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, 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 # else 37 # undef SQLITE_OS_OTHER 38 # endif 39 #endif 40 #if !defined(SQLITE_OS_UNIX) && !defined(SQLITE_OS_OTHER) 41 # define SQLITE_OS_OTHER 0 42 # ifndef SQLITE_OS_WIN 43 # if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__) 44 # define SQLITE_OS_WIN 1 45 # define SQLITE_OS_UNIX 0 46 # else 47 # define SQLITE_OS_WIN 0 48 # define SQLITE_OS_UNIX 1 49 # endif 50 # else 51 # define SQLITE_OS_UNIX 0 52 # endif 53 #else 54 # ifndef SQLITE_OS_WIN 55 # define SQLITE_OS_WIN 0 56 # endif 57 #endif 58 59 #if SQLITE_OS_WIN 60 # include <windows.h> 61 #endif 62 63 /* 64 ** Determine if we are dealing with Windows NT. 65 ** 66 ** We ought to be able to determine if we are compiling for win98 or winNT 67 ** using the _WIN32_WINNT macro as follows: 68 ** 69 ** #if defined(_WIN32_WINNT) 70 ** # define SQLITE_OS_WINNT 1 71 ** #else 72 ** # define SQLITE_OS_WINNT 0 73 ** #endif 74 ** 75 ** However, vs2005 does not set _WIN32_WINNT by default, as it ought to, 76 ** so the above test does not work. We'll just assume that everything is 77 ** winNT unless the programmer explicitly says otherwise by setting 78 ** SQLITE_OS_WINNT to 0. 79 */ 80 #if SQLITE_OS_WIN && !defined(SQLITE_OS_WINNT) 81 # define SQLITE_OS_WINNT 1 82 #endif 83 84 /* 85 ** Determine if we are dealing with WindowsCE - which has a much 86 ** reduced API. 87 */ 88 #if defined(_WIN32_WCE) 89 # define SQLITE_OS_WINCE 1 90 #else 91 # define SQLITE_OS_WINCE 0 92 #endif 93 94 /* 95 ** Determine if we are dealing with WinRT, which provides only a subset of 96 ** the full Win32 API. 97 */ 98 #if !defined(SQLITE_OS_WINRT) 99 # define SQLITE_OS_WINRT 0 100 #endif 101 102 /* 103 ** When compiled for WinCE or WinRT, there is no concept of the current 104 ** directory. 105 */ 106 #if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT 107 # define SQLITE_CURDIR 1 108 #endif 109 110 /* If the SET_FULLSYNC macro is not defined above, then make it 111 ** a no-op 112 */ 113 #ifndef SET_FULLSYNC 114 # define SET_FULLSYNC(x,y) 115 #endif 116 117 /* 118 ** The default size of a disk sector 119 */ 120 #ifndef SQLITE_DEFAULT_SECTOR_SIZE 121 # define SQLITE_DEFAULT_SECTOR_SIZE 4096 122 #endif 123 124 /* 125 ** Temporary files are named starting with this prefix followed by 16 random 126 ** alphanumeric characters, and no file extension. They are stored in the 127 ** OS's standard temporary file directory, and are deleted prior to exit. 128 ** If sqlite is being embedded in another program, you may wish to change the 129 ** prefix to reflect your program's name, so that if your program exits 130 ** prematurely, old temporary files can be easily identified. This can be done 131 ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line. 132 ** 133 ** 2006-10-31: The default prefix used to be "sqlite_". But then 134 ** Mcafee started using SQLite in their anti-virus product and it 135 ** started putting files with the "sqlite" name in the c:/temp folder. 136 ** This annoyed many windows users. Those users would then do a 137 ** Google search for "sqlite", find the telephone numbers of the 138 ** developers and call to wake them up at night and complain. 139 ** For this reason, the default name prefix is changed to be "sqlite" 140 ** spelled backwards. So the temp files are still identified, but 141 ** anybody smart enough to figure out the code is also likely smart 142 ** enough to know that calling the developer will not help get rid 143 ** of the file. 144 */ 145 #ifndef SQLITE_TEMP_FILE_PREFIX 146 # define SQLITE_TEMP_FILE_PREFIX "etilqs_" 147 #endif 148 149 /* 150 ** The following values may be passed as the second argument to 151 ** sqlite3OsLock(). The various locks exhibit the following semantics: 152 ** 153 ** SHARED: Any number of processes may hold a SHARED lock simultaneously. 154 ** RESERVED: A single process may hold a RESERVED lock on a file at 155 ** any time. Other processes may hold and obtain new SHARED locks. 156 ** PENDING: A single process may hold a PENDING lock on a file at 157 ** any one time. Existing SHARED locks may persist, but no new 158 ** SHARED locks may be obtained by other processes. 159 ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks. 160 ** 161 ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a 162 ** process that requests an EXCLUSIVE lock may actually obtain a PENDING 163 ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to 164 ** sqlite3OsLock(). 165 */ 166 #define NO_LOCK 0 167 #define SHARED_LOCK 1 168 #define RESERVED_LOCK 2 169 #define PENDING_LOCK 3 170 #define EXCLUSIVE_LOCK 4 171 172 /* 173 ** File Locking Notes: (Mostly about windows but also some info for Unix) 174 ** 175 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because 176 ** those functions are not available. So we use only LockFile() and 177 ** UnlockFile(). 178 ** 179 ** LockFile() prevents not just writing but also reading by other processes. 180 ** A SHARED_LOCK is obtained by locking a single randomly-chosen 181 ** byte out of a specific range of bytes. The lock byte is obtained at 182 ** random so two separate readers can probably access the file at the 183 ** same time, unless they are unlucky and choose the same lock byte. 184 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range. 185 ** There can only be one writer. A RESERVED_LOCK is obtained by locking 186 ** a single byte of the file that is designated as the reserved lock byte. 187 ** A PENDING_LOCK is obtained by locking a designated byte different from 188 ** the RESERVED_LOCK byte. 189 ** 190 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available, 191 ** which means we can use reader/writer locks. When reader/writer locks 192 ** are used, the lock is placed on the same range of bytes that is used 193 ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme 194 ** will support two or more Win95 readers or two or more WinNT readers. 195 ** But a single Win95 reader will lock out all WinNT readers and a single 196 ** WinNT reader will lock out all other Win95 readers. 197 ** 198 ** The following #defines specify the range of bytes used for locking. 199 ** SHARED_SIZE is the number of bytes available in the pool from which 200 ** a random byte is selected for a shared lock. The pool of bytes for 201 ** shared locks begins at SHARED_FIRST. 202 ** 203 ** The same locking strategy and 204 ** byte ranges are used for Unix. This leaves open the possiblity of having 205 ** clients on win95, winNT, and unix all talking to the same shared file 206 ** and all locking correctly. To do so would require that samba (or whatever 207 ** tool is being used for file sharing) implements locks correctly between 208 ** windows and unix. I'm guessing that isn't likely to happen, but by 209 ** using the same locking range we are at least open to the possibility. 210 ** 211 ** Locking in windows is manditory. For this reason, we cannot store 212 ** actual data in the bytes used for locking. The pager never allocates 213 ** the pages involved in locking therefore. SHARED_SIZE is selected so 214 ** that all locks will fit on a single page even at the minimum page size. 215 ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE 216 ** is set high so that we don't have to allocate an unused page except 217 ** for very large databases. But one should test the page skipping logic 218 ** by setting PENDING_BYTE low and running the entire regression suite. 219 ** 220 ** Changing the value of PENDING_BYTE results in a subtly incompatible 221 ** file format. Depending on how it is changed, you might not notice 222 ** the incompatibility right away, even running a full regression test. 223 ** The default location of PENDING_BYTE is the first byte past the 224 ** 1GB boundary. 225 ** 226 */ 227 #ifdef SQLITE_OMIT_WSD 228 # define PENDING_BYTE (0x40000000) 229 #else 230 # define PENDING_BYTE sqlite3PendingByte 231 #endif 232 #define RESERVED_BYTE (PENDING_BYTE+1) 233 #define SHARED_FIRST (PENDING_BYTE+2) 234 #define SHARED_SIZE 510 235 236 /* 237 ** Wrapper around OS specific sqlite3_os_init() function. 238 */ 239 int sqlite3OsInit(void); 240 241 /* 242 ** Functions for accessing sqlite3_file methods 243 */ 244 int sqlite3OsClose(sqlite3_file*); 245 int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset); 246 int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset); 247 int sqlite3OsTruncate(sqlite3_file*, i64 size); 248 int sqlite3OsSync(sqlite3_file*, int); 249 int sqlite3OsFileSize(sqlite3_file*, i64 *pSize); 250 int sqlite3OsLock(sqlite3_file*, int); 251 int sqlite3OsUnlock(sqlite3_file*, int); 252 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut); 253 int sqlite3OsFileControl(sqlite3_file*,int,void*); 254 void sqlite3OsFileControlHint(sqlite3_file*,int,void*); 255 #define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0 256 int sqlite3OsSectorSize(sqlite3_file *id); 257 int sqlite3OsDeviceCharacteristics(sqlite3_file *id); 258 int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **); 259 int sqlite3OsShmLock(sqlite3_file *id, int, int, int); 260 void sqlite3OsShmBarrier(sqlite3_file *id); 261 int sqlite3OsShmUnmap(sqlite3_file *id, int); 262 263 264 /* 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