[PATCH v4 11/32] tools/xen-9pfsd: add 9pfs create request support

[Juergen Gross <jgross@xxxxxxxx>]

Add the create request of the 9pfs protocol.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
V2:
- set permissions correctly (Jason Andryuk)
V3:
- use opendirat() etc. (Jason Andryuk)
- rework error handling a little bit
---
 tools/xen-9pfsd/io.c | 151 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 151 insertions(+)

diff --git a/tools/xen-9pfsd/io.c b/tools/xen-9pfsd/io.c
index 74efd21c10..583eea6059 100644
--- a/tools/xen-9pfsd/io.c
+++ b/tools/xen-9pfsd/io.c
@@ -32,6 +32,7 @@
 #define P9_CMD_ERROR      107
 #define P9_CMD_WALK       110
 #define P9_CMD_OPEN       112
+#define P9_CMD_CREATE     114
 #define P9_CMD_CLUNK      120
 
 /* P9 protocol open flags. */
@@ -42,6 +43,12 @@
 #define P9_OTRUNC        0x10   /* or'ed in, truncate file first */
 #define P9_OREMOVE       0x40   /* or'ed in, remove file after clunk */
 
+/* P9 protocol create permission masks. */
+#define P9_CREATE_PERM_DIR        0x80000000
+#define P9_CREATE_PERM_NOTSUPP    0x03b00000   /* link, symlink, ... */
+#define P9_CREATE_PERM_DIR_MASK   0777
+#define P9_CREATE_PERM_FILE_MASK  0666
+
 #define P9_MIN_MSIZE      2048
 #define P9_VERSION        "9P2000.u"
 #define P9_WALK_MAXELEM   16
@@ -963,6 +970,146 @@ static void p9_open(struct ring *ring, struct p9_header 
*hdr)
     p9_error(ring, hdr->tag, errno);
 }
 
+static void p9_create(struct ring *ring, struct p9_header *hdr)
+{
+    device *device = ring->device;
+    uint32_t fid;
+    unsigned int name_off;
+    uint32_t perm;
+    uint8_t mode;
+    unsigned int ext_off;
+    struct p9_fid *fidp;
+    struct p9_fid *new_fidp;
+    char *path;
+    struct stat st;
+    struct p9_qid qid;
+    uint32_t iounit;
+    int flags;
+    int ret;
+
+    ret = fill_data(ring, "USUbS", &fid, &name_off, &perm, &mode, &ext_off);
+    if ( ret != 5 )
+    {
+        p9_error(ring, hdr->tag, EINVAL);
+        return;
+    }
+
+    if ( !name_ok(ring->str + name_off) )
+    {
+        p9_error(ring, hdr->tag, ENOENT);
+        return;
+    }
+
+    if ( perm & P9_CREATE_PERM_NOTSUPP )
+    {
+        p9_error(ring, hdr->tag, EINVAL);
+        return;
+    }
+
+    fidp = get_fid_ref(device, fid);
+    if ( !fidp || fidp->opened )
+    {
+        free_fid(device, fidp);
+        p9_error(ring, hdr->tag, EINVAL);
+        return;
+    }
+    if ( fstatat(device->root_fd, fidp->path, &st, 0) < 0 )
+    {
+        free_fid(device, fidp);
+        p9_error(ring, hdr->tag, errno);
+        return;
+    }
+
+    path = malloc(strlen(fidp->path) + strlen(ring->str + name_off) + 2);
+    if ( !path )
+    {
+        free_fid(device, fidp);
+        p9_error(ring, hdr->tag, ENOMEM);
+        return;
+    }
+    sprintf(path, "%s/%s", fidp->path, ring->str + name_off);
+    new_fidp = alloc_fid_mem(device, fid, path);
+    free(path);
+    if ( !new_fidp )
+    {
+        free_fid(device, fidp);
+        p9_error(ring, hdr->tag, ENOMEM);
+        return;
+    }
+
+    pthread_mutex_lock(&device->fid_mutex);
+
+    new_fidp->ref = fidp->ref;
+
+    if ( perm & P9_CREATE_PERM_DIR )
+    {
+        perm &= P9_CREATE_PERM_DIR_MASK & st.st_mode;
+        if ( mode != P9_OREAD )
+        {
+            errno = EINVAL;
+            goto err;
+        }
+        if ( mkdirat(device->root_fd, new_fidp->path, perm) < 0 )
+            goto err;
+
+        XEN_TAILQ_REMOVE(&device->fids, fidp, list);
+        XEN_TAILQ_INSERT_HEAD(&device->fids, new_fidp, list);
+        free(fidp);
+        fidp = new_fidp;
+        new_fidp = NULL;
+
+        fidp->fd = openat(device->root_fd, fidp->path, O_RDONLY);
+        if ( fidp->fd < 0 )
+            goto err;
+        fidp->data = fdopendir(fidp->fd);
+        if ( !fidp->data )
+            goto err;
+    }
+    else
+    {
+        flags = open_flags_from_mode(mode);
+        if ( flags < 0 )
+        {
+            errno = EINVAL;
+            goto err;
+        }
+        perm &= P9_CREATE_PERM_FILE_MASK & st.st_mode;
+
+        XEN_TAILQ_REMOVE(&device->fids, fidp, list);
+        XEN_TAILQ_INSERT_HEAD(&device->fids, new_fidp, list);
+        free(fidp);
+        fidp = new_fidp;
+        new_fidp = NULL;
+
+        fidp->fd = openat(device->root_fd, fidp->path, flags | O_CREAT | 
O_EXCL,
+                          perm);
+        if ( fidp->fd < 0 )
+            goto err;
+    }
+
+    if ( fstatat(device->root_fd, fidp->path, &st, 0) < 0 )
+        goto err;
+
+    fill_qid(device, fidp->path, &qid, &st);
+    iounit = get_iounit(ring, &st);
+    fidp->opened = true;
+    fidp->mode = mode;
+
+    pthread_mutex_unlock(&device->fid_mutex);
+
+    fill_buffer(ring, hdr->cmd + 1, hdr->tag, "QU", &qid, &iounit);
+
+    return;
+
+ err:
+    p9_error(ring, hdr->tag, errno);
+
+    pthread_mutex_unlock(&device->fid_mutex);
+
+    free(new_fidp);
+    free_fid(device, fidp);
+}
+
 static void p9_clunk(struct ring *ring, struct p9_header *hdr)
 {
     device *device = ring->device;
@@ -1072,6 +1219,10 @@ void *io_thread(void *arg)
                 p9_open(ring, &hdr);
                 break;
 
+            case P9_CMD_CREATE:
+                p9_create(ring, &hdr);
+                break;
+
             case P9_CMD_CLUNK:
                 p9_clunk(ring, &hdr);
                 break;
-- 
2.35.3