ceph/src/civetweb/src/third_party/duktape-1.3.0/src-separate/duk_hbuffer.h

   1 /*
   2  *  Heap buffer representation.
   3  *
   4  *  Heap allocated user data buffer which is either:
   5  *
   6  *    1. A fixed size buffer (data follows header statically)
   7  *    2. A dynamic size buffer (data pointer follows header)
   8  *
   9  *  The data pointer for a variable size buffer of zero size may be NULL.
  10  */
  11
  12 #ifndef DUK_HBUFFER_H_INCLUDED
  13 #define DUK_HBUFFER_H_INCLUDED
  14
  15 /*
  16  *  Flags
  17  *
  18  *  Fixed buffer:     0
  19  *  Dynamic buffer:   DUK_HBUFFER_FLAG_DYNAMIC
  20  *  External buffer:  DUK_HBUFFER_FLAG_DYNAMIC | DUK_HBUFFER_FLAG_EXTERNAL
  21  */
  22
  23 #define DUK_HBUFFER_FLAG_DYNAMIC                  DUK_HEAPHDR_USER_FLAG(0)    /* buffer is behind a pointer, dynamic or external */
  24 #define DUK_HBUFFER_FLAG_EXTERNAL                 DUK_HEAPHDR_USER_FLAG(1)    /* buffer pointer is to an externally allocated buffer */
  25
  26 #define DUK_HBUFFER_HAS_DYNAMIC(x)                DUK_HEAPHDR_CHECK_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_DYNAMIC)
  27 #define DUK_HBUFFER_HAS_EXTERNAL(x)               DUK_HEAPHDR_CHECK_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_EXTERNAL)
  28
  29 #define DUK_HBUFFER_SET_DYNAMIC(x)                DUK_HEAPHDR_SET_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_DYNAMIC)
  30 #define DUK_HBUFFER_SET_EXTERNAL(x)               DUK_HEAPHDR_SET_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_EXTERNAL)
  31
  32 #define DUK_HBUFFER_CLEAR_DYNAMIC(x)              DUK_HEAPHDR_CLEAR_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_DYNAMIC)
  33 #define DUK_HBUFFER_CLEAR_EXTERNAL(x)             DUK_HEAPHDR_CLEAR_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_EXTERNAL)
  34
  35 /*
  36  *  Misc defines
  37  */
  38
  39 /* Impose a maximum buffer length for now.  Restricted artificially to
  40  * ensure resize computations or adding a heap header length won't
  41  * overflow size_t and that a signed duk_int_t can hold a buffer
  42  * length.  The limit should be synchronized with DUK_HSTRING_MAX_BYTELEN.
  43  */
  44
  45 #if defined(DUK_USE_BUFLEN16)
  46 #define DUK_HBUFFER_MAX_BYTELEN                   (0x0000ffffUL)
  47 #else
  48 /* Intentionally not 0x7fffffffUL; at least JSON code expects that
  49  * 2*len + 2 fits in 32 bits.
  50  */
  51 #define DUK_HBUFFER_MAX_BYTELEN                   (0x7ffffffeUL)
  52 #endif
  53
  54 /*
  55  *  Field access
  56  */
  57
  58 /* Get/set the current user visible size, without accounting for a dynamic
  59  * buffer's "spare" (= usable size).
  60  */
  61 #if defined(DUK_USE_BUFLEN16)
  62 /* size stored in duk_heaphdr unused flag bits */
  63 #define DUK_HBUFFER_GET_SIZE(x)     ((x)->hdr.h_flags >> 16)
  64 #define DUK_HBUFFER_SET_SIZE(x,v)   do { \
  65                 (x)->hdr.h_flags = ((x)->hdr.h_flags & 0x0000ffffUL) | ((v) << 16); \
  66         } while (0)
  67 #define DUK_HBUFFER_ADD_SIZE(x,dv)  do { \
  68                 (x)->hdr.h_flags += ((dv) << 16); \
  69         } while (0)
  70 #define DUK_HBUFFER_SUB_SIZE(x,dv)  do { \
  71                 (x)->hdr.h_flags -= ((dv) << 16); \
  72         } while (0)
  73 #else
  74 #define DUK_HBUFFER_GET_SIZE(x)     (((duk_hbuffer *) (x))->size)
  75 #define DUK_HBUFFER_SET_SIZE(x,v)   do { \
  76                 ((duk_hbuffer *) (x))->size = (v); \
  77         } while (0)
  78 #define DUK_HBUFFER_ADD_SIZE(x,dv)  do { \
  79                 (x)->size += (dv); \
  80         } while (0)
  81 #define DUK_HBUFFER_SUB_SIZE(x,dv)  do { \
  82                 (x)->size -= (dv); \
  83         } while (0)
  84 #endif
  85
  86 #define DUK_HBUFFER_FIXED_GET_SIZE(x)       DUK_HBUFFER_GET_SIZE((duk_hbuffer *) (x))
  87 #define DUK_HBUFFER_FIXED_SET_SIZE(x,v)     DUK_HBUFFER_SET_SIZE((duk_hbuffer *) (x))
  88
  89 #define DUK_HBUFFER_DYNAMIC_GET_SIZE(x)     DUK_HBUFFER_GET_SIZE((duk_hbuffer *) (x))
  90 #define DUK_HBUFFER_DYNAMIC_SET_SIZE(x,v)   DUK_HBUFFER_SET_SIZE((duk_hbuffer *) (x), (v))
  91 #define DUK_HBUFFER_DYNAMIC_ADD_SIZE(x,dv)  DUK_HBUFFER_ADD_SIZE((duk_hbuffer *) (x), (dv))
  92 #define DUK_HBUFFER_DYNAMIC_SUB_SIZE(x,dv)  DUK_HBUFFER_SUB_SIZE((duk_hbuffer *) (x), (dv))
  93
  94 #define DUK_HBUFFER_EXTERNAL_GET_SIZE(x)    DUK_HBUFFER_GET_SIZE((duk_hbuffer *) (x))
  95 #define DUK_HBUFFER_EXTERNAL_SET_SIZE(x,v)  DUK_HBUFFER_SET_SIZE((duk_hbuffer *) (x), (v))
  96
  97 #define DUK_HBUFFER_FIXED_GET_DATA_PTR(heap,x)    ((duk_uint8_t *) (((duk_hbuffer_fixed *) (x)) + 1))
  98
  99 #if defined(DUK_USE_HEAPPTR16)
 100 #define DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(heap,x) \
 101         ((void *) DUK_USE_HEAPPTR_DEC16((heap)->heap_udata, ((duk_heaphdr *) (x))->h_extra16))
 102 #define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR(heap,x,v)     do { \
 103                 ((duk_heaphdr *) (x))->h_extra16 = DUK_USE_HEAPPTR_ENC16((heap)->heap_udata, (void *) (v)); \
 104         } while (0)
 105 #define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR_NULL(heap,x)  do { \
 106                 ((duk_heaphdr *) (x))->h_extra16 = 0;  /* assume 0 <=> NULL */ \
 107         } while (0)
 108 #else
 109 #define DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(heap,x)       ((x)->curr_alloc)
 110 #define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR(heap,x,v)     do { \
 111                 (x)->curr_alloc = (void *) (v); \
 112         } while (0)
 113 #define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR_NULL(heap,x)  do { \
 114                 (x)->curr_alloc = (void *) NULL; \
 115         } while (0)
 116 #endif
 117
 118 /* No pointer compression because pointer is potentially outside of
 119  * Duktape heap.
 120  */
 121 #if defined(DUK_USE_HEAPPTR16)
 122 #define DUK_HBUFFER_EXTERNAL_GET_DATA_PTR(heap,x) \
 123         ((void *) (x)->curr_alloc)
 124 #define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR(heap,x,v)     do { \
 125                 (x)->curr_alloc = (void *) (v); \
 126         } while (0)
 127 #define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR_NULL(heap,x)  do { \
 128                 (x)->curr_alloc = (void *) NULL; \
 129         } while (0)
 130 #else
 131 #define DUK_HBUFFER_EXTERNAL_GET_DATA_PTR(heap,x) \
 132         ((void *) (x)->curr_alloc)
 133 #define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR(heap,x,v)     do { \
 134                 (x)->curr_alloc = (void *) (v); \
 135         } while (0)
 136 #define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR_NULL(heap,x)  do { \
 137                 (x)->curr_alloc = (void *) NULL; \
 138         } while (0)
 139 #endif
 140
 141 /* Get a pointer to the current buffer contents (matching current allocation
 142  * size).  May be NULL for zero size dynamic/external buffer.
 143  */
 144 #if defined(DUK_USE_HEAPPTR16)
 145 #define DUK_HBUFFER_GET_DATA_PTR(heap,x)  ( \
 146         DUK_HBUFFER_HAS_DYNAMIC((x)) ? \
 147                 ( \
 148                         DUK_HBUFFER_HAS_EXTERNAL((x)) ? \
 149                                 DUK_HBUFFER_EXTERNAL_GET_DATA_PTR((heap), (duk_hbuffer_external *) (x)) : \
 150                                 DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((heap), (duk_hbuffer_dynamic *) (x)) \
 151                 ) : \
 152                 DUK_HBUFFER_FIXED_GET_DATA_PTR((heap), (duk_hbuffer_fixed *) (x)) \
 153         )
 154 #else
 155 /* Without heap pointer compression duk_hbuffer_dynamic and duk_hbuffer_external
 156  * have the same layout so checking for fixed vs. dynamic (or external) is enough.
 157  */
 158 #define DUK_HBUFFER_GET_DATA_PTR(heap,x)  ( \
 159         DUK_HBUFFER_HAS_DYNAMIC((x)) ? \
 160                 DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((heap), (duk_hbuffer_dynamic *) (x)) : \
 161                 DUK_HBUFFER_FIXED_GET_DATA_PTR((heap), (duk_hbuffer_fixed *) (x)) \
 162         )
 163 #endif
 164
 165 /*
 166  *  Structs
 167  */
 168
 169 /* Shared prefix for all buffer types. */
 170 struct duk_hbuffer {
 171         duk_heaphdr hdr;
 172
 173         /* It's not strictly necessary to track the current size, but
 174          * it is useful for writing robust native code.
 175          */
 176
 177         /* Current size (not counting a dynamic buffer's "spare"). */
 178 #if defined(DUK_USE_BUFLEN16)
 179         /* Stored in duk_heaphdr unused flags. */
 180 #else
 181         duk_size_t size;
 182 #endif
 183
 184         /*
 185          *  Data following the header depends on the DUK_HBUFFER_FLAG_DYNAMIC
 186          *  flag.
 187          *
 188          *  If the flag is clear (the buffer is a fixed size one), the buffer
 189          *  data follows the header directly, consisting of 'size' bytes.
 190          *
 191          *  If the flag is set, the actual buffer is allocated separately, and
 192          *  a few control fields follow the header.  Specifically:
 193          *
 194          *    - a "void *" pointing to the current allocation
 195          *    - a duk_size_t indicating the full allocated size (always >= 'size')
 196          *
 197          *  If DUK_HBUFFER_FLAG_EXTERNAL is set, the buffer has been allocated
 198          *  by user code, so that Duktape won't be able to resize it and won't
 199          *  free it.  This allows buffers to point to e.g. an externally
 200          *  allocated structure such as a frame buffer.
 201          *
 202          *  Unlike strings, no terminator byte (NUL) is guaranteed after the
 203          *  data.  This would be convenient, but would pad aligned user buffers
 204          *  unnecessarily upwards in size.  For instance, if user code requested
 205          *  a 64-byte dynamic buffer, 65 bytes would actually be allocated which
 206          *  would then potentially round upwards to perhaps 68 or 72 bytes.
 207          */
 208 };
 209
 210 /* Fixed buffer; data follows struct, with proper alignment guaranteed by
 211  * struct size.
 212  */
 213 #if (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_MSVC_PRAGMA)
 214 #pragma pack(push, 8)
 215 #endif
 216 struct duk_hbuffer_fixed {
 217         /* A union is used here as a portable struct size / alignment trick:
 218          * by adding a 32-bit or a 64-bit (unused) union member, the size of
 219          * the struct is effectively forced to be a multiple of 4 or 8 bytes
 220          * (respectively) without increasing the size of the struct unless
 221          * necessary.
 222          */
 223         union {
 224                 struct {
 225                         duk_heaphdr hdr;
 226 #if defined(DUK_USE_BUFLEN16)
 227                         /* Stored in duk_heaphdr unused flags. */
 228 #else
 229                         duk_size_t size;
 230 #endif
 231                 } s;
 232 #if (DUK_USE_ALIGN_BY == 4)
 233                 duk_uint32_t dummy_for_align4;
 234 #elif (DUK_USE_ALIGN_BY == 8)
 235                 duk_double_t dummy_for_align8;
 236 #elif (DUK_USE_ALIGN_BY == 1)
 237                 /* no extra padding */
 238 #else
 239 #error invalid DUK_USE_ALIGN_BY
 240 #endif
 241         } u;
 242
 243         /*
 244          *  Data follows the struct header.  The struct size is padded by the
 245          *  compiler based on the struct members.  This guarantees that the
 246          *  buffer data will be aligned-by-4 but not necessarily aligned-by-8.
 247          *
 248          *  On platforms where alignment does not matter, the struct padding
 249          *  could be removed (if there is any).  On platforms where alignment
 250          *  by 8 is required, the struct size must be forced to be a multiple
 251          *  of 8 by some means.  Without it, some user code may break, and also
 252          *  Duktape itself breaks (e.g. the compiler stores duk_tvals in a
 253          *  dynamic buffer).
 254          */
 255 }
 256 #if (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_GCC_ATTR)
 257 __attribute__ ((aligned (8)))
 258 #elif (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_CLANG_ATTR)
 259 __attribute__ ((aligned (8)))
 260 #endif
 261 ;
 262 #if (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_MSVC_PRAGMA)
 263 #pragma pack(pop)
 264 #endif
 265
 266 /* Dynamic buffer with 'curr_alloc' pointing to a dynamic area allocated using
 267  * heap allocation primitives.  Also used for external buffers when low memory
 268  * options are not used.
 269  */
 270 struct duk_hbuffer_dynamic {
 271         duk_heaphdr hdr;
 272
 273 #if defined(DUK_USE_BUFLEN16)
 274         /* Stored in duk_heaphdr unused flags. */
 275 #else
 276         duk_size_t size;
 277 #endif
 278
 279 #if defined(DUK_USE_HEAPPTR16)
 280         /* Stored in duk_heaphdr h_extra16. */
 281 #else
 282         void *curr_alloc;  /* may be NULL if alloc_size == 0 */
 283 #endif
 284
 285         /*
 286          *  Allocation size for 'curr_alloc' is alloc_size.  There is no
 287          *  automatic NUL terminator for buffers (see above for rationale).
 288          *
 289          *  'curr_alloc' is explicitly allocated with heap allocation
 290          *  primitives and will thus always have alignment suitable for
 291          *  e.g. duk_tval and an IEEE double.
 292          */
 293 };
 294
 295 /* External buffer with 'curr_alloc' managed by user code and pointing to an
 296  * arbitrary address.  When heap pointer compression is not used, this struct
 297  * has the same layout as duk_hbuffer_dynamic.
 298  */
 299 struct duk_hbuffer_external {
 300         duk_heaphdr hdr;
 301
 302 #if defined(DUK_USE_BUFLEN16)
 303         /* Stored in duk_heaphdr unused flags. */
 304 #else
 305         duk_size_t size;
 306 #endif
 307
 308         /* Cannot be compressed as a heap pointer because may point to
 309          * an arbitrary address.
 310          */
 311         void *curr_alloc;  /* may be NULL if alloc_size == 0 */
 312 };
 313
 314 /*
 315  *  Prototypes
 316  */
 317
 318 DUK_INTERNAL_DECL duk_hbuffer *duk_hbuffer_alloc(duk_heap *heap, duk_size_t size, duk_small_uint_t flags, void **out_bufdata);
 319 DUK_INTERNAL_DECL void *duk_hbuffer_get_dynalloc_ptr(duk_heap *heap, void *ud);  /* indirect allocs */
 320
 321 /* dynamic buffer ops */
 322 DUK_INTERNAL_DECL void duk_hbuffer_resize(duk_hthread *thr, duk_hbuffer_dynamic *buf, duk_size_t new_size);
 323 DUK_INTERNAL_DECL void duk_hbuffer_reset(duk_hthread *thr, duk_hbuffer_dynamic *buf);
 324
 325 #endif  /* DUK_HBUFFER_H_INCLUDED */