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(Conventions): Use `system-error-errno' instead of explicit code

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This commit is contained in:
Marius Vollmer 2001-06-16 20:16:12 +00:00
parent 019ac1c987
commit daabbf15d7
1 changed files with 5 additions and 11 deletions
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16
doc/posix.texi
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@ -68,15 +68,12 @@ the documentation.
For ways to deal with exceptions, @ref{Exceptions}.
Errors which the C-library would report by returning a NULL
pointer or through some other means are reported by raising a
@code{system-error} exception.
The value of the Unix @code{errno} variable is available
Errors which the C-library would report by returning a NULL pointer or
through some other means are reported by raising a @code{system-error}
exception. The value of the Unix @code{errno} variable is available
in the data passed by the exception.
Here's an ad-hoc@footnote{This may be changed in the future; be prepared
to rewrite this sort of code.} way to extract the @code{errno} value
from an exception:
It can be extracted with the function @code{system-error-errno}:
@example
(catch
@ -84,7 +81,7 @@ from an exception:
(lambda ()
(mkdir "/this-ought-to-fail-if-I'm-not-root"))
(lambda stuff
(let ((errno (car (list-ref stuff 4))))
(let ((errno (system-error-errno 4)))
(cond
((= errno EACCES)
(display "You're not allowed to do that."))
@ -95,9 +92,6 @@ from an exception:
(newline))))
@end example
The important thing to note is that the @code{errno} value can be
extracted with @code{(car (list-ref stuff 4))}.
@node Ports and File Descriptors
@section Ports and File Descriptors