libast.so and /usr/lib/extendedFILE.so / was: Re: [request-sponsor] telnet(1) cannot handle more than 15 fds
Casper.Dik at Sun.COM wrote: Due to the 32-bit ABI's stdio file descriptor limit, an interposer is being used to F_DUPFD non-stdio file descriptors to 256 and above. This mitigates a problem with 3rd party modules and plugins that use fopen(3C), et al. streams in processes such as Apache HTTP Server that open a large number of file descriptors. Unfortunately, using the interposer causes failures when a child process (e.g. CGI program) subsequently invokes telnet(1). If telnet passed the correct nfds value to select(3C), that failure would be eliminated. In build 39 of Nevada we provide a standard interposer, /usr/lib/extendedFILE.so, which has a similar, but different property. Umpf... for the same reason we were thinking about making the stdio-replacement API in libast public since it it supports an almost unlimited number of stdio channels... Note that /usr/lib/extendedFILE.so does *not* use F_DUPFD; it calls enable_extended_FILE_stdio(-1, -1) which makes a gaurantee on behalf of the application that it does not reference FILE._file and in return the C Library allows for the use of file descriptors 255. The kernel and the C library conspire such that any use of a FILE._file for FILE's opened with a file descriptor over 255 will cause the application to die with SIGABRT. Casper
libast.so and /usr/lib/extendedFILE.so / was: Re: [request-sponsor] telnet(1) cannot handle more than 15 fds
Casper.Dik at Sun.COM wrote: Due to the 32-bit ABI's stdio file descriptor limit, an interposer is being used to F_DUPFD non-stdio file descriptors to 256 and above. This mitigates a problem with 3rd party modules and plugins that use fopen(3C), et al. streams in processes such as Apache HTTP Server that open a large number of file descriptors. Unfortunately, using the interposer causes failures when a child process (e.g. CGI program) subsequently invokes telnet(1). If telnet passed the correct nfds value to select(3C), that failure would be eliminated. In build 39 of Nevada we provide a standard interposer, /usr/lib/extendedFILE.so, which has a similar, but different property. Umpf... for the same reason we were thinking about making the stdio-replacement API in libast public since it it supports an almost unlimited number of stdio channels... Bye, Roland P.S.: Reply-To: set to ksh93-integration-discuss at opensolaris.org as this is more or less libast-related -- __ . . __ (o.\ \/ /.o) roland.mainz at nrubsig.org \__\/\/__/ MPEG specialist, CJAVASunUnix programmer /O /==\ O\ TEL +49 641 7950090 (;O/ \/ \O;)
