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some clarifications

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svn: r12835
This commit is contained in:
Eli Barzilay 2008-12-13 19:09:54 +00:00
parent 607567d301
commit 510d9f081f
1 changed files with 23 additions and 4 deletions
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27
collects/scribblings/reference/sandbox.scrbl
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@ -16,7 +16,10 @@
The @schememodname[scheme/sandbox] module provides utilities for The @schememodname[scheme/sandbox] module provides utilities for
creating ``sandboxed'' evaluators, which are configured in a creating ``sandboxed'' evaluators, which are configured in a
particular way and can have restricted resources (memory and time), particular way and can have restricted resources (memory and time),
filesystem access, and network access. filesystem access, and network access. The common use case for this
module is for a restricted sandboxed environment, so the defaults are
set up to make it safe. For other uses you will likely need to change
mane of these settings.
@defproc*[([(make-evaluator [language (or/c module-path? @defproc*[([(make-evaluator [language (or/c module-path?
(list/c 'special symbol?) (list/c 'special symbol?)
@ -498,8 +501,14 @@ is @scheme[(list 30 20)].
Note that these limits apply to the creation of the sandbox Note that these limits apply to the creation of the sandbox
environment too --- even @scheme[(make-evaluator 'scheme/base)] can environment too --- even @scheme[(make-evaluator 'scheme/base)] can
fail if the limits are strict enough. Therefore, to avoid surprises fail if the limits are strict enough. For example,
you need to catch errors that happen when the sandbox is created. @schemeblock[
(parameterize ([sandbox-eval-limits '(0.25 5)])
(make-evaluator 'scheme/base '(sleep 2)))
]
will throw an error instead of creating an evaluator. Therefore, to
avoid surprises you need to catch errors that happen when the sandbox
is created.
When limits are set, @scheme[call-with-limits] (see below) is wrapped When limits are set, @scheme[call-with-limits] (see below) is wrapped
around each use of the evaluator, so consuming too much time or memory around each use of the evaluator, so consuming too much time or memory
@ -701,7 +710,17 @@ used for evaluating expressions.
This is usually similar to @scheme[(evaluator (list thunk))], except This is usually similar to @scheme[(evaluator (list thunk))], except
that this relies on the common meaning of list expressions as function that this relies on the common meaning of list expressions as function
application (which is not true in all languages), and it relies on application (which is not true in all languages), and it relies on
MzScheme's @scheme[eval] forgiving a non-S-expression input.} MzScheme's @scheme[eval] forgiving a non-S-expression input. In
addition, you can avoid some of the sandboxed restrictions by using
your own permissions, for example,
@codebox[
(let ([guard (current-security-guard)])
(call-in-sandbox-context
(lambda ()
(parameterize ([current-security-guard guard])
(code:comment #, @t{can access anything you want here})
))))
]}
@; ---------------------------------------------------------------------- @; ----------------------------------------------------------------------