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load_ramdisk_or_iso: use sendfile when possible

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This commit is contained in:
Alexey Sheplyakov 2021-08-21 00:26:37 +04:00
parent 705cac1f94
commit 5a10623827
1 changed files with 41 additions and 1 deletions
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42
tools.c
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@ -35,6 +35,7 @@
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/poll.h>
#include <sys/sendfile.h>
#include <sys/sysinfo.h>
#include <sys/mman.h> /* memfd_create */
@ -362,7 +363,7 @@ static int write_exactly(int fd, const char *buf, size_t len)
* @return 0 on success, -1 on error
* @note if size == 0 keep copying until EOF on src_fd
*/
static int copy_loop(int dst_fd, int src_fd, unsigned long size)
static int copy_loop_dumb(int dst_fd, int src_fd, unsigned long size)
{
char buf[32768];
unsigned long bytes_written = 0;
@ -390,6 +391,45 @@ static int copy_loop(int dst_fd, int src_fd, unsigned long size)
return 0;
}
static int copy_loop_sendfile(int dst_fd, int src_fd, unsigned long size)
{
ssize_t dl;
size_t chunk = 1024*1024;
unsigned long bytes_written = 0;
while (size > 0) {
dl = sendfile(dst_fd, src_fd, NULL, chunk < size ? chunk : size);
if (dl < 0) {
log_message("%s: sendfile: error %s", __func__, strerror(errno));
return -1;
}
size -= (unsigned long)dl;
bytes_written += (unsigned long)dl;
update_progression((int)BYTES2MB(bytes_written));
}
return 0;
}
static int is_mmapable(int fd)
{
void *dummy;
size_t len = 65536; /* don't bother to figure out page size */
dummy = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
if (dummy != MAP_FAILED) {
munmap(dummy, len);
return 1;
} else {
return 0;
}
}
static int copy_loop(int dst_fd, int src_fd, unsigned long size)
{
if (!size || !is_mmapable(src_fd))
return copy_loop_dumb(dst_fd, src_fd, size);
else
return copy_loop_sendfile(dst_fd, src_fd, size);
}
int make_ramfd(unsigned long size)
{
int ramfd;