On Mon, Oct 19, 2020 at 10:06:52PM +0200, Christian Weisgerber wrote:
> [Picking this up again after a month:]
>
> Our basename(3) and dirname(3) take a const argument:
>
> char *basename(const char *);
> char *dirname(const char *);
>
> POSIX says otherwise...
>
> char *basename(char *path);
> char *dirname(char *path);
>
> ... and explicitly says the functions may modify the input string.
>
>
> Our functions were const-ified in 1999 by espie@:
>
> proper const semantics for dirname & basename.
> (this follows FreeBSD and Linux. Single Unix 2 is still illogical)
>
> Well, four years ago, FreeBSD finally switched to the POSIX prototypes
> https://svnweb.freebsd.org/base/head/include/libgen.h?revision=303451&view=markup
> and in fact now has an implementation that modifies the string.
>
> Linux (GNU libc) has a bizarro solution where you get a const basename()
> and no dirname() if you just include <string.h>, but POSIX basename()
> and dirname() if you instead or also include <libgen.h>.
>
> This is a portability trap. Code written on OpenBSD may not be
> prepared for basename() or dirname() to splat a '\0' into the input
> string, despite the warning in the man page. This is not hypothetical.
> Both Got and OpenCVS have fallen victim to the unportable assumption.
>
>
> The patch below aligns the function prototypes with POSIX. All
> resulting warnings "passing 'const char *' to parameter of type
> 'char *' discards qualifiers" in the base system have been cleaned
> up. It successfully passes "make release". For good measure I'm
> also running a package bulk build with it as we speak.
>
> OK?
Ok by me.
> Index: include/libgen.h
> ===================================================================
> RCS file: /cvs/src/include/libgen.h,v
> retrieving revision 1.9
> diff -u -p -r1.9 libgen.h
> --- include/libgen.h 25 Jan 2019 00:19:25 -0000 1.9
> +++ include/libgen.h 11 Sep 2020 20:41:34 -0000
> @@ -22,8 +22,8 @@
> #include <sys/cdefs.h>
>
> __BEGIN_DECLS
> -char *basename(const char *);
> -char *dirname(const char *);
> +char *basename(char *);
> +char *dirname(char *);
> __END_DECLS
>
> #endif /* _LIBGEN_H_ */
> Index: lib/libc/gen/basename.3
> ===================================================================
> RCS file: /cvs/src/lib/libc/gen/basename.3,v
> retrieving revision 1.24
> diff -u -p -r1.24 basename.3
> --- lib/libc/gen/basename.3 25 Jan 2019 00:19:25 -0000 1.24
> +++ lib/libc/gen/basename.3 11 Sep 2020 20:46:30 -0000
> @@ -23,7 +23,7 @@
> .Sh SYNOPSIS
> .In libgen.h
> .Ft char *
> -.Fn basename "const char *path"
> +.Fn basename "char *path"
> .Sh DESCRIPTION
> The
> .Fn basename
> Index: lib/libc/gen/basename.c
> ===================================================================
> RCS file: /cvs/src/lib/libc/gen/basename.c,v
> retrieving revision 1.16
> diff -u -p -r1.16 basename.c
> --- lib/libc/gen/basename.c 25 Jan 2019 00:19:25 -0000 1.16
> +++ lib/libc/gen/basename.c 11 Sep 2020 20:43:13 -0000
> @@ -22,7 +22,7 @@
> #include <string.h>
>
> char *
> -basename(const char *path)
> +basename(char *path)
> {
> static char bname[PATH_MAX];
> size_t len;
> Index: lib/libc/gen/dirname.3
> ===================================================================
> RCS file: /cvs/src/lib/libc/gen/dirname.3,v
> retrieving revision 1.23
> diff -u -p -r1.23 dirname.3
> --- lib/libc/gen/dirname.3 8 Mar 2019 17:33:23 -0000 1.23
> +++ lib/libc/gen/dirname.3 11 Sep 2020 20:47:08 -0000
> @@ -23,7 +23,7 @@
> .Sh SYNOPSIS
> .In libgen.h
> .Ft char *
> -.Fn dirname "const char *path"
> +.Fn dirname "char *path"
> .Sh DESCRIPTION
> The
> .Fn dirname
> Index: lib/libc/gen/dirname.c
> ===================================================================
> RCS file: /cvs/src/lib/libc/gen/dirname.c,v
> retrieving revision 1.16
> diff -u -p -r1.16 dirname.c
> --- lib/libc/gen/dirname.c 25 Jan 2019 00:19:25 -0000 1.16
> +++ lib/libc/gen/dirname.c 11 Sep 2020 20:43:34 -0000
> @@ -24,7 +24,7 @@
> /* A slightly modified copy of this file exists in libexec/ld.so */
>
> char *
> -dirname(const char *path)
> +dirname(char *path)
> {
> static char dname[PATH_MAX];
> size_t len;
> --
> Christian "naddy" Weisgerber [email protected]
>
>
