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 ** Determine if we are dealing with Windows NT. 70 */ 71 #if defined(_WIN32_WINNT) 72 # define SQLITE_OS_WINNT 1 73 #else 74 # define SQLITE_OS_WINNT 0 75 #endif 76 77 /* 78 ** Determine if we are dealing with WindowsCE - which has a much 79 ** reduced API. 80 */ 81 #if defined(_WIN32_WCE) 82 # define SQLITE_OS_WINCE 1 83 #else 84 # define SQLITE_OS_WINCE 0 85 #endif 86 87 88 /* 89 ** Define the maximum size of a temporary filename 90 */ 91 #if SQLITE_OS_WIN 92 # include <windows.h> 93 # define SQLITE_TEMPNAME_SIZE (MAX_PATH+50) 94 #elif SQLITE_OS_OS2 95 # if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY) 96 # include <os2safe.h> /* has to be included before os2.h for linking to work */ 97 # endif 98 # define INCL_DOSDATETIME 99 # define INCL_DOSFILEMGR 100 # define INCL_DOSERRORS 101 # define INCL_DOSMISC 102 # define INCL_DOSPROCESS 103 # define INCL_DOSMODULEMGR 104 # define INCL_DOSSEMAPHORES 105 # include <os2.h> 106 # include <uconv.h> 107 # define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP) 108 #else 109 # define SQLITE_TEMPNAME_SIZE 200 110 #endif 111 112 /* If the SET_FULLSYNC macro is not defined above, then make it 113 ** a no-op 114 */ 115 #ifndef SET_FULLSYNC 116 # define SET_FULLSYNC(x,y) 117 #endif 118 119 /* 120 ** The default size of a disk sector 121 */ 122 #ifndef SQLITE_DEFAULT_SECTOR_SIZE 123 # define SQLITE_DEFAULT_SECTOR_SIZE 512 124 #endif 125 126 /* 127 ** Temporary files are named starting with this prefix followed by 16 random 128 ** alphanumeric characters, and no file extension. They are stored in the 129 ** OS's standard temporary file directory, and are deleted prior to exit. 130 ** If sqlite is being embedded in another program, you may wish to change the 131 ** prefix to reflect your program's name, so that if your program exits 132 ** prematurely, old temporary files can be easily identified. This can be done 133 ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line. 134 ** 135 ** 2006-10-31: The default prefix used to be "sqlite_". But then 136 ** Mcafee started using SQLite in their anti-virus product and it 137 ** started putting files with the "sqlite" name in the c:/temp folder. 138 ** This annoyed many windows users. Those users would then do a 139 ** Google search for "sqlite", find the telephone numbers of the 140 ** developers and call to wake them up at night and complain. 141 ** For this reason, the default name prefix is changed to be "sqlite" 142 ** spelled backwards. So the temp files are still identified, but 143 ** anybody smart enough to figure out the code is also likely smart 144 ** enough to know that calling the developer will not help get rid 145 ** of the file. 146 */ 147 #ifndef SQLITE_TEMP_FILE_PREFIX 148 # define SQLITE_TEMP_FILE_PREFIX "etilqs_" 149 #endif 150 151 /* 152 ** The following values may be passed as the second argument to 153 ** sqlite3OsLock(). The various locks exhibit the following semantics: 154 ** 155 ** SHARED: Any number of processes may hold a SHARED lock simultaneously. 156 ** RESERVED: A single process may hold a RESERVED lock on a file at 157 ** any time. Other processes may hold and obtain new SHARED locks. 158 ** PENDING: A single process may hold a PENDING lock on a file at 159 ** any one time. Existing SHARED locks may persist, but no new 160 ** SHARED locks may be obtained by other processes. 161 ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks. 162 ** 163 ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a 164 ** process that requests an EXCLUSIVE lock may actually obtain a PENDING 165 ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to 166 ** sqlite3OsLock(). 167 */ 168 #define NO_LOCK 0 169 #define SHARED_LOCK 1 170 #define RESERVED_LOCK 2 171 #define PENDING_LOCK 3 172 #define EXCLUSIVE_LOCK 4 173 174 /* 175 ** File Locking Notes: (Mostly about windows but also some info for Unix) 176 ** 177 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because 178 ** those functions are not available. So we use only LockFile() and 179 ** UnlockFile(). 180 ** 181 ** LockFile() prevents not just writing but also reading by other processes. 182 ** A SHARED_LOCK is obtained by locking a single randomly-chosen 183 ** byte out of a specific range of bytes. The lock byte is obtained at 184 ** random so two separate readers can probably access the file at the 185 ** same time, unless they are unlucky and choose the same lock byte. 186 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range. 187 ** There can only be one writer. A RESERVED_LOCK is obtained by locking 188 ** a single byte of the file that is designated as the reserved lock byte. 189 ** A PENDING_LOCK is obtained by locking a designated byte different from 190 ** the RESERVED_LOCK byte. 191 ** 192 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available, 193 ** which means we can use reader/writer locks. When reader/writer locks 194 ** are used, the lock is placed on the same range of bytes that is used 195 ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme 196 ** will support two or more Win95 readers or two or more WinNT readers. 197 ** But a single Win95 reader will lock out all WinNT readers and a single 198 ** WinNT reader will lock out all other Win95 readers. 199 ** 200 ** The following #defines specify the range of bytes used for locking. 201 ** SHARED_SIZE is the number of bytes available in the pool from which 202 ** a random byte is selected for a shared lock. The pool of bytes for 203 ** shared locks begins at SHARED_FIRST. 204 ** 205 ** The same locking strategy and 206 ** byte ranges are used for Unix. This leaves open the possiblity of having 207 ** clients on win95, winNT, and unix all talking to the same shared file 208 ** and all locking correctly. To do so would require that samba (or whatever 209 ** tool is being used for file sharing) implements locks correctly between 210 ** windows and unix. I'm guessing that isn't likely to happen, but by 211 ** using the same locking range we are at least open to the possibility. 212 ** 213 ** Locking in windows is manditory. For this reason, we cannot store 214 ** actual data in the bytes used for locking. The pager never allocates 215 ** the pages involved in locking therefore. SHARED_SIZE is selected so 216 ** that all locks will fit on a single page even at the minimum page size. 217 ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE 218 ** is set high so that we don't have to allocate an unused page except 219 ** for very large databases. But one should test the page skipping logic 220 ** by setting PENDING_BYTE low and running the entire regression suite. 221 ** 222 ** Changing the value of PENDING_BYTE results in a subtly incompatible 223 ** file format. Depending on how it is changed, you might not notice 224 ** the incompatibility right away, even running a full regression test. 225 ** The default location of PENDING_BYTE is the first byte past the 226 ** 1GB boundary. 227 ** 228 */ 229 #ifdef SQLITE_OMIT_WSD 230 # define PENDING_BYTE (0x40000000) 231 #else 232 # define PENDING_BYTE sqlite3PendingByte 233 #endif 234 #define RESERVED_BYTE (PENDING_BYTE+1) 235 #define SHARED_FIRST (PENDING_BYTE+2) 236 #define SHARED_SIZE 510 237 238 /* 239 ** Wrapper around OS specific sqlite3_os_init() function. 240 */ 241 int sqlite3OsInit(void); 242 243 /* 244 ** Functions for accessing sqlite3_file methods 245 */ 246 int sqlite3OsClose(sqlite3_file*); 247 int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset); 248 int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset); 249 int sqlite3OsTruncate(sqlite3_file*, i64 size); 250 int sqlite3OsSync(sqlite3_file*, int); 251 int sqlite3OsFileSize(sqlite3_file*, i64 *pSize); 252 int sqlite3OsLock(sqlite3_file*, int); 253 int sqlite3OsUnlock(sqlite3_file*, int); 254 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut); 255 int sqlite3OsFileControl(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 ** Functions for accessing sqlite3_vfs methods 266 */ 267 int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *); 268 int sqlite3OsDelete(sqlite3_vfs *, const char *, int); 269 int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut); 270 int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *); 271 #ifndef SQLITE_OMIT_LOAD_EXTENSION 272 void *sqlite3OsDlOpen(sqlite3_vfs *, const char *); 273 void sqlite3OsDlError(sqlite3_vfs *, int, char *); 274 void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void); 275 void sqlite3OsDlClose(sqlite3_vfs *, void *); 276 #endif /* SQLITE_OMIT_LOAD_EXTENSION */ 277 int sqlite3OsRandomness(sqlite3_vfs *, int, char *); 278 int sqlite3OsSleep(sqlite3_vfs *, int); 279 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*); 280 281 /* 282 ** Convenience functions for opening and closing files using 283 ** sqlite3_malloc() to obtain space for the file-handle structure. 284 */ 285 int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*); 286 int sqlite3OsCloseFree(sqlite3_file *); 287 288 #endif /* _SQLITE_OS_H_ */ 289