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copy: add splice() based fallback

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Apparently, sendfile() does not work between fifos and ttys, but
splice() does, hence let's optionally fall back to that. This is useful
to implement the fallback pager this way.
This commit is contained in:
Lennart Poettering 2015-08-28 00:10:35 +02:00
parent d56cc29880
commit 81d20007f9
1 changed files with 18 additions and 2 deletions
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20
src/basic/copy.c
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@ -30,7 +30,7 @@
#define COPY_BUFFER_SIZE (16*1024)
int copy_bytes(int fdf, int fdt, off_t max_bytes, bool try_reflink) {
bool try_sendfile = true;
bool try_sendfile = true, try_splice = true;
int r;
assert(fdf >= 0);
@ -69,7 +69,23 @@ int copy_bytes(int fdf, int fdt, off_t max_bytes, bool try_reflink) {
} else if (n == 0) /* EOF */
break;
else if (n > 0)
/* Succcess! */
/* Success! */
goto next;
}
/* The try splice, unless we already tried */
if (try_splice) {
n = splice(fdf, NULL, fdt, NULL, m, 0);
if (n < 0) {
if (errno != EINVAL && errno != ENOSYS)
return -errno;
try_splice = false;
/* use fallback below */
} else if (n == 0) /* EOF */
break;
else if (n > 0)
/* Success! */
goto next;
}