Restructure the OS interface yet again. This time make the OsFile object

a virtual base class which is subclassed for unix, windows, and the crash
test simulator.  Add the new file "os.c" for common os layer code.  Move
all OS-specific routines into the sqlite3Os structure. (CVS 2795)

FossilOrigin-Name: bd8740d1aecba69e1b5d64d43db07e8ad8841f07

src/os.c

@@ -0,0 +1,71 @@
+/*
+** 2005 November 29
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+** This file contains OS interface code that is common to all
+** architectures.
+*/
+#include "sqliteInt.h"
+#include "os.h"
+
+/*
+** The following routines are convenience wrappers around methods
+** of the OsFile object.  This is mostly just syntactic sugar.  All
+** of this would be completely automatic if SQLite were coded using
+** C++ instead of plain old C.
+*/
+int sqlite3OsClose(OsFile **pId){
+  OsFile *id;
+  if( pId!=0 && (id = *pId)!=0 ){
+    return id->pMethod->xClose(pId);
+  }else{
+    return SQLITE_OK;
+  }
+}
+int sqlite3OsOpenDirectory(OsFile *id, const char *zName){
+  return id->pMethod->xOpenDirectory(id, zName);
+}
+int sqlite3OsRead(OsFile *id, void *pBuf, int amt){
+  return id->pMethod->xRead(id, pBuf, amt);
+}
+int sqlite3OsWrite(OsFile *id, const void *pBuf, int amt){
+  return id->pMethod->xWrite(id, pBuf, amt);
+}
+int sqlite3OsSeek(OsFile *id, i64 offset){
+  return id->pMethod->xSeek(id, offset);
+}
+int sqlite3OsTruncate(OsFile *id, i64 size){
+  return id->pMethod->xTruncate(id, size);
+}
+int sqlite3OsSync(OsFile *id, int fullsync){
+  return id->pMethod->xSync(id, fullsync);
+}
+void sqlite3OsSetFullSync(OsFile *id, int value){
+  id->pMethod->xSetFullSync(id, value);
+}
+int sqlite3OsFileHandle(OsFile *id){
+  return id->pMethod->xFileHandle(id);
+}
+int sqlite3OsFileSize(OsFile *id, i64 *pSize){
+  return id->pMethod->xFileSize(id, pSize);
+}
+int sqlite3OsLock(OsFile *id, int lockType){
+  return id->pMethod->xLock(id, lockType);
+}
+int sqlite3OsUnlock(OsFile *id, int lockType){
+  return id->pMethod->xUnlock(id, lockType);
+}
+int sqlite3OsLockState(OsFile *id){
+  return id->pMethod->xLockState(id);
+}
+int sqlite3OsCheckReservedLock(OsFile *id){
+  return id->pMethod->xCheckReservedLock(id);
+}