duktape-1.5.2/examples/debug-trans-dvalue/duk_trans_dvalue.c

Go to the documentation of this file.

/*
 *  Example debug transport with a local debug message encoder/decoder.
 *
 *  Provides a "received dvalue" callback for a fully parsed dvalue (user
 *  code frees dvalue) and a "cooperate" callback for e.g. UI integration.
 *  There are a few other callbacks.  See test.c for usage examples.
 *
 *  This transport implementation is not multithreaded which means that:
 *
 *    - Callbacks to "received dvalue" callback come from the Duktape thread,
 *      either during normal execution or from duk_debugger_cooperate().
 *
 *    - Calls into duk_trans_dvalue_send() must be made from the callbacks
 *      provided (e.g. "received dvalue" or "cooperate") which use the active
 *      Duktape thread.
 *
 *    - The only exception to this is when Duktape is idle: you can then call
 *      duk_trans_dvalue_send() from any thread (only one thread at a time).
 *      When you next call into Duktape or call duk_debugger_cooperate(), the
 *      queued data will be read and processed by Duktape.
 *
 *  There are functions for creating and freeing values; internally they use
 *  malloc() and free() for memory management.  Duktape heap alloc functions
 *  are not used to minimize disturbances to the Duktape heap under debugging.
 *
 *  Doesn't depend on C99 types; assumes "int" is at least 32 bits, and makes
 *  a few assumptions about format specifiers.
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include "duktape.h"
#include "duk_trans_dvalue.h"
 
/* Define to enable debug prints to stderr. */
#if 0
#define DEBUG_PRINTS
#endif
 
/* Define to enable error prints to stderr. */
#if 1
#define ERROR_PRINTS
#endif
 
/*
 *  Dvalue handling
 */
 
duk_dvalue *duk_dvalue_alloc(void) {
    duk_dvalue *dv = (duk_dvalue *) malloc(sizeof(duk_dvalue));
    if (dv) {
        memset((void *) dv, 0, sizeof(duk_dvalue));
        dv->buf = NULL;
    }
    return dv;
}
 
void duk_dvalue_free(duk_dvalue *dv) {
    if (dv) {
        free(dv->buf);  /* tolerates NULL */
        dv->buf = NULL;
        free(dv);
    }
}
 
static void duk__dvalue_bufesc(duk_dvalue *dv, char *buf, size_t maxbytes, int stresc) {
    size_t i, limit;
 
    *buf = (char) 0;
    limit = dv->len > maxbytes ? maxbytes : dv->len;
    for (i = 0; i < limit; i++) {
        unsigned char c = dv->buf[i];
        if (stresc) {
            if (c >= 0x20 && c <= 0x7e && c != (char) '"' && c != (char) '\'') {
                sprintf(buf, "%c", c);
                buf++;
            } else {
                sprintf(buf, "\\x%02x", (unsigned int) c);
                buf += 4;
            }
        } else {
            sprintf(buf, "%02x", (unsigned int) c);
            buf += 2;
        }
    }
    if (dv->len > maxbytes) {
        sprintf(buf, "...");
        buf += 3;
    }
}
 
/* Caller must provide a buffer at least DUK_DVALUE_TOSTRING_BUFLEN in size. */
void duk_dvalue_to_string(duk_dvalue *dv, char *buf) {
    char hexbuf[32 * 4 + 4];  /* 32 hex encoded or \xXX escaped bytes, possible "...", NUL */
 
    if (!dv) {
        sprintf(buf, "NULL");
        return;
    }
 
    switch (dv->tag) {
    case DUK_DVALUE_EOM:
        sprintf(buf, "EOM");
        break;
    case DUK_DVALUE_REQ:
        sprintf(buf, "REQ");
        break;
    case DUK_DVALUE_REP:
        sprintf(buf, "REP");
        break;
    case DUK_DVALUE_ERR:
        sprintf(buf, "ERR");
        break;
    case DUK_DVALUE_NFY:
        sprintf(buf, "NFY");
        break;
    case DUK_DVALUE_INTEGER:
        sprintf(buf, "%d", dv->i);
        break;
    case DUK_DVALUE_STRING:
        duk__dvalue_bufesc(dv, hexbuf, 32, 1);
        sprintf(buf, "str:%ld:\"%s\"", (long) dv->len, hexbuf);
        break;
    case DUK_DVALUE_BUFFER:
        duk__dvalue_bufesc(dv, hexbuf, 32, 0);
        sprintf(buf, "buf:%ld:%s", (long) dv->len, hexbuf);
        break;
    case DUK_DVALUE_UNUSED:
        sprintf(buf, "undefined");
        break;
    case DUK_DVALUE_UNDEFINED:
        sprintf(buf, "undefined");
        break;
    case DUK_DVALUE_NULL:
        sprintf(buf, "null");
        break;
    case DUK_DVALUE_TRUE:
        sprintf(buf, "true");
        break;
    case DUK_DVALUE_FALSE:
        sprintf(buf, "false");
        break;
    case DUK_DVALUE_NUMBER:
        if (fpclassify(dv->d) == FP_ZERO) {
            if (signbit(dv->d)) {
                sprintf(buf, "-0");
            } else {
                sprintf(buf, "0");
            }
        } else {
            sprintf(buf, "%lg", dv->d);
        }
        break;
    case DUK_DVALUE_OBJECT:
        duk__dvalue_bufesc(dv, hexbuf, 32, 0);
        sprintf(buf, "obj:%d:%s", (int) dv->i, hexbuf);
        break;
    case DUK_DVALUE_POINTER:
        duk__dvalue_bufesc(dv, hexbuf, 32, 0);
        sprintf(buf, "ptr:%s", hexbuf);
        break;
    case DUK_DVALUE_LIGHTFUNC:
        duk__dvalue_bufesc(dv, hexbuf, 32, 0);
        sprintf(buf, "lfunc:%04x:%s", (unsigned int) dv->i, hexbuf);
        break;
    case DUK_DVALUE_HEAPPTR:
        duk__dvalue_bufesc(dv, hexbuf, 32, 0);
        sprintf(buf, "heapptr:%s", hexbuf);
        break;
    default:
        sprintf(buf, "unknown:%d", (int) dv->tag);
    }
}
 
duk_dvalue *duk_dvalue_make_tag(int tag) {
    duk_dvalue *dv = duk_dvalue_alloc();
    if (!dv) { return NULL; }
    dv->tag = tag;
    return dv;
}
 
duk_dvalue *duk_dvalue_make_tag_int(int tag, int intval) {
    duk_dvalue *dv = duk_dvalue_alloc();
    if (!dv) { return NULL; }
    dv->tag = tag;
    dv->i = intval;
    return dv;
}
 
duk_dvalue *duk_dvalue_make_tag_double(int tag, double dblval) {
    duk_dvalue *dv = duk_dvalue_alloc();
    if (!dv) { return NULL; }
    dv->tag = tag;
    dv->d = dblval;
    return dv;
}
 
duk_dvalue *duk_dvalue_make_tag_data(int tag, const char *buf, size_t len) {
    unsigned char *p;
    duk_dvalue *dv = duk_dvalue_alloc();
    if (!dv) { return NULL; }
    /* Alloc size is len + 1 so that a NUL terminator is always
     * guaranteed which is convenient, e.g. you can printf() the
     * value safely.
     */
    p = (unsigned char *) malloc(len + 1);
    if (!p) {
        free(dv);
        return NULL;
    }
    memcpy((void *) p, (const void *) buf, len);
    p[len] = (unsigned char) 0;
    dv->tag = tag;
    dv->buf = p;
    dv->len = len;
    return dv;
}
 
duk_dvalue *duk_dvalue_make_tag_int_data(int tag, int intval, const char *buf, size_t len) {
    duk_dvalue *dv = duk_dvalue_make_tag_data(tag, buf, len);
    if (!dv) { return NULL; }
    dv->i = intval;
    return dv;
}
 
/*
 *  Dvalue transport handling
 */
 
static void duk__trans_dvalue_double_byteswap(duk_trans_dvalue_ctx *ctx, volatile unsigned char *p) {
    unsigned char t;
 
    /* Portable IEEE double byteswap.  Relies on runtime detection of
     * host endianness.
     */
 
    if (ctx->double_byteorder == 0) {
        /* little endian */
        t = p[0]; p[0] = p[7]; p[7] = t;
        t = p[1]; p[1] = p[6]; p[6] = t;
        t = p[2]; p[2] = p[5]; p[5] = t;
        t = p[3]; p[3] = p[4]; p[4] = t;
    } else if (ctx->double_byteorder == 1) {
        /* big endian: ok as is */
        ;
    } else {
        /* mixed endian */
        t = p[0]; p[0] = p[3]; p[3] = t;
        t = p[1]; p[1] = p[2]; p[2] = t;
        t = p[4]; p[4] = p[7]; p[7] = t;
        t = p[5]; p[5] = p[6]; p[6] = t;
    }
}
 
static unsigned int duk__trans_dvalue_parse_u32(duk_trans_dvalue_ctx *ctx, unsigned char *p) {
    /* Integers are network endian, read back into host format in
     * a portable manner.
     */
    (void) ctx;
    return (((unsigned int) p[0]) << 24) +
           (((unsigned int) p[1]) << 16) +
           (((unsigned int) p[2]) << 8) +
           (((unsigned int) p[3]) << 0);
}
 
static int duk__trans_dvalue_parse_i32(duk_trans_dvalue_ctx *ctx, unsigned char *p) {
    /* Portable sign handling, doesn't assume 'int' is exactly 32 bits
     * like a direct cast would.
     */
    unsigned int tmp = duk__trans_dvalue_parse_u32(ctx, p);
    if (tmp & 0x80000000UL) {
        return -((int) ((tmp ^ 0xffffffffUL) + 1UL));
    } else {
        return tmp;
    }
}
 
static unsigned int duk__trans_dvalue_parse_u16(duk_trans_dvalue_ctx *ctx, unsigned char *p) {
    /* Integers are network endian, read back into host format. */
    (void) ctx;
    return (((unsigned int) p[0]) << 8) +
           (((unsigned int) p[1]) << 0);
}
 
static double duk__trans_dvalue_parse_double(duk_trans_dvalue_ctx *ctx, unsigned char *p) {
    /* IEEE doubles are network endian, read back into host format. */
    volatile union {
        double d;
        unsigned char b[8];
    } u;
    memcpy((void *) u.b, (const void *) p, 8);
    duk__trans_dvalue_double_byteswap(ctx, u.b);
    return u.d;
}
 
static unsigned char *duk__trans_dvalue_encode_u32(duk_trans_dvalue_ctx *ctx, unsigned char *p, unsigned int val) {
    /* Integers are written in network endian format. */
    (void) ctx;
    *p++ = (unsigned char) ((val >> 24) & 0xff);
    *p++ = (unsigned char) ((val >> 16) & 0xff);
    *p++ = (unsigned char) ((val >> 8) & 0xff);
    *p++ = (unsigned char) (val & 0xff);
    return p;
}
 
static unsigned char *duk__trans_dvalue_encode_i32(duk_trans_dvalue_ctx *ctx, unsigned char *p, int val) {
    return duk__trans_dvalue_encode_u32(ctx, p, (unsigned int) val & 0xffffffffUL);
}
 
static unsigned char *duk__trans_dvalue_encode_u16(duk_trans_dvalue_ctx *ctx, unsigned char *p, unsigned int val) {
    /* Integers are written in network endian format. */
    (void) ctx;
    *p++ = (unsigned char) ((val >> 8) & 0xff);
    *p++ = (unsigned char) (val & 0xff);
    return p;
}
 
static unsigned char *duk__trans_dvalue_encode_double(duk_trans_dvalue_ctx *ctx, unsigned char *p, double val) {
    /* IEEE doubles are written in network endian format. */
    volatile union {
        double d;
        unsigned char b[8];
    } u;
    u.d = val;
    duk__trans_dvalue_double_byteswap(ctx, u.b);
    memcpy((void *) p, (const void *) u.b, 8);
    p += 8;
    return p;
}
 
static unsigned char *duk__trans_buffer_ensure(duk_trans_buffer *dbuf, size_t space) {
    size_t avail;
    size_t used;
    size_t new_size;
    void *new_alloc;
 
    used = dbuf->write_offset;
    avail = dbuf->alloc_size - dbuf->write_offset;
 
    if (avail >= space) {
        if (avail - space > 256) {
            /* Too big, resize so that we reclaim memory if we have just
             * received a large string/buffer value.
             */
            goto do_realloc;
        }
    } else {
        /* Too small, resize. */
        goto do_realloc;
    }
 
    return dbuf->base + dbuf->write_offset;
 
 do_realloc:
    new_size = used + space + 256;  /* some extra to reduce resizes */
    new_alloc = realloc(dbuf->base, new_size);
    if (new_alloc) {
        dbuf->base = (unsigned char *) new_alloc;
        dbuf->alloc_size = new_size;
#if defined(DEBUG_PRINTS)
        fprintf(stderr, "%s: resized buffer %p to %ld bytes, read_offset=%ld, write_offset=%ld\n",
                __func__, (void *) dbuf, (long) new_size, (long) dbuf->read_offset, (long) dbuf->write_offset);
        fflush(stderr);
#endif
        return dbuf->base + dbuf->write_offset;
    } else {
        return NULL;
    }
}
 
/* When read_offset is large enough, "rebase" buffer by deleting already
 * read data and updating offsets.
 */
static void duk__trans_buffer_rebase(duk_trans_buffer *dbuf) {
    if (dbuf->read_offset > 64) {
#if defined(DEBUG_PRINTS)
        fprintf(stderr, "%s: rebasing buffer %p, read_offset=%ld, write_offset=%ld\n",
                __func__, (void *) dbuf, (long) dbuf->read_offset, (long) dbuf->write_offset);
        fflush(stderr);
#endif
        if (dbuf->write_offset > dbuf->read_offset) {
            memmove((void *) dbuf->base, (const void *) (dbuf->base + dbuf->read_offset), dbuf->write_offset - dbuf->read_offset);
        }
        dbuf->write_offset -= dbuf->read_offset;
        dbuf->read_offset = 0;
    }
}
 
duk_trans_dvalue_ctx *duk_trans_dvalue_init(void) {
    volatile union {
        double d;
        unsigned char b[8];
    } u;
    duk_trans_dvalue_ctx *ctx = NULL;
 
    ctx = (duk_trans_dvalue_ctx *) malloc(sizeof(duk_trans_dvalue_ctx));
    if (!ctx) { goto fail; }
    memset((void *) ctx, 0, sizeof(duk_trans_dvalue_ctx));
    ctx->received = NULL;
    ctx->cooperate = NULL;
    ctx->handshake = NULL;
    ctx->detached = NULL;
    ctx->send_buf.base = NULL;
    ctx->recv_buf.base = NULL;
 
    ctx->send_buf.base = malloc(256);
    if (!ctx->send_buf.base) { goto fail; }
    ctx->send_buf.alloc_size = 256;
 
    ctx->recv_buf.base = malloc(256);
    if (!ctx->recv_buf.base) { goto fail; }
    ctx->recv_buf.alloc_size = 256;
 
    /* IEEE double byte order, detect at run time (could also use
     * preprocessor defines but that's verbose to make portable).
     *
     * >>> struct.unpack('>d', '1122334455667788'.decode('hex'))
     * (3.841412024471731e-226,)
     * >>> struct.unpack('>d', '8877665544332211'.decode('hex'))
     * (-7.086876636573014e-268,)
     * >>> struct.unpack('>d', '4433221188776655'.decode('hex'))
     * (3.5294303071877444e+20,)
     */
    u.b[0] = 0x11; u.b[1] = 0x22; u.b[2] = 0x33; u.b[3] = 0x44;
    u.b[4] = 0x55; u.b[5] = 0x66; u.b[6] = 0x77; u.b[7] = 0x88;
    if (u.d < 0.0) {
        ctx->double_byteorder = 0;  /* little endian */
    } else if (u.d < 1.0) {
        ctx->double_byteorder = 1;  /* big endian */
    } else {
        ctx->double_byteorder = 2;  /* mixed endian (arm) */
    }
#if defined(DEBUG_PRINTS)
    fprintf(stderr, "double endianness test value is %lg -> byteorder %d\n",
            u.d, ctx->double_byteorder);
    fflush(stderr);
#endif
 
    return ctx;
 
 fail:
    if (ctx) {
        free(ctx->recv_buf.base);  /* tolerates NULL */
        free(ctx->send_buf.base);  /* tolerates NULL */
        free(ctx);
    }
    return NULL;
}
 
void duk_trans_dvalue_free(duk_trans_dvalue_ctx *ctx) {
    if (ctx) {
        free(ctx->send_buf.base);  /* tolerates NULL */
        free(ctx->recv_buf.base);  /* tolerates NULL */
        free(ctx);
    }
}
 
void duk_trans_dvalue_send(duk_trans_dvalue_ctx *ctx, duk_dvalue *dv) {
    unsigned char *p;
 
    /* Convert argument dvalue into Duktape debug protocol format.
     * Literal constants are used here for the debug protocol,
     * e.g. initial byte 0x02 is REP, see doc/debugger.rst.
     */
 
#if defined(DEBUG_PRINTS)
    {
        char buf[DUK_DVALUE_TOSTRING_BUFLEN];
        duk_dvalue_to_string(dv, buf);
        fprintf(stderr, "%s: sending dvalue: %s\n", __func__, buf);
        fflush(stderr);
    }
#endif
 
    switch (dv->tag) {
    case DUK_DVALUE_EOM: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x00;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_REQ: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x01;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_REP: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x02;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_ERR: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x03;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_NFY: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x04;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_INTEGER: {
        int i = dv->i;
        if (i >= 0 && i <= 63) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
            if (!p) { goto alloc_error; }
            *p++ = (unsigned char) (0x80 + i);
            ctx->send_buf.write_offset += 1;
        } else if (i >= 0 && i <= 16383L) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 2);
            if (!p) { goto alloc_error; }
            *p++ = (unsigned char) (0xc0 + (i >> 8));
            *p++ = (unsigned char) (i & 0xff);
            ctx->send_buf.write_offset += 2;
        } else if (i >= -0x80000000L && i <= 0x7fffffffL) {  /* Harmless warning on some platforms (re: range) */
            p = duk__trans_buffer_ensure(&ctx->send_buf, 5);
            if (!p) { goto alloc_error; }
            *p++ = 0x10;
            p = duk__trans_dvalue_encode_i32(ctx, p, i);
            ctx->send_buf.write_offset += 5;
        } else {
            goto dvalue_error;
        }
        break;
    }
    case DUK_DVALUE_STRING: {
        size_t i = dv->len;
        if (i <= 0x1fUL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 1 + i);
            if (!p) { goto alloc_error; }
            *p++ = (unsigned char) (0x60 + i);
            memcpy((void *) p, (const void *) dv->buf, i);
            p += i;
            ctx->send_buf.write_offset += 1 + i;
        } else if (i <= 0xffffUL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 3 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x12;
            p = duk__trans_dvalue_encode_u16(ctx, p, (unsigned int) i);
            memcpy((void *) p, (const void *) dv->buf, i);
            p += i;
            ctx->send_buf.write_offset += 3 + i;
        } else if (i <= 0xffffffffUL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 5 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x11;
            p = duk__trans_dvalue_encode_u32(ctx, p, (unsigned int) i);
            memcpy((void *) p, (const void *) dv->buf, i);
            p += i;
            ctx->send_buf.write_offset += 5 + i;
        } else {
            goto dvalue_error;
        }
        break;
    }
    case DUK_DVALUE_BUFFER: {
        size_t i = dv->len;
        if (i <= 0xffffUL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 3 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x14;
            p = duk__trans_dvalue_encode_u16(ctx, p, (unsigned int) i);
            memcpy((void *) p, (const void *) dv->buf, i);
            p += i;
            ctx->send_buf.write_offset += 3 + i;
        } else if (i <= 0xffffffffUL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 5 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x13;
            p = duk__trans_dvalue_encode_u32(ctx, p, (unsigned int) i);
            memcpy((void *) p, (const void *) dv->buf, i);
            p += i;
            ctx->send_buf.write_offset += 5 + i;
        } else {
            goto dvalue_error;
        }
        break;
    }
    case DUK_DVALUE_UNUSED: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x15;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_UNDEFINED: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x16;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_NULL: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x17;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_TRUE: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x18;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_FALSE: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 1);
        if (!p) { goto alloc_error; }
        *p++ = 0x19;
        ctx->send_buf.write_offset += 1;
        break;
    }
    case DUK_DVALUE_NUMBER: {
        p = duk__trans_buffer_ensure(&ctx->send_buf, 9);
        if (!p) { goto alloc_error; }
        *p++ = 0x1a;
        p = duk__trans_dvalue_encode_double(ctx, p, dv->d);
        ctx->send_buf.write_offset += 9;
        break;
    }
    case DUK_DVALUE_OBJECT: {
        size_t i = dv->len;
        if (i <= 0xffUL && dv->i >= 0 && dv->i <= 0xffL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 3 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x1b;
            *p++ = (unsigned char) dv->i;
            *p++ = (unsigned char) i;
            memcpy((void *) p, (const void *) dv->buf, i);
            ctx->send_buf.write_offset += 3 + i;
        } else {
            goto dvalue_error;
        }
        break;
    }
    case DUK_DVALUE_POINTER: {
        size_t i = dv->len;
        if (i <= 0xffUL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 2 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x1c;
            *p++ = (unsigned char) i;
            memcpy((void *) p, (const void *) dv->buf, i);
            ctx->send_buf.write_offset += 2 + i;
        } else {
            goto dvalue_error;
        }
        break;
    }
    case DUK_DVALUE_LIGHTFUNC: {
        size_t i = dv->len;
        if (i <= 0xffUL && dv->i >= 0 && dv->i <= 0xffffL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 4 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x1d;
            p = duk__trans_dvalue_encode_u16(ctx, p, (unsigned int) dv->i);
            *p++ = (unsigned char) i;
            memcpy((void *) p, (const void *) dv->buf, i);
            ctx->send_buf.write_offset += 4 + i;
        } else {
            goto dvalue_error;
        }
        break;
    }
    case DUK_DVALUE_HEAPPTR: {
        size_t i = dv->len;
        if (i <= 0xffUL) {
            p = duk__trans_buffer_ensure(&ctx->send_buf, 2 + i);
            if (!p) { goto alloc_error; }
            *p++ = 0x1e;
            *p++ = (unsigned char) i;
            memcpy((void *) p, (const void *) dv->buf, i);
            ctx->send_buf.write_offset += 2 + i;
        } else {
            goto dvalue_error;
        }
        break;
    }
    default: {
        goto dvalue_error;
    }
    }  /* end switch */
 
    return;
 
 dvalue_error:
#if defined(ERROR_PRINTS)
    fprintf(stderr, "%s: internal error, argument dvalue is invalid\n", __func__);
    fflush(stdout);
#endif
    return;
 
 alloc_error:
#if defined(ERROR_PRINTS)
    fprintf(stderr, "%s: internal error, failed to allocate space for write\n", __func__);
    fflush(stdout);
#endif
    return;
}
 
static void duk__trans_dvalue_send_and_free(duk_trans_dvalue_ctx *ctx, duk_dvalue *dv) {
    if (!dv) { return; }
    duk_trans_dvalue_send(ctx, dv);
    duk_dvalue_free(dv);
}
 
void duk_trans_dvalue_send_eom(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_EOM));
}
 
void duk_trans_dvalue_send_req(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_REQ));
}
 
void duk_trans_dvalue_send_rep(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_REP));
}
 
void duk_trans_dvalue_send_err(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_ERR));
}
 
void duk_trans_dvalue_send_nfy(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_NFY));
}
 
void duk_trans_dvalue_send_integer(duk_trans_dvalue_ctx *ctx, int val) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_int(DUK_DVALUE_INTEGER, val));
}
 
void duk_trans_dvalue_send_string(duk_trans_dvalue_ctx *ctx, const char *str) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_data(DUK_DVALUE_STRING, str, strlen(str)));
}
 
void duk_trans_dvalue_send_lstring(duk_trans_dvalue_ctx *ctx, const char *str, size_t len) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_data(DUK_DVALUE_STRING, str, len));
}
 
void duk_trans_dvalue_send_buffer(duk_trans_dvalue_ctx *ctx, const char *buf, size_t len) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_data(DUK_DVALUE_BUFFER, buf, len));
}
 
void duk_trans_dvalue_send_unused(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_UNUSED));
}
 
void duk_trans_dvalue_send_undefined(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_UNDEFINED));
}
 
void duk_trans_dvalue_send_null(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_NULL));
}
 
void duk_trans_dvalue_send_true(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_TRUE));
}
 
void duk_trans_dvalue_send_false(duk_trans_dvalue_ctx *ctx) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag(DUK_DVALUE_FALSE));
}
 
void duk_trans_dvalue_send_number(duk_trans_dvalue_ctx *ctx, double val) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_double(DUK_DVALUE_NUMBER, val));
}
 
void duk_trans_dvalue_send_object(duk_trans_dvalue_ctx *ctx, int classnum, const char *ptr_data, size_t ptr_len) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_int_data(DUK_DVALUE_OBJECT, classnum, ptr_data, ptr_len));
}
 
void duk_trans_dvalue_send_pointer(duk_trans_dvalue_ctx *ctx, const char *ptr_data, size_t ptr_len) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_data(DUK_DVALUE_POINTER, ptr_data, ptr_len));
}
 
void duk_trans_dvalue_send_lightfunc(duk_trans_dvalue_ctx *ctx, int lf_flags, const char *ptr_data, size_t ptr_len) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_int_data(DUK_DVALUE_LIGHTFUNC, lf_flags, ptr_data, ptr_len));
}
 
void duk_trans_dvalue_send_heapptr(duk_trans_dvalue_ctx *ctx, const char *ptr_data, size_t ptr_len) {
    duk__trans_dvalue_send_and_free(ctx, duk_dvalue_make_tag_data(DUK_DVALUE_HEAPPTR, ptr_data, ptr_len));
}
 
void duk_trans_dvalue_send_req_cmd(duk_trans_dvalue_ctx *ctx, int cmd) {
    duk_trans_dvalue_send_req(ctx);
    duk_trans_dvalue_send_integer(ctx, cmd);
}
 
static duk_dvalue *duk__trans_trial_parse_dvalue(duk_trans_dvalue_ctx *ctx) {
    unsigned char *p;
    size_t len;
    unsigned char ib;
    duk_dvalue *dv;
    size_t datalen;
 
    p = ctx->recv_buf.base + ctx->recv_buf.read_offset;
    len = ctx->recv_buf.write_offset - ctx->recv_buf.read_offset;
 
    if (len == 0) {
        return NULL;
    }
    ib = p[0];
 
#if defined(DEBUG_PRINTS)
    {
        size_t i;
        fprintf(stderr, "%s: parsing dvalue, window:", __func__);
        for (i = 0; i < 16; i++) {
            if (i < len) {
                fprintf(stderr, " %02x", (unsigned int) p[i]);
            } else {
                fprintf(stderr, " ??");
            }
        }
        fprintf(stderr, " (length %ld, read_offset %ld, write_offset %ld, alloc_size %ld)\n",
                (long) len, (long) ctx->recv_buf.read_offset, (long) ctx->recv_buf.write_offset,
                (long) ctx->recv_buf.alloc_size);
        fflush(stderr);
    }
#endif
 
    if (ib <= 0x1fU) {
        /* 0x00 ... 0x1f */
        switch (ib) {
        case 0x00: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_EOM);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x01: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_REQ);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x02: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_REP);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x03: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_ERR);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x04: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_NFY);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x10: {
            int intval;
            if (len < 5) { goto partial; }
            intval = duk__trans_dvalue_parse_i32(ctx, p + 1);
            ctx->recv_buf.read_offset += 5;
            dv = duk_dvalue_make_tag_int(DUK_DVALUE_INTEGER, intval);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x11: {
            if (len < 5) { goto partial; }
            datalen = (size_t) duk__trans_dvalue_parse_u32(ctx, p + 1);
            if (len < 5 + datalen) { goto partial; }
            ctx->recv_buf.read_offset += 5 + datalen;
            dv = duk_dvalue_make_tag_data(DUK_DVALUE_STRING, (const char *) (p + 5), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x12: {
            if (len < 3) { goto partial; }
            datalen = (size_t) duk__trans_dvalue_parse_u16(ctx, p + 1);
            if (len < 3 + datalen) { goto partial; }
            ctx->recv_buf.read_offset += 3 + datalen;
            dv = duk_dvalue_make_tag_data(DUK_DVALUE_STRING, (const char *) (p + 3), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x13: {
            if (len < 5) { goto partial; }
            datalen = (size_t) duk__trans_dvalue_parse_u32(ctx, p + 1);
            if (len < 5 + datalen) { goto partial; }
            ctx->recv_buf.read_offset += 5 + datalen;
            dv = duk_dvalue_make_tag_data(DUK_DVALUE_BUFFER, (const char *) (p + 5), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x14: {
            if (len < 3) { goto partial; }
            datalen = (size_t) duk__trans_dvalue_parse_u16(ctx, p + 1);
            if (len < 3 + datalen) { goto partial; }
            ctx->recv_buf.read_offset += 3 + datalen;
            dv = duk_dvalue_make_tag_data(DUK_DVALUE_BUFFER, (const char *) (p + 3), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x15: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_UNUSED);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x16: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_UNDEFINED);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x17: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_NULL);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x18: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_TRUE);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x19: {
            ctx->recv_buf.read_offset += 1;
            dv = duk_dvalue_make_tag(DUK_DVALUE_FALSE);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x1a: {
            double dblval;
            if (len < 9) { goto partial; }
            dblval = duk__trans_dvalue_parse_double(ctx, p + 1);
            ctx->recv_buf.read_offset += 9;
            dv = duk_dvalue_make_tag_double(DUK_DVALUE_NUMBER, dblval);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x1b: {
            int classnum;
            if (len < 3) { goto partial; }
            datalen = (size_t) p[2];
            if (len < 3 + datalen) { goto partial; }
            classnum = (int) p[1];
            ctx->recv_buf.read_offset += 3 + datalen;
            dv = duk_dvalue_make_tag_int_data(DUK_DVALUE_OBJECT, classnum, (const char *) (p + 3), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x1c: {
            if (len < 2) { goto partial; }
            datalen = (size_t) p[1];
            if (len < 2 + datalen) { goto partial; }
            ctx->recv_buf.read_offset += 2 + datalen;
            dv = duk_dvalue_make_tag_data(DUK_DVALUE_POINTER, (const char *) (p + 2), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x1d: {
            int lf_flags;
            if (len < 4) { goto partial; }
            datalen = (size_t) p[3];
            if (len < 4 + datalen) { goto partial; }
            lf_flags = (int) duk__trans_dvalue_parse_u16(ctx, p + 1);
            ctx->recv_buf.read_offset += 4 + datalen;
            dv = duk_dvalue_make_tag_int_data(DUK_DVALUE_LIGHTFUNC, lf_flags, (const char *) (p + 4), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        case 0x1e: {
            if (len < 2) { goto partial; }
            datalen = (size_t) p[1];
            if (len < 2 + datalen) { goto partial; }
            ctx->recv_buf.read_offset += 2 + datalen;
            dv = duk_dvalue_make_tag_data(DUK_DVALUE_HEAPPTR, (const char *) (p + 2), datalen);
            if (!dv) { goto alloc_error; }
            return dv;
        }
        default: {
            goto format_error;
        }
        }  /* end switch */
    } else if (ib <= 0x5fU) {
        /* 0x20 ... 0x5f */
        goto format_error;
    } else if (ib <= 0x7fU) {
        /* 0x60 ... 0x7f */
        datalen = (size_t) (ib - 0x60U);
        if (len < 1 + datalen) { goto partial; }
        ctx->recv_buf.read_offset += 1 + datalen;
        dv = duk_dvalue_make_tag_data(DUK_DVALUE_STRING, (const char *) (p + 1), datalen);
        if (!dv) { goto alloc_error; }
        return dv;
    } else if (ib <= 0xbfU) {
        /* 0x80 ... 0xbf */
        int intval;
        intval = (int) (ib - 0x80U);
        ctx->recv_buf.read_offset += 1;
        dv = duk_dvalue_make_tag_int(DUK_DVALUE_INTEGER, intval);
        if (!dv) { goto alloc_error; }
        return dv;
    } else {
        /* 0xc0 ... 0xff */
        int intval;
        if (len < 2) { goto partial; }
        intval = (((int) (ib - 0xc0U)) << 8) + (int) p[1];
        ctx->recv_buf.read_offset += 2;
        dv = duk_dvalue_make_tag_int(DUK_DVALUE_INTEGER, intval);
        if (!dv) { goto alloc_error; }
        return dv;
    }
 
    /* never here */
 
 partial:
    return NULL;
 
 alloc_error:
#if defined(ERROR_PRINTS)
    fprintf(stderr, "%s: internal error, cannot allocate space for dvalue\n", __func__);
    fflush(stdout);
#endif
    return NULL;
 
 format_error:
#if defined(ERROR_PRINTS)
    fprintf(stderr, "%s: internal error, dvalue format error\n", __func__);
    fflush(stdout);
#endif
    return NULL;
}
 
static duk_dvalue *duk__trans_trial_parse_handshake(duk_trans_dvalue_ctx *ctx) {
    unsigned char *p;
    size_t len;
    duk_dvalue *dv;
    size_t i;
 
    p = ctx->recv_buf.base + ctx->recv_buf.read_offset;
    len = ctx->recv_buf.write_offset - ctx->recv_buf.read_offset;
 
    for (i = 0; i < len; i++) {
        if (p[i] == 0x0a) {
            /* Handshake line is returned as a dvalue for convenience; it's
             * not actually a part of the dvalue phase of the protocol.
             */
            ctx->recv_buf.read_offset += i + 1;
            dv = duk_dvalue_make_tag_data(DUK_DVALUE_STRING, (const char *) p, i);
            if (!dv) { goto alloc_error; }
            return dv;
        }
    }
 
    return NULL;
 
 alloc_error:
#if defined(ERROR_PRINTS)
    fprintf(stderr, "%s: internal error, cannot allocate space for handshake line\n", __func__);
    fflush(stdout);
#endif
    return NULL;
}
 
static void duk__trans_call_cooperate(duk_trans_dvalue_ctx *ctx, int block) {
    if (ctx->cooperate) {
        ctx->cooperate(ctx, block);
    }
}
 
static void duk__trans_call_received(duk_trans_dvalue_ctx *ctx, duk_dvalue *dv) {
    if (ctx->received) {
        ctx->received(ctx, dv);
    }
}
 
static void duk__trans_call_handshake(duk_trans_dvalue_ctx *ctx, const char *line) {
    if (ctx->handshake) {
        ctx->handshake(ctx, line);
    }
}
 
static void duk__trans_call_detached(duk_trans_dvalue_ctx *ctx) {
    if (ctx->detached) {
        ctx->detached(ctx);
    }
}
 
/*
 *  Duktape callbacks
 */
 
duk_size_t duk_trans_dvalue_read_cb(void *udata, char *buffer, duk_size_t length) {
    duk_trans_dvalue_ctx *ctx = (duk_trans_dvalue_ctx *) udata;
 
#if defined(DEBUG_PRINTS)
    fprintf(stderr, "%s: %p %p %ld\n", __func__, udata, (void *) buffer, (long) length);
    fflush(stderr);
#endif
 
    duk__trans_call_cooperate(ctx, 0);
 
    for (;;) {
        size_t avail, now;
 
        avail = (size_t) (ctx->send_buf.write_offset - ctx->send_buf.read_offset);
        if (avail == 0) {
            /* Must cooperate until user callback provides data.  From
             * Duktape's perspective we MUST block until data is received.
             */
            duk__trans_call_cooperate(ctx, 1);
        } else {
            now = avail;
            if (now > length) {
                now = length;
            }
            memcpy((void *) buffer, (const void *) (ctx->send_buf.base + ctx->send_buf.read_offset), now);
            duk__trans_buffer_rebase(&ctx->send_buf);
            ctx->send_buf.read_offset += now;
            return now;
        }
    }
}
 
duk_size_t duk_trans_dvalue_write_cb(void *udata, const char *buffer, duk_size_t length) {
    duk_trans_dvalue_ctx *ctx = (duk_trans_dvalue_ctx *) udata;
    unsigned char *p;
 
#if defined(DEBUG_PRINTS)
    fprintf(stderr, "%s: %p %p %ld\n", __func__, udata, (void *) buffer, (long) length);
    fflush(stderr);
#endif
 
    duk__trans_call_cooperate(ctx, 0);
 
    /* Append data. */
    duk__trans_buffer_rebase(&ctx->recv_buf);
    p = duk__trans_buffer_ensure(&ctx->recv_buf, length);
    memcpy((void *) p, (const void *) buffer, (size_t) length);
    ctx->recv_buf.write_offset += length;
 
    /* Trial parse handshake line or dvalue(s). */
    if (!ctx->handshake_done) {
        duk_dvalue *dv = duk__trans_trial_parse_handshake(ctx);
        if (dv) {
            /* Handshake line is available for caller for the
             * duration of the callback, and must not be freed
             * by the caller.
             */
            duk__trans_call_handshake(ctx, (const char *) dv->buf);
#if defined(DEBUG_PRINTS)
            fprintf(stderr, "%s: handshake ok\n", __func__);
            fflush(stderr);
#endif
            duk_dvalue_free(dv);
            ctx->handshake_done = 1;
        }
    }
    if (ctx->handshake_done) {
        for (;;) {
            duk_dvalue *dv = duk__trans_trial_parse_dvalue(ctx);
            if (dv) {
#if defined(DEBUG_PRINTS)
                {
                    char buf[DUK_DVALUE_TOSTRING_BUFLEN];
                    duk_dvalue_to_string(dv, buf);
                    fprintf(stderr, "%s: received dvalue: %s\n", __func__, buf);
                    fflush(stderr);
                }
#endif
 
                duk__trans_call_received(ctx, dv);
            } else {
                break;
            }
        }
    }
 
    duk__trans_call_cooperate(ctx, 0);  /* just in case, if dvalues changed something */
 
    return length;
}
 
duk_size_t duk_trans_dvalue_peek_cb(void *udata) {
    duk_trans_dvalue_ctx *ctx = (duk_trans_dvalue_ctx *) udata;
    size_t avail;
 
#if defined(DEBUG_PRINTS)
    fprintf(stderr, "%s: %p\n", __func__, udata);
    fflush(stderr);
#endif
 
    duk__trans_call_cooperate(ctx, 0);
    avail = (size_t) (ctx->send_buf.write_offset - ctx->send_buf.read_offset);
    return (duk_size_t) avail;
}
 
void duk_trans_dvalue_read_flush_cb(void *udata) {
    duk_trans_dvalue_ctx *ctx = (duk_trans_dvalue_ctx *) udata;
 
#if defined(DEBUG_PRINTS)
    fprintf(stderr, "%s: %p\n", __func__, udata);
    fflush(stderr);
#endif
 
    duk__trans_call_cooperate(ctx, 0);
}
 
void duk_trans_dvalue_write_flush_cb(void *udata) {
    duk_trans_dvalue_ctx *ctx = (duk_trans_dvalue_ctx *) udata;
 
#if defined(DEBUG_PRINTS)
    fprintf(stderr, "%s: %p\n", __func__, udata);
    fflush(stderr);
#endif
 
    duk__trans_call_cooperate(ctx, 0);
}
 
void duk_trans_dvalue_detached_cb(void *udata) {
    duk_trans_dvalue_ctx *ctx = (duk_trans_dvalue_ctx *) udata;
 
#if defined(DEBUG_PRINTS)
    fprintf(stderr, "%s: %p\n", __func__, udata);
    fflush(stderr);
#endif
 
    duk__trans_call_detached(ctx);
}