1 .\" Copyright (c) 1998, David Greenman
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26 .\" $FreeBSD: src/lib/libc/sys/sendfile.2,v 1.6.2.6 2001/12/14 18:34:01 ru Exp $
33 .Nd send a file to a socket
41 .Fn sendfile "int fd" "int s" "off_t offset" "size_t nbytes" "struct sf_hdtr *hdtr" "off_t *sbytes" "int flags"
44 sends a regular file specified by descriptor
46 out a stream socket specified by descriptor
51 argument specifies where to begin in the file.
54 argument specifies how many bytes of the file should be sent, with 0 having the special
55 meaning of send until the end of file has been reached.
57 An optional header and/or trailer can be sent before and after the file data by specifying
58 a pointer to a struct sf_hdtr, which has the following structure:
60 .Bd -literal -offset indent -compact
62 struct iovec *headers; /* pointer to header iovecs */
63 int hdr_cnt; /* number of header iovecs */
64 struct iovec *trailers; /* pointer to trailer iovecs */
65 int trl_cnt; /* number of trailer iovecs */
73 pointers, if non-NULL, point to arrays of struct iovec structures.
76 system call for information on the iovec structure.
77 The number of iovecs in these
78 arrays is specified by
83 If non-NULL, the system will write the total number of bytes sent on the socket to the
84 variable pointed to by
89 argument is currently undefined and should be specified as 0.
91 When using a socket marked for non-blocking I/O,
93 may send fewer bytes than requested.
94 In this case, the number of bytes successfully
95 written is returned in
101 .Sh IMPLEMENTATION NOTES
106 is "zero-copy", meaning that it has been optimized so that copying of the file data is avoided.
113 is not a valid file descriptor.
116 is not a valid socket descriptor.
122 is not a regular file.
125 is not a SOCK_STREAM type socket.
128 is negative or out of range.
131 points to an unconnected socket.
133 The socket peer has closed the connection.
135 An error occurred while reading from
138 An invalid address was specified for a parameter.
140 The socket is marked for non-blocking I/O and not all data was sent due to the socket buffer being filled.
141 If specified, the number of bytes successfully sent will be returned in
153 This manual page first appeared in
157 and this manual page were written by
158 .An David Greenman Aq Mt dg@root.com .