[PATCH] reimplement dirname v2

[Matthias Andree]

Am 08.09.2011 22:24, schrieb Tito:
> On Thursday 08 September 2011 18:11:22 Matthias Andree wrote:
>> If libc has a good dirname() implementation it should be used. Please
>> make that configurable and have it default to off on (e)glibc and FreeBSD.
> 
> Hi,
> not that I think that this will ever be checked in,
> nonetheless it would be interesting to know
> what exactly a good dirname implementation is :-)

Let's start with 'POSIX conforming'. :)

> I think that the rationale for an eventual checkin
> of this code is that due to the fact that there are 
> different implementations in different libcs
> and even in the same libc, we want to stick with
> one that works everywhere independently
> of the libc used.

busybox need not patch up b0rked libc implementations.

> I wonder also how the FreeBSD dirname
> plays with busybox code like this in install.c:

Nicely, but...

> 			if (opts & OPT_MKDIR_LEADING) {
> 				char *ddir = xstrdup(dest);
> 				bb_make_directory(dirname(ddir), 0755, FILEUTILS_RECUR);
> 				/* errors are not checked. copy_file
> 				 * will fail if dir is not created. */
> 				free(ddir);
> 			}

...these xstrdup()/free() hoops aren't necessary on FreeBSD because it
leaves the string its argument points to alone.

> Wouldn't this leak memory with the freebsd dirname?

Somewhat. It allocates a static buffer of MAXPATHLEN bytes on first use
and reuses it on subsequent calls (trashing the former contents), and
that gets reclaimed once the application exits.