[Qemu-devel] [V11 13/15] virtio-9p: stat in chroot environment

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

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


Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
---
 hw/9pfs/virtio-9p-chroot-worker.c |   52 ++++++++++++++++++++++++++++++++-
 hw/9pfs/virtio-9p-chroot.c        |   59 ++++++++++++++++++++++++++++++++++++-
 hw/9pfs/virtio-9p-chroot.h        |    3 ++
 hw/9pfs/virtio-9p-local.c         |   30 +++++++++++++++++++
 4 files changed, 142 insertions(+), 2 deletions(-)

diff --git a/hw/9pfs/virtio-9p-chroot-worker.c b/hw/9pfs/virtio-9p-chroot-worker.c
index 8ca4805..c4ebb96 100644
--- a/hw/9pfs/virtio-9p-chroot-worker.c
+++ b/hw/9pfs/virtio-9p-chroot-worker.c
@@ -66,6 +66,29 @@ static void chroot_sendfd(int sockfd, int fd, int fd_valid)
     }
 }
 
+/* Send special information and error status to qemu process */
+static void chroot_sendspecial(int sockfd, void *buff, int size, int error)
+{
+    int retval;
+
+    /* If there is an error, send NULL buff also set status to error */
+    if (error) {
+        memset(buff, 0, size);
+    }
+    do {
+        retval = send(sockfd, &error, sizeof(error), 0);
+    } while (retval < 0 && errno == EINTR);
+    if (retval < 0) {
+        _exit(1);
+    }
+    do {
+        retval = send(sockfd, buff, size, 0);
+    } while (retval < 0 && errno == EINTR);
+    if (retval < 0) {
+        _exit(1);
+    }
+}
+
 /* Read V9fsFileObjectRequest sent by QEMU process */
 static int chroot_read_request(int sockfd, V9fsFileObjectRequest *request)
 {
@@ -267,6 +290,7 @@ int v9fs_chroot(FsContext *fs_ctx)
     pid_t pid;
     uint32_t code;
     int retval, valid_fd;
+    char *buff;
 
     if (socketpair(PF_UNIX, SOCK_STREAM, 0, fd_pair) < 0) {
         error_report("socketpair %s", strerror(errno));
@@ -346,7 +370,33 @@ int v9fs_chroot(FsContext *fs_ctx)
         default:
             retval = -1;
             break;
+        case T_LSTAT:
+            buff = qemu_malloc(request.data.size);
+            retval = lstat(request.path.path, (struct stat *)buff);
+            if (retval  < 0) {
+                retval = -errno;
+            }
+            break;
+        }
+
+        /* Send the results */
+        switch (request.data.type) {
+        case T_OPEN:
+        case T_CREATE:
+        case T_MKDIR:
+        case T_SYMLINK:
+        case T_LINK:
+        case T_MKNOD:
+        case T_REMOVE:
+        case T_RENAME:
+        case T_CHMOD:
+        case T_CHOWN:
+            chroot_sendfd(chroot_sock, retval, valid_fd);
+            break;
+        case T_LSTAT:
+            chroot_sendspecial(chroot_sock, buff, request.data.size, retval);
+            qemu_free(buff);
+            break;
         }
-        chroot_sendfd(chroot_sock, retval, valid_fd);
     }
 }
diff --git a/hw/9pfs/virtio-9p-chroot.c b/hw/9pfs/virtio-9p-chroot.c
index f5b3abc..9480ce0 100644
--- a/hw/9pfs/virtio-9p-chroot.c
+++ b/hw/9pfs/virtio-9p-chroot.c
@@ -77,6 +77,37 @@ static int v9fs_receivefd(int sockfd, int *sock_error)
     return -ENFILE; /* Ancillary data sent but not received */
 }
 
+static int qemu_recv(int sockfd, void *data, size_t size, int flags)
+{
+    int retval;
+    do {
+        retval = recv(sockfd, data, size, 0);
+    } while (retval < 0 && errno == EINTR);
+    return retval;
+}
+
+/*
+ * Return received struct stat on success and -errno on failure.
+ * sock_error is set to 1 whenever there is error in socket IO
+ */
+static int v9fs_special_receive(int sockfd, int *sock_error, char *buff,
+                int size)
+{
+    int retval, status;
+    if (qemu_recv(sockfd, &status, sizeof(status), 0) <= 0) {
+        *sock_error = 1;
+        return -EIO;
+    }
+
+    retval = qemu_recv(sockfd, buff, size, 0);
+    if (retval > 0) {
+        return status;
+    } else {
+        *sock_error = 1;
+        return -EIO;
+    }
+}
+
 /*
  * V9fsFileObjectRequest is written into the socket by QEMU process.
  * Then this request is read by chroot process using v9fs_read_request function
@@ -94,7 +125,7 @@ static int v9fs_write_request(int sockfd, V9fsFileObjectRequest *request)
 /* Return opened file descriptor on success or -errno on error */
 int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *request)
 {
-    int fd, sock_error;
+    int fd, sock_error = 0;
     qemu_mutex_lock(&fs_ctx->chroot_mutex);
     if (fs_ctx->chroot_socket == -1) {
         goto error;
@@ -114,3 +145,29 @@ error:
     qemu_mutex_unlock(&fs_ctx->chroot_mutex);
     return -EIO;
 }
+
+/* Return special information on success or -errno on error */
+int v9fs_special(FsContext *fs_ctx, V9fsFileObjectRequest *request,
+                char *buff, int size)
+{
+    int retval, sock_error = 0;
+    qemu_mutex_lock(&fs_ctx->chroot_mutex);
+    if (fs_ctx->chroot_socket == -1) {
+        goto error;
+    }
+    if (v9fs_write_request(fs_ctx->chroot_socket, request) < 0) {
+        goto error;
+    }
+    retval = v9fs_special_receive(fs_ctx->chroot_socket, &sock_error, buff,
+                    size);
+    if (retval < 0 && sock_error) {
+        goto error;
+    }
+    qemu_mutex_unlock(&fs_ctx->chroot_mutex);
+    return retval;
+error:
+    close(fs_ctx->chroot_socket);
+    fs_ctx->chroot_socket = -1;
+    qemu_mutex_unlock(&fs_ctx->chroot_mutex);
+    return -EIO;
+}
diff --git a/hw/9pfs/virtio-9p-chroot.h b/hw/9pfs/virtio-9p-chroot.h
index 07c6627..9ed3f4d 100644
--- a/hw/9pfs/virtio-9p-chroot.h
+++ b/hw/9pfs/virtio-9p-chroot.h
@@ -13,6 +13,7 @@
 #define T_RENAME    8
 #define T_CHMOD     9
 #define T_CHOWN     10
+#define T_LSTAT     11
 
 #define V9FS_FD_VALID INT_MAX
 
@@ -29,6 +30,7 @@ struct V9fsFileObjectData
     gid_t gid;
     dev_t dev;
     int type;
+    int size; /* for special requests */
 };
 
 struct V9fsFileObjectPath
@@ -45,6 +47,7 @@ typedef struct V9fsFileObjectRequest
 
 int v9fs_chroot(FsContext *fs_ctx);
 int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *or);
+int v9fs_special(FsContext *fs_ctx, V9fsFileObjectRequest *or, char *, int);
 int v9fs_create_special(FsContext *fs_ctx, V9fsFileObjectRequest *request);
 
 #endif /* _QEMU_VIRTIO_9P_CHROOT_H */
diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
index ea7d954..eab0854 100644
--- a/hw/9pfs/virtio-9p-local.c
+++ b/hw/9pfs/virtio-9p-local.c
@@ -81,12 +81,42 @@ static int passthrough_request(FsContext *fs_ctx, const char *old_path,
     return retval;
 }
 
+static int passthrough_special_request(FsContext *fs_ctx, const char *path,
+                char *buff, int size, int type)
+{
+    V9fsFileObjectRequest request;
+    int retval;
+
+    retval = fill_fileobjectrequest(&request, NULL, path, 0, NULL, type);
+    if (retval < 0) {
+        errno = -retval;
+        return -1;
+    }
+
+    request.data.size = size;
+    if (type == T_LSTAT) {
+        retval = v9fs_special(fs_ctx, &request, buff, size);
+    } else {
+            return -1;
+    }
+    if (retval < 0) {
+        errno = -retval;
+        retval = -1;
+    }
+    return retval;
+}
+
 static int local_lstat(FsContext *fs_ctx, V9fsPath *fs_path, struct stat *stbuf)
 {
     int err;
     char buffer[PATH_MAX];
     char *path = fs_path->data;
 
+    if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        return passthrough_special_request(fs_ctx, path, (char *)stbuf,
+                        sizeof(*stbuf), T_LSTAT);
+    }
+
     err =  lstat(rpath(fs_ctx, path, buffer), stbuf);
     if (err) {
         return err;
-- 
1.7.5.4