git.saurik.com Git - apple/libplatform.git/blob

3 .\"

4 .\" Subject to the following obligations and disclaimer of warranty,

5 .\" use and redistribution of this software, in source or object code

6 .\" forms, with or without modifications are expressly permitted by

7 .\" Packet Design; provided, however, that:

8 .\"

9 .\" (i) Any and all reproductions of the source or object code

10 .\" must include the copyright notice above and the following

11 .\" disclaimer of warranties; and

12 .\" (ii) No rights are granted, in any manner or form, to use

13 .\" Packet Design trademarks, including the mark "PACKET DESIGN"

14 .\" on advertising, endorsements, or otherwise except as such

15 .\" appears in the above copyright notice or in the software.

16 .\"

17 .\" THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND

18 .\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO

19 .\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING

20 .\" THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED

21 .\" WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,

22 .\" OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE,

23 .\" OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS

24 .\" OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,

25 .\" RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE

26 .\" LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE

27 .\" OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,

28 .\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL

29 .\" DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF

30 .\" USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF

31 .\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

32 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF

33 .\" THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF

34 .\" THE POSSIBILITY OF SUCH DAMAGE.

35 .\"

36 .\" $FreeBSD: src/lib/libc/gen/getcontext.3,v 1.3 2004/12/03 14:10:04 rse Exp $

37 .\"

38 .Dd September 10, 2002

39 .Dt GETCONTEXT 3

40 .Os

41 .Sh NAME

42 .Nm getcontext , setcontext

43 .Nd get and set user thread context

44 .Sh LIBRARY

45 .Lb libc

46 .Sh SYNOPSIS

47 .In ucontext.h

48 .Ft int

49 .Fn getcontext "ucontext_t *ucp"

50 .Ft int

51 .Fn setcontext "const ucontext_t *ucp"

52 .Sh DESCRIPTION

53 The

54 .Fn getcontext

55 function

56 saves the current thread's execution context in the structure pointed to by

57 .Fa ucp .

58 This saved context may then later be restored by calling

59 .Fn setcontext .

60 .Pp

61 The

62 .Fn setcontext

63 function

64 makes a previously saved thread context the current thread context, i.e.,

65 the current context is lost and

66 .Fn setcontext

67 does not return.

68 Instead, execution continues in the context specified by

69 .Fa ucp ,

70 which must have been previously initialized by a call to

71 .Fn getcontext ,

72 .Xr makecontext 3 ,

73 or by being passed as an argument to a signal handler (see

74 .Xr sigaction 2 ) .

75 .Pp

76 If

77 .Fa ucp

78 was initialized by

79 .Fn getcontext ,

80 then execution continues as if the original

81 .Fn getcontext

82 call had just returned (again).

83 .Pp

84 If

85 .Fa ucp

86 was initialized by

87 .Xr makecontext 3 ,

88 execution continues with the invocation of the function specified to

89 .Xr makecontext 3 .

90 When that function returns,

91 .Fa "ucp->uc_link"

92 determines what happens next:

93 if

94 .Fa "ucp->uc_link"

95 is

96 .Dv NULL ,

97 the process exits;

98 otherwise,

99 .Fn setcontext "ucp->uc_link"

100 is implicitly invoked.

101 .Pp

102 If

103 .Fa ucp

104 was initialized by the invocation of a signal handler, execution continues

105 at the point the thread was interrupted by the signal.

106 .Sh RETURN VALUES

107 If successful,

108 .Fn getcontext

109 returns zero and

110 .Fn setcontext

111 does not return; otherwise \-1 is returned.

112 .Sh ERRORS

113 No errors are defined for

114 .Fn getcontext

115 or

116 .Fn setcontext .

117 .Sh SEE ALSO

118 .Xr sigaction 2 ,

119 .Xr sigaltstack 2 ,

120 .Xr makecontext 3 ,

121 .Xr ucontext 3