svcadm(1M)을 검색하려면 섹션에서 1M 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
sendfile(3c)
Standard C Library Functions sendfile(3C)
NAME
sendfile - send files over sockets or copy files to files
SYNOPSIS
#include <sys/sendfile.h>
ssize_t sendfile(int out_fd, int in_fd, off_t *off, size_t len);
DESCRIPTION
The sendfile() function copies data from in_fd to out_fd, starting at
an offset of off bytes and continuing for a length of len bytes.
The in_fd argument should be a file descriptor to a regular file opened
for reading. For more information, see the open(2) man page. The out_fd
argument should be a file descriptor to a regular file opened for writ‐
ing or to a connected AF_INET or AF_INET6 socket of SOCK_STREAM type.
For more information, see the socket(3C) man page.
If the off argument is not null, the off argument is a pointer to a
variable. The variable holds the input file pointer position from which
the data is read. After sendfile() has completed, the variable is set
to the offset of the byte following the last byte that was read.
If the off argument is null, data is read from in_fd starting at its
own file offset, and the file offset of in_fd is updated to the offset
of the byte following the last byte that was read.
The sendfile() function modifies the file pointer for out_fd, if it is
a regular file.
The sendfile() function can also be used to send buffers from the call‐
ing program's memory by setting in_fd to SFV_FD_SELF and off to the
address of the memory buffer.
RETURN VALUES
Upon successful completion, sendfile() returns the total number of
bytes written to out_fd and also updates the offset to point to the
byte that follows the last byte read. Otherwise, it returns −1, and
errno is set to indicate the error.
ERRORS
The sendfile() function will fail if:
EAFNOSUPPORT The implementation does not support the specified
address family of the socket.
EAGAIN Mandatory file or record locking is set on either the
file descriptor or output file descriptor if it points
at regular files. O_NDELAY or O_NONBLOCK 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 O_NDELAY or the O_NONBLOCK flag set.
EBADF The out_fd or in_fd argument is either not a valid file
descriptor, out_fd is not opened for writing, or in_fd
is not opened for reading.
EINVAL The offset cannot be represented by the off_t struc‐
ture, or the length is negative when cast to ssize_t.
EIO An I/O error occurred while accessing the file system.
ENOMEM There is insufficient memory available.
ENOTCONN The socket is not connected.
EOPNOTSUPP The socket type is not supported.
EPIPE The out_fd argument is no longer connected to the peer
endpoint.
EINTR A signal was caught during the write operation and no
data was transferred.
USAGE
The sendfile() function has a transitional interface for 64-bit file
offsets. See lf64(7).
EXAMPLES
Example 1 Sending a Buffer Over a Socket
The following example demonstrates how to send the buffer buf over a
socket. At the end, it prints the number of bytes transferred over the
socket from the buffer. It assumes that addr will be filled up appro‐
priately, depending upon where to send the buffer.
int tfd;
off_t baddr;
struct sockaddr_in sin;
char buf[64 * 1024];
in_addr_t addr;
size_t len;
tfd = socket(AF_INET, SOCK_STREAM, 0);
if (tfd == -1) {
perror("socket");
exit(1);
}
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = addr; /* Fill in the appropriate address. */
sin.sin_port = htons(2345);
if (connect(tfd, (struct sockaddr *)&sin, sizeof(sin))<0) {
perror("connect");
exit(1);
}
baddr = (off_t)buf;
len = sizeof(buf);
while (len > 0) {
ssize_t res;
res = sendfile(tfd, SFV_FD_SELF, &baddr, len);
if (res == -1)
if (errno != EINTR) {
perror("sendfile");
exit(1);
} else continue;
len -= res;
}
Example 2 Transferring Files to Sockets
The following program demonstrates a transfer of files to sockets:
int ffd, tfd;
off_t off;
struct sockaddr_in sin;
in_addr_t addr;
int len;
struct stat stat_buf;
ssize_t len;
ffd = open("file", O_RDONLY);
if (ffd == -1) {
perror("open");
exit(1);
}
tfd = socket(AF_INET, SOCK_STREAM, 0);
if (tfd == -1) {
perror("socket");
exit(1);
}
sin.sin_family = AF_INET;
sin.sin_addr = addr; /* Fill in the appropriate address. */
sin.sin_port = htons(2345);
if (connect(tfd, (struct sockaddr *) &sin, sizeof(sin)) <0) {
perror("connect");
exit(1);
}
if (fstat(ffd, &stat_buf) == -1) {
perror("fstat");
exit(1);
}
len = stat_buf.st_size;
while (len > 0) {
ssize_t res;
res = sendfile(tfd, ffd, &off, len);
if (res == -1)
if (errno != EINTR) {
perror("sendfile");
exit(1);
} else
continue;
len -= res;
}
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ Interface StabilityCommitted _ MT-LevelMT-Safe
SEE ALSO
open(2), sendfilev(3C), socket(3C), attributes(7), lf64(7)
HISTORY
The sendfile() function was added to Oracle Solaris in the Solaris 9
release.
Oracle Solaris 11.4 2 Feb 2021 sendfile(3C)