propagating errno from c extensions

[Ara.T.Howard]

rubyists-

any strong opinions on handling errno from c extentions?

personally, it seems that one would want to raise an exception like

Errno::EACCESS

when errno == EACCESS


however i see many cases where functions simply return Qfalse, Qtrue, etc. for
broad catagories of errno values - leaving the user to guess as to the cause
of the error (eg. rb_file_flock). is there are way of getting at errno that i
am unaware of? if so perhaps this is o.k....

IMHO a VHLL like ruby should either

a) succeed

b) throw an error

and one should never explcitly need to check error codes.

-a
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[nobu.nokada]

Hi,

At Fri, 5 Dec 2003 11:57:05 +0900,

any strong opinions on handling errno from c extentions?
rb_sys_fail()

however i see many cases where functions simply return Qfalse, Qtrue, etc. for
broad catagories of errno values - leaving the user to guess as to the cause
of the error (eg. rb_file_flock). is there are way of getting at errno that i
am unaware of? if so perhaps this is o.k....

rb_file_flock() raises SystemCallError except for the case it
would block.

 

[Ara.T.Howard]

Date: Fri, 5 Dec 2003 12:38:00 +0900
From: (e-mail address removed)
Newsgroups: comp.lang.ruby
Subject: Re: propagating errno from c extensions

Hi,

At Fri, 5 Dec 2003 11:57:05 +0900,


rb_sys_fail()

thanks. didn't realize that's what that did!

rb_file_flock() raises SystemCallError except for the case it
would block.

doesn't this mean that, under certain return values (EACCES), flock would
simply return false?

file.c
================
....
2092 retry:
2093 TRAP_BEG;
2094 ret = flock(fileno(fptr->f), NUM2INT(operation));
2095 TRAP_END;
2096 if (ret < 0) {
2097 switch (errno) {
2098 case EAGAIN:
2099 case EACCES:
2100 #if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
2101 case EWOULDBLOCK:
2102 #endif
2103 return Qfalse;
2104 case EINTR:
2105 #if defined(ERESTART)
2106 case ERESTART:
2107 #endif
2108 goto retry;
2109 }
2110 rb_sys_fail(fptr->path);
2111 }
2112 #endif
2113 return INT2FIX(0);
2114 }



-a
--

ATTN: please update your address books with address below!

===============================================================================
| EMAIL :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
| PHONE :: 303.497.6469
| ADDRESS :: E/GC2 325 Broadway, Boulder, CO 80305-3328
| STP :: http://www.ngdc.noaa.gov/stp/
| NGDC :: http://www.ngdc.noaa.gov/
| NESDIS :: http://www.nesdis.noaa.gov/
| NOAA :: http://www.noaa.gov/
| US DOC :: http://www.commerce.gov/
|
| The difference between art and science is that science is what we
| understand well enough to explain to a computer.
| Art is everything else.
| -- Donald Knuth, "Discover"
|
| /bin/sh -c 'for l in ruby perl;do $l -e "print \"\x3a\x2d\x29\x0a\"";done'
===============================================================================

 

[nobu.nokada]

Hi,

At Fri, 5 Dec 2003 14:02:05 +0900,

doesn't this mean that, under certain return values (EACCES), flock would
simply return false?

On some systems, fcntl() fails with not EAGAIN but EACCES when the
file is locked already.