[Mingw-users] _get_errno and _set_errno missing, but how do I add them?

[Shawn A. <Sha...@te...>]

First, let me apologize if I'm so stupid I cannot see the answer in 
front of my face.  Please feel free to publicly flog me if this is the 
case :)

I noticed that "_get_errno" and "_set_errno" are not defined in the 
latest MinGW sources (w32api-3.11 and mingw-runtime-3.14).  I would be 
more than happy to add these!  Trouble is, I cannot quite figure out 
completely how to do that :).  Here is what I did:

First, I found MSDN documentation telling me these go into stdlib.h 
and/or errno.h 
(http://msdn2.microsoft.com/en-us/library/wwfcfxas(VS.80).aspx) and 
(http://msdn2.microsoft.com/en-us/library/hf1920a7(VS.80).aspx).  Next, 
I inspected the mingw-runtime-3.1.4 and found that _errno is defined in 
both stdlib.h and errno.h, so I figure these two functions should go 
into both as well (very near to the _errno declaration I suppose).  I 
then added these two declarations into those header files right 
underneath the _errno declarations:

 _CRTIMP int* __cdecl __MINGW_NOTHROW    _set_errno(int);
 _CRTIMP int* __cdecl __MINGW_NOTHROW    _get_errno(int*);

Of course, re-compiling my app still gave me errors (expected, because 
they were originally linker errors, so just adding declarations doesn't 
help that).  It is here now that I am stuck.  I assume that the 
implementations for _get_errno and _set_errno are alive and present in 
the CRT (which I am assuming is the libmsvcrt.a archive in the 
mingw-runtime-3.1.4).  But, Google tells me my app is already 
automagically linked with the libmsvcrt.a, so it must be that I need to 
"coax" it out somehow.  I have concluded that perhaps I need to 
re-archive the libmsvcrt.a?

I then tried downloading the mingw-runtime-3.1.4.src.  First off, I 
typed "configure", then "make".  Configure seemed to go fine.  Make 
bombs out immediately not able to find Windows.h.  I admittedly do not 
understand the mingw-runtime project.  I would think somewhere I should 
find the "msvcrt.lib", "msvcrt70.lib", etc. in the project, but I cannot 
locate them.  If I had to guess, perhaps I am not correctly utilizing 
"configure"?  Or, perhaps there are certain prerequisite files and/or 
libraries and/or a certain unmentioned directory structure?  I am doing 
this from a Linux Red Hat EL 4 machine.

Again, I profusely apologize for probably missing the obvious.  Any bit 
of help you can give me, even if it is just to steer me in the correct 
direction, is greatly appreciated!  Thank you so much!

For your convenience, here is a small C snippit showcasing the original 
build problem:

-- BEGIN --
#include <errno.h>

int main(int argc, char **argv)
{
    _set_errno(EAGAIN);
    return 0;
}
-- END --

And, here is the build line:

 >/home/build/Linux/i686/mingw/bin/i386-mingw32msvc-gcc main.c
/tmp/ccUxQxwY.o(.text+0x24):main.c: undefined reference to `_set_errno'

My GCC version:
 >/home/build/Linux/i686/mingw/bin/i386-mingw32msvc-gcc --version
i386-mingw32msvc-gcc (GCC) 3.2.3 (mingw special 20030504-1)
Copyright (C) 2002 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

And, here is what happens when I type "configure", then "make" from the 
mingw-runtime-3.14src:

quark:~/srcruntime/mingw-runtime-3.14>./configure
checking package version... 3.14
checking build system type... i686-pc-linux-gnu
checking host system type... i686-pc-linux-gnu
checking target system type... i686-pc-linux-gnu
checking for gcc... gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ANSI C... none needed
checking for ar... ar
checking for as... as
checking for ranlib... ranlib
checking for ld... ld
checking for dlltool... dlltool
checking for dlltool... dlltool
checking for windres... windres
checking for a BSD-compatible install... /usr/bin/install -c
configure: creating ./config.status
config.status: creating Makefile
configure: configuring in profile
configure: running /bin/sh './configure' --prefix=/usr/local  
--cache-file=/dev/null --srcdir=.
checking build system type... i686-pc-linux-gnu
checking host system type... i686-pc-linux-gnu
checking target system type... i686-pc-linux-gnu
checking for a BSD-compatible install... /usr/bin/install -c
configure: creating ./config.status
config.status: creating Makefile
configure: configuring in mingwex
configure: running /bin/sh './configure' --prefix=/usr/local  
--cache-file=/dev/null --srcdir=.
checking build system type... i686-pc-linux-gnu
checking host system type... i686-pc-linux-gnu
checking target system type... i686-pc-linux-gnu
checking for a BSD-compatible install... /usr/bin/install -c
configure: creating ./config.status
config.status: creating Makefile

quark:~/srcruntime/mingw-runtime-3.14>make
gcc -c -D__CRTDLL__ -U__MSVCRT__ -g -O2 -I./include -I./../include 
-nostdinc -iwithprefixbefore include -I ./../w32api/include  crt1.c -o 
crt1.o
crt1.c:21:21: windows.h: No such file or directory
crt1.c:102: error: syntax error before "long"
crt1.c:103: error: syntax error before '*' token
crt1.c: In function `_gnu_exception_handler':
crt1.c:106: error: `EXCEPTION_CONTINUE_SEARCH' undeclared (first use in 
this function)
crt1.c:106: error: (Each undeclared identifier is reported only once
crt1.c:106: error: for each function it appears in.)
crt1.c:109: error: `exception_data' undeclared (first use in this function)
crt1.c:111: error: `EXCEPTION_ACCESS_VIOLATION' undeclared (first use in 
this function)
crt1.c:119: error: `EXCEPTION_CONTINUE_EXECUTION' undeclared (first use 
in this function)
crt1.c:129: error: `EXCEPTION_ILLEGAL_INSTRUCTION' undeclared (first use 
in this function)
crt1.c:130: error: `EXCEPTION_PRIV_INSTRUCTION' undeclared (first use in 
this function)
crt1.c:148: error: `EXCEPTION_FLT_INVALID_OPERATION' undeclared (first 
use in this function)
crt1.c:149: error: `EXCEPTION_FLT_DIVIDE_BY_ZERO' undeclared (first use 
in this function)
crt1.c:150: error: `EXCEPTION_FLT_DENORMAL_OPERAND' undeclared (first 
use in this function)
crt1.c:151: error: `EXCEPTION_FLT_OVERFLOW' undeclared (first use in 
this function)
crt1.c:152: error: `EXCEPTION_FLT_UNDERFLOW' undeclared (first use in 
this function)
crt1.c:153: error: `EXCEPTION_FLT_INEXACT_RESULT' undeclared (first use 
in this function)
crt1.c:157: error: `EXCEPTION_INT_DIVIDE_BY_ZERO' undeclared (first use 
in this function)
make: *** [crt1.o] Error 1

-- 
Shawn Authement