2013年2月4日 · Like every clever theory this falls apart when meeting reality. Indeed, temporary allocation and the like make longjmp()ing tricky, since you then have to setjmp() multiple times in the call stack (once for every function that needs to perform some sort of cleanup before it exits, which then needs to "re-raise the exception" by longjmp()ing to the …

2016年8月15日 · You cannot portably store the result of setjmp() into a variable. The C standard says: "_An invocation of the setjmp macro shall appear only in one of the following contexts: the entire controlling expression of a selection or iteration statement; one operand of a relational or equality operator with the other operand an integer constant expression, with the resulting expression being the ...

2011年4月4日 · On the portability matter, setjmp() is portable to all hosted C implementations; the <ucontext.h> functions are part of the XSI extensions to POSIX - this makes setjmp() significantly more portable. It is possible to use setjmp() in a thread-safe manner.

2013年5月19日 · As for the control flow: setjmp returns twice, and longjmp never returns. When you call setjmp for the first time, to store the environment, it returns zero, and the when you call longjmp, the control flow passes to return from setjmp with the value provided in the argument. (Note that setjmp needn't actually be functions; it may well be a macro.

2013年8月12日 · The example i got it, thanks. So on first instance setjmp returns "0" so the loop isn't entered, and instead a division by zero happens (SIGFPE) which takes it to signal handler, from where longjmp is called, and it returns non-zero value, hence entering the if statement and finally goes to exit.

2011年11月1日 · The stack pointer marks the division between the "used" and "unused" portions of the stack. When you call setjmp, all current call frames are on the "used" side, and any calls that take place after setjmp, but before the function which called setjmp returns, have their call frames on the "unused" side of the saved stack pointer.

2011年3月30日 · Some specific implementations of setjmp/longjmp may work in such a fashion that one can jinx them to behave as desired, and it's possible that some compilers might even specify that their implementations work in a particular fashion that would allow such a thing without having to rely upon undocumented/undefined behavior when targeting such compilers, but I'd suggest instead using a few lines ...

2011年12月25日 · The man page for setjmp says: setjmp() saves the stack context/environment in env for later use by longjmp(). The stack context will be invalidated if the function which called setjmp() returns. In a simple implementation you might suppose that a jmp_buf contains an address to reset the stack pointer to and an address to jump to.

2012年3月27日 · I'm reading expert c, and got through setjump and longjump section, so want make the code running on my ubuntu 11.10, but when I include setjump.h, the gcc compiler complain that it can't find the header file, I find there is not a …

2016年7月7日 · 7.13.2.1/2 If there has been no such invocation (i.e: of a previous setjmp), or if the invocation was from another thread of execution, or if the function containing the invocation of the setjmp macro has terminated execution in the interim, or if the invocation of the setjmp macro was within the scope of an identifier with variably modified ...