getrlimit.2: old_getrlimit/ugetrlimit and RLIM_INFINITY discrepancies
PATCH v2 1/1 getrlimit.2: old_getrlimit/ugetrlimit and RLIM_INFINITY discrepancies
--- man2/getrlimit.2 | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)
man2/getrlimit.2 +31 -0
@@ -646,6 +646,37 @@ The name of the glibc wrapper function is .BR prlimit (); the underlying system call is .BR prlimit64 (). +The corresponding infinity value constant is provided in +.I <linux/resource.h> +as +.BR RLIM64_INFINITY. +.PP +Original Linux implementation used signed types for limits; that was changed +(along with the value of the +.B RLIM_INFINITY +constant) +.\" http://repo.or.cz/davej-history.git/blobdiff/129f8758d8c41e0378ace0b6e2f56bbb8a1ec694..15305d2e69c3a838bacd78962c07077d2821f255:/include/linux/resource.h +during 2.4 development cycle, as it wasn't compatible +with Single UNIX Specification. +However, in order to preserve backward compatibility, the routine +.IR sys_old_getrlimit +has been implemented under +.B __NR_getrlimit +syscall slot, with infinity checks being performed against hard-coded 0x7fffffff +value, and the routine +.I sys_getrlimit +has been exposed under a new name, +.BR ugetrlimit (). +Note that most newer architectures don't have the latter, with +.BR getrlimit () +providing proper implementation. +Also worth noting that Several architectures decided not to change +.B RLIM_INFINITY +value: 32-bit mips and sparc (but not 64-bit variants, that switched +to the new value of (~0UL)) retained the old 0x7fffffff value, +and alpha retained 0x7ffffffffffffffful. +.\" ...along with a request to call when one runs into it: +.\" https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/alpha/include/uapi/asm/resource.h#n15 .SH BUGS In older Linux kernels, the .B SIGXCPU
Signature · 1 line
2.1.4
* Eugene Syromyatnikov <[email protected]>, 2021-07-08, 14:17:
man2/getrlimit.2 The name of the glibc wrapper function is · line 659
Quoted 6 lines
man2/getrlimit.2 +6
-0+Original Linux implementation used signed types for limits; that was changed +(along with the value of the +.B RLIM_INFINITY +constant) +.\" http://repo.or.cz/davej-history.git/blobdiff/129f8758d8c41e0378ace0b6e2f56bbb8a1ec694..15305d2e69c3a838bacd78962c07077d2821f255:/include/linux/resource.h +during 2.4 development cycle, as it wasn't compatible
Oh, interesting.
That would explain why the man page incorrectly claims the upper limit for RLIMIT_AS is 2 GiB on 32-bit systems.
Quoted 1 line
+Also worth noting that Several architectures decided not to change
s/Several/several/;
or maybe s/Also worth noting that //.
Signature · 1 line
Jakub Wilk
Hi Eugene,
Quoted 13 lines · Jakub Wilk
* Eugene Syromyatnikov <[email protected]>, 2021-07-08, 14:17:
Quoted 9 lines
+Original Linux implementation used signed types for limits; that was changed
man2/getrlimit.2 +4
-0+(along with the value of the +.B RLIM_INFINITY +constant) +.\"+during 2.4 development cycle, as it wasn't compatible
Oh, interesting.
Quoted 7 lines
That would explain why the man page incorrectly claims the upper limit for
RLIMIT_ASis 2 GiB on 32-bit systems.Quoted 1 line
+Also worth noting that Several architectures decided not to change
s/Several/several/;
or maybe s/Also worth noting that //.
When you send a v2 of this, please add me to CC or TO, so that it's easier for me to notice it.
Thanks,
Alex
Signature · 3 lines
Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/