bsd/man/man2/sigreturn.2

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  34 .\"     @(#)sigreturn.2 8.1 (Berkeley) 6/4/93
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  36 .Dd June 4, 1993
  37 .Dt SIGRETURN 2
  38 .Os BSD 4.3
  39 .Sh NAME
  40 .Nm sigreturn
  41 .Nd return from signal
  42 .Sh SYNOPSIS
  43 .Fd #include <signal.h>
  44 .Bd -literal
  45 struct sigcontext {
  46         int sc_onstack;
  47         int sc_mask;
  48         int sc_sp;
  49         int sc_fp;
  50         int sc_ap;
  51         int sc_pc;
  52         int sc_ps;
  53 };
  54 .Ed
  55 .Ft int
  56 .Fn sigreturn "struct sigcontext *scp"
  57 .Sh DESCRIPTION
  58 .Fn Sigreturn
  59 allows users to atomically unmask, switch stacks,
  60 and return from a signal context.
  61 The processes signal mask and stack status are
  62 restored from the context.
  63 The system call does not return;
  64 the users stack pointer, frame pointer, argument pointer,
  65 and processor status longword are restored from the context.
  66 Execution resumes at the specified pc.
  67 This system call is used by the trampoline code and
  68 .Xr longjmp 3
  69 when returning from a signal to the previously executing program.
  70 .Sh NOTES
  71 This system call is not available in 4.2
  72 .Tn BSD
  73 hence it should not be used if backward compatibility is needed.
  74 .Sh RETURN VALUES
  75 If successful, the system call does not return.
  76 Otherwise, a value of -1 is returned and
  77 .Va errno
  78 is set to indicate the error.
  79 .Sh ERRORS
  80 .Fn Sigreturn
  81 will fail and the process context will remain unchanged
  82 if one of the following occurs.
  83 .Bl -tag -width Er
  84 .It Bq Er EFAULT
  85 .Fa Scp
  86 points to memory that is not a valid part of the process
  87 address space.
  88 .It Bq Er EINVAL
  89 The process status longword is invalid or would improperly
  90 raise the privilege level of the process.
  91 .El
  92 .Sh SEE ALSO
  93 .Xr sigaction 2 ,
  94 .Xr setjmp 3
  95 .Sh HISTORY
  96 The
  97 .Fn sigreturn
  98 function call appeared in
  99 .Bx 4.3 .