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Subject: Re: Finding a program's base directory
From: "Rod Pemberton" <do_not_have AT nowhere DOT cmm>
Date: Fri, 1 Jun 2007 04:34:20 -0400
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"Robert Riebisch" <Robert DOT Riebisch AT arcor DOT de> wrote in message
news:465ea4ec$0$23146$9b4e6d93 AT newsspool1 DOT arcor-online DOT net...
> Hi!
>
> I want to find a program's base directory. Program binary is in, e.g.,
> `C:\PROGRAMS\FOO\BIN\BAR.EXE'. get_base_dir() is called with argv[0] in
> pgm and shall return `C:\PROGRAMS\FOO'.
>
> The following code works for me, but as I'm no C expert, I want you to
> have a look at it.

> Specifically I'm not sure about the `base_path !=
> NULL' comparison. Is it necessary or just a waste? Thanks in advance!
>

Waste.

Since, base_path is an object, and therefore isn't NULL when declared, and
strncpy() can't modify it's first argument (passed by value) i.e.,
base_path, base_path can never be NULL.  strncpy() also returns it's first
argument.  So, it doesn't return NULL.

You might want to check that BIN is the final directory. It might be
something else.

I don't use many qualifiers, so someone else will need to comment on whether
'static' is correctly used.

> ***
> # ifdef __DJGPP__
> #  include <crt0.h>
> int _crt0_startup_flags = _CRT0_FLAG_USE_DOS_SLASHES;
> #  endif
> ***
>
> ***
> static char *get_base_dir(char *pgm)
> {
>    static char base_path[MAX_PATH_LEN];
>    char *p;
>
>    strncpy (base_path, pgm, MAX_PATH_LEN);
>    if (base_path != NULL)
>      {
> /* drop file name */
> p = strrchr (base_path, '\\');
> if (p != NULL)
>   {
>      *p = '\0';
>      /* drop also 'bin' */
>      p = strrchr (base_path, '\\');
>      if (p != NULL)
>        *p = '\0';
>   }
>      }
>    return base_path;
> }
> ***
>


Rod Pemberton