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 #if SQLITE_OS_WIN 69 # include <windows.h> 70 #endif 71 72 #if SQLITE_OS_OS2 73 # if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY) 74 # include <os2safe.h> /* has to be included before os2.h for linking to work */ 75 # endif 76 # define INCL_DOSDATETIME 77 # define INCL_DOSFILEMGR 78 # define INCL_DOSERRORS 79 # define INCL_DOSMISC 80 # define INCL_DOSPROCESS 81 # define INCL_DOSMODULEMGR 82 # define INCL_DOSSEMAPHORES 83 # include <os2.h> 84 # include <uconv.h> 85 #endif 86 87 /* 88 ** Determine if we are dealing with Windows NT. 89 ** 90 ** We ought to be able to determine if we are compiling for win98 or winNT 91 ** using the _WIN32_WINNT macro as follows: 92 ** 93 ** #if defined(_WIN32_WINNT) 94 ** # define SQLITE_OS_WINNT 1 95 ** #else 96 ** # define SQLITE_OS_WINNT 0 97 ** #endif 98 ** 99 ** However, vs2005 does not set _WIN32_WINNT by default, as it ought to, 100 ** so the above test does not work. We'll just assume that everything is 101 ** winNT unless the programmer explicitly says otherwise by setting 102 ** SQLITE_OS_WINNT to 0. 103 */ 104 #if SQLITE_OS_WIN && !defined(SQLITE_OS_WINNT) 105 # define SQLITE_OS_WINNT 1 106 #endif 107 108 /* 109 ** Determine if we are dealing with WindowsCE - which has a much 110 ** reduced API. 111 */ 112 #if defined(_WIN32_WCE) 113 # define SQLITE_OS_WINCE 1 114 #else 115 # define SQLITE_OS_WINCE 0 116 #endif 117 118 /* 119 ** Determine if we are dealing with WindowsRT (Metro) as this has a different and 120 ** incompatible API from win32. 121 */ 122 #if !defined(SQLITE_OS_WINRT) 123 # define SQLITE_OS_WINRT 0 124 #endif 125 126 /* If the SET_FULLSYNC macro is not defined above, then make it 127 ** a no-op 128 */ 129 #ifndef SET_FULLSYNC 130 # define SET_FULLSYNC(x,y) 131 #endif 132 133 /* 134 ** The default size of a disk sector 135 */ 136 #ifndef SQLITE_DEFAULT_SECTOR_SIZE 137 # define SQLITE_DEFAULT_SECTOR_SIZE 4096 138 #endif 139 140 /* 141 ** Temporary files are named starting with this prefix followed by 16 random 142 ** alphanumeric characters, and no file extension. They are stored in the 143 ** OS's standard temporary file directory, and are deleted prior to exit. 144 ** If sqlite is being embedded in another program, you may wish to change the 145 ** prefix to reflect your program's name, so that if your program exits 146 ** prematurely, old temporary files can be easily identified. This can be done 147 ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line. 148 ** 149 ** 2006-10-31: The default prefix used to be "sqlite_". But then 150 ** Mcafee started using SQLite in their anti-virus product and it 151 ** started putting files with the "sqlite" name in the c:/temp folder. 152 ** This annoyed many windows users. Those users would then do a 153 ** Google search for "sqlite", find the telephone numbers of the 154 ** developers and call to wake them up at night and complain. 155 ** For this reason, the default name prefix is changed to be "sqlite" 156 ** spelled backwards. So the temp files are still identified, but 157 ** anybody smart enough to figure out the code is also likely smart 158 ** enough to know that calling the developer will not help get rid 159 ** of the file. 160 */ 161 #ifndef SQLITE_TEMP_FILE_PREFIX 162 # define SQLITE_TEMP_FILE_PREFIX "etilqs_" 163 #endif 164 165 /* 166 ** The following values may be passed as the second argument to 167 ** sqlite3OsLock(). The various locks exhibit the following semantics: 168 ** 169 ** SHARED: Any number of processes may hold a SHARED lock simultaneously. 170 ** RESERVED: A single process may hold a RESERVED lock on a file at 171 ** any time. Other processes may hold and obtain new SHARED locks. 172 ** PENDING: A single process may hold a PENDING lock on a file at 173 ** any one time. Existing SHARED locks may persist, but no new 174 ** SHARED locks may be obtained by other processes. 175 ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks. 176 ** 177 ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a 178 ** process that requests an EXCLUSIVE lock may actually obtain a PENDING 179 ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to 180 ** sqlite3OsLock(). 181 */ 182 #define NO_LOCK 0 183 #define SHARED_LOCK 1 184 #define RESERVED_LOCK 2 185 #define PENDING_LOCK 3 186 #define EXCLUSIVE_LOCK 4 187 188 /* 189 ** File Locking Notes: (Mostly about windows but also some info for Unix) 190 ** 191 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because 192 ** those functions are not available. So we use only LockFile() and 193 ** UnlockFile(). 194 ** 195 ** LockFile() prevents not just writing but also reading by other processes. 196 ** A SHARED_LOCK is obtained by locking a single randomly-chosen 197 ** byte out of a specific range of bytes. The lock byte is obtained at 198 ** random so two separate readers can probably access the file at the 199 ** same time, unless they are unlucky and choose the same lock byte. 200 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range. 201 ** There can only be one writer. A RESERVED_LOCK is obtained by locking 202 ** a single byte of the file that is designated as the reserved lock byte. 203 ** A PENDING_LOCK is obtained by locking a designated byte different from 204 ** the RESERVED_LOCK byte. 205 ** 206 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available, 207 ** which means we can use reader/writer locks. When reader/writer locks 208 ** are used, the lock is placed on the same range of bytes that is used 209 ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme 210 ** will support two or more Win95 readers or two or more WinNT readers. 211 ** But a single Win95 reader will lock out all WinNT readers and a single 212 ** WinNT reader will lock out all other Win95 readers. 213 ** 214 ** The following #defines specify the range of bytes used for locking. 215 ** SHARED_SIZE is the number of bytes available in the pool from which 216 ** a random byte is selected for a shared lock. The pool of bytes for 217 ** shared locks begins at SHARED_FIRST. 218 ** 219 ** The same locking strategy and 220 ** byte ranges are used for Unix. This leaves open the possiblity of having 221 ** clients on win95, winNT, and unix all talking to the same shared file 222 ** and all locking correctly. To do so would require that samba (or whatever 223 ** tool is being used for file sharing) implements locks correctly between 224 ** windows and unix. I'm guessing that isn't likely to happen, but by 225 ** using the same locking range we are at least open to the possibility. 226 ** 227 ** Locking in windows is manditory. For this reason, we cannot store 228 ** actual data in the bytes used for locking. The pager never allocates 229 ** the pages involved in locking therefore. SHARED_SIZE is selected so 230 ** that all locks will fit on a single page even at the minimum page size. 231 ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE 232 ** is set high so that we don't have to allocate an unused page except 233 ** for very large databases. But one should test the page skipping logic 234 ** by setting PENDING_BYTE low and running the entire regression suite. 235 ** 236 ** Changing the value of PENDING_BYTE results in a subtly incompatible 237 ** file format. Depending on how it is changed, you might not notice 238 ** the incompatibility right away, even running a full regression test. 239 ** The default location of PENDING_BYTE is the first byte past the 240 ** 1GB boundary. 241 ** 242 */ 243 #ifdef SQLITE_OMIT_WSD 244 # define PENDING_BYTE (0x40000000) 245 #else 246 # define PENDING_BYTE sqlite3PendingByte 247 #endif 248 #define RESERVED_BYTE (PENDING_BYTE+1) 249 #define SHARED_FIRST (PENDING_BYTE+2) 250 #define SHARED_SIZE 510 251 252 /* 253 ** Wrapper around OS specific sqlite3_os_init() function. 254 */ 255 int sqlite3OsInit(void); 256 257 /* 258 ** Functions for accessing sqlite3_file methods 259 */ 260 int sqlite3OsClose(sqlite3_file*); 261 int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset); 262 int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset); 263 int sqlite3OsTruncate(sqlite3_file*, i64 size); 264 int sqlite3OsSync(sqlite3_file*, int); 265 int sqlite3OsFileSize(sqlite3_file*, i64 *pSize); 266 int sqlite3OsLock(sqlite3_file*, int); 267 int sqlite3OsUnlock(sqlite3_file*, int); 268 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut); 269 int sqlite3OsFileControl(sqlite3_file*,int,void*); 270 void sqlite3OsFileControlHint(sqlite3_file*,int,void*); 271 #define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0 272 int sqlite3OsSectorSize(sqlite3_file *id); 273 int sqlite3OsDeviceCharacteristics(sqlite3_file *id); 274 int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **); 275 int sqlite3OsShmLock(sqlite3_file *id, int, int, int); 276 void sqlite3OsShmBarrier(sqlite3_file *id); 277 int sqlite3OsShmUnmap(sqlite3_file *id, int); 278 279 280 /* 281 ** Functions for accessing sqlite3_vfs methods 282 */ 283 int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *); 284 int sqlite3OsDelete(sqlite3_vfs *, const char *, int); 285 int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut); 286 int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *); 287 #ifndef SQLITE_OMIT_LOAD_EXTENSION 288 void *sqlite3OsDlOpen(sqlite3_vfs *, const char *); 289 void sqlite3OsDlError(sqlite3_vfs *, int, char *); 290 void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void); 291 void sqlite3OsDlClose(sqlite3_vfs *, void *); 292 #endif /* SQLITE_OMIT_LOAD_EXTENSION */ 293 int sqlite3OsRandomness(sqlite3_vfs *, int, char *); 294 int sqlite3OsSleep(sqlite3_vfs *, int); 295 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*); 296 297 /* 298 ** Convenience functions for opening and closing files using 299 ** sqlite3_malloc() to obtain space for the file-handle structure. 300 */ 301 int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*); 302 int sqlite3OsCloseFree(sqlite3_file *); 303 304 #endif /* _SQLITE_OS_H_ */ 305