NAME
setjmp, sigsetjmp - save stack context for nonlocal goto SYNOPSIS
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int setjmp(jmpbuf env); int sigsetjmp(sigjmpbuf env, int savesigs); Feature Test Macro Requirements for glibc (see featuretestmacros(7)): setjmp(): see NOTES. sigsetjmp(): POSIXCSOURCE >= 1 || XOPENSOURCE || POSIXCSOURCE DESCRIPTION setjmp() and longjmp(3) are useful for dealing with errors and inter‐ rupts encountered in a low-level subroutine of a program. setjmp() saves the stack context/environment in env for later use by longjmp(3). The stack context will be invalidated if the function which called setjmp() returns. sigsetjmp() is similar to setjmp(). If, and only if, savesigs is nonzero, the process's current signal mask is saved in env and will be restored if a siglongjmp(3) is later performed with this env. RETURN VALUE setjmp() and sigsetjmp() return 0 if returning directly, and nonzero when returning from longjmp(3) or siglongjmp(3) using the saved con‐ text. CONFORMING TO
C89, C99, and POSIX.1-2001 specify setjmp(). POSIX.1-2001 specifies sigsetjmp(). NOTES POSIX does not specify whether setjmp() will save the signal mask. In System V it will not. In 4.3BSD it will, and there is a function setjmp that will not. By default, Linux/glibc follows the System V behavior, but the BSD behavior is provided if the BSDSOURCE feature test macro is defined and none of POSIXSOURCE, POSIXCSOURCE, XOPENSOURCE, XOPENSOURCEEXTENDED, GNUSOURCE, or SVIDSOURCE is defined. If you want to portably save and restore signal masks, use sigsetjmp() and siglongjmp(3). setjmp() and sigsetjmp() make programs hard to understand and maintain. If possible an alternative should be used. SEE ALSO longjmp(3), siglongjmp(3) COLOPHON
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2009-06-26 SETJMP(3)