ado@elsie.UUCP (Arthur David Olson) (02/25/85)
daveb@rtech.ARPA (Dave Brower)-- > . . .If you need to know at compile time whether you're on a Berklix or > a System V system, this might help. . . > # include <fcntl.h> > # ifdef FNDELAY > # define BSD > # else > # define SYS5 > # endif > . . .Can anyone think of a case where this is not true, or > suggest a more convenient/valid alternative? . . . guy@rlgvax.UUCP (Guy Harris)-- > . . .Yes - 4.1BSD. It would produce an error complaining that <fcntl.h> > couldn't be found. . . An alternative might be to include "sys/ioctl.h", which is present on 4.1bsd, 4.2bsd, and System III. If it's also present on System V (and the Berkeley FIONREAD ioctl call hasn't been picked up AT&T) you're in good shape. The code might then look like: # include <sys/ioctl.h> # ifdef FIONREAD # define BSD # else # define ATT # endif A more portable alternative might be: /* ** Skip the following if BSD or ATT is already defined, ** or if unix isn't defined. */ #ifndef BSD #ifndef ATT #ifdef unix /* ** We may be on a 1970's vintage system lacking "sys/ioctl.h". ** To find out, include "stdio.h" and see if fileno is defined. ** Only try to include "sys/ioctl.h" if it is defined. */ #include "stdio.h" #ifdef fileno #include "sys/ioctl.h" #ifdef FIONREAD #define BSD #endif /* FIONREAD */ #ifndef FIONREAD #define ATT #endif /* !FIONREAD */ #endif /* fileno */ #endif /* !ATT */ #endif /* !BSD */ -- UNIX is an AT&T Bell Laboratories trademark. -- UUCP: ..decvax!seismo!elsie!ado ARPA: elsie!ado@seismo.ARPA DEC, VAX and Elsie are Digital Equipment and Borden trademarks
john@genrad.UUCP (John Nelson) (02/26/85)
In article <5068@elsie.UUCP> ado@elsie.UUCP (Arthur David Olson) writes: >An alternative might be to include "sys/ioctl.h", which is present on 4.1bsd, >4.2bsd, and System III. If it's also present on System V (and the Berkeley >FIONREAD ioctl call hasn't been picked up AT&T) you're in good shape. NO! Unisoft ports of System III and System V have implemented the FIONREAD ioctl call (good thing, too - really helps porting some programs!).
guy@rlgvax.UUCP (Guy Harris) (02/26/85)
> An alternative might be to include "sys/ioctl.h", which is present on 4.1bsd, > 4.2bsd, and System III. If it's also present on System V (and the Berkeley > FIONREAD ioctl call hasn't been picked up AT&T) It is, and it hasn't. (In fact, the S5 "sys/ioctl.h" is an empty file; it was a silly idea in the first place - you really want "termio.h" for terminals, "mtio.h" for mag tapes, etc.) Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy
john@genrad.UUCP (John Nelson) (03/03/85)
As an alternative to including <sys/ioctl.h>, here is something that works MUCH BETTER. Include <signal.h>. V7 systems do not have any signal which indicates a child process has terminated. Both SIII and SV call that signal SIGCLD. All berkeley systems have an equivalent signal, but call it SIGCHLD. <signal.h> has other goodies for system differention. I always use SIGSTOP to check for job control, and SIGVTALRM for 4.2 BSD exclusivity.
rpw3@redwood.UUCP (Rob Warnock) (03/07/85)
+--------------- | As an alternative to including <sys/ioctl.h>, here is something that works | MUCH BETTER. | | Include <signal.h>... | <signal.h> has other goodies for system differention. I always use SIGSTOP | to check for job control, and SIGVTALRM for 4.2 BSD exclusivity. +--------------- Much better, and this approach brings us closer to the "real" issue, which is NOT "what system is this?" but "how do I do XYZ?"; NOT "am I on 4.2", but "do I assume 4.2-style signals?" (Example: the 68000 system I use has a "v7" kernel, a "4.1" tty driver, but no "job control". Is it "v.7" or "4.1"?) With the varieties of UNIX ports around, each of which has chosen different combinations of features from different sources, it is better (where possible) to make our "feature tests" be just that, tests of "features" rather than "versions". Unless we set up a central registry which hands out unique labels for versions of UNIX (like Xerox's Ethernet "types"), we will continue to have portability glitches. Rob Warnock Systems Architecture Consultant UUCP: {ihnp4,ucbvax!dual}!fortune!redwood!rpw3 DDD: (415)572-2607 USPS: 510 Trinidad Lane, Foster City, CA 94404
rick@cadtec.UUCP (Rick Auricchio) (03/08/85)
==
Opinions expressed above are my own; nobody else is foolish enough.
Rick Auricchio Cadtec Corp. 2355 Old Oakland Rd, San Jose CA 95131
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