OpenFlags


1   
2   package ch.ethz.ssh2.sftp;
3   
4   /**
5    *
6    * SFTP Open Flags.
7    * 
8    * The following table is provided to assist in mapping POSIX semantics
9    * to equivalent SFTP file open parameters:
10   * <p>
11   * TODO: This comment should be moved to the open method.
12   * <p>
13   * <ul>
14   * <li>O_RDONLY
15   * <ul><li>desired-access = READ_DATA | READ_ATTRIBUTES</li></ul>
16   * </li>
17   * </ul>
18   * <ul>
19   * <li>O_WRONLY
20   * <ul><li>desired-access = WRITE_DATA | WRITE_ATTRIBUTES</li></ul>
21   * </li>
22   * </ul>
23   * <ul>
24   * <li>O_RDWR
25   * <ul><li>desired-access = READ_DATA | READ_ATTRIBUTES | WRITE_DATA | WRITE_ATTRIBUTES</li></ul>
26   * </li>
27   * </ul>
28   * <ul>
29   * <li>O_APPEND
30   * <ul>
31   * <li>desired-access = WRITE_DATA | WRITE_ATTRIBUTES | APPEND_DATA</li>
32   * <li>flags = SSH_FXF_ACCESS_APPEND_DATA and or SSH_FXF_ACCESS_APPEND_DATA_ATOMIC</li>
33   * </ul>
34   * </li>
35   * </ul>
36   * <ul>
37   * <li>O_CREAT
38   * <ul>
39   * <li>flags = SSH_FXF_OPEN_OR_CREATE</li>
40   * </ul>
41   * </li>
42   * </ul>
43   * <ul>
44   * <li>O_TRUNC
45   * <ul>
46   * <li>flags = SSH_FXF_TRUNCATE_EXISTING</li>
47   * </ul>
48   * </li>
49   * </ul>
50   * <ul>
51   * <li>O_TRUNC|O_CREATE
52   * <ul>
53   * <li>flags = SSH_FXF_CREATE_TRUNCATE</li>
54   * </ul>
55   * </li>
56   * </ul>
57   * 
58   * @author Christian Plattner, plattner@inf.ethz.ch
59   * @version $Id: OpenFlags.java,v 1.2 2006/08/02 12:05:00 cplattne Exp $
60   */
61  public class OpenFlags
62  {
63      /**
64       * Disposition is a 3 bit field that controls how the file is opened.
65       * The server MUST support these bits (possible enumaration values:
66       * SSH_FXF_CREATE_NEW, SSH_FXF_CREATE_TRUNCATE, SSH_FXF_OPEN_EXISTING,
67       * SSH_FXF_OPEN_OR_CREATE or SSH_FXF_TRUNCATE_EXISTING).
68       */
69      public static final int SSH_FXF_ACCESS_DISPOSITION = 0x00000007;
70  
71      /**
72       * A new file is created; if the file already exists, the server
73       * MUST return status SSH_FX_FILE_ALREADY_EXISTS.
74       */
75      public static final int SSH_FXF_CREATE_NEW = 0x00000000;
76  
77      /**
78       * A new file is created; if the file already exists, it is opened
79       * and truncated.
80       */
81      public static final int SSH_FXF_CREATE_TRUNCATE = 0x00000001;
82  
83      /**
84       * An existing file is opened.  If the file does not exist, the
85       * server MUST return SSH_FX_NO_SUCH_FILE. If a directory in the
86       * path does not exist, the server SHOULD return
87       * SSH_FX_NO_SUCH_PATH. It is also acceptable if the server
88       * returns SSH_FX_NO_SUCH_FILE in this case.
89       */
90      public static final int SSH_FXF_OPEN_EXISTING = 0x00000002;
91  
92      /**
93       * If the file exists, it is opened. If the file does not exist,
94       * it is created.
95       */
96      public static final int SSH_FXF_OPEN_OR_CREATE = 0x00000003;
97  
98      /**
99       * An existing file is opened and truncated. If the file does not
100      * exist, the server MUST return the same error codes as defined
101      * for SSH_FXF_OPEN_EXISTING.
102      */
103     public static final int SSH_FXF_TRUNCATE_EXISTING = 0x00000004;
104 
105     /**
106      * Data is always written at the end of the file. The offset field
107      * of the SSH_FXP_WRITE requests are ignored.
108      * <p>
109      * Data is not required to be appended atomically. This means that
110      * if multiple writers attempt to append data simultaneously, data
111      * from the first may be lost. However, data MAY be appended
112      * atomically.
113      */
114     public static final int SSH_FXF_ACCESS_APPEND_DATA = 0x00000008;
115 
116     /**
117      * Data is always written at the end of the file. The offset field
118      * of the SSH_FXP_WRITE requests are ignored.
119      * <p>
120      * Data MUST be written atomically so that there is no chance that
121      * multiple appenders can collide and result in data being lost.
122      * <p>
123      * If both append flags are specified, the server SHOULD use atomic
124      * append if it is available, but SHOULD use non-atomic appends
125      * otherwise. The server SHOULD NOT fail the request in this case.
126      */
127     public static final int SSH_FXF_ACCESS_APPEND_DATA_ATOMIC = 0x00000010;
128 
129     /**
130      * Indicates that the server should treat the file as text and
131      * convert it to the canonical newline convention in use.
132      * (See Determining Server Newline Convention in section 5.3 in the
133      * SFTP standard draft).
134      * <p>
135      * When a file is opened with this flag, the offset field in the read
136      * and write functions is ignored.
137      * <p>
138      * Servers MUST process multiple, parallel reads and writes correctly
139      * in this mode.  Naturally, it is permissible for them to do this by
140      * serializing the requests.
141      * <p>
142      * Clients SHOULD use the SSH_FXF_ACCESS_APPEND_DATA flag to append
143      * data to a text file rather then using write with a calculated offset.
144      */
145     public static final int SSH_FXF_ACCESS_TEXT_MODE = 0x00000020;
146 
147     /**
148      * The server MUST guarantee that no other handle has been opened
149      * with ACE4_READ_DATA access, and that no other handle will be
150      * opened with ACE4_READ_DATA access until the client closes the
151      * handle. (This MUST apply both to other clients and to other
152      * processes on the server.)
153      * <p>
154      * If there is a conflicting lock the server MUST return
155      * SSH_FX_LOCK_CONFLICT.  If the server cannot make the locking
156      * guarantee, it MUST return SSH_FX_OP_UNSUPPORTED.
157      * <p>
158      * Other handles MAY be opened for ACE4_WRITE_DATA or any other
159      * combination of accesses, as long as ACE4_READ_DATA is not included
160      * in the mask.
161      */
162     public static final int SSH_FXF_ACCESS_BLOCK_READ = 0x00000040;
163 
164     /**
165      * The server MUST guarantee that no other handle has been opened
166      * with ACE4_WRITE_DATA or ACE4_APPEND_DATA access, and that no other
167      * handle will be opened with ACE4_WRITE_DATA or ACE4_APPEND_DATA
168      * access until the client closes the handle. (This MUST apply both
169      * to other clients and to other processes on the server.)
170      * <p>
171      * If there is a conflicting lock the server MUST return
172      * SSH_FX_LOCK_CONFLICT. If the server cannot make the locking
173      * guarantee, it MUST return SSH_FX_OP_UNSUPPORTED.
174      * <p>
175      * Other handles MAY be opened for ACE4_READ_DATA or any other
176      * combination of accesses, as long as neither ACE4_WRITE_DATA nor
177      * ACE4_APPEND_DATA are included in the mask.
178      */
179     public static final int SSH_FXF_ACCESS_BLOCK_WRITE = 0x00000080;
180 
181     /**
182      * The server MUST guarantee that no other handle has been opened
183      * with ACE4_DELETE access, opened with the
184      * SSH_FXF_ACCESS_DELETE_ON_CLOSE flag set, and that no other handle
185      * will be opened with ACE4_DELETE access or with the
186      * SSH_FXF_ACCESS_DELETE_ON_CLOSE flag set, and that the file itself
187      * is not deleted in any other way until the client closes the handle.
188      * <p>
189      * If there is a conflicting lock the server MUST return
190      * SSH_FX_LOCK_CONFLICT.  If the server cannot make the locking
191      * guarantee, it MUST return SSH_FX_OP_UNSUPPORTED.
192      */
193     public static final int SSH_FXF_ACCESS_BLOCK_DELETE = 0x00000100;
194 
195     /**
196      * If this bit is set, the above BLOCK modes are advisory. In advisory
197      * mode, only other accesses that specify a BLOCK mode need be
198      * considered when determining whether the BLOCK can be granted,
199      * and the server need not prevent I/O operations that violate the
200      * block mode.
201      * <p>
202      * The server MAY perform mandatory locking even if the BLOCK_ADVISORY
203      * bit is set.
204      */
205     public static final int SSH_FXF_ACCESS_BLOCK_ADVISORY = 0x00000200;
206 
207     /**
208      * If the final component of the path is a symlink, then the open
209      * MUST fail, and the error SSH_FX_LINK_LOOP MUST be returned.
210      */
211     public static final int SSH_FXF_ACCESS_NOFOLLOW = 0x00000400;
212 
213     /**
214      * The file should be deleted when the last handle to it is closed.
215      * (The last handle may not be an sftp-handle.)  This MAY be emulated
216      * by a server if the OS doesn't support it by deleting the file when
217      * this handle is closed.
218      * <p>
219      * It is implementation specific whether the directory entry is
220      * removed immediately or when the handle is closed.
221      */
222     public static final int SSH_FXF_ACCESS_DELETE_ON_CLOSE = 0x00000800;
223 }
224
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