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Diffstat (limited to 'src/runtime/builder.c')
| -rw-r--r-- | src/runtime/builder.c | 2035 |
1 files changed, 2035 insertions, 0 deletions
diff --git a/src/runtime/builder.c b/src/runtime/builder.c new file mode 100644 index 0000000..b62c2b6 --- /dev/null +++ b/src/runtime/builder.c @@ -0,0 +1,2035 @@ +/* + * Codegenerator for C, building FlatBuffers. + * + * There are several approaches, some light, some requiring a library, + * some with vectored I/O etc. + * + * Here we focus on a reasonable balance of light code and efficiency. + * + * Builder code is generated to a separate file that includes the + * generated read-only code. + * + * Mutable buffers are not supported in this version. + * + */ + +#include <stdlib.h> +#include <string.h> + +#include "flatcc/flatcc_builder.h" +#include "flatcc/flatcc_emitter.h" + +/* + * `check` is designed to handle incorrect use errors that can be + * ignored in production of a tested product. + * + * `check_error` fails if condition is false and is designed to return an + * error code in production. + */ + +#if FLATCC_BUILDER_ASSERT_ON_ERROR +#define check(cond, reason) FLATCC_BUILDER_ASSERT(cond, reason) +#else +#define check(cond, reason) ((void)0) +#endif + +#if FLATCC_BUILDER_SKIP_CHECKS +#define check_error(cond, err, reason) ((void)0) +#else +#define check_error(cond, err, reason) if (!(cond)) { check(cond, reason); return err; } +#endif + +/* `strnlen` not widely supported. */ +static inline size_t pstrnlen(const char *s, size_t max_len) +{ + const char *end = memchr(s, 0, max_len); + return end ? (size_t)(end - s) : max_len; +} +#undef strnlen +#define strnlen pstrnlen + +/* Padding can be up to 255 zeroes, and 1 zero string termination byte. + * When two paddings are combined at nested buffers, we need twice that. + * Visible to emitter so it can test for zero padding in iov. */ +const uint8_t flatcc_builder_padding_base[512] = { 0 }; +#define _pad flatcc_builder_padding_base + +#define uoffset_t flatbuffers_uoffset_t +#define soffset_t flatbuffers_soffset_t +#define voffset_t flatbuffers_voffset_t +#define utype_t flatbuffers_utype_t + +#define write_uoffset __flatbuffers_uoffset_write_to_pe +#define write_voffset __flatbuffers_voffset_write_to_pe +#define write_identifier __flatbuffers_uoffset_write_to_pe +#define write_utype __flatbuffers_utype_write_to_pe + +#define field_size sizeof(uoffset_t) +#define max_offset_count FLATBUFFERS_COUNT_MAX(field_size) +#define union_size sizeof(flatcc_builder_union_ref_t) +#define max_union_count FLATBUFFERS_COUNT_MAX(union_size) +#define utype_size sizeof(utype_t) +#define max_utype_count FLATBUFFERS_COUNT_MAX(utype_size) + +#define max_string_len FLATBUFFERS_COUNT_MAX(1) +#define identifier_size FLATBUFFERS_IDENTIFIER_SIZE + + +#define iovec_t flatcc_iovec_t +#define frame_size sizeof(__flatcc_builder_frame_t) +#define frame(x) (B->frame[0].x) + + +/* `align` must be a power of 2. */ +static inline uoffset_t alignup_uoffset(uoffset_t x, size_t align) +{ + return (x + (uoffset_t)align - 1u) & ~((uoffset_t)align - 1u); +} + +static inline size_t alignup_size(size_t x, size_t align) +{ + return (x + align - 1u) & ~(align - 1u); +} + + +typedef struct vtable_descriptor vtable_descriptor_t; +struct vtable_descriptor { + /* Where the vtable is emitted. */ + flatcc_builder_ref_t vt_ref; + /* Which buffer it was emitted to. */ + uoffset_t nest_id; + /* Where the vtable is cached. */ + uoffset_t vb_start; + /* Hash table collision chain. */ + uoffset_t next; +}; + +typedef struct flatcc_iov_state flatcc_iov_state_t; +struct flatcc_iov_state { + size_t len; + int count; + flatcc_iovec_t iov[FLATCC_IOV_COUNT_MAX]; +}; + +#define iov_state_t flatcc_iov_state_t + +/* This assumes `iov_state_t iov;` has been declared in scope */ +#define push_iov_cond(base, size, cond) if ((size) > 0 && (cond)) { iov.len += size;\ + iov.iov[iov.count].iov_base = (void *)(base); iov.iov[iov.count].iov_len = (size); ++iov.count; } +#define push_iov(base, size) push_iov_cond(base, size, 1) +#define init_iov() { iov.len = 0; iov.count = 0; } + + +int flatcc_builder_default_alloc(void *alloc_context, iovec_t *b, size_t request, int zero_fill, int hint) +{ + void *p; + size_t n; + + (void)alloc_context; + + if (request == 0) { + if (b->iov_base) { + FLATCC_BUILDER_FREE(b->iov_base); + b->iov_base = 0; + b->iov_len = 0; + } + return 0; + } + switch (hint) { + case flatcc_builder_alloc_ds: + n = 256; + break; + case flatcc_builder_alloc_ht: + /* Should be exact size, or space size is just wasted. */ + n = request; + break; + case flatcc_builder_alloc_fs: + n = sizeof(__flatcc_builder_frame_t) * 8; + break; + case flatcc_builder_alloc_us: + n = 64; + break; + default: + /* + * We have many small structures - vs stack for tables with few + * elements, and few offset fields in patch log. No need to + * overallocate in case of busy small messages. + */ + n = 32; + break; + } + while (n < request) { + n *= 2; + } + if (request <= b->iov_len && b->iov_len / 2 >= n) { + /* Add hysteresis to shrink. */ + return 0; + } + if (!(p = FLATCC_BUILDER_REALLOC(b->iov_base, n))) { + return -1; + } + /* Realloc might also shrink. */ + if (zero_fill && b->iov_len < n) { + memset((uint8_t *)p + b->iov_len, 0, n - b->iov_len); + } + b->iov_base = p; + b->iov_len = n; + return 0; +} + +#define T_ptr(base, pos) ((void *)((uint8_t *)(base) + (uoffset_t)(pos))) +#define ds_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_ds].iov_base, (pos))) +#define vs_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_vs].iov_base, (pos))) +#define pl_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_pl].iov_base, (pos))) +#define us_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_us].iov_base, (pos))) +#define vd_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_vd].iov_base, (pos))) +#define vb_ptr(pos) (T_ptr(B->buffers[flatcc_builder_alloc_vb].iov_base, (pos))) +#define vs_offset(ptr) ((uoffset_t)((size_t)(ptr) - (size_t)B->buffers[flatcc_builder_alloc_vs].iov_base)) +#define pl_offset(ptr) ((uoffset_t)((size_t)(ptr) - (size_t)B->buffers[flatcc_builder_alloc_pl].iov_base)) +#define us_offset(ptr) ((uoffset_t)((size_t)(ptr) - (size_t)B->buffers[flatcc_builder_alloc_us].iov_base)) + +#define table_limit (FLATBUFFERS_VOFFSET_MAX - field_size + 1) +#define data_limit (FLATBUFFERS_UOFFSET_MAX - field_size + 1) + +#define set_identifier(id) memcpy(&B->identifier, (id) ? (void *)(id) : (void *)_pad, identifier_size) + +/* Must also return true when no buffer has been started. */ +#define is_top_buffer(B) (B->nest_id == 0) + +/* + * Tables use a stack represention better suited for quickly adding + * fields to tables, but it must occasionally be refreshed following + * reallocation or reentry from child frame. + */ +static inline void refresh_ds(flatcc_builder_t *B, uoffset_t type_limit) +{ + iovec_t *buf = B->buffers + flatcc_builder_alloc_ds; + + B->ds = ds_ptr(B->ds_first); + B->ds_limit = (uoffset_t)buf->iov_len - B->ds_first; + /* + * So we don't allocate outside tables representation size, nor our + * current buffer size. + */ + if (B->ds_limit > type_limit) { + B->ds_limit = type_limit; + } + /* So exit frame can refresh fast. */ + frame(type_limit) = type_limit; +} + +static int reserve_ds(flatcc_builder_t *B, size_t need, uoffset_t limit) +{ + iovec_t *buf = B->buffers + flatcc_builder_alloc_ds; + + if (B->alloc(B->alloc_context, buf, B->ds_first + need, 1, flatcc_builder_alloc_ds)) { + return -1; + } + refresh_ds(B, limit); + return 0; +} + +/* + * Make sure there is always an extra zero termination on stack + * even if it isn't emitted such that string updates may count + * on zero termination being present always. + */ +static inline void *push_ds(flatcc_builder_t *B, uoffset_t size) +{ + size_t offset; + + offset = B->ds_offset; + if ((B->ds_offset += size) >= B->ds_limit) { + if (reserve_ds(B, B->ds_offset + 1, data_limit)) { + return 0; + } + } + return B->ds + offset; +} + +static inline void unpush_ds(flatcc_builder_t *B, uoffset_t size) +{ + B->ds_offset -= size; + memset(B->ds + B->ds_offset, 0, size); +} + +static inline void *push_ds_copy(flatcc_builder_t *B, const void *data, uoffset_t size) +{ + void *p; + + if (!(p = push_ds(B, size))) { + return 0; + } + memcpy(p, data, size); + return p; +} + +static inline void *push_ds_field(flatcc_builder_t *B, uoffset_t size, uint16_t align, voffset_t id) +{ + uoffset_t offset; + + /* + * We calculate table field alignment relative to first entry, not + * header field with vtable offset. + * + * Note: >= comparison handles special case where B->ds is not + * allocated yet and size is 0 so the return value would be mistaken + * for an error. + */ + offset = alignup_uoffset(B->ds_offset, align); + if ((B->ds_offset = offset + size) >= B->ds_limit) { + if (reserve_ds(B, B->ds_offset + 1, table_limit)) { + return 0; + } + } + B->vs[id] = (voffset_t)(offset + field_size); + if (id >= B->id_end) { + B->id_end = id + 1u; + } + return B->ds + offset; +} + +static inline void *push_ds_offset_field(flatcc_builder_t *B, voffset_t id) +{ + uoffset_t offset; + + offset = alignup_uoffset(B->ds_offset, field_size); + if ((B->ds_offset = offset + field_size) > B->ds_limit) { + if (reserve_ds(B, B->ds_offset, table_limit)) { + return 0; + } + } + B->vs[id] = (voffset_t)(offset + field_size); + if (id >= B->id_end) { + B->id_end = id + 1u; + } + *B->pl++ = (flatbuffers_voffset_t)offset; + return B->ds + offset; +} + +static inline void *reserve_buffer(flatcc_builder_t *B, int alloc_type, size_t used, size_t need, int zero_init) +{ + iovec_t *buf = B->buffers + alloc_type; + + if (used + need > buf->iov_len) { + if (B->alloc(B->alloc_context, buf, used + need, zero_init, alloc_type)) { + check(0, "memory allocation failed"); + return 0; + } + } + return (void *)((size_t)buf->iov_base + used); +} + +static inline int reserve_fields(flatcc_builder_t *B, int count) +{ + size_t used, need; + + /* Provide faster stack operations for common table operations. */ + used = frame(container.table.vs_end) + frame(container.table.id_end) * sizeof(voffset_t); + need = (size_t)(count + 2) * sizeof(voffset_t); + if (!(B->vs = reserve_buffer(B, flatcc_builder_alloc_vs, used, need, 1))) { + return -1; + } + /* Move past header for convenience. */ + B->vs += 2; + used = frame(container.table.pl_end); + /* Add one to handle special case of first table being empty. */ + need = (size_t)count * sizeof(*(B->pl)) + 1; + if (!(B->pl = reserve_buffer(B, flatcc_builder_alloc_pl, used, need, 0))) { + return -1; + } + return 0; +} + +static int alloc_ht(flatcc_builder_t *B) +{ + iovec_t *buf = B->buffers + flatcc_builder_alloc_ht; + + size_t size, k; + /* Allocate null entry so we can check for return errors. */ + FLATCC_ASSERT(B->vd_end == 0); + if (!reserve_buffer(B, flatcc_builder_alloc_vd, B->vd_end, sizeof(vtable_descriptor_t), 0)) { + return -1; + } + B->vd_end = sizeof(vtable_descriptor_t); + size = field_size * FLATCC_BUILDER_MIN_HASH_COUNT; + if (B->alloc(B->alloc_context, buf, size, 1, flatcc_builder_alloc_ht)) { + return -1; + } + while (size * 2 <= buf->iov_len) { + size *= 2; + } + size /= field_size; + for (k = 0; (((size_t)1) << k) < size; ++k) { + } + B->ht_width = k; + return 0; +} + +static inline uoffset_t *lookup_ht(flatcc_builder_t *B, uint32_t hash) +{ + uoffset_t *T; + + if (B->ht_width == 0) { + if (alloc_ht(B)) { + return 0; + } + } + T = B->buffers[flatcc_builder_alloc_ht].iov_base; + + return &T[FLATCC_BUILDER_BUCKET_VT_HASH(hash, B->ht_width)]; +} + +void flatcc_builder_flush_vtable_cache(flatcc_builder_t *B) +{ + iovec_t *buf = B->buffers + flatcc_builder_alloc_ht; + + if (B->ht_width == 0) { + return; + } + memset(buf->iov_base, 0, buf->iov_len); + /* Reserve the null entry. */ + B->vd_end = sizeof(vtable_descriptor_t); + B->vb_end = 0; +} + +int flatcc_builder_custom_init(flatcc_builder_t *B, + flatcc_builder_emit_fun *emit, void *emit_context, + flatcc_builder_alloc_fun *alloc, void *alloc_context) +{ + /* + * Do not allocate anything here. Only the required buffers will be + * allocated. For simple struct buffers, no allocation is required + * at all. + */ + memset(B, 0, sizeof(*B)); + + if (emit == 0) { + B->is_default_emitter = 1; + emit = flatcc_emitter; + emit_context = &B->default_emit_context; + } + if (alloc == 0) { + alloc = flatcc_builder_default_alloc; + } + B->alloc_context = alloc_context; + B->alloc = alloc; + B->emit_context = emit_context; + B->emit = emit; + return 0; +} + +int flatcc_builder_init(flatcc_builder_t *B) +{ + return flatcc_builder_custom_init(B, 0, 0, 0, 0); +} + +int flatcc_builder_custom_reset(flatcc_builder_t *B, int set_defaults, int reduce_buffers) +{ + iovec_t *buf; + int i; + + for (i = 0; i < FLATCC_BUILDER_ALLOC_BUFFER_COUNT; ++i) { + buf = B->buffers + i; + if (buf->iov_base) { + /* Don't try to reduce the hash table. */ + if (i != flatcc_builder_alloc_ht && + reduce_buffers && B->alloc(B->alloc_context, buf, 1, 1, i)) { + return -1; + } + memset(buf->iov_base, 0, buf->iov_len); + } else { + FLATCC_ASSERT(buf->iov_len == 0); + } + } + B->vb_end = 0; + if (B->vd_end > 0) { + /* Reset past null entry. */ + B->vd_end = sizeof(vtable_descriptor_t); + } + B->min_align = 0; + B->emit_start = 0; + B->emit_end = 0; + B->level = 0; + B->limit_level = 0; + B->ds_offset = 0; + B->ds_limit = 0; + B->nest_count = 0; + B->nest_id = 0; + /* Needed for correct offset calculation. */ + B->ds = B->buffers[flatcc_builder_alloc_ds].iov_base; + B->pl = B->buffers[flatcc_builder_alloc_pl].iov_base; + B->vs = B->buffers[flatcc_builder_alloc_vs].iov_base; + B->frame = 0; + if (set_defaults) { + B->vb_flush_limit = 0; + B->max_level = 0; + B->disable_vt_clustering = 0; + } + if (B->is_default_emitter) { + flatcc_emitter_reset(&B->default_emit_context); + } + if (B->refmap) { + flatcc_refmap_reset(B->refmap); + } + return 0; +} + +int flatcc_builder_reset(flatcc_builder_t *B) +{ + return flatcc_builder_custom_reset(B, 0, 0); +} + +void flatcc_builder_clear(flatcc_builder_t *B) +{ + iovec_t *buf; + int i; + + for (i = 0; i < FLATCC_BUILDER_ALLOC_BUFFER_COUNT; ++i) { + buf = B->buffers + i; + B->alloc(B->alloc_context, buf, 0, 0, i); + } + if (B->is_default_emitter) { + flatcc_emitter_clear(&B->default_emit_context); + } + if (B->refmap) { + flatcc_refmap_clear(B->refmap); + } + memset(B, 0, sizeof(*B)); +} + +static inline void set_min_align(flatcc_builder_t *B, uint16_t align) +{ + if (B->min_align < align) { + B->min_align = align; + } +} + +/* + * It's a max, but the minimum viable alignment is the largest observed + * alignment requirement, but no larger. + */ +static inline void get_min_align(uint16_t *align, uint16_t b) +{ + if (*align < b) { + *align = b; + } +} + +void *flatcc_builder_enter_user_frame_ptr(flatcc_builder_t *B, size_t size) +{ + size_t *frame; + + size = alignup_size(size, sizeof(size_t)) + sizeof(size_t); + + if (!(frame = reserve_buffer(B, flatcc_builder_alloc_us, B->user_frame_end, size, 0))) { + return 0; + } + memset(frame, 0, size); + *frame++ = B->user_frame_offset; + B->user_frame_offset = B->user_frame_end + sizeof(size_t); + B->user_frame_end += size; + return frame; +} + +size_t flatcc_builder_enter_user_frame(flatcc_builder_t *B, size_t size) +{ + size_t *frame; + + size = alignup_size(size, sizeof(size_t)) + sizeof(size_t); + + if (!(frame = reserve_buffer(B, flatcc_builder_alloc_us, B->user_frame_end, size, 0))) { + return 0; + } + memset(frame, 0, size); + *frame++ = B->user_frame_offset; + B->user_frame_offset = B->user_frame_end + sizeof(size_t); + B->user_frame_end += size; + return B->user_frame_offset; +} + + +size_t flatcc_builder_exit_user_frame(flatcc_builder_t *B) +{ + size_t *hdr; + + FLATCC_ASSERT(B->user_frame_offset > 0); + + hdr = us_ptr(B->user_frame_offset); + B->user_frame_end = B->user_frame_offset - sizeof(size_t); + return B->user_frame_offset = hdr[-1]; +} + +size_t flatcc_builder_exit_user_frame_at(flatcc_builder_t *B, size_t handle) +{ + FLATCC_ASSERT(B->user_frame_offset >= handle); + + B->user_frame_offset = handle; + return flatcc_builder_exit_user_frame(B); +} + +size_t flatcc_builder_get_current_user_frame(flatcc_builder_t *B) +{ + return B->user_frame_offset; +} + +void *flatcc_builder_get_user_frame_ptr(flatcc_builder_t *B, size_t handle) +{ + return us_ptr(handle); +} + +static int enter_frame(flatcc_builder_t *B, uint16_t align) +{ + if (++B->level > B->limit_level) { + if (B->max_level > 0 && B->level > B->max_level) { + return -1; + } + if (!(B->frame = reserve_buffer(B, flatcc_builder_alloc_fs, + (size_t)(B->level - 1) * frame_size, frame_size, 0))) { + return -1; + } + B->limit_level = (int)(B->buffers[flatcc_builder_alloc_fs].iov_len / frame_size); + if (B->max_level > 0 && B->max_level < B->limit_level) { + B->limit_level = B->max_level; + } + } else { + ++B->frame; + } + frame(ds_offset) = B->ds_offset; + frame(align) = B->align; + B->align = align; + /* Note: do not assume padding before first has been allocated! */ + frame(ds_first) = B->ds_first; + frame(type_limit) = data_limit; + B->ds_first = alignup_uoffset(B->ds_first + B->ds_offset, 8); + B->ds_offset = 0; + return 0; +} + +static inline void exit_frame(flatcc_builder_t *B) +{ + memset(B->ds, 0, B->ds_offset); + B->ds_offset = frame(ds_offset); + B->ds_first = frame(ds_first); + refresh_ds(B, frame(type_limit)); + + /* + * Restore local alignment: e.g. a table should not change alignment + * because a child table was just created elsewhere in the buffer, + * but the overall alignment (min align), should be aware of it. + * Each buffer has its own min align that then migrates up without + * being affected by sibling or child buffers. + */ + set_min_align(B, B->align); + B->align = frame(align); + + --B->frame; + --B->level; +} + +static inline uoffset_t front_pad(flatcc_builder_t *B, uoffset_t size, uint16_t align) +{ + return (uoffset_t)(B->emit_start - (flatcc_builder_ref_t)size) & (align - 1u); +} + +static inline uoffset_t back_pad(flatcc_builder_t *B, uint16_t align) +{ + return (uoffset_t)(B->emit_end) & (align - 1u); +} + +static inline flatcc_builder_ref_t emit_front(flatcc_builder_t *B, iov_state_t *iov) +{ + flatcc_builder_ref_t ref; + + /* + * We might have overflow when including headers, but without + * headers we should have checks to prevent overflow in the + * uoffset_t range, hence we subtract 16 to be safe. With that + * guarantee we can also make a safe check on the soffset_t range. + * + * We only allow buffers half the theoritical size of + * FLATBUFFERS_UOFFSET_MAX so we can safely use signed references. + * + * NOTE: vtables vt_offset field is signed, and the check in create + * table only ensures the signed limit. The check would fail if the + * total buffer size could grow beyond UOFFSET_MAX, and we prevent + * that by limiting the lower end to SOFFSET_MIN, and the upper end + * at emit_back to SOFFSET_MAX. + */ + ref = B->emit_start - (flatcc_builder_ref_t)iov->len; + if ((iov->len > 16 && iov->len - 16 > FLATBUFFERS_UOFFSET_MAX) || ref >= B->emit_start) { + check(0, "buffer too large to represent"); + return 0; + } + if (B->emit(B->emit_context, iov->iov, iov->count, ref, iov->len)) { + check(0, "emitter rejected buffer content"); + return 0; + } + return B->emit_start = ref; +} + +static inline flatcc_builder_ref_t emit_back(flatcc_builder_t *B, iov_state_t *iov) +{ + flatcc_builder_ref_t ref; + + ref = B->emit_end; + B->emit_end = ref + (flatcc_builder_ref_t)iov->len; + /* + * Similar to emit_front check, but since we only emit vtables and + * padding at the back, we are not concerned with iov->len overflow, + * only total buffer overflow. + * + * With this check, vtable soffset references at table header can + * still overflow in extreme cases, so this must be checked + * separately. + */ + if (B->emit_end < ref) { + check(0, "buffer too large to represent"); + return 0; + } + if (B->emit(B->emit_context, iov->iov, iov->count, ref, iov->len)) { + check(0, "emitter rejected buffer content"); + return 0; + } + /* + * Back references always return ref + 1 because ref == 0 is valid and + * should not be mistaken for error. vtables understand this. + */ + return ref + 1; +} + +static int align_to_block(flatcc_builder_t *B, uint16_t *align, uint16_t block_align, int is_nested) +{ + size_t end_pad; + iov_state_t iov; + + block_align = block_align ? block_align : B->block_align ? B->block_align : 1; + get_min_align(align, field_size); + get_min_align(align, block_align); + /* Pad end of buffer to multiple. */ + if (!is_nested) { + end_pad = back_pad(B, block_align); + if (end_pad) { + init_iov(); + push_iov(_pad, end_pad); + if (0 == emit_back(B, &iov)) { + check(0, "emitter rejected buffer content"); + return -1; + } + } + } + return 0; +} + +flatcc_builder_ref_t flatcc_builder_embed_buffer(flatcc_builder_t *B, + uint16_t block_align, + const void *data, size_t size, uint16_t align, flatcc_builder_buffer_flags_t flags) +{ + uoffset_t size_field, pad; + iov_state_t iov; + int with_size = (flags & flatcc_builder_with_size) != 0; + + if (align_to_block(B, &align, block_align, !is_top_buffer(B))) { + return 0; + } + pad = front_pad(B, (uoffset_t)(size + (with_size ? field_size : 0)), align); + write_uoffset(&size_field, (uoffset_t)size + pad); + init_iov(); + /* Add ubyte vector size header if nested buffer. */ + push_iov_cond(&size_field, field_size, !is_top_buffer(B)); + push_iov(data, size); + push_iov(_pad, pad); + return emit_front(B, &iov); +} + +flatcc_builder_ref_t flatcc_builder_create_buffer(flatcc_builder_t *B, + const char identifier[identifier_size], uint16_t block_align, + flatcc_builder_ref_t object_ref, uint16_t align, flatcc_builder_buffer_flags_t flags) +{ + flatcc_builder_ref_t buffer_ref; + uoffset_t header_pad, id_size = 0; + uoffset_t object_offset, buffer_size, buffer_base; + iov_state_t iov; + flatcc_builder_identifier_t id_out = 0; + int is_nested = (flags & flatcc_builder_is_nested) != 0; + int with_size = (flags & flatcc_builder_with_size) != 0; + + if (align_to_block(B, &align, block_align, is_nested)) { + return 0; + } + set_min_align(B, align); + if (identifier) { + FLATCC_ASSERT(sizeof(flatcc_builder_identifier_t) == identifier_size); + FLATCC_ASSERT(sizeof(flatcc_builder_identifier_t) == field_size); + memcpy(&id_out, identifier, identifier_size); + id_out = __flatbuffers_thash_read_from_le(&id_out); + write_identifier(&id_out, id_out); + } + id_size = id_out ? identifier_size : 0; + header_pad = front_pad(B, field_size + id_size + (uoffset_t)(with_size ? field_size : 0), align); + init_iov(); + /* ubyte vectors size field wrapping nested buffer. */ + push_iov_cond(&buffer_size, field_size, is_nested || with_size); + push_iov(&object_offset, field_size); + /* Identifiers are not always present in buffer. */ + push_iov(&id_out, id_size); + push_iov(_pad, header_pad); + buffer_base = (uoffset_t)B->emit_start - (uoffset_t)iov.len + (uoffset_t)((is_nested || with_size) ? field_size : 0); + if (is_nested) { + write_uoffset(&buffer_size, (uoffset_t)B->buffer_mark - buffer_base); + } else { + /* Also include clustered vtables. */ + write_uoffset(&buffer_size, (uoffset_t)B->emit_end - buffer_base); + } + write_uoffset(&object_offset, (uoffset_t)object_ref - buffer_base); + if (0 == (buffer_ref = emit_front(B, &iov))) { + check(0, "emitter rejected buffer content"); + return 0; + } + return buffer_ref; +} + +flatcc_builder_ref_t flatcc_builder_create_struct(flatcc_builder_t *B, const void *data, size_t size, uint16_t align) +{ + size_t pad; + iov_state_t iov; + + check(align >= 1, "align cannot be 0"); + set_min_align(B, align); + pad = front_pad(B, (uoffset_t)size, align); + init_iov(); + push_iov(data, size); + /* + * Normally structs will already be a multiple of their alignment, + * so this padding will not likely be emitted. + */ + push_iov(_pad, pad); + return emit_front(B, &iov); +} + +int flatcc_builder_start_buffer(flatcc_builder_t *B, + const char identifier[identifier_size], uint16_t block_align, flatcc_builder_buffer_flags_t flags) +{ + /* + * This saves the parent `min_align` in the align field since we + * shouldn't use that for the current buffer. `exit_frame` + * automatically aggregates align up, so it is updated when the + * buffer frame exits. + */ + if (enter_frame(B, B->min_align)) { + return -1; + } + /* B->align now has parent min_align, and child frames will save it. */ + B->min_align = 1; + /* Save the parent block align, and set proper defaults for this buffer. */ + frame(container.buffer.block_align) = B->block_align; + B->block_align = block_align; + frame(container.buffer.flags = B->buffer_flags); + B->buffer_flags = (uint16_t)flags; + frame(container.buffer.mark) = B->buffer_mark; + frame(container.buffer.nest_id) = B->nest_id; + /* + * End of buffer when nested. Not defined for top-level because we + * here (on only here) permit strings etc. to be created before buffer start and + * because top-level buffer vtables can be clustered. + */ + B->buffer_mark = B->emit_start; + /* Must be 0 before and after entering top-level buffer, and unique otherwise. */ + B->nest_id = B->nest_count++; + frame(container.buffer.identifier) = B->identifier; + set_identifier(identifier); + frame(type) = flatcc_builder_buffer; + return 0; +} + +flatcc_builder_ref_t flatcc_builder_end_buffer(flatcc_builder_t *B, flatcc_builder_ref_t root) +{ + flatcc_builder_ref_t buffer_ref; + flatcc_builder_buffer_flags_t flags; + + flags = (flatcc_builder_buffer_flags_t)B->buffer_flags & flatcc_builder_with_size; + flags |= is_top_buffer(B) ? 0 : flatcc_builder_is_nested; + check(frame(type) == flatcc_builder_buffer, "expected buffer frame"); + set_min_align(B, B->block_align); + if (0 == (buffer_ref = flatcc_builder_create_buffer(B, (void *)&B->identifier, + B->block_align, root, B->min_align, flags))) { + return 0; + } + B->buffer_mark = frame(container.buffer.mark); + B->nest_id = frame(container.buffer.nest_id); + B->identifier = frame(container.buffer.identifier); + B->buffer_flags = frame(container.buffer.flags); + exit_frame(B); + return buffer_ref; +} + +void *flatcc_builder_start_struct(flatcc_builder_t *B, size_t size, uint16_t align) +{ + /* Allocate space for the struct on the ds stack. */ + if (enter_frame(B, align)) { + return 0; + } + frame(type) = flatcc_builder_struct; + refresh_ds(B, data_limit); + return push_ds(B, (uoffset_t)size); +} + +void *flatcc_builder_struct_edit(flatcc_builder_t *B) +{ + return B->ds; +} + +flatcc_builder_ref_t flatcc_builder_end_struct(flatcc_builder_t *B) +{ + flatcc_builder_ref_t object_ref; + + check(frame(type) == flatcc_builder_struct, "expected struct frame"); + if (0 == (object_ref = flatcc_builder_create_struct(B, B->ds, B->ds_offset, B->align))) { + return 0; + } + exit_frame(B); + return object_ref; +} + +static inline int vector_count_add(flatcc_builder_t *B, uoffset_t count, uoffset_t max_count) +{ + uoffset_t n, n1; + n = frame(container.vector.count); + n1 = n + count; + /* + * This prevents elem_size * count from overflowing iff max_vector + * has been set sensible. Without this check we might allocate to + * little on the ds stack and return a buffer the user thinks is + * much larger which of course is bad even though the buffer eventually + * would fail anyway. + */ + check_error(n <= n1 && n1 <= max_count, -1, "vector too large to represent"); + frame(container.vector.count) = n1; + return 0; +} + +void *flatcc_builder_extend_vector(flatcc_builder_t *B, size_t count) +{ + if (vector_count_add(B, (uoffset_t)count, frame(container.vector.max_count))) { + return 0; + } + return push_ds(B, frame(container.vector.elem_size) * (uoffset_t)count); +} + +void *flatcc_builder_vector_push(flatcc_builder_t *B, const void *data) +{ + check(frame(type) == flatcc_builder_vector, "expected vector frame"); + check_error(frame(container.vector.count) <= frame(container.vector.max_count), 0, "vector max count exceeded"); + frame(container.vector.count) += 1; + return push_ds_copy(B, data, frame(container.vector.elem_size)); +} + +void *flatcc_builder_append_vector(flatcc_builder_t *B, const void *data, size_t count) +{ + check(frame(type) == flatcc_builder_vector, "expected vector frame"); + if (vector_count_add(B, (uoffset_t)count, frame(container.vector.max_count))) { + return 0; + } + return push_ds_copy(B, data, frame(container.vector.elem_size) * (uoffset_t)count); +} + +flatcc_builder_ref_t *flatcc_builder_extend_offset_vector(flatcc_builder_t *B, size_t count) +{ + if (vector_count_add(B, (uoffset_t)count, max_offset_count)) { + return 0; + } + return push_ds(B, (uoffset_t)(field_size * count)); +} + +flatcc_builder_ref_t *flatcc_builder_offset_vector_push(flatcc_builder_t *B, flatcc_builder_ref_t ref) +{ + flatcc_builder_ref_t *p; + + check(frame(type) == flatcc_builder_offset_vector, "expected offset vector frame"); + if (frame(container.vector.count) == max_offset_count) { + return 0; + } + frame(container.vector.count) += 1; + if (0 == (p = push_ds(B, field_size))) { + return 0; + } + *p = ref; + return p; +} + +flatcc_builder_ref_t *flatcc_builder_append_offset_vector(flatcc_builder_t *B, const flatcc_builder_ref_t *refs, size_t count) +{ + check(frame(type) == flatcc_builder_offset_vector, "expected offset vector frame"); + if (vector_count_add(B, (uoffset_t)count, max_offset_count)) { + return 0; + } + return push_ds_copy(B, refs, (uoffset_t)(field_size * count)); +} + +char *flatcc_builder_extend_string(flatcc_builder_t *B, size_t len) +{ + check(frame(type) == flatcc_builder_string, "expected string frame"); + if (vector_count_add(B, (uoffset_t)len, max_string_len)) { + return 0; + } + return push_ds(B, (uoffset_t)len); +} + +char *flatcc_builder_append_string(flatcc_builder_t *B, const char *s, size_t len) +{ + check(frame(type) == flatcc_builder_string, "expected string frame"); + if (vector_count_add(B, (uoffset_t)len, max_string_len)) { + return 0; + } + return push_ds_copy(B, s, (uoffset_t)len); +} + +char *flatcc_builder_append_string_str(flatcc_builder_t *B, const char *s) +{ + return flatcc_builder_append_string(B, s, strlen(s)); +} + +char *flatcc_builder_append_string_strn(flatcc_builder_t *B, const char *s, size_t max_len) +{ + return flatcc_builder_append_string(B, s, strnlen(s, max_len)); +} + +int flatcc_builder_truncate_vector(flatcc_builder_t *B, size_t count) +{ + check(frame(type) == flatcc_builder_vector, "expected vector frame"); + check_error(frame(container.vector.count) >= count, -1, "cannot truncate vector past empty"); + frame(container.vector.count) -= (uoffset_t)count; + unpush_ds(B, frame(container.vector.elem_size) * (uoffset_t)count); + return 0; +} + +int flatcc_builder_truncate_offset_vector(flatcc_builder_t *B, size_t count) +{ + check(frame(type) == flatcc_builder_offset_vector, "expected offset vector frame"); + check_error(frame(container.vector.count) >= (uoffset_t)count, -1, "cannot truncate vector past empty"); + frame(container.vector.count) -= (uoffset_t)count; + unpush_ds(B, frame(container.vector.elem_size) * (uoffset_t)count); + return 0; +} + +int flatcc_builder_truncate_string(flatcc_builder_t *B, size_t len) +{ + check(frame(type) == flatcc_builder_string, "expected string frame"); + check_error(frame(container.vector.count) >= len, -1, "cannot truncate string past empty"); + frame(container.vector.count) -= (uoffset_t)len; + unpush_ds(B, (uoffset_t)len); + return 0; +} + +int flatcc_builder_start_vector(flatcc_builder_t *B, size_t elem_size, uint16_t align, size_t max_count) +{ + get_min_align(&align, field_size); + if (enter_frame(B, align)) { + return -1; + } + frame(container.vector.elem_size) = (uoffset_t)elem_size; + frame(container.vector.count) = 0; + frame(container.vector.max_count) = (uoffset_t)max_count; + frame(type) = flatcc_builder_vector; + refresh_ds(B, data_limit); + return 0; +} + +int flatcc_builder_start_offset_vector(flatcc_builder_t *B) +{ + if (enter_frame(B, field_size)) { + return -1; + } + frame(container.vector.elem_size) = field_size; + frame(container.vector.count) = 0; + frame(type) = flatcc_builder_offset_vector; + refresh_ds(B, data_limit); + return 0; +} + +flatcc_builder_ref_t flatcc_builder_create_offset_vector(flatcc_builder_t *B, + const flatcc_builder_ref_t *vec, size_t count) +{ + flatcc_builder_ref_t *_vec; + + if (flatcc_builder_start_offset_vector(B)) { + return 0; + } + if (!(_vec = flatcc_builder_extend_offset_vector(B, count))) { + return 0; + } + memcpy(_vec, vec, count * field_size); + return flatcc_builder_end_offset_vector(B); +} + +int flatcc_builder_start_string(flatcc_builder_t *B) +{ + if (enter_frame(B, 1)) { + return -1; + } + frame(container.vector.elem_size) = 1; + frame(container.vector.count) = 0; + frame(type) = flatcc_builder_string; + refresh_ds(B, data_limit); + return 0; +} + +int flatcc_builder_reserve_table(flatcc_builder_t *B, int count) +{ + check(count >= 0, "cannot reserve negative count"); + return reserve_fields(B, count); +} + +int flatcc_builder_start_table(flatcc_builder_t *B, int count) +{ + if (enter_frame(B, field_size)) { + return -1; + } + frame(container.table.vs_end) = vs_offset(B->vs); + frame(container.table.pl_end) = pl_offset(B->pl); + frame(container.table.vt_hash) = B->vt_hash; + frame(container.table.id_end) = B->id_end; + B->vt_hash = 0; + FLATCC_BUILDER_INIT_VT_HASH(B->vt_hash); + B->id_end = 0; + frame(type) = flatcc_builder_table; + if (reserve_fields(B, count)) { + return -1; + } + refresh_ds(B, table_limit); + return 0; +} + +flatcc_builder_vt_ref_t flatcc_builder_create_vtable(flatcc_builder_t *B, + const voffset_t *vt, voffset_t vt_size) +{ + flatcc_builder_vt_ref_t vt_ref; + iov_state_t iov; + voffset_t *vt_; + size_t i; + + /* + * Only top-level buffer can cluster vtables because only it can + * extend beyond the end. + * + * We write the vtable after the referencing table to maintain + * the construction invariant that any offset reference has + * valid emitted data at a higher address, and also that any + * issued negative emit address represents an offset reference + * to some flatbuffer object or vector (or possibly a root + * struct). + * + * The vt_ref is stored as the reference + 1 to avoid having 0 as a + * valid reference (which usally means error). It also idententifies + * vtable references as the only uneven references, and the only + * references that can be used multiple times in the same buffer. + * + * We do the vtable conversion here so cached vtables can be built + * hashed and compared more efficiently, and so end users with + * direct vtable construction don't have to worry about endianness. + * This also ensures the hash function works the same wrt. + * collision frequency. + */ + + if (!flatbuffers_is_native_pe()) { + /* Make space in vtable cache for temporary endian conversion. */ + if (!(vt_ = reserve_buffer(B, flatcc_builder_alloc_vb, B->vb_end, vt_size, 0))) { + return 0; + } + for (i = 0; i < vt_size / sizeof(voffset_t); ++i) { + write_voffset(&vt_[i], vt[i]); + } + vt = vt_; + /* We don't need to free the reservation since we don't advance any base pointer. */ + } + + init_iov(); + push_iov(vt, vt_size); + if (is_top_buffer(B) && !B->disable_vt_clustering) { + /* Note that `emit_back` already returns ref + 1 as we require for vtables. */ + if (0 == (vt_ref = emit_back(B, &iov))) { + return 0; + } + } else { + if (0 == (vt_ref = emit_front(B, &iov))) { + return 0; + } + /* + * We don't have a valid 0 ref here, but to be consistent with + * clustered vtables we offset by one. This cannot be zero + * either. + */ + vt_ref += 1; + } + return vt_ref; +} + +flatcc_builder_vt_ref_t flatcc_builder_create_cached_vtable(flatcc_builder_t *B, + const voffset_t *vt, voffset_t vt_size, uint32_t vt_hash) +{ + vtable_descriptor_t *vd, *vd2; + uoffset_t *pvd, *pvd_head; + uoffset_t next; + voffset_t *vt_; + + /* This just gets the hash table slot, we still have to inspect it. */ + if (!(pvd_head = lookup_ht(B, vt_hash))) { + return 0; + } + pvd = pvd_head; + next = *pvd; + /* Tracks if there already is a cached copy. */ + vd2 = 0; + while (next) { + vd = vd_ptr(next); + vt_ = vb_ptr(vd->vb_start); + if (vt_[0] != vt_size || 0 != memcmp(vt, vt_, vt_size)) { + pvd = &vd->next; + next = vd->next; + continue; + } + /* Can't share emitted vtables between buffers, */ + if (vd->nest_id != B->nest_id) { + /* but we don't have to resubmit to cache. */ + vd2 = vd; + /* See if there is a better match. */ + pvd = &vd->next; + next = vd->next; + continue; + } + /* Move to front hash strategy. */ + if (pvd != pvd_head) { + *pvd = vd->next; + vd->next = *pvd_head; + *pvd_head = next; + } + /* vtable exists and has been emitted within current buffer. */ + return vd->vt_ref; + } + /* Allocate new descriptor. */ + if (!(vd = reserve_buffer(B, flatcc_builder_alloc_vd, B->vd_end, sizeof(vtable_descriptor_t), 0))) { + return 0; + } + next = B->vd_end; + B->vd_end += (uoffset_t)sizeof(vtable_descriptor_t); + + /* Identify the buffer this vtable descriptor belongs to. */ + vd->nest_id = B->nest_id; + + /* Move to front hash strategy. */ + vd->next = *pvd_head; + *pvd_head = next; + if (0 == (vd->vt_ref = flatcc_builder_create_vtable(B, vt, vt_size))) { + return 0; + } + if (vd2) { + /* Reuse cached copy. */ + vd->vb_start = vd2->vb_start; + } else { + if (B->vb_flush_limit && B->vb_flush_limit < B->vb_end + vt_size) { + flatcc_builder_flush_vtable_cache(B); + } else { + /* Make space in vtable cache. */ + if (!(vt_ = reserve_buffer(B, flatcc_builder_alloc_vb, B->vb_end, vt_size, 0))) { + return -1; + } + vd->vb_start = B->vb_end; + B->vb_end += vt_size; + memcpy(vt_, vt, vt_size); + } + } + return vd->vt_ref; +} + +flatcc_builder_ref_t flatcc_builder_create_table(flatcc_builder_t *B, const void *data, size_t size, uint16_t align, + flatbuffers_voffset_t *offsets, int offset_count, flatcc_builder_vt_ref_t vt_ref) +{ + int i; + uoffset_t pad, vt_offset, vt_offset_field, vt_base, base, offset, *offset_field; + iov_state_t iov; + + check(offset_count >= 0, "expected non-negative offset_count"); + /* + * vtable references are offset by 1 to avoid confusion with + * 0 as an error reference. It also uniquely identifies them + * as vtables being the only uneven reference type. + */ + check(vt_ref & 1, "invalid vtable referenc"); + get_min_align(&align, field_size); + set_min_align(B, align); + /* Alignment is calculated for the first element, not the header. */ + pad = front_pad(B, (uoffset_t)size, align); + base = (uoffset_t)B->emit_start - (uoffset_t)(pad + size + field_size); + /* Adjust by 1 to get unencoded vtable reference. */ + vt_base = (uoffset_t)(vt_ref - 1); + vt_offset = base - vt_base; + /* Avoid overflow. */ + if (base - vt_offset != vt_base) { + return -1; + } + /* Protocol endian encoding. */ + write_uoffset(&vt_offset_field, vt_offset); + for (i = 0; i < offset_count; ++i) { + offset_field = (uoffset_t *)((size_t)data + offsets[i]); + offset = *offset_field - base - offsets[i] - (uoffset_t)field_size; + write_uoffset(offset_field, offset); + } + init_iov(); + push_iov(&vt_offset_field, field_size); + push_iov(data, size); + push_iov(_pad, pad); + return emit_front(B, &iov); +} + +int flatcc_builder_check_required_field(flatcc_builder_t *B, flatbuffers_voffset_t id) +{ + check(frame(type) == flatcc_builder_table, "expected table frame"); + + return id < B->id_end && B->vs[id] != 0; +} + +int flatcc_builder_check_union_field(flatcc_builder_t *B, flatbuffers_voffset_t id) +{ + check(frame(type) == flatcc_builder_table, "expected table frame"); + + if (id == 0 || id >= B->id_end) { + return 0; + } + if (B->vs[id - 1] == 0) { + return B->vs[id] == 0; + } + if (*(uint8_t *)(B->ds + B->vs[id - 1])) { + return B->vs[id] != 0; + } + return B->vs[id] == 0; +} + +int flatcc_builder_check_required(flatcc_builder_t *B, const flatbuffers_voffset_t *required, int count) +{ + int i; + + check(frame(type) == flatcc_builder_table, "expected table frame"); + + if (B->id_end < count) { + return 0; + } + for (i = 0; i < count; ++i) { + if (B->vs[required[i]] == 0) { + return 0; + } + } + return 1; +} + +flatcc_builder_ref_t flatcc_builder_end_table(flatcc_builder_t *B) +{ + voffset_t *vt, vt_size; + flatcc_builder_ref_t table_ref, vt_ref; + int pl_count; + voffset_t *pl; + + check(frame(type) == flatcc_builder_table, "expected table frame"); + + /* We have `ds_limit`, so we should not have to check for overflow here. */ + + vt = B->vs - 2; + vt_size = (voffset_t)(sizeof(voffset_t) * (B->id_end + 2u)); + /* Update vtable header fields, first vtable size, then object table size. */ + vt[0] = vt_size; + /* + * The `ds` buffer is always at least `field_size` aligned but excludes the + * initial vtable offset field. Therefore `field_size` is added here + * to the total table size in the vtable. + */ + vt[1] = (voffset_t)(B->ds_offset + field_size); + FLATCC_BUILDER_UPDATE_VT_HASH(B->vt_hash, (uint32_t)vt[0], (uint32_t)vt[1]); + /* Find already emitted vtable, or emit a new one. */ + if (!(vt_ref = flatcc_builder_create_cached_vtable(B, vt, vt_size, B->vt_hash))) { + return 0; + } + /* Clear vs stack so it is ready for the next vtable (ds stack is cleared by exit frame). */ + memset(vt, 0, vt_size); + + pl = pl_ptr(frame(container.table.pl_end)); + pl_count = (int)(B->pl - pl); + if (0 == (table_ref = flatcc_builder_create_table(B, B->ds, B->ds_offset, B->align, pl, pl_count, vt_ref))) { + return 0; + } + B->vt_hash = frame(container.table.vt_hash); + B->id_end = frame(container.table.id_end); + B->vs = vs_ptr(frame(container.table.vs_end)); + B->pl = pl_ptr(frame(container.table.pl_end)); + exit_frame(B); + return table_ref; +} + +flatcc_builder_ref_t flatcc_builder_create_vector(flatcc_builder_t *B, + const void *data, size_t count, size_t elem_size, uint16_t align, size_t max_count) +{ + /* + * Note: it is important that vec_size is uoffset not size_t + * in case sizeof(uoffset_t) > sizeof(size_t) because max_count is + * defined in terms of uoffset_t representation size, and also + * because we risk accepting too large a vector even if max_count is + * not violated. + */ + uoffset_t vec_size, vec_pad, length_prefix; + iov_state_t iov; + + check_error(count <= max_count, 0, "vector max_count violated"); + get_min_align(&align, field_size); + set_min_align(B, align); + vec_size = (uoffset_t)count * (uoffset_t)elem_size; + /* + * That can happen on 32 bit systems when uoffset_t is defined as 64-bit. + * `emit_front/back` captures overflow, but not if our size type wraps first. + */ +#if FLATBUFFERS_UOFFSET_MAX > SIZE_MAX + check_error(vec_size < SIZE_MAX, 0, "vector larger than address space"); +#endif + write_uoffset(&length_prefix, (uoffset_t)count); + /* Alignment is calculated for the first element, not the header. */ + vec_pad = front_pad(B, vec_size, align); + init_iov(); + push_iov(&length_prefix, field_size); + push_iov(data, vec_size); + push_iov(_pad, vec_pad); + return emit_front(B, &iov); +} + +/* + * Note: FlatBuffers official documentation states that the size field of a + * vector is a 32-bit element count. It is not quite clear if the + * intention is to have the size field be of type uoffset_t since tables + * also have a uoffset_t sized header, or if the vector size should + * remain unchanged if uoffset is changed to 16- or 64-bits + * respectively. Since it makes most sense to have a vector compatible + * with the addressable space, we choose to use uoffset_t as size field, + * which remains compatible with the default 32-bit version of uoffset_t. + */ +flatcc_builder_ref_t flatcc_builder_end_vector(flatcc_builder_t *B) +{ + flatcc_builder_ref_t vector_ref; + + check(frame(type) == flatcc_builder_vector, "expected vector frame"); + + if (0 == (vector_ref = flatcc_builder_create_vector(B, B->ds, + frame(container.vector.count), frame(container.vector.elem_size), + B->align, frame(container.vector.max_count)))) { + return 0; + } + exit_frame(B); + return vector_ref; +} + +size_t flatcc_builder_vector_count(flatcc_builder_t *B) +{ + return frame(container.vector.count); +} + +void *flatcc_builder_vector_edit(flatcc_builder_t *B) +{ + return B->ds; +} + +/* This function destroys the source content but avoids stack allocation. */ +static flatcc_builder_ref_t _create_offset_vector_direct(flatcc_builder_t *B, + flatcc_builder_ref_t *vec, size_t count, const utype_t *types) +{ + uoffset_t vec_size, vec_pad; + uoffset_t length_prefix, offset; + uoffset_t i; + soffset_t base; + iov_state_t iov; + + if ((uoffset_t)count > max_offset_count) { + return 0; + } + set_min_align(B, field_size); + vec_size = (uoffset_t)(count * field_size); + write_uoffset(&length_prefix, (uoffset_t)count); + /* Alignment is calculated for the first element, not the header. */ + vec_pad = front_pad(B, vec_size, field_size); + init_iov(); + push_iov(&length_prefix, field_size); + push_iov(vec, vec_size); + push_iov(_pad, vec_pad); + base = B->emit_start - (soffset_t)iov.len; + for (i = 0; i < (uoffset_t)count; ++i) { + /* + * 0 is either end of buffer, start of vtables, or start of + * buffer depending on the direction in which the buffer is + * built. None of these can create a valid 0 reference but it + * is easy to create by mistake when manually building offset + * vectors. + * + * Unions do permit nulls, but only when the type is NONE. + */ + if (vec[i] != 0) { + offset = (uoffset_t) + (vec[i] - base - (soffset_t)(i * field_size) - (soffset_t)field_size); + write_uoffset(&vec[i], offset); + if (types) { + check(types[i] != 0, "union vector cannot have non-null element with type NONE"); + } + } else { + if (types) { + check(types[i] == 0, "union vector cannot have null element without type NONE"); + } else { + check(0, "offset vector cannot have null element"); + } + } + } + return emit_front(B, &iov); +} + +flatcc_builder_ref_t flatcc_builder_create_offset_vector_direct(flatcc_builder_t *B, + flatcc_builder_ref_t *vec, size_t count) +{ + return _create_offset_vector_direct(B, vec, count, 0); +} + +flatcc_builder_ref_t flatcc_builder_end_offset_vector(flatcc_builder_t *B) +{ + flatcc_builder_ref_t vector_ref; + + check(frame(type) == flatcc_builder_offset_vector, "expected offset vector frame"); + if (0 == (vector_ref = flatcc_builder_create_offset_vector_direct(B, + (flatcc_builder_ref_t *)B->ds, frame(container.vector.count)))) { + return 0; + } + exit_frame(B); + return vector_ref; +} + +flatcc_builder_ref_t flatcc_builder_end_offset_vector_for_unions(flatcc_builder_t *B, const utype_t *types) +{ + flatcc_builder_ref_t vector_ref; + + check(frame(type) == flatcc_builder_offset_vector, "expected offset vector frame"); + if (0 == (vector_ref = _create_offset_vector_direct(B, + (flatcc_builder_ref_t *)B->ds, frame(container.vector.count), types))) { + return 0; + } + exit_frame(B); + return vector_ref; +} + +void *flatcc_builder_offset_vector_edit(flatcc_builder_t *B) +{ + return B->ds; +} + +size_t flatcc_builder_offset_vector_count(flatcc_builder_t *B) +{ + return frame(container.vector.count); +} + +int flatcc_builder_table_add_union(flatcc_builder_t *B, int id, + flatcc_builder_union_ref_t uref) +{ + flatcc_builder_ref_t *pref; + flatcc_builder_utype_t *putype; + + check(frame(type) == flatcc_builder_table, "expected table frame"); + check_error(uref.type != 0 || uref.value == 0, -1, "expected null value for type NONE"); + if (uref.value != 0) { + pref = flatcc_builder_table_add_offset(B, id); + check_error(pref != 0, -1, "unable to add union value"); + *pref = uref.value; + } + putype = flatcc_builder_table_add(B, id - 1, utype_size, utype_size); + check_error(putype != 0, -1, "unable to add union type"); + write_utype(putype, uref.type); + return 0; +} + +int flatcc_builder_table_add_union_vector(flatcc_builder_t *B, int id, + flatcc_builder_union_vec_ref_t uvref) +{ + flatcc_builder_ref_t *pref; + + check(frame(type) == flatcc_builder_table, "expected table frame"); + check_error((uvref.type == 0) == (uvref.value == 0), -1, "expected both type and value vector, or neither"); + if (uvref.type != 0) { + pref = flatcc_builder_table_add_offset(B, id - 1); + check_error(pref != 0, -1, "unable to add union member"); + *pref = uvref.type; + + pref = flatcc_builder_table_add_offset(B, id); + check_error(pref != 0, -1, "unable to add union member"); + *pref = uvref.value; + } + return 0; +} + +flatcc_builder_union_vec_ref_t flatcc_builder_create_union_vector(flatcc_builder_t *B, + const flatcc_builder_union_ref_t *urefs, size_t count) +{ + flatcc_builder_union_vec_ref_t uvref = { 0, 0 }; + flatcc_builder_utype_t *types; + flatcc_builder_ref_t *refs; + size_t i; + + if (flatcc_builder_start_offset_vector(B)) { + return uvref; + } + if (0 == flatcc_builder_extend_offset_vector(B, count)) { + return uvref; + } + if (0 == (types = push_ds(B, (uoffset_t)(utype_size * count)))) { + return uvref; + } + + /* Safe even if push_ds caused stack reallocation. */ + refs = flatcc_builder_offset_vector_edit(B); + + for (i = 0; i < count; ++i) { + types[i] = urefs[i].type; + refs[i] = urefs[i].value; + } + uvref = flatcc_builder_create_union_vector_direct(B, + types, refs, count); + /* No need to clean up after out temporary types vector. */ + exit_frame(B); + return uvref; +} + +flatcc_builder_union_vec_ref_t flatcc_builder_create_union_vector_direct(flatcc_builder_t *B, + const flatcc_builder_utype_t *types, flatcc_builder_ref_t *data, size_t count) +{ + flatcc_builder_union_vec_ref_t uvref = { 0, 0 }; + + if (0 == (uvref.value = _create_offset_vector_direct(B, data, count, types))) { + return uvref; + } + if (0 == (uvref.type = flatcc_builder_create_type_vector(B, types, count))) { + return uvref; + } + return uvref; +} + +flatcc_builder_ref_t flatcc_builder_create_type_vector(flatcc_builder_t *B, + const flatcc_builder_utype_t *types, size_t count) +{ + return flatcc_builder_create_vector(B, types, count, + utype_size, utype_size, max_utype_count); +} + +int flatcc_builder_start_union_vector(flatcc_builder_t *B) +{ + if (enter_frame(B, field_size)) { + return -1; + } + frame(container.vector.elem_size) = union_size; + frame(container.vector.count) = 0; + frame(type) = flatcc_builder_union_vector; + refresh_ds(B, data_limit); + return 0; +} + +flatcc_builder_union_vec_ref_t flatcc_builder_end_union_vector(flatcc_builder_t *B) +{ + flatcc_builder_union_vec_ref_t uvref = { 0, 0 }; + flatcc_builder_utype_t *types; + flatcc_builder_union_ref_t *urefs; + flatcc_builder_ref_t *refs; + size_t i, count; + + check(frame(type) == flatcc_builder_union_vector, "expected union vector frame"); + + /* + * We could split the union vector in-place, but then we would have + * to deal with strict pointer aliasing rules which is not worthwhile + * so we create a new offset and type vector on the stack. + * + * We assume the stack is sufficiently aligned as is. + */ + count = flatcc_builder_union_vector_count(B); + if (0 == (refs = push_ds(B, (uoffset_t)(count * (utype_size + field_size))))) { + return uvref; + } + types = (flatcc_builder_utype_t *)(refs + count); + + /* Safe even if push_ds caused stack reallocation. */ + urefs = flatcc_builder_union_vector_edit(B); + + for (i = 0; i < count; ++i) { + types[i] = urefs[i].type; + refs[i] = urefs[i].value; + } + uvref = flatcc_builder_create_union_vector_direct(B, types, refs, count); + /* No need to clean up after out temporary types vector. */ + exit_frame(B); + return uvref; +} + +void *flatcc_builder_union_vector_edit(flatcc_builder_t *B) +{ + return B->ds; +} + +size_t flatcc_builder_union_vector_count(flatcc_builder_t *B) +{ + return frame(container.vector.count); +} + +flatcc_builder_union_ref_t *flatcc_builder_extend_union_vector(flatcc_builder_t *B, size_t count) +{ + if (vector_count_add(B, (uoffset_t)count, max_union_count)) { + return 0; + } + return push_ds(B, (uoffset_t)(union_size * count)); +} + +int flatcc_builder_truncate_union_vector(flatcc_builder_t *B, size_t count) +{ + check(frame(type) == flatcc_builder_union_vector, "expected union vector frame"); + check_error(frame(container.vector.count) >= (uoffset_t)count, -1, "cannot truncate vector past empty"); + frame(container.vector.count) -= (uoffset_t)count; + unpush_ds(B, frame(container.vector.elem_size) * (uoffset_t)count); + return 0; +} + +flatcc_builder_union_ref_t *flatcc_builder_union_vector_push(flatcc_builder_t *B, + flatcc_builder_union_ref_t uref) +{ + flatcc_builder_union_ref_t *p; + + check(frame(type) == flatcc_builder_union_vector, "expected union vector frame"); + if (frame(container.vector.count) == max_union_count) { + return 0; + } + frame(container.vector.count) += 1; + if (0 == (p = push_ds(B, union_size))) { + return 0; + } + *p = uref; + return p; +} + +flatcc_builder_union_ref_t *flatcc_builder_append_union_vector(flatcc_builder_t *B, + const flatcc_builder_union_ref_t *urefs, size_t count) +{ + check(frame(type) == flatcc_builder_union_vector, "expected union vector frame"); + if (vector_count_add(B, (uoffset_t)count, max_union_count)) { + return 0; + } + return push_ds_copy(B, urefs, (uoffset_t)(union_size * count)); +} + +flatcc_builder_ref_t flatcc_builder_create_string(flatcc_builder_t *B, const char *s, size_t len) +{ + uoffset_t s_pad; + uoffset_t length_prefix; + iov_state_t iov; + + if (len > max_string_len) { + return 0; + } + write_uoffset(&length_prefix, (uoffset_t)len); + /* Add 1 for zero termination. */ + s_pad = front_pad(B, (uoffset_t)len + 1, field_size) + 1; + init_iov(); + push_iov(&length_prefix, field_size); + push_iov(s, len); + push_iov(_pad, s_pad); + return emit_front(B, &iov); +} + +flatcc_builder_ref_t flatcc_builder_create_string_str(flatcc_builder_t *B, const char *s) +{ + return flatcc_builder_create_string(B, s, strlen(s)); +} + +flatcc_builder_ref_t flatcc_builder_create_string_strn(flatcc_builder_t *B, const char *s, size_t max_len) +{ + return flatcc_builder_create_string(B, s, strnlen(s, max_len)); +} + +flatcc_builder_ref_t flatcc_builder_end_string(flatcc_builder_t *B) +{ + flatcc_builder_ref_t string_ref; + + check(frame(type) == flatcc_builder_string, "expected string frame"); + FLATCC_ASSERT(frame(container.vector.count) == B->ds_offset); + if (0 == (string_ref = flatcc_builder_create_string(B, + (const char *)B->ds, B->ds_offset))) { + return 0; + } + exit_frame(B); + return string_ref; +} + +char *flatcc_builder_string_edit(flatcc_builder_t *B) +{ + return (char *)B->ds; +} + +size_t flatcc_builder_string_len(flatcc_builder_t *B) +{ + return frame(container.vector.count); +} + +void *flatcc_builder_table_add(flatcc_builder_t *B, int id, size_t size, uint16_t align) +{ + /* + * We align the offset relative to the first table field, excluding + * the header holding the vtable reference. On the stack, `ds_first` + * is aligned to 8 bytes thanks to the `enter_frame` logic, and this + * provides a safe way to update the fields on the stack, but here + * we are concerned with the target buffer alignment. + * + * We could also have aligned relative to the end of the table which + * would allow us to emit each field immediately, but it would be a + * confusing user experience wrt. field ordering, and it would add + * more variability to vtable layouts, thus reducing reuse, and + * frequent emissions to external emitter interface would be + * sub-optimal. Also, with that appoach, the vtable offsets would + * have to be adjusted at table end. + * + * As we have it, each emit occur at table end, vector end, string + * end, or buffer end, which might be helpful to various backend + * processors. + */ + check(frame(type) == flatcc_builder_table, "expected table frame"); + check(id >= 0 && id <= (int)FLATBUFFERS_ID_MAX, "table id out of range"); + if (align > B->align) { + B->align = align; + } +#if FLATCC_BUILDER_ALLOW_REPEAT_TABLE_ADD + if (B->vs[id] != 0) { + return B->ds + B->vs[id] - field_size; + } +#else + if (B->vs[id] != 0) { + check(0, "table field already set"); + return 0; + } +#endif + FLATCC_BUILDER_UPDATE_VT_HASH(B->vt_hash, (uint32_t)id, (uint32_t)size); + return push_ds_field(B, (uoffset_t)size, align, (voffset_t)id); +} + +void *flatcc_builder_table_edit(flatcc_builder_t *B, size_t size) +{ + check(frame(type) == flatcc_builder_table, "expected table frame"); + + return B->ds + B->ds_offset - size; +} + +void *flatcc_builder_table_add_copy(flatcc_builder_t *B, int id, const void *data, size_t size, uint16_t align) +{ + void *p; + + if ((p = flatcc_builder_table_add(B, id, size, align))) { + memcpy(p, data, size); + } + return p; +} + +flatcc_builder_ref_t *flatcc_builder_table_add_offset(flatcc_builder_t *B, int id) +{ + check(frame(type) == flatcc_builder_table, "expected table frame"); + check(id >= 0 && id <= (int)FLATBUFFERS_ID_MAX, "table id out of range"); +#if FLATCC_BUILDER_ALLOW_REPEAT_TABLE_ADD + if (B->vs[id] != 0) { + return B->ds + B->vs[id] - field_size; + } +#else + if (B->vs[id] != 0) { + check(0, "table field already set"); + return 0; + } +#endif + FLATCC_BUILDER_UPDATE_VT_HASH(B->vt_hash, (uint32_t)id, (uint32_t)field_size); + return push_ds_offset_field(B, (voffset_t)id); +} + +uint16_t flatcc_builder_push_buffer_alignment(flatcc_builder_t *B) +{ + uint16_t old_min_align = B->min_align; + + B->min_align = field_size; + return old_min_align; +} + +void flatcc_builder_pop_buffer_alignment(flatcc_builder_t *B, uint16_t pushed_align) +{ + set_min_align(B, pushed_align); +} + +uint16_t flatcc_builder_get_buffer_alignment(flatcc_builder_t *B) +{ + return B->min_align; +} + +void flatcc_builder_set_vtable_clustering(flatcc_builder_t *B, int enable) +{ + /* Inverted because we zero all memory in B on init. */ + B->disable_vt_clustering = !enable; +} + +void flatcc_builder_set_block_align(flatcc_builder_t *B, uint16_t align) +{ + B->block_align = align; +} + +int flatcc_builder_get_level(flatcc_builder_t *B) +{ + return B->level; +} + +void flatcc_builder_set_max_level(flatcc_builder_t *B, int max_level) +{ + B->max_level = max_level; + if (B->limit_level < B->max_level) { + B->limit_level = B->max_level; + } +} + +size_t flatcc_builder_get_buffer_size(flatcc_builder_t *B) +{ + return (size_t)(B->emit_end - B->emit_start); +} + +flatcc_builder_ref_t flatcc_builder_get_buffer_start(flatcc_builder_t *B) +{ + return B->emit_start; +} + +flatcc_builder_ref_t flatcc_builder_get_buffer_end(flatcc_builder_t *B) +{ + return B->emit_end; +} + +void flatcc_builder_set_vtable_cache_limit(flatcc_builder_t *B, size_t size) +{ + B->vb_flush_limit = size; +} + +void flatcc_builder_set_identifier(flatcc_builder_t *B, const char identifier[identifier_size]) +{ + set_identifier(identifier); +} + +enum flatcc_builder_type flatcc_builder_get_type(flatcc_builder_t *B) +{ + return B->frame ? frame(type) : flatcc_builder_empty; +} + +enum flatcc_builder_type flatcc_builder_get_type_at(flatcc_builder_t *B, int level) +{ + if (level < 1 || level > B->level) { + return flatcc_builder_empty; + } + return B->frame[level - B->level].type; +} + +void *flatcc_builder_get_direct_buffer(flatcc_builder_t *B, size_t *size_out) +{ + if (B->is_default_emitter) { + return flatcc_emitter_get_direct_buffer(&B->default_emit_context, size_out); + } else { + if (size_out) { + *size_out = 0; + } + } + return 0; +} + +void *flatcc_builder_copy_buffer(flatcc_builder_t *B, void *buffer, size_t size) +{ + /* User is allowed to call tentatively to see if there is support. */ + if (!B->is_default_emitter) { + return 0; + } + buffer = flatcc_emitter_copy_buffer(&B->default_emit_context, buffer, size); + check(buffer, "default emitter declined to copy buffer"); + return buffer; +} + +void *flatcc_builder_finalize_buffer(flatcc_builder_t *B, size_t *size_out) +{ + void * buffer; + size_t size; + + size = flatcc_builder_get_buffer_size(B); + + if (size_out) { + *size_out = size; + } + + buffer = FLATCC_BUILDER_ALLOC(size); + + if (!buffer) { + check(0, "failed to allocated memory for finalized buffer"); + goto done; + } + if (!flatcc_builder_copy_buffer(B, buffer, size)) { + check(0, "default emitter declined to copy buffer"); + FLATCC_BUILDER_FREE(buffer); + buffer = 0; + } +done: + if (!buffer && size_out) { + *size_out = 0; + } + return buffer; +} + +void *flatcc_builder_finalize_aligned_buffer(flatcc_builder_t *B, size_t *size_out) +{ + void * buffer; + size_t align; + size_t size; + + size = flatcc_builder_get_buffer_size(B); + + if (size_out) { + *size_out = size; + } + align = flatcc_builder_get_buffer_alignment(B); + + size = (size + align - 1) & ~(align - 1); + buffer = FLATCC_BUILDER_ALIGNED_ALLOC(align, size); + + if (!buffer) { + goto done; + } + if (!flatcc_builder_copy_buffer(B, buffer, size)) { + FLATCC_BUILDER_ALIGNED_FREE(buffer); + buffer = 0; + goto done; + } +done: + if (!buffer && size_out) { + *size_out = 0; + } + return buffer; +} + +void *flatcc_builder_aligned_alloc(size_t alignment, size_t size) +{ + return FLATCC_BUILDER_ALIGNED_ALLOC(alignment, size); +} + +void flatcc_builder_aligned_free(void *p) +{ + FLATCC_BUILDER_ALIGNED_FREE(p); +} + +void *flatcc_builder_alloc(size_t size) +{ + return FLATCC_BUILDER_ALLOC(size); +} + +void flatcc_builder_free(void *p) +{ + FLATCC_BUILDER_FREE(p); +} + +void *flatcc_builder_get_emit_context(flatcc_builder_t *B) +{ + return B->emit_context; +} |