Annotation of embedaddon/sqlite3/src/os.h, revision 1.1.1.1
1.1 misho 1: /*
2: ** 2001 September 16
3: **
4: ** The author disclaims copyright to this source code. In place of
5: ** a legal notice, here is a blessing:
6: **
7: ** May you do good and not evil.
8: ** May you find forgiveness for yourself and forgive others.
9: ** May you share freely, never taking more than you give.
10: **
11: ******************************************************************************
12: **
13: ** This header file (together with is companion C source-code file
14: ** "os.c") attempt to abstract the underlying operating system so that
15: ** the SQLite library will work on both POSIX and windows systems.
16: **
17: ** This header file is #include-ed by sqliteInt.h and thus ends up
18: ** being included by every source file.
19: */
20: #ifndef _SQLITE_OS_H_
21: #define _SQLITE_OS_H_
22:
23: /*
24: ** Figure out if we are dealing with Unix, Windows, or some other
25: ** operating system. After the following block of preprocess macros,
26: ** all of SQLITE_OS_UNIX, SQLITE_OS_WIN, SQLITE_OS_OS2, and SQLITE_OS_OTHER
27: ** will defined to either 1 or 0. One of the four will be 1. The other
28: ** three will be 0.
29: */
30: #if defined(SQLITE_OS_OTHER)
31: # if SQLITE_OS_OTHER==1
32: # undef SQLITE_OS_UNIX
33: # define SQLITE_OS_UNIX 0
34: # undef SQLITE_OS_WIN
35: # define SQLITE_OS_WIN 0
36: # undef SQLITE_OS_OS2
37: # define SQLITE_OS_OS2 0
38: # else
39: # undef SQLITE_OS_OTHER
40: # endif
41: #endif
42: #if !defined(SQLITE_OS_UNIX) && !defined(SQLITE_OS_OTHER)
43: # define SQLITE_OS_OTHER 0
44: # ifndef SQLITE_OS_WIN
45: # if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__)
46: # define SQLITE_OS_WIN 1
47: # define SQLITE_OS_UNIX 0
48: # define SQLITE_OS_OS2 0
49: # elif defined(__EMX__) || defined(_OS2) || defined(OS2) || defined(_OS2_) || defined(__OS2__)
50: # define SQLITE_OS_WIN 0
51: # define SQLITE_OS_UNIX 0
52: # define SQLITE_OS_OS2 1
53: # else
54: # define SQLITE_OS_WIN 0
55: # define SQLITE_OS_UNIX 1
56: # define SQLITE_OS_OS2 0
57: # endif
58: # else
59: # define SQLITE_OS_UNIX 0
60: # define SQLITE_OS_OS2 0
61: # endif
62: #else
63: # ifndef SQLITE_OS_WIN
64: # define SQLITE_OS_WIN 0
65: # endif
66: #endif
67:
68: /*
69: ** Define the maximum size of a temporary filename
70: */
71: #if SQLITE_OS_WIN
72: # include <windows.h>
73: # define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
74: #elif SQLITE_OS_OS2
75: # if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY)
76: # include <os2safe.h> /* has to be included before os2.h for linking to work */
77: # endif
78: # define INCL_DOSDATETIME
79: # define INCL_DOSFILEMGR
80: # define INCL_DOSERRORS
81: # define INCL_DOSMISC
82: # define INCL_DOSPROCESS
83: # define INCL_DOSMODULEMGR
84: # define INCL_DOSSEMAPHORES
85: # include <os2.h>
86: # include <uconv.h>
87: # define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP)
88: #else
89: # define SQLITE_TEMPNAME_SIZE 200
90: #endif
91:
92: /*
93: ** Determine if we are dealing with Windows NT.
94: */
95: #if defined(_WIN32_WINNT)
96: # define SQLITE_OS_WINNT 1
97: #else
98: # define SQLITE_OS_WINNT 0
99: #endif
100:
101: /*
102: ** Determine if we are dealing with WindowsCE - which has a much
103: ** reduced API.
104: */
105: #if defined(_WIN32_WCE)
106: # define SQLITE_OS_WINCE 1
107: #else
108: # define SQLITE_OS_WINCE 0
109: #endif
110:
111: /* If the SET_FULLSYNC macro is not defined above, then make it
112: ** a no-op
113: */
114: #ifndef SET_FULLSYNC
115: # define SET_FULLSYNC(x,y)
116: #endif
117:
118: /*
119: ** The default size of a disk sector
120: */
121: #ifndef SQLITE_DEFAULT_SECTOR_SIZE
122: # define SQLITE_DEFAULT_SECTOR_SIZE 4096
123: #endif
124:
125: /*
126: ** Temporary files are named starting with this prefix followed by 16 random
127: ** alphanumeric characters, and no file extension. They are stored in the
128: ** OS's standard temporary file directory, and are deleted prior to exit.
129: ** If sqlite is being embedded in another program, you may wish to change the
130: ** prefix to reflect your program's name, so that if your program exits
131: ** prematurely, old temporary files can be easily identified. This can be done
132: ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line.
133: **
134: ** 2006-10-31: The default prefix used to be "sqlite_". But then
135: ** Mcafee started using SQLite in their anti-virus product and it
136: ** started putting files with the "sqlite" name in the c:/temp folder.
137: ** This annoyed many windows users. Those users would then do a
138: ** Google search for "sqlite", find the telephone numbers of the
139: ** developers and call to wake them up at night and complain.
140: ** For this reason, the default name prefix is changed to be "sqlite"
141: ** spelled backwards. So the temp files are still identified, but
142: ** anybody smart enough to figure out the code is also likely smart
143: ** enough to know that calling the developer will not help get rid
144: ** of the file.
145: */
146: #ifndef SQLITE_TEMP_FILE_PREFIX
147: # define SQLITE_TEMP_FILE_PREFIX "etilqs_"
148: #endif
149:
150: /*
151: ** The following values may be passed as the second argument to
152: ** sqlite3OsLock(). The various locks exhibit the following semantics:
153: **
154: ** SHARED: Any number of processes may hold a SHARED lock simultaneously.
155: ** RESERVED: A single process may hold a RESERVED lock on a file at
156: ** any time. Other processes may hold and obtain new SHARED locks.
157: ** PENDING: A single process may hold a PENDING lock on a file at
158: ** any one time. Existing SHARED locks may persist, but no new
159: ** SHARED locks may be obtained by other processes.
160: ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks.
161: **
162: ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a
163: ** process that requests an EXCLUSIVE lock may actually obtain a PENDING
164: ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to
165: ** sqlite3OsLock().
166: */
167: #define NO_LOCK 0
168: #define SHARED_LOCK 1
169: #define RESERVED_LOCK 2
170: #define PENDING_LOCK 3
171: #define EXCLUSIVE_LOCK 4
172:
173: /*
174: ** File Locking Notes: (Mostly about windows but also some info for Unix)
175: **
176: ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
177: ** those functions are not available. So we use only LockFile() and
178: ** UnlockFile().
179: **
180: ** LockFile() prevents not just writing but also reading by other processes.
181: ** A SHARED_LOCK is obtained by locking a single randomly-chosen
182: ** byte out of a specific range of bytes. The lock byte is obtained at
183: ** random so two separate readers can probably access the file at the
184: ** same time, unless they are unlucky and choose the same lock byte.
185: ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range.
186: ** There can only be one writer. A RESERVED_LOCK is obtained by locking
187: ** a single byte of the file that is designated as the reserved lock byte.
188: ** A PENDING_LOCK is obtained by locking a designated byte different from
189: ** the RESERVED_LOCK byte.
190: **
191: ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,
192: ** which means we can use reader/writer locks. When reader/writer locks
193: ** are used, the lock is placed on the same range of bytes that is used
194: ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme
195: ** will support two or more Win95 readers or two or more WinNT readers.
196: ** But a single Win95 reader will lock out all WinNT readers and a single
197: ** WinNT reader will lock out all other Win95 readers.
198: **
199: ** The following #defines specify the range of bytes used for locking.
200: ** SHARED_SIZE is the number of bytes available in the pool from which
201: ** a random byte is selected for a shared lock. The pool of bytes for
202: ** shared locks begins at SHARED_FIRST.
203: **
204: ** The same locking strategy and
205: ** byte ranges are used for Unix. This leaves open the possiblity of having
206: ** clients on win95, winNT, and unix all talking to the same shared file
207: ** and all locking correctly. To do so would require that samba (or whatever
208: ** tool is being used for file sharing) implements locks correctly between
209: ** windows and unix. I'm guessing that isn't likely to happen, but by
210: ** using the same locking range we are at least open to the possibility.
211: **
212: ** Locking in windows is manditory. For this reason, we cannot store
213: ** actual data in the bytes used for locking. The pager never allocates
214: ** the pages involved in locking therefore. SHARED_SIZE is selected so
215: ** that all locks will fit on a single page even at the minimum page size.
216: ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE
217: ** is set high so that we don't have to allocate an unused page except
218: ** for very large databases. But one should test the page skipping logic
219: ** by setting PENDING_BYTE low and running the entire regression suite.
220: **
221: ** Changing the value of PENDING_BYTE results in a subtly incompatible
222: ** file format. Depending on how it is changed, you might not notice
223: ** the incompatibility right away, even running a full regression test.
224: ** The default location of PENDING_BYTE is the first byte past the
225: ** 1GB boundary.
226: **
227: */
228: #ifdef SQLITE_OMIT_WSD
229: # define PENDING_BYTE (0x40000000)
230: #else
231: # define PENDING_BYTE sqlite3PendingByte
232: #endif
233: #define RESERVED_BYTE (PENDING_BYTE+1)
234: #define SHARED_FIRST (PENDING_BYTE+2)
235: #define SHARED_SIZE 510
236:
237: /*
238: ** Wrapper around OS specific sqlite3_os_init() function.
239: */
240: int sqlite3OsInit(void);
241:
242: /*
243: ** Functions for accessing sqlite3_file methods
244: */
245: int sqlite3OsClose(sqlite3_file*);
246: int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset);
247: int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset);
248: int sqlite3OsTruncate(sqlite3_file*, i64 size);
249: int sqlite3OsSync(sqlite3_file*, int);
250: int sqlite3OsFileSize(sqlite3_file*, i64 *pSize);
251: int sqlite3OsLock(sqlite3_file*, int);
252: int sqlite3OsUnlock(sqlite3_file*, int);
253: int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut);
254: int sqlite3OsFileControl(sqlite3_file*,int,void*);
255: void sqlite3OsFileControlHint(sqlite3_file*,int,void*);
256: #define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0
257: int sqlite3OsSectorSize(sqlite3_file *id);
258: int sqlite3OsDeviceCharacteristics(sqlite3_file *id);
259: int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **);
260: int sqlite3OsShmLock(sqlite3_file *id, int, int, int);
261: void sqlite3OsShmBarrier(sqlite3_file *id);
262: int sqlite3OsShmUnmap(sqlite3_file *id, int);
263:
264:
265: /*
266: ** Functions for accessing sqlite3_vfs methods
267: */
268: int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *);
269: int sqlite3OsDelete(sqlite3_vfs *, const char *, int);
270: int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut);
271: int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *);
272: #ifndef SQLITE_OMIT_LOAD_EXTENSION
273: void *sqlite3OsDlOpen(sqlite3_vfs *, const char *);
274: void sqlite3OsDlError(sqlite3_vfs *, int, char *);
275: void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void);
276: void sqlite3OsDlClose(sqlite3_vfs *, void *);
277: #endif /* SQLITE_OMIT_LOAD_EXTENSION */
278: int sqlite3OsRandomness(sqlite3_vfs *, int, char *);
279: int sqlite3OsSleep(sqlite3_vfs *, int);
280: int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*);
281:
282: /*
283: ** Convenience functions for opening and closing files using
284: ** sqlite3_malloc() to obtain space for the file-handle structure.
285: */
286: int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*);
287: int sqlite3OsCloseFree(sqlite3_file *);
288:
289: #endif /* _SQLITE_OS_H_ */
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