From: random832@fastmail.com (Random832)
Subject: [TUHS] ed.c on Unix v5
Date: Sat, 19 Dec 2015 09:57:32 -0500 [thread overview]
Message-ID: <m2si2y4hb7.fsf@fastmail.com> (raw)
In-Reply-To: <CADxT5N4HL7PgqGSRo_EDRD1crGSdSG5KthLR1CHXZ7w01eXs-Q@mail.gmail.com>
Mark Longridge <cubexyz at gmail.com> writes:
>>> I trimmed the source a bit, there's a function at the
>>> end called getpid() which is commented out.
>
>> If your V5 has getpid(), then it's a... strange version...
>
> I went back to the original uv5swre.zip file which was what I started
> with and had another look to be sure.
>
> It's not listed on tuhs under v5 but if one looks at /lib/libc.a via
> 'ar t getpid.o' you can see the object file getpid.o
Plus, you know, the syscall itself.
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V5/usr/sys/ken/sys4.c
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V5/usr/sys/ken/sysent.c
There are four (well, five with ctime) objects in libc.a with no
matching source file in /usr/source/s4: alloc, getpid, ladd, and
snstat. Also, mon and qsort have assembly versions in s3 and C
versions in s4, and ctime is in s3 despite the fact that almost
every other libc file is in s4.
jnc at mercury.lcs.mit.edu (Noel Chiappa)
writes:
> > From: Mark Longridge <cubexyz at gmail.com>
>
> > if one looks at /lib/libc.a via 'ar t getpid.o' you can see the object
> > file getpid.o
>
> Library, schlibrary! The important question is 'is it in the kernel source'?
> (Although now that I think about it, if the library routine tries to use a
> non-existent system call, it should return an error. It would be interested
> to disassemble the library routine, and see what it thinks it is doing.)
getpid.o consists of two instructions: sys getpid; rts pc. So it
unconditionally returns whatever the syscall puts in r0.
Non-existent syscalls map to nosys, which sets u_error to 100
(so, in principle, it will return 100, but), which causes the
process to be sent a signal SIGSYS.
next prev parent reply other threads:[~2015-12-19 14:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-17 15:13 Mark Longridge
2015-12-19 2:27 ` Dave Horsfall
2015-12-19 8:34 ` Mark Longridge
2015-12-19 14:57 ` Random832 [this message]
2015-12-19 16:18 ` John Cowan
2015-12-19 17:02 ` Craig Lennox
2015-12-19 20:05 ` Random832
2015-12-19 18:36 ` Marc Rochkind
2015-12-19 12:12 Noel Chiappa
2015-12-19 12:40 ` Mark Longridge
2015-12-19 13:56 Noel Chiappa
2015-12-19 15:10 Noel Chiappa
2015-12-19 15:22 ` Random832
2015-12-19 15:47 Noel Chiappa
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=m2si2y4hb7.fsf@fastmail.com \
--to=random832@fastmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).