GNULib save-cwd.c on Windows & Visual Studio 6.0
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Hi Jim,
The CVS project compiles the Windows CVS binary with Microsoft Visual
Studio 6.0 which doesn't have a "fchdir" implementation which is used
in "save-cwd.c" module. The comments say:
Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin,
SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it
doesn't work for partitions on which auditing is enabled. If
you're still using an obsolete system with these problems, please
send email to the maintainer of this code.
Function "fchdir" is also used in "chdir-long.c" and "openat.c" modules
which may not be used in Windows build.
What would you suggest for this issue?
Best regards,
Conrad T. Pino
The "grep fchdir ..." and build error outputs follow:
File lib\chdir-long.c:
56 cdb_fchdir (struct cd_buf const *cdb)
58return fchdir (cdb->fd);
200 if (cdb_fchdir (&cdb) != 0)
File lib\openat.c:
39 Simulate it by doing save_cwd/fchdir/open/restore_cwd.
72if (fchdir (fd) != 0)
95 Simulate it by doing save_cwd/fchdir/opendir(".")/restore_cwd.
114 if (fchdir (fd) != 0)
137Simulate it by doing save_cwd/fchdir/(stat|lstat)/restore_cwd.
158 if (fchdir (fd) != 0)
File lib\save-cwd.c:
58 So, we prefer to use the open/fchdir approach, but fall back on
61 Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin,
87 Upon failure, return -1 (errno is set by chdir or fchdir).
94 return fchdir (cwd->desc);
- Configuration: cvsnt - Win32 Debug
Linking...
libdiff.lib(save-cwd.obj) : error LNK2001: unresolved external symbol _fchdir
.\WinDebug\cvs.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.
cvs.exe - 2 error(s), 0 warning(s)
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Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
"Conrad T. Pino" <[EMAIL PROTECTED]> wrote: > The CVS project compiles the Windows CVS binary with Microsoft Visual > Studio 6.0 which doesn't have a "fchdir" implementation which is used > in "save-cwd.c" module. The comments say: > >Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin, >SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it >doesn't work for partitions on which auditing is enabled. If >you're still using an obsolete system with these problems, please >send email to the maintainer of this code. > > Function "fchdir" is also used in "chdir-long.c" and "openat.c" modules > which may not be used in Windows build. > > What would you suggest for this issue? Hi Conrad, Is it an option to use a more modern/POSIX-compliant development environment on Windows? I know that Cygwin now has fchdir and it looks like MKS has support for it, too. POSIX has required fchdir for a long time, now, and having fchdir lets programs do things like save and restore the working directory much more efficiently and robustly than the alternative getcwd-based implementation would. For example, if you `return' to a saved working directory using chdir, you have to wonder if maybe you've been tricked into changing to some other directory -- or incur the cost of getting/saving/comparing before and after device and inode numbers. If you opt to continue using Visual Studio 6 in spite of this, it must have some important redeeming features. The Unix systems that lack support for fchdir stopped being reasonable porting targets a couple of years ago. And since Cygwin has had fchdir support for over three years, I thought we'd be safe on the WOE side, too. So about a month ago we removed from the save-cwd module support for systems with missing or flaky fchdir support. Although that module could work around the lack of a working fchdir function, the openat module cannot. And since the chdir-long module also uses openat, its use of fchdir is moot. If you have no alternative, it wouldn't be hard to revert the last change to the save-cwd module, but it'd feel like a step backwards. Jim ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
RE: GNULib save-cwd.c on Windows & Visual Studio 6.0
Jim Meyering wrote: > Is it an option to use a more modern/POSIX-compliant development > environment on Windows? I know that Cygwin now has fchdir > and it looks > like MKS has support for it, too. > If you opt to continue using Visual Studio 6 in > spite of this, it must have some important redeeming features. The problem with the cygwin build is that it requires Cygwin.dll as well. The MSVC build stands alone, not requiring any external DLLs. I don't think it is reasonable to require all Windows users to download and install Cygwin just to run CVS. -- Jim Hyslop Senior Software Designer Leitch Technology International Inc. ( http://www.leitch.com ) Columnist, C/C++ Users Journal ( http://www.cuj.com/experts ) ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Jim.Hyslop wrote: | Jim Meyering wrote: | |> Is it an option to use a more modern/POSIX-compliant development |> environment on Windows? I know that Cygwin now has fchdir and it |> looks like MKS has support for it, too. | | |> If you opt to continue using Visual Studio 6 in spite of this, it |> must have some important redeeming features. | | | The problem with the cygwin build is that it requires Cygwin.dll as | well. The MSVC build stands alone, not requiring any external DLLs. | | | I don't think it is reasonable to require all Windows users to | download and install Cygwin just to run CVS. I'm afraid I have to agree with Jim Hyslop. Whatever Microsoft's flaws, I still believe that some of our mutual user base is at least relatively innocent and should still be catered to. Regards, Derek -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.0 (Cygwin) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFCLcarLD1OTBfyMaQRAu5RAJ9NJMTJgEZkPrSjdOGLZBYHaIH6KQCg/RnD un34isGInces/lodh1MM4NQ= =emIY -END PGP SIGNATURE- ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
RE: GNULib save-cwd.c on Windows & Visual Studio 6.0
[CVS support for MSVC] By the way, I just had a quick look at Visual Studio .NET 2003, and it does not appear to have POSIX support. At least, there's not fchdir function, which is what triggered this whole discussion ;=) -- Jim Hyslop Senior Software Designer Leitch Technology International Inc. ( http://www.leitch.com ) Columnist, C/C++ Users Journal ( http://www.cuj.com/experts ) ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
On Tuesday 08 March 2005 16:37, Derek Price wrote: > Jim.Hyslop wrote: > | Jim Meyering wrote: > |> Is it an option to use a more modern/POSIX-compliant development > |> environment on Windows? I know that Cygwin now has fchdir and it > |> looks like MKS has support for it, too. > |> > |> > |> If you opt to continue using Visual Studio 6 in spite of this, it > |> must have some important redeeming features. > | > | The problem with the cygwin build is that it requires Cygwin.dll as > | well. The MSVC build stands alone, not requiring any external DLLs. > | > | > | I don't think it is reasonable to require all Windows users to > | download and install Cygwin just to run CVS. > > I'm afraid I have to agree with Jim Hyslop. Whatever Microsoft's > flaws, I still believe that some of our mutual user base is at least > relatively innocent and should still be catered to. I agree with this. Even though I'm not an ms disciple, I know quite some users that would be affected ... -- - The LinCVS Team - http://www.lincvs.com ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
Derek Price <[EMAIL PROTECTED]> wrote: > I'm afraid I have to agree with Jim Hyslop. Whatever Microsoft's > flaws, I still believe that some of our mutual user base is at least > relatively innocent and should still be catered to. This is not about Microsoft per se, but simply about the lack of fchdir (or POSIX support in general) in WOE. I suppose it's a long shot, but... is there a way, in WOE/MSVC, to emulate fchdir's behavior? I.e., given a file descriptor that is the result of opening a directory, can you obtain an absolute path name of that directory? BTW if we end up reverting the changes to save-cwd.c, we'll also have to do something about its use of chdir_long, which won't work on systems lacking fchdir: #if !HAVE_FCHDIR # undef chdir_long # define chdir_long(d) chdir (d) #endif ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Jim Meyering wrote: | Derek Price <[EMAIL PROTECTED]> wrote: | |> I'm afraid I have to agree with Jim Hyslop. Whatever Microsoft's |> flaws, I still believe that some of our mutual user base is at |> least relatively innocent and should still be catered to. | | | This is not about Microsoft per se, but simply about the lack of | fchdir (or POSIX support in general) in WOE. I'm very, very reluctant to introduce a dependency on Cygwin for a single function... | I suppose it's a long shot, but... is there a way, in WOE/MSVC, to | emulate fchdir's behavior? I.e., given a file descriptor that is | the result of opening a directory, can you obtain an absolute path | name of that directory? Glancing at the sources for cygwin, it looks like they decided to save the file name via their open() function and look up the stored value in their fchdir(), then call chdir() on it. Regards, Derek -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.0 (Cygwin) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFCLdnTLD1OTBfyMaQRAgH3AKCV4TwsCiIK2V1M3Ub4zKzeiKyZDgCg0zOZ N0MOMsKS+B3K5zqbg2uzaTY= =qePb -END PGP SIGNATURE- ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
Here's a patch that should restore the ability of save-cwd to work on systems without the fchdir function. Would you please see if this is sufficient? If so, I'll check it in to gnulib (with an AC_CHECK_FUNCS(fchdir) in save-cwd.m4). Index: save-cwd.c === RCS file: /fetish/cu/lib/save-cwd.c,v retrieving revision 1.24 diff -u -p -r1.24 save-cwd.c --- save-cwd.c 20 Jan 2005 22:17:26 - 1.24 +++ save-cwd.c 9 Mar 2005 07:49:19 - @@ -44,6 +44,18 @@ #include "chdir-long.h" #include "xgetcwd.h" +/* On systems without the fchdir function (WOE), pretend that open + always returns -1 so that save_cwd resorts to using xgetcwd. + Since chdir_long requires fchdir, use chdir instead. */ +#if !HAVE_FCHDIR +# undef open +# define open(File, Flags) -1 +# undef fchdir +# define fchdir(Fd) abort () +# undef chdir_long +# define chdir_long(Dir) chdir (Dir) +#endif + /* Record the location of the current working directory in CWD so that the program may change to other directories and later use restore_cwd to return to the recorded location. This function may allocate ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
RE: GNULib save-cwd.c on Windows & Visual Studio 6.0
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Hi Jim,
> From: Jim Meyering [mailto:[EMAIL PROTECTED]
>
> This is not about Microsoft per se, but simply about
> the lack of fchdir (or POSIX support in general) in WOE.
I agree let's not enumerate Microsoft's flaws as we would never
finish. :)
> I suppose it's a long shot, but...
> is there a way, in WOE/MSVC, to emulate fchdir's behavior?
I think not. My research on http://msdn.microsoft.com site came
up with no hint of a method to translate an open file / directory
handle into a path name.
> I.e., given a file descriptor that is the result of opening a
> directory, can you obtain an absolute path name of that directory?
Worse, if "C:\work" is a directory attempts to use the Visual C 6.0
"open" function with "_O_RDONLY" argument to open "." or "C:\work"
will both return -1 value i.e. error. Sample program follows.
Conrad
#include
#include
#include
static int opendir( char *name )
{
int fd;
fd = open( name, _O_RDONLY );
printf( "open %s = %d\n", name, fd );
close( fd );
return fd;
}
int main(int argc, char* argv[])
{
int fd;
printf("Hello World!\n");
fd = opendir( "test.txt" );
fd = opendir( "." );
fd = opendir( "C:\\work" );
return 0;
}
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RE: GNULib save-cwd.c on Windows & Visual Studio 6.0
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi Jim, > From: Jim Meyering [mailto:[EMAIL PROTECTED] > > Here's a patch that should restore the ability of save-cwd to > work on systems without the fchdir function. > > Would you please see if this is sufficient? > If so, I'll check it in to gnulib (with an AC_CHECK_FUNCS(fchdir) > in save-cwd.m4). The patch as submitted does not compile. This line fails: return fchdir (cwd->desc); The patch at message end does compile and the build completes. Conrad Index: save-cwd.c === RCS file: /cvs/ccvs/lib/save-cwd.c,v retrieving revision 1.6 diff -u -p -r1.6 save-cwd.c - --- save-cwd.c 1 Mar 2005 18:15:42 - 1.6 +++ save-cwd.c 9 Mar 2005 14:50:43 - @@ -44,6 +44,18 @@ #include "chdir-long.h" #include "xgetcwd.h" +/* On systems without the fchdir function (WOE), pretend that open + always returns -1 so that save_cwd resorts to using xgetcwd. + Since chdir_long requires fchdir, use chdir instead. */ +#if !HAVE_FCHDIR +# undef open +# define open(File, Flags) -1 +# undef fchdir +# define fchdir(Fd) ( abort (), -1 ) +# undef chdir_long +# define chdir_long(Dir) chdir (Dir) +#endif + /* Record the location of the current working directory in CWD so that the program may change to other directories and later use restore_cwd to return to the recorded location. This function may allocate -BEGIN PGP SIGNATURE- Version: PGP 7.0.4 iQA/AwUBQi8OqrNM28ubzTo9EQKCQACglWgegbLzUqZdLaxd+HC+ls9Jv7oAn1J5 0z2tXUL54UlQZECFNzsG4PuC =7E/O -END PGP SIGNATURE- ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
"Conrad T. Pino" <[EMAIL PROTECTED]> wrote: ... >> Would you please see if this is sufficient? >> If so, I'll check it in to gnulib (with an AC_CHECK_FUNCS(fchdir) >> in save-cwd.m4). > > The patch as submitted does not compile. This line fails: > > return fchdir (cwd->desc); > > The patch at message end does compile and the build completes. Thanks. I've checked that in. ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
RE: GNULib save-cwd.c on Windows & Visual Studio 6.0
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi Jim, > From: Jim Meyering [mailto:[EMAIL PROTECTED] > > "Conrad T. Pino" <[EMAIL PROTECTED]> wrote: > ... > >> Would you please see if this is sufficient? > >> If so, I'll check it in to gnulib (with an AC_CHECK_FUNCS(fchdir) > >> in save-cwd.m4). > > > > The patch as submitted does not compile. This line fails: > > > > return fchdir (cwd->desc); > > > > The patch at message end does compile and the build completes. > > Thanks. > I've checked that in. I've seen the "lib/save-cwd.c" change in GULLib CVS on Savannah but I didn't see the "AC_CHECK_FUNCS(fchdir) in save-cwd.m4" change. Conrad -BEGIN PGP SIGNATURE- Version: PGP 7.0.4 iQA/AwUBQi+5KrNM28ubzTo9EQLWKwCgp1C8kpucYC92QRaGblHAp5+z0xIAniOF WX8BVodiTSIchNoDxIi4ZwT9 =Nwqu -END PGP SIGNATURE- ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: GNULib save-cwd.c on Windows & Visual Studio 6.0
"Conrad T. Pino" <[EMAIL PROTECTED]> wrote: ... >> I've checked that in. > > I've seen the "lib/save-cwd.c" change in GULLib CVS on Savannah but > I didn't see the "AC_CHECK_FUNCS(fchdir) in save-cwd.m4" change. It was too late :) I've just done it. Index: m4/save-cwd.m4 === RCS file: /cvsroot/gnulib/gnulib/m4/save-cwd.m4,v retrieving revision 1.4 retrieving revision 1.5 diff -u -p -u -r1.4 -r1.5 --- m4/save-cwd.m4 20 Jan 2005 22:21:01 - 1.4 +++ m4/save-cwd.m4 10 Mar 2005 08:55:38 - 1.5 @@ -1,4 +1,4 @@ -# save-cwd.m4 serial 4 +#serial 5 dnl Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -9,5 +9,6 @@ AC_DEFUN([gl_SAVE_CWD], AC_LIBSOURCES([save-cwd.c, save-cwd.h]) AC_LIBOBJ([save-cwd]) dnl Prerequisites for lib/save-cwd.c. + AC_CHECK_FUNCS_ONCE(fchdir) AC_CHECK_HEADERS_ONCE(fcntl.h unistd.h) ]) ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
Re: [bug-gnulib] RE: GNULib save-cwd.c on Windows & Visual Studio 6.0
On Tue, Mar 08, 2005 at 09:26:47AM -0500, Jim.Hyslop wrote: > The MSVC build stands alone, not requiring any external DLLs. > > I don't think it is reasonable to require all Windows users to download and > install Cygwin just to run CVS. So how does Tony Hoyle's CVSNT deal with this issue? > > -- > Jim Hyslop > Senior Software Designer > Leitch Technology International Inc. ( http://www.leitch.com ) > Columnist, C/C++ Users Journal ( http://www.cuj.com/experts ) ___ Bug-cvs mailing list Bug-cvs@gnu.org http://lists.gnu.org/mailman/listinfo/bug-cvs
