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Diffstat (limited to 'lib/libc/stdio/fopencookie.3')
| -rw-r--r-- | lib/libc/stdio/fopencookie.3 | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/lib/libc/stdio/fopencookie.3 b/lib/libc/stdio/fopencookie.3 new file mode 100644 index 0000000000000..349b3499b6bbe --- /dev/null +++ b/lib/libc/stdio/fopencookie.3 @@ -0,0 +1,156 @@ +.\" Copyright (c) 2016, EMC / Isilon Storage Division +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS +.\" IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +.\" THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR +.\" CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, +.\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; +.\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, +.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR +.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF +.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd May 9, 2016 +.Dt FOPENCOOKIE 3 +.Os +.Sh NAME +.Nm fopencookie +.Nd open a stream +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In stdio.h +.Ft typedef ssize_t +.Fn (*cookie_read_function_t) "void *cookie" "char *buf" "size_t size" +.Ft typedef ssize_t +.Fn (*cookie_write_function_t) "void *cookie" "const char *buf" "size_t size" +.Ft typedef int +.Fn (*cookie_seek_function_t) "void *cookie" "off64_t *offset" "int whence" +.Ft typedef int +.Fn (*cookie_close_function_t) "void *cookie" +.Bd -literal +typedef struct { + cookie_read_function_t *read; + cookie_write_function_t *write; + cookie_seek_function_t *seek; + cookie_close_function_t *close; +} cookie_io_functions_t; +.Ed +.Ft FILE * +.Fn fopencookie "void *cookie" "const char *mode" "cookie_io_functions_t io_funcs" +.Sh DESCRIPTION +The +.Nm +function +associates a stream with up to four +.Dq Tn I/O No functions . +These +.Tn I/O +functions will be used to read, write, seek and +close the new stream. +.Pp +In general, omitting a function means that any attempt to perform the +associated operation on the resulting stream will fail. +If the write function is omitted, data written to the stream is discarded. +If the close function is omitted, closing the stream will flush +any buffered output and then succeed. +.Pp +The calling conventions of +.Fa read , +.Fa write , +and +.Fa close +must match those, respectively, of +.Xr read 2 , +.Xr write 2 , +and +.Xr close 2 +with the single exception that they are passed the +.Fa cookie +argument specified to +.Nm +in place of the traditional file descriptor argument. +The +.Fa seek +function updates the current stream offset using +.Fa *offset +and +.Fa whence . +If +.Fa *offset +is non-NULL, it updates +.Fa *offset +with the current stream offset. +.Pp +.Nm +is implemented as a thin shim around the +.Xr funopen 3 +interface. +Limitations, possibilities, and requirements of that interface apply to +.Nm . +.Sh RETURN VALUES +Upon successful completion, +.Nm +returns a +.Dv FILE +pointer. +Otherwise, +.Dv NULL +is returned and the global variable +.Va errno +is set to indicate the error. +.Sh ERRORS +.Bl -tag -width Er +.It Bq Er EINVAL +A bogus +.Fa mode +was provided to +.Nm . +.It Bq Er ENOMEM +The +.Nm +function +may fail and set +.Va errno +for any of the errors +specified for the +.Xr malloc 3 +routine. +.El +.Sh SEE ALSO +.Xr fcntl 2 , +.Xr open 2 , +.Xr fclose 3 , +.Xr fopen 3 , +.Xr fseek 3 , +.Xr funopen 3 +.Sh HISTORY +The +.Fn funopen +functions first appeared in +.Bx 4.4 . +The +.Nm +function first appeared in +.Fx 11 . +.Sh BUGS +The +.Nm +function is a nonstandard glibc extension and may not be portable to systems +other than +.Fx +and Linux. |