RE: Porting git to HP NonStop

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> From: Junio C Hamano [mailto:gitster@xxxxxxxxx]
> Sent: Sunday, August 19, 2012 7:23 PM
> To: Joachim Schmitz
> Cc: 'Shawn Pearce'; git@xxxxxxxxxxxxxxx; rsbecker@xxxxxxxxxxxxx
> Subject: Re: Porting git to HP NonStop
> 
> "Joachim Schmitz" <jojo@xxxxxxxxxxxxxxxxxx> writes:
> 
> > Found the problem: our mkdir(dir,flags) fails with ENOENT when dir
> > ends with a '/'.
> > Not sure whether this us a bug on out platform or just allowed by
> > POSIX and as such a wrong assumption in git though?
> >
> > [shortly after]
> > A bit of googleing revealed that there is a GNUlib solution for this,
> > which claims that at least NetBSD 1.5.2 has the same problem.
> > (http://www.opensource.apple.com/source/gpatch/gpatch-2/patch/mkdir.c)
> >
> > And apparently this has been discussed on the git mailing list too, 2
> > years
> > ago:
> > http://lists-archives.com/git/728359-git-s-use-of-mkdir-2.html,
> > there's a patch too.
> 
> Given that newer BSDs have fixed libc to accept directory name with a
trailing
> slash, and that we use mkdir(2) in many places, I think the right way to
do so is
> still what I suggested in that old thread in the last paragraph of my
message
> 
>   http://thread.gmane.org/gmane.comp.version-
> control.git/155812/focus=155876
> 
> That is, have compat/tandem.c and define a replacement mkdir(2) in a way
> similar to how MinGW does so.

OK, I'll go for a compat/mkdir.c though.
We shouldn't call it tandem.c as Tandem, the Company, doesn't exist anymore
and since more than a decade (bough by Compaq, then HP), only the __TANDEM
survived in our compiler and headers/libraries. Could call it NonStop.c, but
I don't really like that idea either, I'd rather keep it more generic, just
in case someone else might need it too, or that issue someday gets fixed for
NonStop.

> > For now I've fixed it like this:
> > /usr/local/bin/diff -EBbu ./builtin/init-db.c.orig ./builtin/init-db.c
> > --- ./builtin/init-db.c.orig    2012-08-19 03:55:50 -0500
> > +++ ./builtin/init-db.c 2012-08-19 03:39:57 -0500
> > @@ -25,7 +25,16 @@
> >
> >  static void safe_create_dir(const char *dir, int share)  {
> > +#ifdef __TANDEM /* our mkdir() can't cope with a trailing '/' */
> > +       char mydir[PATH_MAX];
> > +
> > +       strcpy(mydir,dir);
> > +       if (dir[strlen(dir)-1] == '/')
> > +               mydir[strlen(dir)-1] = '\0';
> > +       if (mkdir(mydir, 0777) < 0) {
> > +#else
> >         if (mkdir(dir, 0777) < 0) {
> > +#endif
> 
> Move that part inside #ifdef __TANDEM to define
> 
> 	int tandem_mkdir(const char *dir, mode_t mode)
>         {
> 		...
> 	}

I'll go for git_mkdir(), similar to other git wrappers, (like for mmap,
pread, fopen, snprintf, vsnprintf, qsort). Could call it gitmkdir() too
(like for basename, setenv, mkdtemp, mkstemps, unsetenv, strcasestr,
strlcpy, strtoumax, strtoimax, strtok_r, hstrerror, memmem, strchrnul,
memcpy), Opinions?
It seems the ones without the "_" are for missing APIs and the ones with "_"
to wrap existing APIs (not sure about mmap and pread)?

Here it's current state:
$ cat compat/mkdir.c
#include "../git-compat-util.h"
#undef mkdir

/* for platforms that can't deal with a trailing '/' */
int git_mkdir(const char *dir, mode_t mode)
{
        int retval;
        char *tmp_dir = NULL;
        size_t len = strlen(dir);

        if (len && dir[len-1] == '/') {
                if ((tmp_dir = strdup(dir)) == NULL)
                        return -1;
                tmp_dir[len-1] = '\0';
        }
        else
                tmp_dir = (char *)dir;

        retval = mkdir(tmp_dir, mode);
        if (tmp_dir != dir)
                free(tmp_dir);

        return retval;
}
$
 
There is room for improvement though: it only removes one trailing slash. By
far not as advanced and generic as GNUlib's mkdir wrapper, but should be
good enough for git's usage.

> in your new file compat/tandem.c, add
> 
> 	#ifdef __TANDEM
>         #define mkdir(a,b) tandem_mkdir((a), (b))
> 	#endif
> 
> to git-compat-util.h

Again, git_mkdir, see above

> and then add compat/tandem.o to COMPAT_OBJS in the
> top-level Makefile.

For now I've added it to the (new) NOSTOP_KERNEL section. 

We may want it to go along with some
MKDIR_DISLIKES_TRAILING_SLASH or MKDIR_BOGUS_TRAILING_SLASH some such.
Opinions, Ideas?

> That way we do not have to keep an ugly platform specific ifdef in the
very
> generic codepath.

Agreed, it was my quick and dirty fix for it.

Bye, Jojo

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