[Qemu-devel] [V7 PATCH 5/9] virtio-9p: Add support to open a file in chroot environment

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

This patch adds both chroot worker and qemu side support to open a file/
directory in the chroot environment

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
---
 hw/9pfs/virtio-9p-chroot.c |   28 ++++++++++++++-----
 hw/9pfs/virtio-9p-chroot.h |    2 +-
 hw/9pfs/virtio-9p-local.c  |   62 +++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 79 insertions(+), 13 deletions(-)

diff --git a/hw/9pfs/virtio-9p-chroot.c b/hw/9pfs/virtio-9p-chroot.c
index 4aa3b43..0c91db6 100644
--- a/hw/9pfs/virtio-9p-chroot.c
+++ b/hw/9pfs/virtio-9p-chroot.c
@@ -80,13 +80,25 @@ static int v9fs_write_request(int sockfd, V9fsFileObjectRequest *request)
     return 0;
 }
 
-/*
- * This patch adds v9fs_receivefd and v9fs_write_request functions,
- * but there is no callers. To avoid compiler warning message,
- * refer these two functions
- */
-void chroot_dummy(void)
+/* Return opened file descriptor on success or -errno on error */
+int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *request)
 {
-    (void)v9fs_receivefd;
-    (void)v9fs_write_request;
+    int fd, sock_error;
+    qemu_mutex_lock(&fs_ctx->chroot_mutex);
+    if (fs_ctx->chroot_ioerror) {
+        fd = -EIO;
+        goto unlock;
+    }
+    if (v9fs_write_request(fs_ctx->chroot_socket, request) < 0) {
+        fs_ctx->chroot_ioerror = 1;
+        fd = -EIO;
+        goto unlock;
+    }
+    fd = v9fs_receivefd(fs_ctx->chroot_socket, &sock_error);
+    if (fd < 0 && sock_error) {
+        fs_ctx->chroot_ioerror = 1;
+    }
+unlock:
+    qemu_mutex_unlock(&fs_ctx->chroot_mutex);
+    return fd;
 }
diff --git a/hw/9pfs/virtio-9p-chroot.h b/hw/9pfs/virtio-9p-chroot.h
index 0c020f8..6f676e9 100644
--- a/hw/9pfs/virtio-9p-chroot.h
+++ b/hw/9pfs/virtio-9p-chroot.h
@@ -39,6 +39,6 @@ typedef struct V9fsFileObjectRequest
 } V9fsFileObjectRequest;
 
 int v9fs_chroot(FsContext *fs_ctx);
-void chroot_dummy(void);
+int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *or);
 
 #endif /* _QEMU_VIRTIO_9P_CHROOT_H */
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index 0a015de..8c187d7 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -13,6 +13,9 @@
 #include "virtio.h"
 #include "virtio-9p.h"
 #include "virtio-9p-xattr.h"
+#include "qemu_socket.h"
+#include "fsdev/qemu-fsdev.h"
+#include "virtio-9p-chroot.h"
 #include <arpa/inet.h>
 #include <pwd.h>
 #include <grp.h>
@@ -20,6 +23,44 @@
 #include <sys/un.h>
 #include <attr/xattr.h>
 
+/* Helper routine to fill V9fsFileObjectRequest structure */
+static int fill_fileobjectrequest(V9fsFileObjectRequest *request,
+                const char *path, FsCred *credp)
+{
+    if (strlen(path) >= PATH_MAX) {
+        return -ENAMETOOLONG;
+    }
+    memset(request, 0, sizeof(*request));
+    request->data.path_len = strlen(path);
+    strcpy(request->path.path, path);
+    if (credp) {
+        request->data.mode = credp->fc_mode;
+        request->data.uid = credp->fc_uid;
+        request->data.gid = credp->fc_gid;
+        request->data.dev = credp->fc_rdev;
+    }
+    return 0;
+}
+
+static int passthrough_open(FsContext *fs_ctx, const char *path, int flags)
+{
+    V9fsFileObjectRequest request;
+    int fd;
+
+    fd = fill_fileobjectrequest(&request, path, NULL);
+    if (fd < 0) {
+        errno = -fd;
+        return -1;
+    }
+    request.data.flags = flags;
+    request.data.type = T_OPEN;
+    fd = v9fs_request(fs_ctx, &request);
+    if (fd < 0) {
+        errno = -fd;
+        fd = -1;
+    }
+    return fd;
+}
 
 static int local_lstat(FsContext *fs_ctx, const char *path, struct stat *stbuf)
 {
@@ -138,14 +179,27 @@ static int local_closedir(FsContext *ctx, DIR *dir)
     return closedir(dir);
 }
 
-static int local_open(FsContext *ctx, const char *path, int flags)
+static int local_open(FsContext *fs_ctx, const char *path, int flags)
 {
-    return open(rpath(ctx, path), flags);
+    if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        return passthrough_open(fs_ctx, path, flags);
+    } else {
+        return open(rpath(fs_ctx, path), flags);
+    }
 }
 
-static DIR *local_opendir(FsContext *ctx, const char *path)
+static DIR *local_opendir(FsContext *fs_ctx, const char *path)
 {
-    return opendir(rpath(ctx, path));
+    if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        int fd;
+        fd = passthrough_open(fs_ctx, path, O_DIRECTORY);
+        if (fd < 0) {
+            return NULL;
+        }
+        return fdopendir(fd);
+    } else {
+        return opendir(rpath(fs_ctx, path));
+    }
 }
 
 static void local_rewinddir(FsContext *ctx, DIR *dir)
-- 
1.7.3.4