Date: Fri, 23 Jun 2000 13:04:46 -0400 From: "Bohne, Peter" <Peter.Bohne@hboc.com> To: 'FengYue' <fengyue@bluerose.windmoon.nu>, "Bohne, Peter" <Peter.Bohne@hboc.com> Cc: "'andrew@ugh.net.au'" <andrew@ugh.net.au>, hackers@FreeBSD.ORG Subject: RE: libc_r/_read(), should the errno be reset to 0? Message-ID: <35BEC7ED0A15D21199F000805F6F6D6A01CB00E7@bldexc01ntms.clinicom.com>
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True enough. That's the best advice. However, your original post indicated an expectation on your part that errno would be somehow automatically reset to 0 before a system call, which is definitely *not* the case. You have to clear it - the kernel does not do it for you. pete > -----Original Message----- > From: FengYue [mailto:fengyue@bluerose.windmoon.nu] > Sent: Friday, June 23, 2000 11:08 AM > To: Bohne, Peter > Cc: 'andrew@ugh.net.au'; hackers@FreeBSD.ORG > Subject: RE: libc_r/_read(), should the errno be reset to 0? > > > > Wait, that's not going to do anything, the errno is set inside the > _thread_sys_read(). But I agree with Andrew, why bother to check > errno if read() returns no error. > > On Fri, 23 Jun 2000, Bohne, Peter wrote: > > > This means that *you* should set errno to 0 just before you > do the read > > call. At this point, you no longer care what it had been before. > > -- > > pete > > > > ====== pbohne at hboc dot com > > Peter Bohne -- McKessonHBOC -- Louisville, CO > > Work: 303-926-2218 -- Cell: 303-817-8312 -- Home Ofc: 970-586-9031 > > ====== "Very funny, Scottie. Now beam down my clothes!" > > > > > > > > > -----Original Message----- > > > From: andrew@ugh.net.au [mailto:andrew@ugh.net.au] > > > Sent: Friday, June 23, 2000 3:02 AM > > > To: FengYue > > > Cc: hackers@FreeBSD.ORG > > > Subject: Re: libc_r/_read(), should the errno be reset to 0? > > > > > > > > > > > > > > > On Fri, 23 Jun 2000, FengYue wrote: > > > > > > > My question is, shouldn't it be reset to zero? > > > > > > From intro(2): > > > > > > Successful calls never set errno; once set, it remains until > > > another error > > > occurs. It should only be examined after an error. > > > > > > Andrew > > > > > > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > > with "unsubscribe freebsd-hackers" in the body of the message > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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