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/*
* Copyright (c) 2003 Gunnar Ritter
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute
* it freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
*
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
*
* 3. This notice may not be removed or altered from any source distribution.
*/
/* Sccsid @(#)sfile.c 1.9 (gritter) 6/7/04 */
#ifdef __linux__
#undef _FILE_OFFSET_BITS
#include <sys/types.h>
#include <sys/sendfile.h>
#include <sys/stat.h>
#include <unistd.h>
#include <limits.h>
#include <errno.h>
#include "sfile.h"
long long
sfile(int dfd, int sfd, mode_t mode, long long count)
{
static int enosys, einval, success;
off_t offset;
ssize_t sent, total;
extern void writerr(void *, int, int);
/*
* A process is not interruptible while executing a sendfile()
* system call. So it is not advisable to to send an entire
* file with one call; it is sent in parts so signals can
* be delivered in between.
*/
const ssize_t chunk = 196608;
/*
* If a previous call returned ENOSYS, the operating system does
* not support sendfile() at all and it makes no sense to try it
* again.
*
* If a previous call returned EINVAL and there was no successful
* call yet, it is very likely that this is a permanent error
* condition (on Linux 2.6.0-test4, sendfile() may be used for
* socket targets only; older versions don't support tmpfs as
* source file system etc.).
*/
if (enosys || !success && einval ||
(mode&S_IFMT) != S_IFREG || count > SSIZE_MAX)
return 0;
offset = lseek(sfd, 0, SEEK_CUR);
sent = 0, total = 0;
while (count > 0 && (sent = sendfile(dfd, sfd, &offset,
count > chunk ? chunk : count)) > 0) {
count -= sent, total += sent;
}
if (total && lseek(sfd, offset, SEEK_SET) == (off_t)-1)
return -1;
if (count == 0 || sent == 0) {
success = 1;
return total;
}
switch (errno) {
case ENOSYS:
enosys = 1;
return 0;
case EINVAL:
einval = 1;
return 0;
case ENOMEM:
return 0;
default:
writerr(NULL, count > chunk ? chunk : count, 0);
return -1;
}
}
#else /* !__linux__ */
#include <sys/types.h>
/*ARGSUSED*/
long long
sfile(int dfd, int sfd, mode_t mode, long long count)
{
return 0;
}
#endif /* __linux__ */
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