Date: Thu, 29 Jan 2004 12:01:18 +0100 From: Oliver Eikemeier <eikemeier@fillmore-labs.com> To: Marc van Woerkom <marc.vanwoerkom@fernuni-hagen.de> Cc: ports@freebsd.org Subject: Re: SIZE criterion in distinfo Message-ID: <4018E7FE.3030205@fillmore-labs.com> In-Reply-To: <opr2iwjx1mdmv4ke@mailstore.fernuni-hagen.de> References: <opr2iwjx1mdmv4ke@mailstore.fernuni-hagen.de>
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Marc van Woerkom wrote: > Hi porters, > > I just see there is a new criterion in distinfo: > > root@oranje# cat distinfo > MD5 (xcdplayer-2.2.tar.Z) = d5d1d86abc4a0f5e2ea99a40ee63f98d > SIZE (xcdplayer-2.2.tar.Z) = 89435 > > May I ask the rationale behind adding SIZE? > > According to > > http://www.faqs.org/rfcs/rfc1321.html > > ("3.2 Step 2. Append Length") the size of the input data > is used in the calculation of the MD5 hash. > > In other words, if a fetched file has a different file length, > than the original file, it will for sure have a different MD5 > hash. > > So what is the benefit to have that SIZE checked? - You can check if the file is just truncated (so that a resumed download will probably help) or has a mismatched checksum - You can notify the user about the expected size of the download, including estimated download time (something like make downloadsize-recursive) - You can check if the server has a valid file by asking the it for the size of the file without downloading it - It is cheap ;-) The distinfo file is smaller than a typical blocksize anyway, so you won't loose any disk space by adding it. So go ahead, write a `downloadsize-recursive' before someone else does it ;) -Oliver
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