SQLite

#define osFchmod    ((int(*)(int,mode_t))aSyscall[14].pCurrent)

#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
  { "fallocate",    (sqlite3_syscall_ptr)posix_fallocate,  0 },
#else
  { "fallocate",    (sqlite3_syscall_ptr)0,                0 },
#endif
#define osFallocate ((int(*)(int,off_t,off_t))aSyscall[15].pCurrent)

}; /* End of the overrideable system calls */

/*
** This is the xSetSystemCall() method of sqlite3_vfs for all of the
** "unix" VFSes.  Return SQLITE_OK opon successfully updating the
** system call pointer, or SQLITE_NOTFOUND if there is no configurable

/*
** Return the name of the first system call after zName.  If zName==NULL
** then return the name of the first system call.  Return NULL if zName
** is the last system call or if zName is not the name of a valid
** system call.
*/
static const char *unixNextSystemCall(sqlite3_vfs *p, const char *zName){
  int i = -1;

  UNUSED_PARAMETER(p);
  if( zName ){


    for(i=0; i<ArraySize(aSyscall)-1; i++){
      if( strcmp(zName, aSyscall[i].zName)==0 ) break;
    }
  }
  for(i++; i<ArraySize(aSyscall); i++){
    if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName;
  }
  return 0;
}

/*
** Retry open() calls that fail due to EINTR
*/

    if( osFstat(pFile->h, &buf) ) return SQLITE_IOERR_FSTAT;

    nSize = ((nByte+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk;
    if( nSize>(i64)buf.st_size ){
#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
      int rc;
      do{
        rc = osFallocate(pFile->h, buf.st_size, nSize-buf.st_size);
      }while( rc<0 && errno==EINTR );
      if( rc ) return SQLITE_IOERR_WRITE;
#else
      /* If the OS does not have posix_fallocate(), fake it. First use
      ** ftruncate() to set the file size, then write a single byte to
      ** the last byte in each block within the extended region. This
      ** is the same technique used by glibc to implement posix_fallocate()
      ** on systems that do not have a real fallocate() system call.

**   test_syscall errno CALL ERRNO
**     Set the value that the global "errno" is set to following a fault
**     in call CALL. Argument CALL must be one of the system call names
**     listed above (under [test_syscall install]). ERRNO is a symbolic
**     name (i.e. "EACCES"). Not all errno codes are supported. Add extra
**     to the aErrno table in function test_syscall_errno() below as 
**     required.
**
**   test_syscall reset ?SYSTEM-CALL?
**     With no argument, this is an alias for the [uninstall] command. However,
**     this command uses a VFS call of the form:
**
**       xSetSystemCall(pVfs, 0, 0);
**
**     To restore the default system calls. The [uninstall] command restores
**     each system call individually by calling (i.e.):
**
**       xSetSystemCall(pVfs, "open", 0);
**
**     With an argument, this command attempts to reset the system call named
**     by the parameter using the same method as [uninstall].
**
**   test_syscall exists SYSTEM-CALL
**     Return true if the named system call exists. Or false otherwise.
**
**   test_syscall list
**     Return a list of all system calls. The list is constructed using
**     the xNextSystemCall() VFS method.
*/

#include "sqlite3.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#ifdef SQLITE_OS_UNIX

/* From test1.c */
extern const char *sqlite3TestErrorName(int);

#include <sys/types.h>
#include <errno.h>

static struct TestSyscallGlobal {
  int bPersist;                   /* 1 for persistent errors, 0 for transient */
  int nCount;                     /* Fail after this many more calls */
  int nFail;                      /* Number of failures that have occurred */

    Tcl_WrongNumArgs(interp, 2, objv, "");
    return TCL_ERROR;
  }

  pVfs = sqlite3_vfs_find(0);
  for(i=0; aSyscall[i].zName; i++){
    if( aSyscall[i].xOrig ){
      pVfs->xSetSystemCall(pVfs, aSyscall[i].zName, 0);
      aSyscall[i].xOrig = 0;
    }
  }
  return TCL_OK;
}

static int test_syscall_reset(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3_vfs *pVfs; 
  int i;
  int rc;

  if( objc!=2 && objc!=3 ){
    Tcl_WrongNumArgs(interp, 2, objv, "");
    return TCL_ERROR;
  }

  pVfs = sqlite3_vfs_find(0);
  if( objc==2 ){
    rc = pVfs->xSetSystemCall(pVfs, 0, 0);
    for(i=0; aSyscall[i].zName; i++) aSyscall[i].xOrig = 0;
  }else{
    int nFunc;
    char *zFunc = Tcl_GetStringFromObj(objv[2], &nFunc);
    rc = pVfs->xSetSystemCall(pVfs, Tcl_GetString(objv[2]), 0);
    for(i=0; rc==SQLITE_OK && aSyscall[i].zName; i++){
      if( strlen(aSyscall[i].zName)!=nFunc ) continue;
      if( memcmp(aSyscall[i].zName, zFunc, nFunc) ) continue;
      aSyscall[i].xOrig = 0;
    }
  }
  if( rc!=SQLITE_OK ){
    Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3TestErrorName(rc), -1));
    return TCL_ERROR;
  }

  Tcl_ResetResult(interp);
  return TCL_OK;
}

static int test_syscall_exists(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3_vfs *pVfs; 
  sqlite3_syscall_ptr x;

  if( objc!=3 ){
    Tcl_WrongNumArgs(interp, 2, objv, "");
    return TCL_ERROR;
  }

  pVfs = sqlite3_vfs_find(0);
  x = pVfs->xGetSystemCall(pVfs, Tcl_GetString(objv[2]));

  Tcl_SetObjResult(interp, Tcl_NewBooleanObj(x!=0));
  return TCL_OK;
}

static int test_syscall_fault(
  void * clientData,
  Tcl_Interp *interp,
  int objc,

      objv[3], aErrno, sizeof(aErrno[0]), "errno", 0, &iErrno
  );
  if( rc!=TCL_OK ) return rc;

  aSyscall[iCall].custom_errno = aErrno[iErrno].i;
  return TCL_OK;
}

static int test_syscall_list(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  const char *zSys;
  sqlite3_vfs *pVfs; 
  Tcl_Obj *pList;

  if( objc!=2 ){
    Tcl_WrongNumArgs(interp, 2, objv, "");
    return TCL_ERROR;
  }

  pVfs = sqlite3_vfs_find(0);
  pList = Tcl_NewObj();
  Tcl_IncrRefCount(pList);
  for(zSys = pVfs->xNextSystemCall(pVfs, 0); 
      zSys!=0;
      zSys = pVfs->xNextSystemCall(pVfs, zSys)
  ){
    Tcl_ListObjAppendElement(interp, pList, Tcl_NewStringObj(zSys, -1));
  }

  Tcl_SetObjResult(interp, pList);
  Tcl_DecrRefCount(pList);
  return TCL_OK;
}

static int test_syscall(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  struct SyscallCmd {
    const char *zName;
    Tcl_ObjCmdProc *xCmd;
  } aCmd[] = {
    { "fault",     test_syscall_fault },
    { "install",   test_syscall_install },
    { "uninstall", test_syscall_uninstall },
    { "reset",     test_syscall_reset },
    { "errno",     test_syscall_errno },
    { "exists",    test_syscall_exists },
    { "list",      test_syscall_list },
    { 0, 0 }
  };
  int iCmd;
  int rc;

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUB-COMMAND ...");

# 2011 March 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.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
source $testdir/malloc_common.tcl

if {[llength [info commands test_syscall]]==0} {
  finish_test
  return
} 
set testprefix syscall


#-------------------------------------------------------------------------
# Tests for the xSetSystemCall method.
#
do_test 1.1.1 {
  list [catch { test_syscall reset open } msg] $msg
} {0 {}}
do_test 1.1.2 {
  list [catch { test_syscall reset nosuchcall } msg] $msg
} {1 SQLITE_NOTFOUND}
do_test 1.1.3 {
  list [catch { test_syscall reset open } msg] $msg
} {0 {}}
do_test 1.1.4 {
  list [catch { test_syscall reset ""} msg] $msg
} {1 SQLITE_NOTFOUND}

do_test 1.2 { test_syscall reset } {}

do_test 1.3.1 { test_syscall install {open getcwd access} } {}
do_test 1.3.2 { test_syscall reset } {}

#-------------------------------------------------------------------------
# Tests for the xGetSystemCall method.
#
do_test 2.1.1 { test_syscall exists open } 1
do_test 2.1.2 { test_syscall exists nosuchcall } 0

#-------------------------------------------------------------------------
# Tests for the xNextSystemCall method.
#
set syscall_list [list                                \
    open close access getcwd stat fstat ftruncate     \
    fcntl read pread write pwrite fchmod              \
]
if {[test_syscall exists fallocate]} {lappend syscall_list fallocate}
do_test 3.1 { test_syscall list } $syscall_list

finish_test