RE: Porting git to HP NonStop

From: Junio C Hamano [mailto:gitster@pobox.com]
Sent: Wednesday, August 22, 2012 8:25 PM
To: Joachim Schmitz
Cc: 'Brandon Casey'; 'Shawn Pearce'; git@vger.kernel.org;
rsbecker@nexbridge.com
Subject: Re: Porting git to HP NonStop

"Joachim Schmitz" [off-list ref] writes:

quoted

quoted

Nice.  And we have xmemdupz() would be even better as you followed-up.

How's that one used?

I forgot that we frown upon use of any x<allocate>() wrapper in the

compat/

layer as J6t mentioned.

So probably something along these lines...

	int retval;
	char *dir_to_free = NULL;
	size_t len = strlen(dir);

        if (len && dir[len - 1] == '/') {
		dir_to_free = malloc(len);
                if (!dir_to_free) {
			fprintf(stderr, "malloc failed!\n");
			exit(1);
		}
                memcpy(dir_to_free, dir, len - 1);
                dir_to_free[len - 1] = '\0';
                dir = dir_to_free;
	}
	retval = mkdir(dir, mode);
	free(dir_to_free);
        return retval;

So why not just strdup? I stole the idea from gnulib...

int
rpl_mkdir (char const *dir, mode_t mode maybe_unused)
{
  int ret_val;
  char *tmp_dir;
  size_t len = strlen (dir);

  if (len && dir[len - 1] == '/')
    {
      tmp_dir = strdup (dir);
      if (!tmp_dir)
        {
          /* Rather than rely on strdup-posix, we set errno ourselves.  */
          errno = ENOMEM;
          return -1;
        }
      strip_trailing_slashes (tmp_dir);
    }
  else
    {
      tmp_dir = (char *) dir;
    }


They strip more than one trailing slash, but for git's purpose I believed
this to be too much overhead. Also the errno stuff doesn't seem to be really
needed IMHO. Same for the following code

#if FUNC_MKDIR_DOT_BUG
  /* Additionally, cygwin 1.5 mistakenly creates a directory "d/./".  */
  {
    char *last = last_component (tmp_dir);
    if (*last == '.' && (last[1] == '\0'
                         || (last[1] == '.' && last[2] == '\0')))
      {
        struct stat st;
        if (stat (tmp_dir, &st) == 0)
          errno = EEXIST;
        return -1;
      }
  }
#endif /* FUNC_MKDIR_DOT_BUG */

Then it goes on like mine:

  ret_val = mkdir (tmp_dir, mode);

  if (tmp_dir != dir)
    free (tmp_dir);

  return ret_val;
}

Compare:
$ cat compat/mkdir.c
#include "../git-compat-util.h"
#undef mkdir

/* for platforms that can't deal with a trailing '/' */
int compat_mkdir_wo_trailing_slash(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;
}

Bye, Jojo