linux-kernel - RE: [PATCH 1/1] perf beauty: Don't use 'find ... -printf' as it isn't available in busybox

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Message-ID: <970de0610f8e4c9481817f6aea76c5a3@AcuMS.aculab.com>
Date:   Fri, 1 Dec 2023 17:16:20 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Arnaldo Carvalho de Melo' <acme@...nel.org>
CC:     Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Jiri Olsa <jolsa@...nel.org>,
        "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/1] perf beauty: Don't use 'find ... -printf' as it isn't
 available in busybox

From: Arnaldo Carvalho de Melo
> Sent: 01 December 2023 17:02
> 
> Em Fri, Dec 01, 2023 at 12:05:31PM +0000, David Laight escreveu:
> > ...
> > >  # Create list of architectures that have a specific errno.h.
> > >  archlist=""
> > > -for arch in $(find $toolsdir/arch -maxdepth 1 -mindepth 1 -type d -printf "%f\n" | sort -r); do
> > > +for arch in $(find $toolsdir/arch -maxdepth 1 -mindepth 1 -type d | while read arch ; do basename
> > > $arch ; done | sort -r); do
> > >  	test -f $toolsdir/arch/$arch/include/uapi/asm/errno.h && archlist="$archlist $arch"
> > >  done
> >
> > Jeepers ...
> > Does this work?
> > 	for f in $toolsdir/arch/*/include/uapi/asm/errno.h; do
> > 		[ ! -f $f ] && break
> > 		d=${f%/include/uapi/asm/errno.h}
> > 		archlist="${d##*/} $archlist"
> > 	done
> > No fork()s or exec()s.
> > I think it only differs in having a trailing space instead of a leading one.
> 
> ⬢[acme@...lbox perf-tools-next]$ for f in tools/arch/*/include/uapi/asm/errno.h; do
> d=${f%/include/uapi/asm/errno.h} ; arch="${d##*/}" ; echo "'$arch'" ; done
> 'alpha'
> 'mips'
> 'parisc'
> 'powerpc'
> 'sparc'
> 'x86'
> ⬢[acme@...lbox perf-tools-next]$ for arch in $(find tools/arch -maxdepth 1 -mindepth 1 -type d |
> while read arch ; do basename $arch ; done | sort -r) ; do test -f
> tools/arch/$arch/include/uapi/asm/errno.h && echo "'$arch'" ; done
> 'x86'
> 'sparc'
> 'powerpc'
> 'parisc'
> 'mips'
> 'alpha'
> ⬢[acme@...lbox perf-tools-next]$
> 
> There was a reason for having x86 first, lemme dig it... Just to have
> as the first strcmp in:

I reversed the order by adding the names at the front of $archlist - so the order
would still be reverse sorted (the shell sorts filename globs).

The '[ -f $f ] || break' line is only there in case there are no matching files.
If that can happen putting [ "$archlist" = "* " ] && archlist=
after the loop would be slightly better.
But with only 6 item the extra stat() will be noise.

	David

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