From d351981f9e4f9ef5184e35e98ad14df305c91def Mon Sep 17 00:00:00 2001 From: Joshua Haberman Date: Thu, 26 Feb 2009 01:55:39 -0800 Subject: Change to a fixed stack size. Proto2 only allows a nesting depth of 64, so we follow suit. --- pbstream.c | 26 +++++++++----------------- pbstream.h | 3 +++ tests.c | 4 ++-- 3 files changed, 14 insertions(+), 19 deletions(-) diff --git a/pbstream.c b/pbstream.c index 10cfbf9..ce14004 100644 --- a/pbstream.c +++ b/pbstream.c @@ -17,6 +17,11 @@ #define unlikely(x) (x) #endif +#define CHECK(func) do { \ + pbstream_wire_type_t status = func; \ + if(status != PBSTREAM_STATUS_OK) return status; \ + } while (0) + /* Lowest-level functions -- these read integers from the input buffer. * To avoid branches, none of these do bounds checking. So we force clients * to overallocate their buffers by >=9 bytes. */ @@ -97,11 +102,6 @@ static int64_t zz_decode_64(uint64_t n) { return (n >> 1) ^ -(int64_t)(n & 1); } /* Functions for reading wire values and converting them to values. These * are generated with macros because they follow a higly consistent pattern. */ -#define CHECK(func) do { \ - pbstream_wire_type_t status = func; \ - if(status != PBSTREAM_STATUS_OK) return status; \ - } while (0) - /* WVTOV() generates a function: * void wvtov_TYPE(wire_t src, val_t *dst, size_t offset) * (macro invoker defines the body of the function). */ @@ -173,14 +173,7 @@ static pbstream_status_t get_MESSAGE(struct pbstream_parse_state *s, char *buf, s->offset += (b-buf); /* advance past length varint. */ wvtov_delimited(tmp, &d->v.delimited, s->offset); /* Unlike STRING and BYTES, we *don't* advance past delimited here. */ - if (unlikely(++s->top == s->limit)) { - /* Stack has grown beyond its limit, must reallocate. */ - int cur_size = s->top - s->base; - int new_size = cur_size * 2; - s->base = realloc(s->base, new_size * sizeof(*s->top)); - s->top = s->base + cur_size; - s->limit = s->base + new_size; - } + if (unlikely(++s->top == s->limit)) return PBSTREAM_ERROR_STACK_OVERFLOW; s->top->fieldset = d->field->fieldset; s->top->end_offset = d->v.delimited.offset + d->v.delimited.len; return PBSTREAM_STATUS_OK; @@ -299,10 +292,9 @@ void pbstream_init_parser( struct pbstream_fieldset *toplevel_fieldset) { state->offset = 0; - /* Initial stack of <300b, most protobufs are unlikely to nest >20 deep. */ - const int initial_stack = 20; - state->top = state->base = malloc(sizeof(*state->base) * initial_stack); - state->limit = state->base + initial_stack; + /* We match proto2's limit of 64 for maximum stack depth. */ + state->top = state->base = malloc(sizeof(state->base[64])); + state->limit = state->base + 64; state->top->fieldset = toplevel_fieldset; state->top->end_offset = SIZE_MAX; } diff --git a/pbstream.h b/pbstream.h index 89e7329..d564970 100644 --- a/pbstream.h +++ b/pbstream.h @@ -132,6 +132,9 @@ typedef enum pbstream_status { // Encountered a "group" on the wire (deprecated and unsupported). PBSTREAM_ERROR_GROUP = -3, + // Input was nested more than 64 deep. + PBSTREAM_ERROR_STACK_OVERFLOW = -4, + /** NONFATAL ERRORS: the input was invalid, but we can continue if desired. */ // A value was encountered that was not defined in the .proto file. The diff --git a/tests.c b/tests.c index eaf703f..7a6e51b 100644 --- a/tests.c +++ b/tests.c @@ -47,7 +47,7 @@ void test_simple_proto() /* These are the examples from * http://code.google.com/apis/protocolbuffers/docs/encoding.html */ struct pbstream_fieldset *fieldset1 = malloc(sizeof(*fieldset1) + - 2*sizeof(struct pbstream_field)); + sizeof(struct pbstream_field[2])); fieldset1->num_fields = 2; fieldset1->fields[0].field_number = 1; fieldset1->fields[0].type = PBSTREAM_TYPE_INT32; @@ -79,7 +79,7 @@ void test_simple_proto() pbstream_free_parser(&s); struct pbstream_fieldset *fieldset2 = malloc(sizeof(*fieldset1) + - 3*sizeof(struct pbstream_field)); + sizeof(struct pbstream_field[3])); fieldset2->num_fields = 3; fieldset2->fields[2].field_number = 3; fieldset2->fields[2].type = PBSTREAM_TYPE_MESSAGE; -- cgit v1.2.3