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30 .\" @(#)funopen.3 8.1 (Berkeley) 6/9/93
31 .\" $FreeBSD: src/lib/libc/stdio/funopen.3,v 1.16 2007/01/09 00:28:06 imp Exp $
32 .\" $DragonFly: src/lib/libc/stdio/funopen.3,v 1.3 2006/05/26 19:39:37 swildner Exp $
47 .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 *)"
49 .Fn fropen "void *cookie" "int (*readfn)(void *, char *, int)"
51 .Fn fwopen "void *cookie" "int (*writefn)(void *, const char *, int)"
56 associates a stream with up to four
57 .Dq Tn I/O No functions .
63 the others can be given as an appropriately-typed
68 functions will be used to read, write, seek and
71 In general, omitting a function means that any attempt to perform the
72 associated operation on the resulting stream will fail.
73 If the close function is omitted, closing the stream will flush
74 any buffered output and then succeed.
76 The calling conventions of
82 must match those, respectively, of
88 with the single exception that they are passed the
92 in place of the traditional file descriptor argument.
96 functions are allowed to change the underlying buffer
97 on fully buffered or line buffered streams by calling
99 They are also not required to completely fill or empty the buffer.
100 They are not, however, allowed to change streams from unbuffered to buffered
101 or to change the state of the line buffering flag.
102 They must also be prepared to have read or write calls occur on buffers other
103 than the one most recently specified.
107 functions can report an error by returning \-1.
108 Additionally, all of the functions should set the external variable
110 appropriately if an error occurs.
114 does not keep the stream open.
116 As a convenience, the include file
124 with only a read or write function specified.
126 Upon successful completion,
133 is returned and the global variable
135 is set to indicate the error.
142 was called without either a read or write function.
146 may also fail and set
148 for any of the errors
149 specified for the routine
162 functions first appeared in
168 may not be portable to systems other than
173 interface erroneously assumes that
175 is an integral type; see
177 for a discussion of this issue.