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There is a limited number of functions that POSIX defines as async-signal safe. See here.

This includes some fundamental functions such as write.

Since this is really a C standard (since unix is built on C) that makes no mention of C++, I would expect this to be undefined, but the question is: can I use any c++ functions or classes (which involve constructors/destructors etc) inside a signal handler? For example: can I construct a std::string or std::pair?

malloc is not on the list of async-signal safe functions, so it is probably safe to assume that the potential memory allocation used by std::string makes it async-signal unsafe in the general sense (?).

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    Since a signal can interrupt program execution at any point, it takes effort to make arbitrary code execution with data structures (such as used by a heap manager) that could be in a transient state that (temporarily) violates the structure invariants much more difficult. The list of async-signal safe functions for C is also the list of async-signal safe functions for C++. Commented Mar 30 at 11:54
  • so we can't use the subset of c++ that is not C with any guarantees for async-signal safety Commented Mar 30 at 13:28
  • The subset of C++ that is not C which provides async-signal safety guarantees is an empty set. Commented Mar 30 at 14:01
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    @Eljay This ("... an empty set") is incorret. E.g. all functions from numeric_limits and type_traits are signal-safe. The set is perhaps not particularly useful, but it's not empty. Commented Mar 30 at 14:41
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    @Eljay By way of example: numeric.limits#members-1 Each member function defined in this subclause is signal-safe ([support.signal]). Commented Mar 30 at 18:05
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