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POSIX: lseek: support SEEK_DATA and SEEK_HOLE constants

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this is queued for issue 8: https://www.austingroupbugs.net/view.php?id=415
this implementation calls the ioctl hook of the filesystem with BSD-like constants
FIOSEEKDATA and FIOSEEKHOLE. if the hook doesn't know the constants, we use the stat size
to return the last hole (as proposed in the draft spec).

Change-Id: I5d052eed87e29b70491a7ff534e244896469d03e
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3385
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>
This commit is contained in:
Jérôme Duval 2020-11-07 12:02:58 +01:00
parent fe357eb9c9
commit a9c09fcaae
3 changed files with 43 additions and 0 deletions
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3
headers/posix/sys/ioctl.h
View File

@ -12,4 +12,7 @@
#define FIONBIO 0xbe000000
#define FIONREAD 0xbe000001
#define FIOSEEKDATA 0xbe000002
#define FIOSEEKHOLE 0xbe000003
#endif /* _SYS_IOCTL_H */

6
headers/posix/unistd.h
View File

@ -151,6 +151,12 @@
#ifndef SEEK_END
# define SEEK_END 2
#endif
#ifndef SEEK_DATA
# define SEEK_DATA 3
#endif
#ifndef SEEK_HOLE
# define SEEK_HOLE 4
#endif
#ifdef __cplusplus

34
src/system/kernel/fs/vfs.cpp
View File

@ -18,6 +18,7 @@
#include <stdio.h>
#include <string.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <unistd.h>
@ -5858,6 +5859,39 @@ file_seek(struct file_descriptor* descriptor, off_t pos, int seekType)
break;
}
case SEEK_DATA:
case SEEK_HOLE:
{
status_t status = B_BAD_VALUE;
if (HAS_FS_CALL(vnode, ioctl)) {
offset = pos;
status = FS_CALL(vnode, ioctl, descriptor->cookie,
seekType == SEEK_DATA ? FIOSEEKDATA : FIOSEEKHOLE,
&offset, sizeof(offset));
if (status == B_OK) {
if (offset > pos)
offset -= pos;
break;
}
}
if (status != B_BAD_VALUE && status != B_DEV_INVALID_IOCTL)
return status;
// basic implementation with stat() the node
if (!HAS_FS_CALL(vnode, read_stat) || isDevice)
return B_BAD_VALUE;
struct stat stat;
status = FS_CALL(vnode, read_stat, &stat);
if (status != B_OK)
return status;
off_t end = stat.st_size;
if (pos >= end)
return ENXIO;
offset = seekType == SEEK_HOLE ? end - pos : 0;
break;
}
default:
return B_BAD_VALUE;
}