Article View: comp.std.c
Article #5908Re: Testing I/O success
From: John F. Haugh II
Date: Fri, 21 Apr 1989 00:33
Date: Fri, 21 Apr 1989 00:33
19 lines
1692 bytes
1692 bytes
In article <8038@boring.cwi.nl> siebren@cwi.nl (Siebren van der Zee) writes: >In article <8019@boring.cwi.nl>, I, siebren@cwi.nl (Siebren van der Zee) wrote: >> You *CANNOT* detect disk-full always on unix, since I/O is lazy. > >As several people pointed out to me, I was wrong. Even though the actual >write may take place by the time that the program has exited, the disk- >blocks are allocated immediately. Only when the write fails, you won't >be notified, unless you call fsync(int fd). >This is true for 4.3 BSD, SunOS 3.5, Ultrix 2.2; every unix I could check. Part wrong still. The disk blocks aren't allocated until stdio has flushed it's buffers and called write(), etc. A common problem is programs which never fclose() their buffered files and rely on exit() to do so. ALWAYS flush after writes which must check for I/O success. -- John F. Haugh II +-Quote of the Week:------------------- VoiceNet: (214) 250-3311 Data: -6272 | "When everyone else complies InterNet: jfh@rpp386.Dallas.TX.US | I will too ..." UucpNet : <backbone>!killer!rpp386!jfh +------------------- -- Doug Davis --
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!xanth!ames!elroy!gryphon!vector!rpp386!jfh From: jfh@rpp386.Dallas.TX.US (John F. Haugh II) Newsgroups: comp.std.c Subject: Re: Testing I/O success Message-ID: <15944@rpp386.Dallas.TX.US> Date: 21 Apr 89 00:33:58 GMT References: <12144@haddock.ima.isc.com> <12593@haddock.ima.isc.com> <8019@boring.cwi.nl> <8038@boring.cwi.nl> Reply-To: jfh@rpp386.Dallas.TX.US (John F. Haugh II) Organization: River Parishes Programming, Dallas TX Lines: 19