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Re: [Patch] Segfault on unaligned lseek() on /dev/sdX (was: [ITP] ddrescue 1.3)


Christopher Faylor wrote:
On Fri, May 18, 2007 at 09:02:15PM +0200, Christian Franke wrote:
...



It seems like this could be done without the heavyweight use of malloc,
like use an automatic array of length 512 + 4 and calculate an aligned
address from that.

Sorry, no. "unaligned seek" does not refer to memory here.


It should mean "seek position not aligned to raw device sector size".
This is 2048 for CD/DVD and results in a segfault.
Windows may even report larger sizes in DISK_GEOMETRY_EX.BytesPerSector.

Possible slow speed in the unaligned case is IMO a minor issue .
For maximum speed, the related tools like dd can easily be configured to read (a multiple of) sector size.


Christian


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