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From Jeff Trawick <traw...@attglobal.net>
Subject Re: RFC: Unix LFS support for 1.0
Date Mon, 22 Mar 2004 14:16:02 GMT
Joe Orton wrote:
> A concrete proposal... the two requirements are:
> 
> 1. APR 1.0 should support large files on Unix systems which have a 
> 32-bit off_t but support the LFS standard
> and
> 2. APR must not export -D_FILE_OFFSET_BITS=64 by default to get a 64-bit
> off_t, since this breaks the ABI of any other packages which use off_t
> in their API, and is generally a Bad Thing.  But users should be allowed
> to build like this by passing the appropriate CPPFLAGS to configure if
> they want.
> 
> The proposed solution is that APR must use the "transitional" LFS API on
> such platforms, define apr_off_t as off64_t; and use lseek64 and friends
> throughout.  Some of this work is already done for Netware, but it
> appears to be incomplete since it doesn't use readdir{,_r}64, nor struct
> stat64; but maybe Netware does things differently.

+1

> - AIX and Solaris have variants for their sendfile interfaces which take
> an off64_t in the appropriate place; need to hook these up and check
> HP-UX too (### help welcome! :)

AIX: looks to me that the file offset and bytes-to-send fields were always 
64-bit, and there is just one send_file() and just one sendfile-parms structure

> - what to do about old Linux 2.2's which have no sendfile64(): disable
> sendfile support, or disable LFS support? both change the ABI

from an ABI standpoint (given that there is no 1.0 ABI yet), it seems safer to 
turn off sendfile support and turn on lfs support when sendfile and lfs 
conflict...   if an app was built without APR_HAS_SENDFILE and the user 
upgraded the OS and rebuilt apr such that apr could support both sendfile and 
lfs, the old app binary would still work fine with the new apr, since adding 
the sendfile capability would not change the interface to existing capabilities

whatever the decision is, a --disable-lfs is useful because the decision will
be wrong for somebody and there may be specific platform problems that need
an easy work-around

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