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From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: Possible problem with syscall()
Message-ID: <109273@convex.convex.com>
Date: 27 Nov 90 14:58:40 GMT
References: <1454@tharr.UUCP>
Sender: usenet@convex.com
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
Lines: 31

In article <1454@tharr.UUCP> gustav@tharr.UUCP (Paul Moore) writes:
>system routines. These include a "print a string" call, and I noticed the
>problem when I tried to print "1" - as mentioned above.
>
>However, from what I can gather of unix syscall(), it allows you to call
>any system call available - so what about syscall(creat,"1",0666) [or
>however you would say it] to create a file "1"?

This is one of those times that perl cares about strings versus numerics.
Sometimes you might have to add 0 or concat a null to coerce to the right
type, but in practice I find this seldom to be the case.

There's a big difference between
    syscall(&SYS_write,1,1,1)
and
    syscall(&SYS_write,1,"1",1)

The first sets $! to indicate a bad address (0x01) for that expected
(char*) buffer to write (on my system, where the high bit indicates user
space, not system space as on a Vax).  The second actually writes a "1" to
STDOUT.

I course, you would really have uses syswrite() in the above case.

For the record, 

    syscall(&SYS_creat,"1",0666)

does indeed creat a file named "1", as you would hope.

--tom