NAME¶
unw_set_reg -- set register contents
SYNOPSIS¶
#include <libunwind.h>
int unw_set_reg(unw_cursor_t *cp, unw_regnum_t reg, unw_word_t val);
DESCRIPTION¶
The unw_set_reg() routine sets the value of register reg in the stack frame
identified by cursor cp to the value passed in val.
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_set_reg() can only write the contents of registers whose values
fit in a single word. See
unw_set_fpreg(3) for a way to write registers which
do not fit this constraint.
RETURN VALUE¶
On successful completion, unw_set_reg() returns 0. Otherwise the negative value
of one of the error-codes below is returned.
THREAD AND SIGNAL SAFETY¶
unw_set_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 write a register that is either invalid or not
accessible in the current frame.
- UNW_EREADONLY
-
An attempt was made to write to a read-only register.
In addition, unw_set_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_reg(3),
unw_is_signal_frame(3),
unw_set_fpreg(3)
AUTHOR¶
David Mosberger-Tang
Email:
dmosberger@gmail.com
WWW:
http://www.nongnu.org/libunwind/.