NAME
unw_get_reg -- get register contents
SYNOPSIS
#include <libunwind.h>
int unw_get_reg(unw_cursor_t *cp, unw_regnum_t reg, unw_word_t *valp);
DESCRIPTION
The unw_get_reg() routine reads the value of register reg in the stack
frame identified by cursor cp and stores the value in the word pointed
to by valp.
The register numbering is target-dependent and described in separate
manual pages (e.g., libunwind-ia64(3) for the IA-64 target).
Furthermore, the exact set of accessible registers may depend on the
type of frame that cp is referring to. For ordinary stack frames, it is
normally possible to access only the preserved (``callee-saved'')
registers and frame-related registers (such as the stack-pointer).
However, for signal frames (see unw_is_signal_frame(3)), it is usually
possible to access all registers.
Note that unw_get_reg() can only read the contents of registers whose
values fit in a single word. See unw_get_fpreg(3) for a way to read
registers which do not fit this constraint.
RETURN VALUE
On successful completion, unw_get_reg() returns 0. Otherwise the
negative value of one of the error-codes below is returned.
THREAD AND SIGNAL SAFETY
unw_get_reg() is thread-safe as well as safe to use from a signal
handler.
ERRORS
UNW_EUNSPEC
An unspecified error occurred.
UNW_EBADREG
An attempt was made to read a register that is either invalid
or not accessible in the current frame.
In addition, unw_get_reg() may return any error returned by the
access_mem(), access_reg(), and access_fpreg() call-backs (see
unw_create_addr_space(3)).
SEE ALSO
libunwind(3), libunwind-ia64(3), unw_get_fpreg(3),
unw_is_signal_frame(3), unw_set_reg(3)
AUTHOR
David Mosberger-Tang
Email: dmosberger@gmail.com
WWW: http://www.nongnu.org/libunwind/.