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Implement partial write buffering for AES.

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This commit is contained in:
Michael R Sweet 2021-10-23 20:33:12 -04:00
parent 208c3419ff
commit b7ecaeee07
No known key found for this signature in database
GPG Key ID: 999559A027815955
1 changed files with 90 additions and 17 deletions
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107
pdfio-stream.c
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@ -54,8 +54,9 @@ pdfioStreamClose(pdfio_stream_t *st) // I - Stream
while ((status = deflate(&st->flate, Z_FINISH)) != Z_STREAM_END)
{
size_t bytes = sizeof(st->cbuffer) - st->flate.avail_out;
size_t bytes = sizeof(st->cbuffer) - st->flate.avail_out,
// Bytes to write
outbytes; // Actual bytes written
if (status < Z_OK && status != Z_BUF_ERROR)
{
@ -67,17 +68,32 @@ pdfioStreamClose(pdfio_stream_t *st) // I - Stream
if (st->crypto_cb)
{
// Encrypt it first...
bytes = (st->crypto_cb)(&st->crypto_ctx, st->cbuffer, st->cbuffer, bytes);
outbytes = (st->crypto_cb)(&st->crypto_ctx, st->cbuffer, st->cbuffer, bytes & ~15);
}
else
{
// No encryption
outbytes = bytes;
}
if (!_pdfioFileWrite(st->pdf, st->cbuffer, bytes))
if (!_pdfioFileWrite(st->pdf, st->cbuffer, outbytes))
{
ret = false;
goto done;
}
st->flate.next_out = (Bytef *)st->cbuffer;
st->flate.avail_out = (uInt)sizeof(st->cbuffer);
if (bytes > outbytes)
{
bytes -= outbytes;
memmove(st->cbuffer, st->cbuffer + outbytes, bytes);
}
else
{
bytes = 0;
}
st->flate.next_out = (Bytef *)st->cbuffer + bytes;
st->flate.avail_out = (uInt)sizeof(st->cbuffer) - bytes;
}
if (st->flate.avail_out < (uInt)sizeof(st->cbuffer))
@ -99,6 +115,19 @@ pdfioStreamClose(pdfio_stream_t *st) // I - Stream
}
}
}
else if (st->crypto_cb && st->bufptr > st->buffer)
{
// Encrypt and flush
uint8_t temp[8192]; // Temporary buffer
size_t outbytes; // Output bytes
outbytes = (st->crypto_cb)(&st->crypto_ctx, temp, st->buffer, (size_t)(st->bufptr - st->buffer));
if (!_pdfioFileWrite(st->pdf, temp, outbytes))
{
ret = false;
goto done;
}
}
// Save the length of this stream...
st->obj->stream_length = (size_t)(_pdfioFileTell(st->pdf) - st->obj->stream_offset);
@ -177,6 +206,8 @@ _pdfioStreamCreate(
st->obj = obj;
st->length_obj = length_obj;
st->filter = compression;
st->bufptr = st->buffer;
st->bufend = st->buffer + sizeof(st->buffer);
if (obj->pdf->encryption)
{
@ -760,20 +791,47 @@ pdfioStreamWrite(
if (st->crypto_cb)
{
// Encrypt data before writing...
unsigned char temp[8192]; // Temporary buffer
size_t cbytes, // Current bytes
outbytes; // Output bytes
uint8_t temp[8192]; // Temporary buffer
size_t cbytes, // Current bytes
outbytes; // Output bytes
bufptr = (const unsigned char *)buffer;
while (bytes > 0)
{
if ((cbytes = bytes) > sizeof(temp))
cbytes = sizeof(temp);
if (st->bufptr > st->buffer || bytes < 16)
{
// Write through the stream's buffer...
if ((cbytes = bytes) > (st->bufend - st->bufptr))
cbytes = st->bufend - st->bufptr;
outbytes = (st->crypto_cb)(&st->crypto_ctx, temp, bufptr, cbytes);
if (!_pdfioFileWrite(st->pdf, temp, outbytes))
return (false);
memcpy(st->bufptr, bufptr, cbytes);
st->bufptr += cbytes;
if (st->bufptr >= st->bufend)
{
// Encrypt and flush
outbytes = (st->crypto_cb)(&st->crypto_ctx, temp, st->buffer, sizeof(st->buffer));
if (!_pdfioFileWrite(st->pdf, temp, outbytes))
return (false);
st->bufptr = st->buffer;
}
}
else
{
// Write directly up to sizeof(temp) bytes...
if ((cbytes = bytes) > sizeof(temp))
cbytes = sizeof(temp);
if (cbytes & 15)
{
// AES has a 16-byte block size, so save the last few bytes...
cbytes &= ~15;
}
outbytes = (st->crypto_cb)(&st->crypto_ctx, temp, bufptr, cbytes);
if (!_pdfioFileWrite(st->pdf, temp, outbytes))
return (false);
}
bytes -= cbytes;
bufptr += cbytes;
@ -1160,19 +1218,34 @@ stream_write(pdfio_stream_t *st, // I - Stream
if (st->flate.avail_out < (sizeof(st->cbuffer) / 8))
{
// Flush the compression buffer...
size_t bytes = sizeof(st->cbuffer) - st->flate.avail_out;
size_t bytes = sizeof(st->cbuffer) - st->flate.avail_out,
outbytes;
if (st->crypto_cb)
{
// Encrypt it first...
bytes = (st->crypto_cb)(&st->crypto_ctx, st->cbuffer, st->cbuffer, bytes);
outbytes = (st->crypto_cb)(&st->crypto_ctx, st->cbuffer, st->cbuffer, bytes & ~15);
}
else
{
outbytes = bytes;
}
if (!_pdfioFileWrite(st->pdf, st->cbuffer, bytes))
return (false);
st->flate.next_out = (Bytef *)st->cbuffer;
st->flate.avail_out = sizeof(st->cbuffer);
if (bytes > outbytes)
{
bytes -= outbytes;
memmove(st->cbuffer, st->cbuffer + outbytes, bytes);
}
else
{
bytes = 0;
}
st->flate.next_out = (Bytef *)st->cbuffer + bytes;
st->flate.avail_out = sizeof(st->cbuffer) - bytes;
}
// Deflate what we can this time...