On 2024-08-05 16:20, Corinna Vinschen via Cygwin-apps wrote:
Hi Marco,
Achim made me aware yesterday, that less(1) shows nothing at all when
called on files under /proc.
Turns out, this only works on Linux, because there's a Linux-specific
kludge in less, checking if a file of size 0 is on the /proc filesystem
and if so, handles it accordingly.
Unfortunately the Linux kludge won't work for Cygwin without adding new
stuff to Cygwin:
- A <linux/magic.h> file, which sounds a bit weird, and
- adding real f_type info to statfs().
This would make less on /proc files only work starting with Cygwin 3.6,
but there's another, simpler solution working with all recent Cygwin
versions. I created a small patch to less, doing a simple path check
and then handling /proc files just as in the Linux-specific code:
--- origsrc/less-643/ch.c 2023-07-21 00:43:12.000000000 +0200
+++ src/less-643/ch.c 2024-08-05 22:37:03.103333500 +0200
@@ -719,6 +719,20 @@ public void ch_flush(void)
}
}
}
+#elif defined (__CYGWIN__)
+ if (ch_fsize == 0)
+ {
+ char proclink[PATH_MAX];
+ char filename[PATH_MAX];
+ snprintf(proclink, sizeof proclink, "/proc/%u/fd/%d",
+ getpid(), ch_file);
+ if (readlink(proclink, filename, sizeof filename) > 6 &&
+ strncmp (filename, "/proc/", 6) == 0)
+ {
+ ch_fsize = NULL_POSITION;
+ ch_flags &= ~CH_CANSEEK;
+ }
+ }
#endif
if (lseek(ch_file, (off_t)0, SEEK_SET) == BAD_LSEEK)
Would it be ok for you to push out a new less release with this or a
similar patch?
Current less 661 now handles that unconditionally in cl_flush() from ch_init():
https://github.com/gwsw/less/blob/master/ch.c#L860
I got rid of my ~/.lessfilter to feed 'more /proc/...' to less!
--
Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut
-- Antoine de Saint-Exupéry
