Extended Library Functions sendfilev(3EXT)
NAME
sendfilev - send a file
SYNOPSIS
cc [ flag... ] file... -lsendfile [ library... ]
#include
ssizet sendfilev(int fildes, const struct sendfilevec *vec,
int sfvcnt, sizet *xferred);
PARAMETERS
The sendfilev() function supports the following parameters:
fildes A file descriptor to a regular file or to a
AFNCA, AFINET, or AFINET6 family type
SOCKSTREAM socket that is open for writing. For
AFNCA, the protocol type should be zero.
vec An array of SENDFILEVECT, as defined in the
sendfilevec structure above.
sfvcnt The number of members in vec.
xferred The total number of bytes written to outfd.
DESCRIPTION
The sendfilev() function attempts to write data from the
sfvcnt buffers specified by the members of vec array:
vec[0], vec[1], ... , vec[sfvcnt-1]. The fildes argument is
a file descriptor to a regular file or to an AFNCA,
AFINET, or AFINET6 family type SOCKSTREAM socket that is
open for writing.
This function is analogous to writev(2), but can read from
both buffers and file descriptors. Unlike writev(), in the
case of multiple writers to a file the effect of sendfilev()
is not necessarily atomic; the writes may be interleaved.
Application-specific synchronization methods must be
employed if this causes problems.
The following is the sendfilevec structure:
typedef struct sendfilevec {
int sfvfd; /* input fd */
uintt sfvflag; /* Flags. see below */
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Extended Library Functions sendfilev(3EXT)
offt sfvoff; /* offset to start reading from */
sizet sfvlen; /* amount of data */
} sendfilevect;
#define SFVFDSELF (-2)
To send a file, open the file for reading and point sfvfd
to the file descriptor returned as a result. See open(2).
sfvoff should contain the offset within the file. sfvlen
should have the length of the file to be transferred.
The xferred argument is updated to record the total number
of bytes written to outfd.
The sfvflag field is reserved and should be set to zero.
To send data directly from the address space of the process,
set sfvfd to SFVFDSELF. sfvoff should point to the data,
with sfvlen containing the length of the buffer.
RETURN VALUES
Upon successful completion, the sendfilev() function returns
total number of bytes written to outfd. Otherwise, it
returns -1, and errno is set to indicate the error. The
xferred argument contains the amount of data successfuly
transferred, which can be used to discover the error vector.
ERORS
EACES The process does not have appropriate
privileges or one of the files pointed by
sfvfd does not have appropriate permis-
sions.
EAFNOSUPORT The implementation does not support the
specified address family for socket.
EAGAIN Mandatory file or record locking is set on
either the file descriptor or output file
descriptor if it points at regular files.
ONDELAY or ONONBLOCK is set, and there is
a blocking record lock. An attempt has been
made to write to a stream that cannot accept
data with the ONDELAY or the ONONBLOCK
flag set.
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Extended Library Functions sendfilev(3EXT)
EBADF The fildes argument is not a valid descrip-
tor open for writing or an sfvfd is invalid
or not open for reading.
EFAULT The vec argument points to an illegal
address.
The xferred argument points to an illegal
address.
EINTR A signal was caught during the write opera-
tion and no data was transferred.
EINVAL The sfvcnt argument was less than or equal
to 0. One of the sfvlen values in vec array
was less than or equal to 0, or greater than
the file size. An sfvfd is not seekable.
Fewer bytes were transferred than were
requested.
EIO An I/O error occurred while accessing the
file system.
EPIPE The fildes argument is a socket that has
been shut down for writing.
EPROTOTYPE The socket type is not supported.
USAGE
The sendfilev() function has a transitional interface for
64-bit file offsets. See lf64(5).
EXAMPLES
The following example sends 2 vectors, one of HEADER data
and a file of length 100 over sockfd. sockfd is in a con-
nected state, that is, socket(), accept(), and bind() opera-
tion are complete.
#include
.
.
.
int
main (int argc, char *argv[]){
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Extended Library Functions sendfilev(3EXT)
int sockfd;
ssizet ret;
sizet xfer;
struct sendfilevec vec[2];
.
.
.
vec[0].sfvfd = SFVFDSELF;
vec[0].sfvflag = 0;
vec[0].sfvoff = "HEADERDATA";
vec[0].sfvlen = strlen("HEADERDATA");
vec[1].sfvfd = open("inputfile",.... );
vec[1].sfvflag = 0;
vec[1].sfvoff = 0;
vec[1].sfvlen = 100;
ret = sendfilev(sockfd, vec, 2, &xfer);
.
.
.
}
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Interface Stability Committed
MT-Level MT-Safe
SEE ALSO
open(2), writev(2), libsendfile(3LIB), sendfile(3EXT),
socket(3SOCKET), attributes(5)
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