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 WindowsCE - which has a much 70 ** reduced API. 71 */ 72 #if defined(_WIN32_WCE) 73 # define SQLITE_OS_WINCE 1 74 #else 75 # define SQLITE_OS_WINCE 0 76 #endif 77 78 79 /* 80 ** Define the maximum size of a temporary filename 81 */ 82 #if SQLITE_OS_WIN 83 # include <windows.h> 84 # define SQLITE_TEMPNAME_SIZE (MAX_PATH+50) 85 #elif SQLITE_OS_OS2 86 # if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY) 87 # include <os2safe.h> /* has to be included before os2.h for linking to work */ 88 # endif 89 # define INCL_DOSDATETIME 90 # define INCL_DOSFILEMGR 91 # define INCL_DOSERRORS 92 # define INCL_DOSMISC 93 # define INCL_DOSPROCESS 94 # define INCL_DOSMODULEMGR 95 # define INCL_DOSSEMAPHORES 96 # include <os2.h> 97 # include <uconv.h> 98 # define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP) 99 #else 100 # define SQLITE_TEMPNAME_SIZE 200 101 #endif 102 103 /* If the SET_FULLSYNC macro is not defined above, then make it 104 ** a no-op 105 */ 106 #ifndef SET_FULLSYNC 107 # define SET_FULLSYNC(x,y) 108 #endif 109 110 /* 111 ** The default size of a disk sector 112 */ 113 #ifndef SQLITE_DEFAULT_SECTOR_SIZE 114 # define SQLITE_DEFAULT_SECTOR_SIZE 512 115 #endif 116 117 /* 118 ** Temporary files are named starting with this prefix followed by 16 random 119 ** alphanumeric characters, and no file extension. They are stored in the 120 ** OS's standard temporary file directory, and are deleted prior to exit. 121 ** If sqlite is being embedded in another program, you may wish to change the 122 ** prefix to reflect your program's name, so that if your program exits 123 ** prematurely, old temporary files can be easily identified. This can be done 124 ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line. 125 ** 126 ** 2006-10-31: The default prefix used to be "sqlite_". But then 127 ** Mcafee started using SQLite in their anti-virus product and it 128 ** started putting files with the "sqlite" name in the c:/temp folder. 129 ** This annoyed many windows users. Those users would then do a 130 ** Google search for "sqlite", find the telephone numbers of the 131 ** developers and call to wake them up at night and complain. 132 ** For this reason, the default name prefix is changed to be "sqlite" 133 ** spelled backwards. So the temp files are still identified, but 134 ** anybody smart enough to figure out the code is also likely smart 135 ** enough to know that calling the developer will not help get rid 136 ** of the file. 137 */ 138 #ifndef SQLITE_TEMP_FILE_PREFIX 139 # define SQLITE_TEMP_FILE_PREFIX "etilqs_" 140 #endif 141 142 /* 143 ** The following values may be passed as the second argument to 144 ** sqlite3OsLock(). The various locks exhibit the following semantics: 145 ** 146 ** SHARED: Any number of processes may hold a SHARED lock simultaneously. 147 ** RESERVED: A single process may hold a RESERVED lock on a file at 148 ** any time. Other processes may hold and obtain new SHARED locks. 149 ** PENDING: A single process may hold a PENDING lock on a file at 150 ** any one time. Existing SHARED locks may persist, but no new 151 ** SHARED locks may be obtained by other processes. 152 ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks. 153 ** 154 ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a 155 ** process that requests an EXCLUSIVE lock may actually obtain a PENDING 156 ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to 157 ** sqlite3OsLock(). 158 */ 159 #define NO_LOCK 0 160 #define SHARED_LOCK 1 161 #define RESERVED_LOCK 2 162 #define PENDING_LOCK 3 163 #define EXCLUSIVE_LOCK 4 164 165 /* 166 ** File Locking Notes: (Mostly about windows but also some info for Unix) 167 ** 168 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because 169 ** those functions are not available. So we use only LockFile() and 170 ** UnlockFile(). 171 ** 172 ** LockFile() prevents not just writing but also reading by other processes. 173 ** A SHARED_LOCK is obtained by locking a single randomly-chosen 174 ** byte out of a specific range of bytes. The lock byte is obtained at 175 ** random so two separate readers can probably access the file at the 176 ** same time, unless they are unlucky and choose the same lock byte. 177 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range. 178 ** There can only be one writer. A RESERVED_LOCK is obtained by locking 179 ** a single byte of the file that is designated as the reserved lock byte. 180 ** A PENDING_LOCK is obtained by locking a designated byte different from 181 ** the RESERVED_LOCK byte. 182 ** 183 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available, 184 ** which means we can use reader/writer locks. When reader/writer locks 185 ** are used, the lock is placed on the same range of bytes that is used 186 ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme 187 ** will support two or more Win95 readers or two or more WinNT readers. 188 ** But a single Win95 reader will lock out all WinNT readers and a single 189 ** WinNT reader will lock out all other Win95 readers. 190 ** 191 ** The following #defines specify the range of bytes used for locking. 192 ** SHARED_SIZE is the number of bytes available in the pool from which 193 ** a random byte is selected for a shared lock. The pool of bytes for 194 ** shared locks begins at SHARED_FIRST. 195 ** 196 ** The same locking strategy and 197 ** byte ranges are used for Unix. This leaves open the possiblity of having 198 ** clients on win95, winNT, and unix all talking to the same shared file 199 ** and all locking correctly. To do so would require that samba (or whatever 200 ** tool is being used for file sharing) implements locks correctly between 201 ** windows and unix. I'm guessing that isn't likely to happen, but by 202 ** using the same locking range we are at least open to the possibility. 203 ** 204 ** Locking in windows is manditory. For this reason, we cannot store 205 ** actual data in the bytes used for locking. The pager never allocates 206 ** the pages involved in locking therefore. SHARED_SIZE is selected so 207 ** that all locks will fit on a single page even at the minimum page size. 208 ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE 209 ** is set high so that we don't have to allocate an unused page except 210 ** for very large databases. But one should test the page skipping logic 211 ** by setting PENDING_BYTE low and running the entire regression suite. 212 ** 213 ** Changing the value of PENDING_BYTE results in a subtly incompatible 214 ** file format. Depending on how it is changed, you might not notice 215 ** the incompatibility right away, even running a full regression test. 216 ** The default location of PENDING_BYTE is the first byte past the 217 ** 1GB boundary. 218 ** 219 */ 220 #ifdef SQLITE_OMIT_WSD 221 # define PENDING_BYTE (0x40000000) 222 #else 223 # define PENDING_BYTE sqlite3PendingByte 224 #endif 225 #define RESERVED_BYTE (PENDING_BYTE+1) 226 #define SHARED_FIRST (PENDING_BYTE+2) 227 #define SHARED_SIZE 510 228 229 /* 230 ** Wrapper around OS specific sqlite3_os_init() function. 231 */ 232 int sqlite3OsInit(void); 233 234 /* 235 ** Functions for accessing sqlite3_file methods 236 */ 237 int sqlite3OsClose(sqlite3_file*); 238 int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset); 239 int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset); 240 int sqlite3OsTruncate(sqlite3_file*, i64 size); 241 int sqlite3OsSync(sqlite3_file*, int); 242 int sqlite3OsFileSize(sqlite3_file*, i64 *pSize); 243 int sqlite3OsLock(sqlite3_file*, int); 244 int sqlite3OsUnlock(sqlite3_file*, int); 245 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut); 246 int sqlite3OsFileControl(sqlite3_file*,int,void*); 247 #define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0 248 int sqlite3OsSectorSize(sqlite3_file *id); 249 int sqlite3OsDeviceCharacteristics(sqlite3_file *id); 250 int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **); 251 int sqlite3OsShmLock(sqlite3_file *id, int, int, int); 252 void sqlite3OsShmBarrier(sqlite3_file *id); 253 int sqlite3OsShmUnmap(sqlite3_file *id, int); 254 255 /* 256 ** Functions for accessing sqlite3_vfs methods 257 */ 258 int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *); 259 int sqlite3OsDelete(sqlite3_vfs *, const char *, int); 260 int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut); 261 int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *); 262 #ifndef SQLITE_OMIT_LOAD_EXTENSION 263 void *sqlite3OsDlOpen(sqlite3_vfs *, const char *); 264 void sqlite3OsDlError(sqlite3_vfs *, int, char *); 265 void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void); 266 void sqlite3OsDlClose(sqlite3_vfs *, void *); 267 #endif /* SQLITE_OMIT_LOAD_EXTENSION */ 268 int sqlite3OsRandomness(sqlite3_vfs *, int, char *); 269 int sqlite3OsSleep(sqlite3_vfs *, int); 270 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*); 271 272 /* 273 ** Convenience functions for opening and closing files using 274 ** sqlite3_malloc() to obtain space for the file-handle structure. 275 */ 276 int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*); 277 int sqlite3OsCloseFree(sqlite3_file *); 278 279 #endif /* _SQLITE_OS_H_ */ 280