[Qemu-devel] [V11 15/15] virtio-9p: Chroot environment for other functions

["M. Mohan Kumar" <mohan@in.ibm.com>]

From: "M. Mohan Kumar" <mohan@in.ibm.com>

Add chroot functionality for system calls that can operate on a file using
relative directory file descriptor.

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
---
 hw/9pfs/virtio-9p-local.c |   41 +++++++++++++++++++++++++++++++++++++++--
 1 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index e865cc8..5847d43 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -608,7 +608,25 @@ static int local_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size)
     char buffer[PATH_MAX];
     char *path = fs_path->data;
 
-    return truncate(rpath(ctx, path, buffer), size);
+    if (ctx->fs_sm == SM_PASSTHROUGH) {
+        int fd, retval, serrno;
+        fd = passthrough_request(ctx, NULL, path, O_RDWR, NULL, T_OPEN);
+        if (fd < 0) {
+            errno = -fd;
+            return -1;
+        }
+        retval = ftruncate(fd, size);
+        if (retval < 0) {
+            serrno = errno;
+        }
+        close(fd);
+        if (retval < 0) {
+            errno = serrno;
+        }
+        return retval;
+    } else {
+        return truncate(rpath(ctx, path, buffer), size);
+    }
 }
 
 static int local_rename(FsContext *ctx, const char *oldpath,
@@ -648,8 +666,27 @@ static int local_utimensat(FsContext *s, V9fsPath *fs_path,
     char buffer[PATH_MAX];
     char *path = fs_path->data;
 
-    return qemu_utimensat(AT_FDCWD, rpath(s, path, buffer), buf,
+    if (s->fs_sm == SM_PASSTHROUGH) {
+        int fd, retval, serrno = 0;
+        fd = passthrough_request(s, NULL, path,
+                        O_RDONLY | O_NONBLOCK | O_NOFOLLOW, NULL, T_OPEN);
+        if (fd < 0) {
+            errno = -fd;
+            return -1;
+        }
+        retval = futimens(fd, buf);
+        if (retval < 0) {
+            serrno = errno;
+        }
+        close(fd);
+        if (retval < 0) {
+            errno = serrno;
+        }
+        return retval;
+    } else {
+        return qemu_utimensat(AT_FDCWD, rpath(s, path, buffer), buf,
                           AT_SYMLINK_NOFOLLOW);
+    }
 }
 
 static int local_remove(FsContext *ctx, const char *path)
-- 
1.7.5.4