symlink: create cygwin symlinks

when given a NfsSymlinkTargetName EA on create, marshall the unicode target name to the daemon, which issues a CREATE rpc to create the symlink

modified the driver's marshall_unicode_as_utf8() function to handle the NULL string buffer for non-symlink opens

Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>

daemon/open.c

@@ -256,6 +256,23 @@ static int open_or_delegate(
 }
 
 
+static int parse_abs_path(unsigned char **buffer, uint32_t *length, nfs41_abs_path *path)
+{
+    int status = safe_read(buffer, length, &path->len, sizeof(USHORT));
+    if (status) goto out;
+    if (path->len == 0)
+        goto out;
+    if (path->len >= NFS41_MAX_PATH_LEN) {
+        status = ERROR_BUFFER_OVERFLOW;
+        goto out;
+    }
+    status = safe_read(buffer, length, path->path, path->len);
+    if (status) goto out;
+    path->len--; /* subtract 1 for null */
+out:
+    return status;
+}
+
 /* NFS41_OPEN */
 static int parse_open(unsigned char *buffer, uint32_t length, nfs41_upcall *upcall)
 {
@@ -280,15 +297,18 @@ static int parse_open(unsigned char *buffer, uint32_t length, nfs41_upcall *upca
     if (status) goto out;
     status = safe_read(&buffer, &length, &args->srv_open, sizeof(HANDLE));
     if (status) goto out;
+    status = parse_abs_path(&buffer, &length, &args->symlink);
+    if (status) goto out;
     status = safe_read(&buffer, &length, &args->ea, sizeof(HANDLE));
     if (status) goto out;
 
     dprintf(1, "parsing NFS41_OPEN: filename='%s' access mask=%d "
         "access mode=%d\n\tfile attrs=0x%x create attrs=0x%x "
         "(kernel) disposition=%d\n\topen_owner_id=%d mode=%o "
-        "srv_open=%p ea=%p\n", args->path, args->access_mask, args->access_mode,
+        "srv_open=%p symlink=%s ea=%p\n", args->path, args->access_mask,
-        args->file_attrs, args->create_opts, args->disposition,
+        args->access_mode, args->file_attrs, args->create_opts,
-        args->open_owner_id, args->mode, args->srv_open, args->ea);
+        args->disposition, args->open_owner_id, args->mode, args->srv_open,
+        args->symlink.path, args->ea);
     print_disposition(2, args->disposition);
     print_access_mask(2, args->access_mask);
     print_share_mode(2, args->access_mode);
@@ -590,6 +610,29 @@ static int handle_open(nfs41_upcall *upcall)
         state->file.fh.superblock = state->parent.fh.superblock;
 
         status = NO_ERROR;
+    } else if (args->symlink.len) {
+        /* handle cygwin symlinks */
+        nfs41_file_info createattrs;
+        createattrs.attrmask.count = 2;
+        createattrs.attrmask.arr[0] = 0;
+        createattrs.attrmask.arr[1] = FATTR4_WORD1_MODE;
+        createattrs.mode = 0777;
+
+        dprintf(1, "creating cygwin symlink %s -> %s\n",
+            state->file.name.name, args->symlink.path);
+
+        status = nfs41_create(state->session, NF4LNK, &createattrs,
+            args->symlink.path, &state->parent, &state->file, &info);
+        if (status) {
+            eprintf("nfs41_create() for symlink=%s failed with %s\n",
+                args->symlink.path, nfs_error_string(status));
+            status = map_symlink_errors(status);
+            goto out_free_state;
+        }
+        nfs_to_basic_info(&info, &args->basic_info);
+        nfs_to_standard_info(&info, &args->std_info);
+        args->mode = info.mode;
+        args->changeattr = info.change;
     } else if (open_for_attributes(state->type, args->access_mask, 
                 args->disposition, status)) {
         if (status) {

daemon/symlink.c

@@ -208,18 +208,6 @@ out:
     return status;
 }
 
-static int map_symlink_errors(int status)
-{
-    switch (status) {
-    case NFS4ERR_BADCHAR:
-    case NFS4ERR_BADNAME:       return ERROR_INVALID_REPARSE_DATA;
-    case NFS4ERR_WRONG_TYPE:    return ERROR_NOT_A_REPARSE_POINT;
-    case NFS4ERR_ACCESS:        return ERROR_ACCESS_DENIED;
-    case NFS4ERR_NOTEMPTY:      return ERROR_NOT_EMPTY;
-    default: return nfs_to_windows_error(status, ERROR_BAD_NET_RESP);
-    }
-}
-
 static int handle_symlink(nfs41_upcall *upcall)
 {
     symlink_upcall_args *args = &upcall->args.symlink;
@@ -250,7 +238,7 @@ static int handle_symlink(nfs41_upcall *upcall)
         }
 
         /* create the symlink */
-        createattrs.attrmask.count = 1;
+        createattrs.attrmask.count = 2;
         createattrs.attrmask.arr[0] = 0;
         createattrs.attrmask.arr[1] = FATTR4_WORD1_MODE;
         createattrs.mode = 0777;

daemon/util.c

@@ -290,6 +290,18 @@ int nfs_to_windows_error(int status, int default_error)
     }
 }
 
+int map_symlink_errors(int status)
+{
+    switch (status) {
+    case NFS4ERR_BADCHAR:
+    case NFS4ERR_BADNAME:       return ERROR_INVALID_REPARSE_DATA;
+    case NFS4ERR_WRONG_TYPE:    return ERROR_NOT_A_REPARSE_POINT;
+    case NFS4ERR_ACCESS:        return ERROR_ACCESS_DENIED;
+    case NFS4ERR_NOTEMPTY:      return ERROR_NOT_EMPTY;
+    default: return nfs_to_windows_error(status, ERROR_BAD_NET_RESP);
+    }
+}
+
 bool_t next_component(
     IN const char *path,
     IN const char *path_end,

daemon/util.h

@@ -185,6 +185,7 @@ bool_t multi_addr_find(
  */
 int nfs_to_windows_error(int status, int default_error);
 
+int map_symlink_errors(int status);
 
 __inline uint32_t align8(uint32_t offset) {
     return 8 + ((offset - 1) & ~7);

sys/nfs41_driver.c

@@ -527,6 +527,13 @@ NTSTATUS marshall_unicode_as_utf8(
     ULONG ActualCount;
     NTSTATUS status;
 
+    if (str->Length == 0) {
+        status = STATUS_SUCCESS;
+        ActualCount = 0;
+        ansi.MaximumLength = 1;
+        goto out_copy;
+    }
+
     /* query the number of bytes required for the utf8 encoding */
     status = RtlUnicodeToUTF8N(NULL, 0xffff,
         &ActualCount, str->Buffer, str->Length);
@@ -547,6 +554,7 @@ NTSTATUS marshall_unicode_as_utf8(
         goto out;
     }
 
+out_copy:
     RtlCopyMemory(*pos, &ansi.MaximumLength, sizeof(ansi.MaximumLength));
     *pos += sizeof(ansi.MaximumLength);
     (*pos)[ActualCount] = '\0';
@@ -683,7 +691,8 @@ NTSTATUS marshal_nfs41_open(
     else 
         tmp += *len;
     header_len = *len + length_as_utf8(entry->u.Open.filename) +
-        5 * sizeof(ULONG) + sizeof(LONG) + sizeof(DWORD) + 2 * sizeof(HANDLE);
+        7 * sizeof(ULONG) + 2 * sizeof(HANDLE) +
+        length_as_utf8(&entry->u.Open.symlink);
     if (header_len > buf_len) { 
         status = STATUS_INSUFFICIENT_RESOURCES;
         goto out;
@@ -709,6 +718,8 @@ NTSTATUS marshal_nfs41_open(
     tmp += sizeof(DWORD);
     RtlCopyMemory(tmp, &entry->u.Open.srv_open, sizeof(HANDLE));
     tmp += sizeof(HANDLE);
+    status = marshall_unicode_as_utf8(&tmp, &entry->u.Open.symlink);
+    if (status) goto out;
 
     __try {
         if (entry->u.Open.EaMdl) {
@@ -3408,6 +3419,7 @@ NTSTATUS map_open_errors(
     case ERROR_ACCESS_DENIED:
         if (len > 0)                    return STATUS_ACCESS_DENIED;
         else                            return STATUS_SUCCESS;
+    case ERROR_INVALID_REPARSE_DATA:
     case ERROR_INVALID_NAME:            return STATUS_OBJECT_NAME_INVALID;
     case ERROR_FILE_EXISTS:             return STATUS_OBJECT_NAME_COLLISION;
     case ERROR_FILE_INVALID:            return STATUS_FILE_INVALID;
@@ -3455,7 +3467,7 @@ static BOOLEAN create_should_pass_ea(
     IN PFILE_FULL_EA_INFORMATION ea,
     IN ULONG disposition)
 {
-    /* don't pass cygwin EAs (until we support NfsSymlinkTargetName) */
+    /* don't pass cygwin EAs */
     if (AnsiStrEq(&NfsV3Attributes, ea->EaName, ea->EaNameLength)
         || AnsiStrEq(&NfsActOnLink, ea->EaName, ea->EaNameLength)
         || AnsiStrEq(&NfsSymlinkTargetName, ea->EaName, ea->EaNameLength))
@@ -3654,7 +3666,12 @@ NTSTATUS nfs41_Create(
         if (params->FileAttributes & FILE_ATTRIBUTE_READONLY)
             entry->u.Open.mode = 0444;
     }
-
+    if (entry->u.Open.disp == FILE_CREATE && ea &&
+            AnsiStrEq(&NfsSymlinkTargetName, ea->EaName, ea->EaNameLength)) {
+        /* for a cygwin symlink, given as a unicode string */
+        entry->u.Open.symlink.Buffer = (PWCH)(ea->EaName + ea->EaNameLength + 1);
+        entry->u.Open.symlink.MaximumLength = entry->u.Open.symlink.Length = ea->EaValueLength;
+    }
     if (ea && create_should_pass_ea(ea, params->Disposition)) {
         /* lock the extended attribute buffer for read access in user space */
         entry->u.Open.EaMdl = IoAllocateMdl(ea,
@@ -6353,10 +6370,12 @@ NTSTATUS check_nfs41_getreparse_args(
         status = STATUS_INVALID_PARAMETER;
         goto out;
     }
+    /* ifs reparse tests expect STATUS_INVALID_PARAMETER,
+     * but 'dir' passes a buffer here when querying symlinks
     if (FsCtl->pInputBuffer != NULL) {
         status = STATUS_INVALID_PARAMETER;
         goto out;
-    }
+    } */
     if (!FsCtl->pOutputBuffer) {
         status = STATUS_INVALID_USER_BUFFER;
         goto out;