'\" t .\" Manual page created with latex2man on Thu Aug 16 09:44:45 MDT 2007 .\" NOTE: This file is generated, DO NOT EDIT. .de Vb .ft CW .nf .. .de Ve .ft R .fi .. .TH "UNW\\_RESUME" "3" "16 August 2007" "Programming Library " "Programming Library " .SH NAME unw_resume \-\- resume execution in a particular stack frame .PP .SH SYNOPSIS .PP #include <libunwind.h> .br .PP int unw_resume(unw_cursor_t *cp); .br .PP .SH DESCRIPTION .PP The unw_resume() routine resumes execution at the stack frame identified by cp\&. The behavior of this routine differs slightly for local and remote unwinding. .PP For local unwinding, unw_resume() restores the machine state and then directly resumes execution in the target stack frame. Thus unw_resume() does not return in this case. Restoring the machine state normally involves restoring the ``preserved\&'' (callee\-saved) registers. However, if execution in any of the stack frames younger (more deeply nested) than the one identified by cp was interrupted by a signal, then unw_resume() will restore all registers as well as the signal mask. Attempting to call unw_resume() on a cursor which identifies the stack frame of another thread results in undefined behavior (e.g., the program may crash). .PP For remote unwinding, unw_resume() installs the machine state identified by the cursor by calling the access_reg and access_fpreg accessor callbacks as needed. Once that is accomplished, the resume accessor callback is invoked. The unw_resume routine then returns normally (that is, unlikely for local unwinding, unw_resume will always return for remote unwinding). .PP Most platforms reserve some registers to pass arguments to exception handlers (e.g., IA\-64 uses r15\-r18 for this purpose). These registers are normally treated like ``scratch\&'' registers. However, if libunwind is used to set an exception argument register to a particular value (e.g., via unw_set_reg()), then unw_resume() will install this value as the contents of the register. In other words, the exception handling arguments are installed even in cases where normally only the ``preserved\&'' registers are restored. .PP Note that unw_resume() does \fInot\fP invoke any unwind handlers (aka, ``personality routines\&''). If a program needs this, it will have to do so on its own by obtaining the unw_proc_info_t of each unwound frame and appropriately processing its unwind handler and language\-specific data area (lsda). These steps are generally dependent on the target\-platform and are regulated by the processor\-specific ABI (application\-binary interface). .PP .SH RETURN VALUE .PP For local unwinding, unw_resume() does not return on success. For remote unwinding, it returns 0 on success. On failure, the negative value of one of the errors below is returned. .PP .SH THREAD AND SIGNAL SAFETY .PP unw_resume() is thread\-safe. If cursor cp is in the local address\-space, this routine is also safe to use from a signal handler. .PP .SH ERRORS .PP .TP UNW_EUNSPEC An unspecified error occurred. .TP UNW_EBADREG A register needed by unw_resume() wasn\&'t accessible. .TP UNW_EINVALIDIP The instruction pointer identified by cp is not valid. .TP UNW_BADFRAME The stack frame identified by cp is not valid. .PP .SH SEE ALSO .PP libunwind(3), unw_set_reg(3), sigprocmask(2) .PP .SH AUTHOR .PP David Mosberger\-Tang .br Email: \fBdmosberger@gmail.com\fP .br WWW: \fBhttp://www.nongnu.org/libunwind/\fP\&. .\" NOTE: This file is generated, DO NOT EDIT.