/*
** 2022-11-18
**
** 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 is a SQLite extension for converting in either direction
** between a (binary) blob and base64 text. Base64 can transit a
** sane USASCII channel unmolested. It also plays nicely in CSV or
** written as TCL brace-enclosed literals or SQL string literals,
** and can be used unmodified in XML-like documents.
**
** This is an independent implementation of conversions specified in
** RFC 4648, done on the above date by the author (Larry Brasfield)
** who thereby has the right to put this into the public domain.
**
** The conversions meet RFC 4648 requirements, provided that this
** C source specifies that line-feeds are included in the encoded
** data to limit visible line lengths to 72 characters and to
** terminate any encoded blob having non-zero length.
**
** Length limitations are not imposed except that the runtime
** SQLite string or blob length limits are respected. Otherwise,
** any length binary sequence can be represented and recovered.
** Generated base64 sequences, with their line-feeds included,
** can be concatenated; the result converted back to binary will
** be the concatenation of the represented binary sequences.
**
** This SQLite3 extension creates a function, base64(x), which
** either: converts text x containing base64 to a returned blob;
** or converts a blob x to returned text containing base64. An
** error will be thrown for other input argument types.
**
** This code relies on UTF-8 encoding only with respect to the
** meaning of the first 128 (7-bit) codes matching that of USASCII.
** It will fail miserably if somehow made to try to convert EBCDIC.
** Because it is table-driven, it could be enhanced to handle that,
** but the world and SQLite have moved on from that anachronism.
**
** To build the extension:
** Set shell variable SQDIR=<your favorite SQLite checkout directory>
** *Nix: gcc -O2 -shared -I$SQDIR -fPIC -o base64.so base64.c
** OSX: gcc -O2 -dynamiclib -fPIC -I$SQDIR -o base64.dylib base64.c
** Win32: gcc -O2 -shared -I%SQDIR% -o base64.dll base64.c
** Win32: cl /Os -I%SQDIR% base64.c -link -dll -out:base64.dll
*/
#include <assert.h>
#include "sqlite3ext.h"
#ifndef deliberate_fall_through
/* Quiet some compilers about some of our intentional code. */
# if GCC_VERSION>=7000000
# define deliberate_fall_through __attribute__((fallthrough));
# else
# define deliberate_fall_through
# endif
#endif
SQLITE_EXTENSION_INIT1;
#define PC 0x80 /* pad character */
#define WS 0x81 /* whitespace */
#define ND 0x82 /* Not above or digit-value */
#define PAD_CHAR '='
#ifndef U8_TYPEDEF
typedef unsigned char u8;
#define U8_TYPEDEF
#endif
/* Decoding table, ASCII (7-bit) value to base 64 digit value or other */
static const u8 b64DigitValues[128] = {
/* HT LF VT FF CR */
ND,ND,ND,ND, ND,ND,ND,ND, ND,WS,WS,WS, WS,WS,ND,ND,
/* US */
ND,ND,ND,ND, ND,ND,ND,ND, ND,ND,ND,ND, ND,ND,ND,ND,
/*sp + / */
WS,ND,ND,ND, ND,ND,ND,ND, ND,ND,ND,62, ND,ND,ND,63,
/* 0 1 5 9 = */
52,53,54,55, 56,57,58,59, 60,61,ND,ND, ND,PC,ND,ND,
/* A O */
ND, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11,12,13,14,
/* P Z */
15,16,17,18, 19,20,21,22, 23,24,25,ND, ND,ND,ND,ND,
/* a o */
ND,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
/* p z */
41,42,43,44, 45,46,47,48, 49,50,51,ND, ND,ND,ND,ND
};
static const char b64Numerals[64+1]
= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
#define BX_DV_PROTO(c) \
((((u8)(c))<0x80)? (u8)(b64DigitValues[(u8)(c)]) : 0x80)
#define IS_BX_DIGIT(bdp) (((u8)(bdp))<0x80)
#define IS_BX_WS(bdp) ((bdp)==WS)
#define IS_BX_PAD(bdp) ((bdp)==PC)
#define BX_NUMERAL(dv) (b64Numerals[(u8)(dv)])
/* Width of base64 lines. Should be an integer multiple of 4. */
#define B64_DARK_MAX 72
/* Encode a byte buffer into base64 text with linefeeds appended to limit
** encoded group lengths to B64_DARK_MAX or to terminate the last group.
*/
static char* toBase64( u8 *pIn, int nbIn, char *pOut ){
int nCol = 0;
while( nbIn >= 3 ){
/* Do the bit-shuffle, exploiting unsigned input to avoid masking. */
pOut[0] = BX_NUMERAL(pIn[0]>>2);
pOut[1] = BX_NUMERAL(((pIn[0]<<4)|(pIn[1]>>4))&0x3f);
pOut[2] = BX_NUMERAL(((pIn[1]&0xf)<<2)|(pIn[2]>>6));
pOut[3] = BX_NUMERAL(pIn[2]&0x3f);
pOut += 4;
nbIn -= 3;
pIn += 3;
if( (nCol += 4)>=B64_DARK_MAX || nbIn<=0 ){
*pOut++ = '\n';
nCol = 0;
}
}
if( nbIn > 0 ){
signed char nco = nbIn+1;
int nbe;
unsigned long qv = *pIn++;
for( nbe=1; nbe<3; ++nbe ){
qv <<= 8;
if( nbe<nbIn ) qv |= *pIn++;
}
for( nbe=3; nbe>=0; --nbe ){
char ce = (nbe<nco)? BX_NUMERAL((u8)(qv & 0x3f)) : PAD_CHAR;
qv >>= 6;
pOut[nbe] = ce;
}
pOut += 4;
*pOut++ = '\n';
}
*pOut = 0;
return pOut;
}
/* Skip over text which is not base64 numeral(s). */
static char * skipNonB64( char *s, int nc ){
char c;
while( nc-- > 0 && (c = *s) && !IS_BX_DIGIT(BX_DV_PROTO(c)) ) ++s;
return s;
}
/* Decode base64 text into a byte buffer. */
static u8* fromBase64( char *pIn, int ncIn, u8 *pOut ){
if( ncIn>0 && pIn[ncIn-1]=='\n' ) --ncIn;
while( ncIn>0 && *pIn!=PAD_CHAR ){
static signed char nboi[] = { 0, 0, 1, 2, 3 };
char *pUse = skipNonB64(pIn, ncIn);
unsigned long qv = 0L;
int nti, nbo, nac;
ncIn -= (pUse - pIn);
pIn = pUse;
nti = (ncIn>4)? 4 : ncIn;
ncIn -= nti;
nbo = nboi[nti];
if( nbo==0 ) break;
for( nac=0; nac<4; ++nac ){
char c = (nac<nti)? *pIn++ : b64Numerals[0];
u8 bdp = BX_DV_PROTO(c);
switch( bdp ){
case ND:
/* Treat dark non-digits as pad, but they terminate decode too. */
ncIn = 0;
deliberate_fall_through;
case WS:
/* Treat whitespace as pad and terminate this group.*/
nti = nac;
deliberate_fall_through;
case PC:
bdp = 0;
--nbo;
deliberate_fall_through;
default: /* bdp is the digit value. */
qv = qv<<6 | bdp;
break;
}
}
switch( nbo ){
case 3:
pOut[2] = (qv) & 0xff;
case 2:
pOut[1] = (qv>>8) & 0xff;
case 1:
pOut[0] = (qv>>16) & 0xff;
}
pOut += nbo;
}
return pOut;
}
/* This function does the work for the SQLite base64(x) UDF. */
static void base64(sqlite3_context *context, int na, sqlite3_value *av[]){
int nb, nc, nv = sqlite3_value_bytes(av[0]);
int nvMax = sqlite3_limit(sqlite3_context_db_handle(context),
SQLITE_LIMIT_LENGTH, -1);
char *cBuf;
u8 *bBuf;
assert(na==1);
switch( sqlite3_value_type(av[0]) ){
case SQLITE_BLOB:
nb = nv;
nc = 4*(nv+2/3); /* quads needed */
nc += (nc+(B64_DARK_MAX-1))/B64_DARK_MAX + 1; /* LFs and a 0-terminator */
if( nvMax < nc ){
sqlite3_result_error(context, "blob expanded to base64 too big", -1);
return;
}
bBuf = (u8*)sqlite3_value_blob(av[0]);
if( !bBuf ){
if( SQLITE_NOMEM==sqlite3_errcode(sqlite3_context_db_handle(context)) ){
goto memFail;
}
sqlite3_result_text(context,"",-1,SQLITE_STATIC);
break;
}
cBuf = sqlite3_malloc(nc);
if( !cBuf ) goto memFail;
nc = (int)(toBase64(bBuf, nb, cBuf) - cBuf);
sqlite3_result_text(context, cBuf, nc, sqlite3_free);
break;
case SQLITE_TEXT:
nc = nv;
nb = 3*((nv+3)/4); /* may overestimate due to LF and padding */
if( nvMax < nb ){
sqlite3_result_error(context, "blob from base64 may be too big", -1);
return;
}else if( nb<1 ){
nb = 1;
}
cBuf = (char *)sqlite3_value_text(av[0]);
if( !cBuf ){
if( SQLITE_NOMEM==sqlite3_errcode(sqlite3_context_db_handle(context)) ){
goto memFail;
}
sqlite3_result_zeroblob(context, 0);
break;
}
bBuf = sqlite3_malloc(nb);
if( !bBuf ) goto memFail;
nb = (int)(fromBase64(cBuf, nc, bBuf) - bBuf);
sqlite3_result_blob(context, bBuf, nb, sqlite3_free);
break;
default:
sqlite3_result_error(context, "base64 accepts only blob or text", -1);
return;
}
return;
memFail:
sqlite3_result_error(context, "base64 OOM", -1);
}
/*
** Establish linkage to running SQLite library.
*/
#ifndef SQLITE_SHELL_EXTFUNCS
#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_base_init
#else
static int sqlite3_base64_init
#endif
(sqlite3 *db, char **pzErr, const sqlite3_api_routines *pApi){
SQLITE_EXTENSION_INIT2(pApi);
(void)pzErr;
return sqlite3_create_function
(db, "base64", 1,
SQLITE_DETERMINISTIC|SQLITE_INNOCUOUS|SQLITE_DIRECTONLY|SQLITE_UTF8,
0, base64, 0, 0);
}
/*
** Define some macros to allow this extension to be built into the shell
** conveniently, in conjunction with use of SQLITE_SHELL_EXTFUNCS. This
** allows shell.c, as distributed, to have this extension built in.
*/
#define BASE64_INIT(db) sqlite3_base64_init(db, 0, 0)
#define BASE64_EXPOSE(db, pzErr) /* Not needed, ..._init() does this. */