Re: [PATCH] strverscmp.3: this is NOT the ordering used by ls -v
From: Alejandro Colomar <alx@kernel.org>
Date: 2024-12-15 20:44:01
Hi nab, On Sun, Dec 15, 2024 at 09:17:59PM +0100, Ahelenia Ziemiańska wrote:
Compare, given:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int compar(const char **l, const char **r) {
return strverscmp(*l, *r);
}
int main(int argc, char ** argv) {
qsort(argv + 1, argc - 1, sizeof(*argv), compar);
for(int i = 1; i < argc; ++i)
puts(argv[i]);
}
yields:
$ /bin/ls -v1 a* # coreutils ls
a-1.0a
a-1.0.1a
$ ../vers a* # as above
a-1.0.1a
a-1.0a
$ ls -v1 a* # voreutils ls @ 5781698 with strverscmp()-equivalent sorting
a-1.0.1a
a-1.0aShould we file a bug against glibc strverscmp(3)? We probably should.
compare also the results for real data like
netstat-nat-1.{0,1{,.1},2,3.1,4{,.{1,2,3,4,5,6,7,8,9,10}}}.tar.gzThus, coreutils ls -v does NOT use strverscmp(3), it uses a similar algorithm that actually properly sorts versions, not just single numbers.
First time I learn about ls(1) having a -v option. :| Was people too lazy to type `ls | sort -V`?
quoted hunk ↗ jump to hunk
Signed-off-by: Ahelenia Ziemiańska <redacted> --- man/man3/strverscmp.3 | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-)diff --git a/man/man3/strverscmp.3 b/man/man3/strverscmp.3 index 41bc1ddbd..7c3643860 100644 --- a/man/man3/strverscmp.3 +++ b/man/man3/strverscmp.3@@ -25,16 +25,7 @@ .SH DESCRIPTION orders them .IR jan1 ", " jan10 ", ..., " jan2 ", ..., " jan9 . .\" classical solution: "rename jan jan0 jan?" -In order to rectify this, GNU introduced the -.I \-v -option to -.BR ls (1), -which is implemented using -.BR versionsort (3), -which again uses -.BR strverscmp (). -.P -Thus, the task of +The task of .BR strverscmp () is to compare two strings and find the "right" order, while .BR strcmp (3)@@ -44,6 +35,10 @@ .SH DESCRIPTION .BR LC_COLLATE , so is meant mostly for situations where the strings are expected to be in ASCII. +This is not actually the ordering produced by +.BR ls (1) +.BR -v . +.\" because it considers a-1.0.1a < a-1.0a; this is not what you want
I hate this reference to ls(1). ls(1) should not even have a -v option. Please refer to sort(1) instead. I would wipe any references to file names in this page, as I don't think they are relevant at all. And the reference to sort(1), I'd put it in BUGS, saying that this API is broken, and does not sort properly. Sounds good? Have a lovely night! Alex
.P What this function does is the following. If both strings are equal, return 0. -- 2.39.5
-- <https://www.alejandro-colomar.es/>
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