ossig.h

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// ossig.h - written and placed in the public domain by Jeffrey Walton
//
 
#ifndef CRYPTOPP_OS_SIGNAL_H
#define CRYPTOPP_OS_SIGNAL_H
 
#include "config.h"
 
#if defined(UNIX_SIGNALS_AVAILABLE)
# include <signal.h>
#endif
 
NAMESPACE_BEGIN(CryptoPP)
 
// ************** Unix and Linux compatibles ***************
 
#if defined(UNIX_SIGNALS_AVAILABLE) || defined(CRYPTOPP_DOXYGEN_PROCESSING)
 
extern "C" {
    typedef void (*SignalHandlerFn) (int);
}
 
extern "C" {
    inline void NullSignalHandler(int unused) {CRYPTOPP_UNUSED(unused);}
}
 
template <int S, bool O=false>
struct SignalHandler
{
    SignalHandler(SignalHandlerFn pfn = NULLPTR, int flags = 0) : m_installed(false)
    {
        // http://pubs.opengroup.org/onlinepubs/007908799/xsh/sigaction.html
        struct sigaction new_handler;
 
        do
        {
            int ret = 0;
 
            ret = sigaction (S, 0, &m_old);
            if (ret != 0) break; // Failed
 
            // Don't step on another's handler if Overwrite=false
            if (m_old.sa_handler != 0 && !O) break;
 
            // Cygwin/Newlib requires -D_XOPEN_SOURCE=700
            ret = sigemptyset (&new_handler.sa_mask);
            if (ret != 0) break; // Failed
 
            new_handler.sa_handler = (pfn ? pfn : &NullSignalHandler);
            new_handler.sa_flags = (pfn ? flags : 0);
 
            // Install it
            ret = sigaction (S, &new_handler, 0);
            if (ret != 0) break; // Failed
 
            m_installed = true;
 
        } while(0);
    }
 
    ~SignalHandler()
    {
        if (m_installed)
            sigaction (S, &m_old, 0);
    }
 
private:
    struct sigaction m_old;
    bool m_installed;
 
private:
    // Not copyable
    SignalHandler(const SignalHandler &);
    void operator=(const SignalHandler &);
};
#endif
 
NAMESPACE_END
 
#endif // CRYPTOPP_OS_SIGNAL_H