4.4BSD/usr/share/man/cat2/sigreturn.0

SIGRETURN(2)                BSD Programmer's Manual               SIGRETURN(2)

NNAAMMEE
     ssiiggrreettuurrnn - return from signal

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<ssiiggnnaall..hh>>
     struct sigcontext {
             int sc_onstack;
             int sc_mask;
             int sc_sp;
             int sc_fp;
             int sc_ap;
             int sc_pc;
             int sc_ps;
     };

     _i_n_t
     ssiiggrreettuurrnn(_s_t_r_u_c_t _s_i_g_c_o_n_t_e_x_t _*_s_c_p);

DDEESSCCRRIIPPTTIIOONN
     SSiiggrreettuurrnn() allows users to atomically unmask, switch stacks, and return
     from a signal context.  The processes signal mask and stack status are
     restored from the context.  The system call does not return; the users
     stack pointer, frame pointer, argument pointer, and processor status
     longword are restored from the context.  Execution resumes at the speci-
     fied pc.  This system call is used by the trampoline code and longjmp(3)
     when returning from a signal to the previously executing program.

NNOOTTEESS
     This system call is not available in 4.2 BSD hence it should not be used
     if backward compatibility is needed.

RREETTUURRNN VVAALLUUEESS
     If successful, the system call does not return.  Otherwise, a value of -1
     is returned and _e_r_r_n_o is set to indicate the error.

EERRRROORRSS
     SSiiggrreettuurrnn() will fail and the process context will remain unchanged if
     one of the following occurs.

     [EFAULT]  _S_c_p points to memory that is not a valid part of the process
               address space.

     [EINVAL]  The process status longword is invalid or would improperly
               raise the privilege level of the process.

SSEEEE AALLSSOO
     sigvec(2),  setjmp(3)

HHIISSTTOORRYY
     The ssiiggrreettuurrnn function call appeared in 4.3BSD.

4.3 Berkeley Distribution        June 4, 1993                                1