state->syminfo_fn, NULL, coff_nosyms);
+    }
+
+  if (!state->threaded)
+    {
+      if (state->fileline_fn == NULL || state->fileline_fn == coff_nodebug)
+	*fileline_fn = coff_fileline_fn;
+    }
+  else
+    {
+      fileline current_fn;
+
+      current_fn = backtrace_atomic_load_pointer (&state->fileline_fn);
+      if (current_fn == NULL || current_fn == coff_nodebug)
+	*fileline_fn = coff_fileline_fn;
+    }
+
+  return 1;
+}