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UNW_SET_REG(3) Programming Library UNW_SET_REG(3)
unw_set_reg -- set register contents
int unw_set_reg(unw_cursor_t *cp, unw_regnum_t reg, unw_word_t val);
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.
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
An unspecified error occurred.
An attempt was made to write a register that is either invalid
or not accessible in the current frame.
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
libunwind(3), libunwind-ia64(3), unw_get_reg(3),
Programming Library 16 August 2007 UNW_SET_REG(3)