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Functions | |
int | setjmp (jmp_buf __jmpb) |
void | longjmp (jmp_buf __jmpb, int __ret) __ATTR_NORETURN__ |
goto
statement, it can only be used to jump to a label in the same (local) function. In order to jump directly to another (non-local) function, the C library provides the setjmp() and longjmp() functions. setjmp() and longjmp() are useful for dealing with errors and interrupts encountered in a low-level subroutine of a program.
longjmp() can destroy changes made to global register variables (see How to permanently bind a variable to a register?).
Example:
#include <setjmp.h> jmp_buf env; int main (void) { if (setjmp (env)) { ... handle error ... } while (1) { ... main processing loop which calls foo() some where ... } } ... void foo (void) { ... blah, blah, blah ... if (err) { longjmp (env, 1); } }
void longjmp | ( | jmp_buf | __jmpb, | |
int | __ret | |||
) |
Non-local jump to a saved stack context.
#include <setjmp.h>
longjmp() restores the environment saved by the last call of setjmp() with the corresponding __jmpb argument. After longjmp() is completed, program execution continues as if the corresponding call of setjmp() had just returned the value __ret.
__jmpb | Information saved by a previous call to setjmp(). | |
__ret | Value to return to the caller of setjmp(). |
int setjmp | ( | jmp_buf | __jmpb | ) |
Save stack context for non-local goto.
#include <setjmp.h>
setjmp() saves the stack context/environment in __jmpb for later use by longjmp(). The stack context will be invalidated if the function which called setjmp() returns.
__jmpb | Variable of type jmp_buf which holds the stack information such that the environment can be restored. |