** See also: [sqlite3_blob_write()].
*/
int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);

/*
** CAPI3REF: Write Data Into A BLOB Incrementally
**
** ^This function is used to write data into an open [BLOB handle] from a
** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
** into the open BLOB, starting at offset iOffset.






**
** ^If the [BLOB handle] passed as the first argument was not opened for
** writing (the flags parameter to [sqlite3_blob_open()] was zero),
** this function returns [SQLITE_READONLY].
**
** ^This function may only modify the contents of the BLOB; it is
** not possible to increase the size of a BLOB using this API.
** ^If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is written.  ^If N is
** less than zero [SQLITE_ERROR] is returned and no data is written.
** The size of the BLOB (and hence the maximum value of N+iOffset)
** can be determined using the [sqlite3_blob_bytes()] interface.

**
** ^An attempt to write to an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
** before the [BLOB handle] expired are not rolled back by the
** expiration of the handle, though of course those changes might
** have been overwritten by the statement that expired the BLOB handle
** or by other independent statements.
**
** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
** Otherwise, an  [error code] or an [extended error code] is returned.)^
**
** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
**
** See also: [sqlite3_blob_read()].
*/

** See also: [sqlite3_blob_write()].
*/
int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);

/*
** CAPI3REF: Write Data Into A BLOB Incrementally
**
** ^(This function is used to write data into an open [BLOB handle] from a
** caller-supplied buffer. N bytes of data are copied from the buffer Z
** into the open BLOB, starting at offset iOffset.)^
**
** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
** Otherwise, an  [error code] or an [extended error code] is returned.)^
** ^Unless SQLITE_MISUSE is returned, this function sets the 
** [database connection] error code and message accessible via 
** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions. 
**
** ^If the [BLOB handle] passed as the first argument was not opened for
** writing (the flags parameter to [sqlite3_blob_open()] was zero),
** this function returns [SQLITE_READONLY].
**
** This function may only modify the contents of the BLOB; it is
** not possible to increase the size of a BLOB using this API.
** ^If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is written. The size of the 

** BLOB (and hence the maximum value of N+iOffset) can be determined 
** using the [sqlite3_blob_bytes()] interface. ^If N or iOffset are less 
** than zero [SQLITE_ERROR] is returned and no data is written.
**
** ^An attempt to write to an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
** before the [BLOB handle] expired are not rolled back by the
** expiration of the handle, though of course those changes might
** have been overwritten by the statement that expired the BLOB handle
** or by other independent statements.
**



** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
**
** See also: [sqlite3_blob_read()].
*/

  db = p->db;
  sqlite3_mutex_enter(db->mutex);
  v = (Vdbe*)p->pStmt;

  if( n<0 || iOffset<0 || (iOffset+n)>p->nByte ){
    /* Request is out of range. Return a transient error. */
    rc = SQLITE_ERROR;
    sqlite3Error(db, SQLITE_ERROR);
  }else if( v==0 ){
    /* If there is no statement handle, then the blob-handle has
    ** already been invalidated. Return SQLITE_ABORT in this case.
    */
    rc = SQLITE_ABORT;
  }else{
    /* Call either BtreeData() or BtreePutData(). If SQLITE_ABORT is
................................................................................
    sqlite3BtreeEnterCursor(p->pCsr);
    rc = xCall(p->pCsr, iOffset+p->iOffset, n, z);
    sqlite3BtreeLeaveCursor(p->pCsr);
    if( rc==SQLITE_ABORT ){
      sqlite3VdbeFinalize(v);
      p->pStmt = 0;
    }else{
      db->errCode = rc;
      v->rc = rc;
    }
  }

  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

/*
** Read data from a blob handle.

  db = p->db;
  sqlite3_mutex_enter(db->mutex);
  v = (Vdbe*)p->pStmt;

  if( n<0 || iOffset<0 || (iOffset+n)>p->nByte ){
    /* Request is out of range. Return a transient error. */
    rc = SQLITE_ERROR;

  }else if( v==0 ){
    /* If there is no statement handle, then the blob-handle has
    ** already been invalidated. Return SQLITE_ABORT in this case.
    */
    rc = SQLITE_ABORT;
  }else{
    /* Call either BtreeData() or BtreePutData(). If SQLITE_ABORT is
................................................................................
    sqlite3BtreeEnterCursor(p->pCsr);
    rc = xCall(p->pCsr, iOffset+p->iOffset, n, z);
    sqlite3BtreeLeaveCursor(p->pCsr);
    if( rc==SQLITE_ABORT ){
      sqlite3VdbeFinalize(v);
      p->pStmt = 0;
    }else{

      v->rc = rc;
    }
  }
  sqlite3Error(db, rc);
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}

/*
** Read data from a blob handle.

# 2014 October 30
#
# 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
set testprefix e_blobwrite

#--------------------------------------------------------------------------
# EVIDENCE-OF: R-62898-22698 This function is used to write data into an
# open BLOB handle from a caller-supplied buffer. N bytes of data are
# copied from the buffer Z into the open BLOB, starting at offset
# iOffset.
#
set dots [string repeat . 40]
do_execsql_test 1.0 {
  CREATE TABLE t1(a INTEGER PRIMARY KEY, t TEXT);
  INSERT INTO t1 VALUES(-1, $dots);
  INSERT INTO t1 VALUES(-2, $dots);
  INSERT INTO t1 VALUES(-3, $dots);
  INSERT INTO t1 VALUES(-4, $dots);
  INSERT INTO t1 VALUES(-5, $dots);
  INSERT INTO t1 VALUES(-6, $dots);
}

proc blob_write_test {tn id iOffset blob nData final} {
  sqlite3_blob_open db main t1 t $id 1 B

  # EVIDENCE-OF: R-45864-01884 On success, sqlite3_blob_write() returns
  # SQLITE_OK. Otherwise, an error code or an extended error code is
  # returned.
  #
  #   This block tests the SQLITE_OK case in the requirement above (the
  #   Tcl sqlite3_blob_write() wrapper uses an empty string in place of
  #   "SQLITE_OK"). The error cases are tested by the "blob_write_error_test"
  #   tests below.
  #
  set res [sqlite3_blob_write $B $iOffset $blob $nData]
  uplevel [list do_test $tn.1 [list set {} $res] {}]

  sqlite3_blob_close $B
  uplevel [list do_execsql_test $tn.3 "SELECT t FROM t1 WHERE a=$id" $final]
}

set blob "0123456789012345678901234567890123456789"
blob_write_test 1.1 -1 0 $blob 10  { 0123456789.............................. }
blob_write_test 1.2 -2 8 $blob 10  { ........0123456789...................... }
blob_write_test 1.3 -3 8 $blob 1   { ........0............................... }
blob_write_test 1.4 -4 18 $blob 22 { ..................0123456789012345678901 }
blob_write_test 1.5 -5 18 $blob 0  { ........................................ }
blob_write_test 1.6 -6 0 $blob 40  { 0123456789012345678901234567890123456789 }


proc blob_write_error_test {tn B iOffset blob nData errcode errmsg} {

  # In cases where the underlying sqlite3_blob_write() function returns
  # SQLITE_OK, the Tcl wrapper returns an empty string. If the underlying
  # function returns an error, the Tcl wrapper throws an exception with
  # the error code as the Tcl exception message.
  #
  if {$errcode=="SQLITE_OK"} {
    set ret ""
    set isError 0
  } else {
    set ret $errcode
    set isError 1
  }

  set cmd [list sqlite3_blob_write $B $iOffset $blob $nData]
  uplevel [list do_test $tn.1 [subst -nocommands {
    list [catch {$cmd} msg] [set msg]              
  }] [list $isError $ret]]

  # EVIDENCE-OF: R-34782-18311 Unless SQLITE_MISUSE is returned, this
  # function sets the database connection error code and message
  # accessible via sqlite3_errcode() and sqlite3_errmsg() and related
  # functions.
  #
  if {$errcode == "SQLITE_MISUSE"} { error "test proc misuse!" }
  uplevel [list do_test $tn.2 [list sqlite3_errcode db] $errcode]
  uplevel [list do_test $tn.3 [list sqlite3_errmsg db] $errmsg]
}

do_execsql_test 2.0 {
  CREATE TABLE t2(a TEXT, b INTEGER PRIMARY KEY);
  INSERT INTO t2 VALUES($dots, 43);
  INSERT INTO t2 VALUES($dots, 44);
  INSERT INTO t2 VALUES($dots, 45);
}

# EVIDENCE-OF: R-63341-57517 If the BLOB handle passed as the first
# argument was not opened for writing (the flags parameter to
# sqlite3_blob_open() was zero), this function returns SQLITE_READONLY.
#
sqlite3_blob_open db main t2 a 43 0 B
blob_write_error_test 2.1 $B 0 $blob 10   \
    SQLITE_READONLY {attempt to write a readonly database}
sqlite3_blob_close $B

# EVIDENCE-OF: R-29804-27366 If offset iOffset is less than N bytes from
# the end of the BLOB, SQLITE_ERROR is returned and no data is written.
#
sqlite3_blob_open db main t2 a 44 3 B
blob_write_error_test 2.2.1 $B 31 $blob 10   \
    SQLITE_ERROR {SQL logic error or missing database}

# Make a successful write to the blob handle. This shows that the
# sqlite3_errcode() and sqlite3_errmsg() values are set even if the
# blob_write() call succeeds (see requirement in the [blob_write_error_test]
# proc).
blob_write_error_test 2.2.1 $B 30 $blob 10 SQLITE_OK {not an error}

# EVIDENCE-OF: R-58570-38916 If N or iOffset are less than zero
# SQLITE_ERROR is returned and no data is written.
#
blob_write_error_test 2.2.2 $B 31 $blob -1   \
    SQLITE_ERROR {SQL logic error or missing database}
blob_write_error_test 2.2.3 $B 20 $blob 10 SQLITE_OK {not an error}
blob_write_error_test 2.2.4 $B -1 $blob 10   \
    SQLITE_ERROR {SQL logic error or missing database}
sqlite3_blob_close $B

# EVIDENCE-OF: R-20958-54138 An attempt to write to an expired BLOB
# handle fails with an error code of SQLITE_ABORT.
#
do_test 2.3 {
  sqlite3_blob_open db main t2 a 43 0 B
  execsql { DELETE FROM t2 WHERE b=43 }
} {}
blob_write_error_test 2.3.1 $B 5 $blob 5 \
    SQLITE_ABORT {callback requested query abort}
do_test 2.3.2 {
  execsql { SELECT 1, 2, 3 }
  sqlite3_errcode db
} {SQLITE_OK}
blob_write_error_test 2.3.3 $B 5 $blob 5 \
    SQLITE_ABORT {callback requested query abort}
sqlite3_blob_close $B

# EVIDENCE-OF: R-08382-59936 Writes to the BLOB that occurred before the
# BLOB handle expired are not rolled back by the expiration of the
# handle, though of course those changes might have been overwritten by
# the statement that expired the BLOB handle or by other independent
# statements.
#
#   3.1.*: not rolled back, 
#   3.2.*: overwritten.
#
do_execsql_test 3.0 {
  CREATE TABLE t3(i INTEGER PRIMARY KEY, j TEXT, k TEXT);
  INSERT INTO t3 VALUES(1, $dots, $dots);
  INSERT INTO t3 VALUES(2, $dots, $dots);
  SELECT * FROM t3 WHERE i=1;
} {
  1
  ........................................
  ........................................
}
sqlite3_blob_open db main t3 j 1 1 B
blob_write_error_test 3.1.1 $B 5 $blob 10 SQLITE_OK {not an error}
do_execsql_test 3.1.2 {
  UPDATE t3 SET k = 'xyz' WHERE i=1;
  SELECT * FROM t3 WHERE i=1;
} {
  1 .....0123456789......................... xyz
}
blob_write_error_test 3.1.3 $B 15 $blob 10 \
    SQLITE_ABORT {callback requested query abort}
sqlite3_blob_close $B
do_execsql_test 3.1.4 {
  SELECT * FROM t3 WHERE i=1;
} {
  1 .....0123456789......................... xyz
}

sqlite3_blob_open db main t3 j 2 1 B
blob_write_error_test 3.2.1 $B 5 $blob 10 SQLITE_OK {not an error}
do_execsql_test 3.2.2 {
  UPDATE t3 SET j = 'xyz' WHERE i=2;
  SELECT * FROM t3 WHERE i=2;
} {
  2 xyz ........................................
}
blob_write_error_test 3.2.3 $B 15 $blob 10 \
    SQLITE_ABORT {callback requested query abort}
sqlite3_blob_close $B
do_execsql_test 3.2.4 {
  SELECT * FROM t3 WHERE i=2;
} {
  2 xyz ........................................
}



finish_test