SAFEREAD

(SAFEREAD <stream> [<error-value> [<eof-value> [<package>]]]])
   OR 
(SAFEREAD <string> [<error-value> [<eof-value> [<package>]]]])

Reads an S-expression from the given <stream> or <string>. The
<stream> (or <string>) argument is mandatory. 

<Error-value> gives the value to return in case of a syntax error
(e.g., EOF within an unterminated list, etc). <Eof-value> is what to
return in case EOF is encountered before anything was read (e.g.,
there were some whitespace, then EOF). Both values default to the
empty list '().

<Package> specifies the package to use to generate symbols. By default, 
no package is used and SExpressionClassicAtom's are generated instead
of symbols (note that in this case the corresponding objects will be
EQL, but not EQ; classic atom is effectively a string which is printed
without quotes). Please note that since InteLib 0.5.81 it is possible to
establish a default InteLib Reader (with the help from PTheIntelibReader
global variable), which itself can hold a package. Use NIL as this
parameter to enforce using the DummyPackage -- the one which generate
ClassicAtoms.

WARNING! Since this envolves a global variable, please be warned that
establishing an alternative default reader AND using the 4th parameter in
SAFEREAD make the function non-multithread-safe. This is likely to be
fixed, though.

The function is called so because, as opposit to the CL's READ, it
doesn't encourage the programmer to trust the incoming data thus
producing vulnerabilities.