xref: /freebsd/lib/libsys/syscall.2 (revision 8269e7673cf033aba67dab8264fe719920c70f87)
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28*8269e767SBrooks Davis.Dd June 16, 1993
29*8269e767SBrooks Davis.Dt SYSCALL 2
30*8269e767SBrooks Davis.Os
31*8269e767SBrooks Davis.Sh NAME
32*8269e767SBrooks Davis.Nm syscall ,
33*8269e767SBrooks Davis.Nm __syscall
34*8269e767SBrooks Davis.Nd indirect system call
35*8269e767SBrooks Davis.Sh LIBRARY
36*8269e767SBrooks Davis.Lb libc
37*8269e767SBrooks Davis.Sh SYNOPSIS
38*8269e767SBrooks Davis.In sys/syscall.h
39*8269e767SBrooks Davis.In unistd.h
40*8269e767SBrooks Davis.Ft int
41*8269e767SBrooks Davis.Fn syscall "int number" ...
42*8269e767SBrooks Davis.Ft off_t
43*8269e767SBrooks Davis.Fn __syscall "quad_t number" ...
44*8269e767SBrooks Davis.Sh DESCRIPTION
45*8269e767SBrooks DavisThe
46*8269e767SBrooks Davis.Fn syscall
47*8269e767SBrooks Davisfunction
48*8269e767SBrooks Davisperforms the system call whose assembly language
49*8269e767SBrooks Davisinterface has the specified
50*8269e767SBrooks Davis.Fa number
51*8269e767SBrooks Daviswith the specified arguments.
52*8269e767SBrooks DavisSymbolic constants for system calls can be found in the header file
53*8269e767SBrooks Davis.In sys/syscall.h .
54*8269e767SBrooks DavisThe
55*8269e767SBrooks Davis.Fn __syscall
56*8269e767SBrooks Davisform should be used when one or more of the arguments is a
57*8269e767SBrooks Davis64-bit argument to ensure that argument alignment is correct.
58*8269e767SBrooks DavisThis system call is useful for testing new system calls that
59*8269e767SBrooks Davisdo not have entries in the C library.
60*8269e767SBrooks Davis.Sh RETURN VALUES
61*8269e767SBrooks DavisThe return values are defined by the system call being invoked.
62*8269e767SBrooks DavisIn general, a 0 return value indicates success.
63*8269e767SBrooks DavisA -1 return value indicates an error,
64*8269e767SBrooks Davisand an error code is stored in
65*8269e767SBrooks Davis.Va errno .
66*8269e767SBrooks Davis.Sh HISTORY
67*8269e767SBrooks DavisThe
68*8269e767SBrooks Davis.Fn syscall
69*8269e767SBrooks Davisfunction appeared in
70*8269e767SBrooks Davis.Bx 4.0 .
71*8269e767SBrooks Davis.Sh BUGS
72*8269e767SBrooks DavisThere is no way to simulate system calls that have multiple return values
73*8269e767SBrooks Davissuch as
74*8269e767SBrooks Davis.Xr pipe 2 .
75