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UNW_SET_REG(3)               Programming Library                UNW_SET_REG(3)


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/.

Programming Library             16 August 2007                  UNW_SET_REG(3)

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