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Change the API for pb_make_string_substream() to use less stack.

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If your own application uses this function, you have to change
the old style:

    pb_istream_t substream;
    if (!pb_make_string_substream(stream, &substream))
        return false;
    .. do stuff with substream ..
    pb_close_string_substream(stream, &substream);

to the new style:

    size_t remaining;
    if (!pb_make_string_substream(stream, &remaining))
        return false;
    .. do stuff with stream ..
    pb_close_string_substream(stream, remaining);
This commit is contained in:
Petteri Aimonen
2013-11-14 19:16:49 +02:00
parent eff9e11150
commit cace53dfbd
2 changed files with 32 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
pb_decode.c
View File

@@ -313,28 +313,23 @@ static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire
/* Decode string length from stream and return a substream with limited length. /* Decode string length from stream and return a substream with limited length.
* Remember to close the substream using pb_close_string_substream(). * Remember to close the substream using pb_close_string_substream().
*/ */
bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream) bool checkreturn pb_make_string_substream(pb_istream_t *stream, size_t *remaining_length)
{ {
uint32_t size; uint32_t size;
if (!pb_decode_varint32(stream, &size)) if (!pb_decode_varint32(stream, &size))
return false; return false;
*substream = *stream; if (stream->bytes_left < size)
if (substream->bytes_left < size)
PB_RETURN_ERROR(stream, "parent stream too short"); PB_RETURN_ERROR(stream, "parent stream too short");
substream->bytes_left = size; *remaining_length = stream->bytes_left - size;
stream->bytes_left -= size; stream->bytes_left = size;
return true; return true;
} }
void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream) void pb_close_string_substream(pb_istream_t *stream, size_t remaining_length)
{ {
stream->state = substream->state; stream->bytes_left += remaining_length;
#ifndef PB_NO_ERRMSG
stream->errmsg = substream->errmsg;
#endif
} }
static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct) static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
@@ -425,24 +420,25 @@ static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t
/* Packed array */ /* Packed array */
bool status = true; bool status = true;
size_t *size = (size_t*)iter->pSize; size_t *size = (size_t*)iter->pSize;
pb_istream_t substream; size_t remaining_length;
if (!pb_make_string_substream(stream, &substream)) if (!pb_make_string_substream(stream, &remaining_length))
return false; return false;
while (substream.bytes_left && *size < iter->pos->array_size) while (stream->bytes_left)
{ {
void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size); void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
if (!func(&substream, iter->pos, pItem))
if (*size >= iter->pos->array_size)
PB_RETURN_ERROR(stream, "array overflow");
if (!func(stream, iter->pos, pItem))
{ {
status = false; status = false;
break; break;
} }
(*size)++; (*size)++;
} }
pb_close_string_substream(stream, &substream); pb_close_string_substream(stream, remaining_length);
if (substream.bytes_left != 0)
PB_RETURN_ERROR(stream, "array overflow");
return status; return status;
} }
@@ -478,18 +474,18 @@ static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type
if (wire_type == PB_WT_STRING) if (wire_type == PB_WT_STRING)
{ {
pb_istream_t substream; size_t remaining_length;
if (!pb_make_string_substream(stream, &substream)) if (!pb_make_string_substream(stream, &remaining_length))
return false; return false;
do do
{ {
if (!pCallback->funcs.decode(&substream, iter->pos, arg)) if (!pCallback->funcs.decode(stream, iter->pos, arg))
PB_RETURN_ERROR(stream, "callback failed"); PB_RETURN_ERROR(stream, "callback failed");
} while (substream.bytes_left); } while (stream->bytes_left);
pb_close_string_substream(stream, &substream); pb_close_string_substream(stream, remaining_length);
return true; return true;
} }
else else
@@ -746,14 +742,14 @@ bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void
bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct) bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
{ {
pb_istream_t substream; size_t remaining_length;
bool status; bool status;
if (!pb_make_string_substream(stream, &substream)) if (!pb_make_string_substream(stream, &remaining_length))
return false; return false;
status = pb_decode(&substream, fields, dest_struct); status = pb_decode(stream, fields, dest_struct);
pb_close_string_substream(stream, &substream); pb_close_string_substream(stream, remaining_length);
return status; return status;
} }
@@ -896,10 +892,10 @@ bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, vo
bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest) bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
{ {
bool status; bool status;
pb_istream_t substream; size_t remaining_length;
const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr; const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
if (!pb_make_string_substream(stream, &substream)) if (!pb_make_string_substream(stream, &remaining_length))
return false; return false;
if (field->ptr == NULL) if (field->ptr == NULL)
@@ -908,10 +904,10 @@ bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field
/* New array entries need to be initialized, while required and optional /* New array entries need to be initialized, while required and optional
* submessages have already been initialized in the top-level pb_decode. */ * submessages have already been initialized in the top-level pb_decode. */
if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED) if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
status = pb_decode(&substream, submsg_fields, dest); status = pb_decode(stream, submsg_fields, dest);
else else
status = pb_decode_noinit(&substream, submsg_fields, dest); status = pb_decode_noinit(stream, submsg_fields, dest);
pb_close_string_substream(stream, &substream); pb_close_string_substream(stream, remaining_length);
return status; return status;
} }

4
pb_decode.h
View File

@@ -128,8 +128,8 @@ bool pb_decode_fixed32(pb_istream_t *stream, void *dest);
bool pb_decode_fixed64(pb_istream_t *stream, void *dest); bool pb_decode_fixed64(pb_istream_t *stream, void *dest);
/* Make a limited-length substream for reading a PB_WT_STRING field. */ /* Make a limited-length substream for reading a PB_WT_STRING field. */
bool pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream); bool pb_make_string_substream(pb_istream_t *stream, size_t *remaining_length);
void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream); void pb_close_string_substream(pb_istream_t *stream, size_t remaining_length);
#ifdef __cplusplus #ifdef __cplusplus
} /* extern "C" */ } /* extern "C" */