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34 .\" @(#)funopen.3 8.1 (Berkeley) 6/9/93
35 .\" $FreeBSD: src/lib/libc/stdio/funopen.3,v 1.7.2.4 2001/12/14 18:33:57 ru Exp $
36 .\" $DragonFly: src/lib/libc/stdio/funopen.3,v 1.3 2006/05/26 19:39:37 swildner Exp $
51 .Fn funopen "const void *cookie" "int (*readfn)(void *, char *, int)" "int (*writefn)(void *, const char *, int)" "fpos_t (*seekfn)(void *, fpos_t, int)" "int (*closefn)(void *)"
53 .Fn fropen "void *cookie" "int (*readfn)(void *, char *, int)"
55 .Fn fwopen "void *cookie" "int (*writefn)(void *, const char *, int)"
60 associates a stream with up to four
61 .Dq Tn I/O No functions .
67 the others can be given as an appropriately-typed
72 functions will be used to read, write, seek and
75 In general, omitting a function means that any attempt to perform the
76 associated operation on the resulting stream will fail.
77 If the close function is omitted, closing the stream will flush
78 any buffered output and then succeed.
80 The calling conventions of
86 must match those, respectively, of
92 with the single exception that they are passed the
96 in place of the traditional file descriptor argument.
100 functions are allowed to change the underlying buffer
101 on fully buffered or line buffered streams by calling
103 They are also not required to completely fill or empty the buffer.
104 They are not, however, allowed to change streams from unbuffered to buffered
105 or to change the state of the line buffering flag.
106 They must also be prepared to have read or write calls occur on buffers other
107 than the one most recently specified.
111 functions can report an error by returning \-1.
112 Additionally, all of the functions should set the external variable
114 appropriately if an error occurs.
118 does not keep the stream open.
120 As a convenience, the include file
128 with only a read or write function specified.
130 Upon successful completion,
137 is returned and the global variable
139 is set to indicate the error.
146 was called without either a read or write function.
150 may also fail and set
152 for any of the errors
153 specified for the routine
166 functions first appeared in
172 may not be portable to systems other than