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The and functions save their calling environment in
Each of these functions returns 0. The corresponding functions restore
the environment saved by their most recent respective invocations of the
function. They then return so that program execution continues as if the
corresponding invocation of the call had just returned the value specified
by instead of 0. Pairs of calls may be intermixed, i.e. both and and
and combinations may be used in the same program, however, individual
calls may not, e.g. the argument to may not be passed to The routines
may not be called after the routine which called the routines returns.
All accessible objects have values as of the time routine was called,
except that the values of objects of automatic storage invocation duration
that do not have the type and have been changed between the invocation
and call are indeterminate. The pairs save and restore the signal mask
while pairs save and restore only the register set and the stack. (See
The function pairs save and restore the signal mask if the argument
is non-zero, otherwise only the register set and the stack are saved.
If
the contents of the are corrupted, or correspond to an environment that
has already returned, the routine calls the routine If returns the program
is aborted (see The default version of prints the message to standard
error and returns. User programs wishing to exit more gracefully should
write their own versions of
The and functions conform
to The and functions conform to
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