On 10/31/2015 09:45 PM, Eduardo Habkost wrote:
On Sat, Oct 31, 2015 at 04:46:05PM +0800, Xiao Guangrong wrote:
On 10/31/2015 01:30 AM, Eduardo Habkost wrote:
On Fri, Oct 30, 2015 at 01:56:05PM +0800, Xiao Guangrong wrote:
Use the whole file size if @size is not specified which is useful
if we want to directly pass a file to guest
Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
---
backends/hostmem-file.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 44 insertions(+), 4 deletions(-)
diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index 9097a57..e1bc9ff 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -9,6 +9,9 @@
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
+#include <sys/ioctl.h>
+#include <linux/fs.h>
This code needs to build on other platforms too. e.g. using mingw32:
Err... You did it on Windows? It's surprised that the file is only built
on Linux:
common-obj-$(CONFIG_LINUX) += hostmem-file.o
How it can happen...
I did it using mingw32. I don't remember what I did, but I probably tried
something stupid to test just the build of hostmem-file.o and didn't notice it
was conditional on CONFIG_LINUX. Sorry for the noise.
No problem. :)
CC backends/hostmem-file.o
/home/ehabkost/rh/proj/virt/qemu/backends/hostmem-file.c:12:23: fatal error: sys/ioctl.h: No such file or directory
#include <sys/ioctl.h>
^
compilation terminated.
/home/ehabkost/rh/proj/virt/qemu/rules.mak:57: recipe for target 'backends/hostmem-file.o' failed
make: *** [backends/hostmem-file.o] Error 1
+
#include "qemu-common.h"
#include "sysemu/hostmem.h"
#include "sysemu/sysemu.h"
@@ -33,20 +36,57 @@ struct HostMemoryBackendFile {
char *mem_path;
};
+static uint64_t get_file_size(const char *file)
+{
+ struct stat stat_buf;
+ uint64_t size = 0;
+ int fd;
+
+ fd = open(file, O_RDONLY);
+ if (fd < 0) {
+ return 0;
+ }
+
+ if (stat(file, &stat_buf) < 0) {
+ goto exit;
+ }
+
+ if ((S_ISBLK(stat_buf.st_mode)) && !ioctl(fd, BLKGETSIZE64, &size)) {
+ goto exit;
+ }
+
I have another question: if our block device code at raw-posix.c doesn't need
the Linux-specific BLKGETSIZE64 call, why exactly do we need it in
hostmem-file.c? In which cases it would break without BLKGETSIZE64?
I guess the function at raw-posix.c did not realize it will work
on raw block device directly.
+ size = lseek(fd, 0, SEEK_END);
+ if (size == -1) {
+ size = 0;
+ }
+exit:
+ close(fd);
+ return size;
+}
This code seems to duplicate what block/raw-posix.c:raw_getlength() does
(except for the BLKGETSIZE64 part). Have you considered using the same
code for both?
We can probably move all the raw-posix.c raw_getlength(BlockDriverState
*bs) code to fd_getlength(int fd) functions (on osdep.c?), and just
implement raw-posix.c:raw_getlength(s) as fd_getlength(s->fd).
Actually, Paolo has the same suggestion before... but
| The function you pointed out is really complex - it mixed 9 platforms and each
| platform has its own specific implementation. It is hard for us to verify the
| change.
|
| I'd prefer to make it for Linux specific first then share it to other platforms
| if it's needed in the future.
I do not know if it's really worth doing it. :(
If hostmem-file.c is Linux-specific we don't need to move or reuse the code for
all the other 9 platforms right now, that's true. But now you are adding a new
arch-specific function that does exactly the same thing in a different file to
the mix. What if somebody want to make hostmem-file.c work in another platform
in the future, and begin to duplicate the same #ifdef mess from raw-posix.c?
I was considering this:
1) Move the arch-independent raw_getlength() code to fd_getlength() (at
osdep.c, maybe?), as:
int64_t fd_getlength(int fd)
{
int64_t size;
size = lseek(s->fd, 0, SEEK_END);
if (size < 0) {
return -errno;
}
return size;
}
2) Change the arch-independent version of raw_getlength() to:
[...]
#else
static int64_t raw_getlength(BlockDriverState *bs)
{
BDRVRawState *s = bs->opaque;
int ret;
int64_t size;
ret = fd_open(bs);
if (ret < 0) {
return ret;
}
return fd_getlength(s->fd);
}
#endif
3) Implement get_file_size() using fd_getlength():
uint64_t get_file_size(const char *file, Error **errp)
{
struct stat stat_buf;
int64_t size = 0;
int fd;
fd = open(file, O_RDONLY);
if (fd < 0) {
error_setg_errno(errp, errno, "can't open file %s", file);
return 0;
}
size = fd_getlength(fd);
if (size < 0) {
error_setg_errno(errp, -size, "can't get size of file %s", file);
size = 0;
}
exit:
close(fd);
return size;
}
4) In case BLKGETSIZE64 is really necesary, add a Linux-specific block to
fd_getlength():
int64_t fd_getlength(int fd)
{
int64_t size;
#ifdef CONFIG_LINUX
struct stat stat_buf;
if (fstat(fd, &stat_buf) < 0) {
return -errno;
}
if ((S_ISBLK(stat_buf.st_mode)) && !ioctl(fd, BLKGETSIZE64, &size)) {
if (size < 0) {
return -EOVERFLOW;
}
return size;
}
#endif
size = lseek(fd, 0, SEEK_END);
if (size < 0) {
return -errno;
}
return size;
}
People working on other platforms will be able to move arch-specific code to
fd_getlength() later, if they want to.
Fair enough to me and really smart. Will do it in next version.
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