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https://github.com/aljazceru/lightning.git
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common/json: make json_scan return an error string.
This makes for more useful errors. It prints where it was up to in the guide, but doesn't print the entire JSON it's scanning. Suggested-by: Christian Decker Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
committed by
Christian Decker
Christian Decker
parent
53582a0f81
commit
3b7d0e7a62
299
common/json.c
299
common/json.c
@@ -720,30 +720,42 @@ void json_tok_remove(jsmntok_t **tokens,
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}
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/* talfmt take a ctx pointer and return NULL or a valid pointer.
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* fmt takes the argument, and returns a bool. */
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static bool handle_percent(const char *buffer,
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const jsmntok_t *tok,
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va_list *ap)
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* fmt takes the argument, and returns a bool.
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*
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* This function returns NULL on success, or errmsg on failure.
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*/
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static const char *handle_percent(const char *buffer,
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const jsmntok_t *tok,
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va_list *ap)
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{
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void *ctx;
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const char *fmtname;
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/* This is set to (dummy) json_scan if it's a non-tal fmt */
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ctx = va_arg(*ap, void *);
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fmtname = va_arg(*ap, const char *);
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if (ctx != json_scan) {
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void *(*talfmt)(void *, const char *, const jsmntok_t *);
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void **p;
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p = va_arg(*ap, void **);
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talfmt = va_arg(*ap, void *(*)(void *, const char *, const jsmntok_t *));
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*p = talfmt(ctx, buffer, tok);
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return *p != NULL;
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if (*p != NULL)
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return NULL;
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} else {
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bool (*fmt)(const char *, const jsmntok_t *, void *);
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void *p;
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p = va_arg(*ap, void *);
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fmt = va_arg(*ap, bool (*)(const char *, const jsmntok_t *, void *));
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return fmt(buffer, tok, p);
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if (fmt(buffer, tok, p))
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return NULL;
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}
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return tal_fmt(tmpctx, "%s could not parse %.*s",
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fmtname,
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json_tok_full_len(tok),
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json_tok_full(buffer, tok));
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}
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/* GUIDE := OBJ | ARRAY | '%'
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@@ -756,235 +768,280 @@ static bool handle_percent(const char *buffer,
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* ARRELEM := NUMBER ':' FIELDVAL
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*/
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/* Returns NULL on failure, or offset into guide */
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static const char *parse_literal(const char *guide,
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const char **literal,
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size_t *len)
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static void parse_literal(const char **guide,
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const char **literal,
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size_t *len)
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{
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*literal = guide;
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*len = strspn(guide,
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*literal = *guide;
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*len = strspn(*guide,
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789"
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"_-");
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return guide + *len;
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*guide += *len;
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}
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static const char *parse_number(const char *guide, u32 *number)
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static void parse_number(const char **guide, u32 *number)
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{
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char *endp;
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long int l;
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l = strtol(guide, &endp, 10);
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if (endp == guide || errno == ERANGE)
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return NULL;
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l = strtol(*guide, &endp, 10);
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assert(endp != *guide);
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assert(errno != ERANGE);
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/* Test for overflow */
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*number = l;
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if (*number != l)
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return NULL;
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assert(*number == l);
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return endp;
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*guide = endp;
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}
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/* Recursion */
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static char guide_consume_one(const char **guide)
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{
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char c = **guide;
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(*guide)++;
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return c;
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}
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static void guide_must_be(const char **guide, char c)
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{
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char actual = guide_consume_one(guide);
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assert(actual == c);
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}
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/* Recursion: return NULL on success, errmsg on fail */
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static const char *parse_obj(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap);
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static const char *parse_arr(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap);
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static const char *parse_guide(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap)
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{
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if (*guide == '{') {
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guide = parse_obj(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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assert(*guide == '}');
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return guide + 1;
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} else if (*guide == '[') {
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guide = parse_arr(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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assert(*guide == ']');
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return guide + 1;
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const char *errmsg;
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if (**guide == '{') {
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errmsg = parse_obj(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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} else if (**guide == '[') {
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errmsg = parse_arr(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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} else {
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assert(*guide == '%');
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if (!handle_percent(buffer, tok, ap))
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return NULL;
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return guide + 1;
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guide_must_be(guide, '%');
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errmsg = handle_percent(buffer, tok, ap);
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if (errmsg)
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return errmsg;
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}
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return NULL;
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}
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static const char *parse_fieldval(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap)
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{
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if (*guide == '{') {
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guide = parse_obj(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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assert(*guide == '}');
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return guide + 1;
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} else if (*guide == '[') {
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guide = parse_arr(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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assert(*guide == ']');
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return guide + 1;
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} else if (*guide == '%') {
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if (!handle_percent(buffer, tok, ap))
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return NULL;
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return guide + 1;
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const char *errmsg;
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if (**guide == '{') {
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errmsg = parse_obj(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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} else if (**guide == '[') {
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errmsg = parse_arr(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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} else if (**guide == '%') {
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guide_consume_one(guide);
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errmsg = handle_percent(buffer, tok, ap);
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if (errmsg)
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return errmsg;
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} else {
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const char *literal;
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size_t len;
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/* Literal must match exactly */
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guide = parse_literal(guide, &literal, &len);
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/* Literal must match exactly (modulo quotes for strings) */
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parse_literal(guide, &literal, &len);
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if (!memeq(buffer + tok->start, tok->end - tok->start,
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literal, len))
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return NULL;
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return guide;
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literal, len)) {
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return tal_fmt(tmpctx,
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"%.*s does not match expected %.*s",
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json_tok_full_len(tok),
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json_tok_full(buffer, tok),
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(int)len, literal);
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}
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}
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return NULL;
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}
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static const char *parse_field(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap)
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{
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const jsmntok_t *member;
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size_t len;
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const char *memname;
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guide = parse_literal(guide, &memname, &len);
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assert(*guide == ':');
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parse_literal(guide, &memname, &len);
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guide_must_be(guide, ':');
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member = json_get_membern(buffer, tok, memname, guide - memname);
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if (!member)
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return NULL;
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member = json_get_membern(buffer, tok, memname, len);
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if (!member) {
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return tal_fmt(tmpctx, "object does not have member %.*s",
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(int)len, memname);
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}
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return parse_fieldval(buffer, member, guide + 1, ap);
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return parse_fieldval(buffer, member, guide, ap);
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}
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static const char *parse_fieldlist(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap)
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{
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for (;;) {
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guide = parse_field(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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if (*guide != ',')
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const char *errmsg;
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errmsg = parse_field(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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if (**guide != ',')
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break;
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guide++;
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guide_consume_one(guide);
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}
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return guide;
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return NULL;
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}
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static const char *parse_obj(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap)
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{
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assert(*guide == '{');
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const char *errmsg;
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if (tok->type != JSMN_OBJECT)
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return NULL;
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guide_must_be(guide, '{');
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guide = parse_fieldlist(buffer, tok, guide + 1, ap);
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if (!guide)
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return NULL;
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return guide;
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if (tok->type != JSMN_OBJECT) {
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return tal_fmt(tmpctx, "token is not an object: %.*s",
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json_tok_full_len(tok),
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json_tok_full(buffer, tok));
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}
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errmsg = parse_fieldlist(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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guide_must_be(guide, '}');
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return NULL;
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}
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static const char *parse_arrelem(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap)
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{
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const jsmntok_t *member;
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u32 idx;
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guide = parse_number(guide, &idx);
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assert(*guide == ':');
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parse_number(guide, &idx);
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guide_must_be(guide, ':');
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member = json_get_arr(tok, idx);
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if (!member)
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return NULL;
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if (!member) {
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return tal_fmt(tmpctx, "token has no index %u: %.*s",
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idx,
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json_tok_full_len(tok),
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json_tok_full(buffer, tok));
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}
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return parse_fieldval(buffer, member, guide + 1, ap);
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return parse_fieldval(buffer, member, guide, ap);
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}
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static const char *parse_arrlist(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list *ap)
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const jsmntok_t *tok,
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const char **guide,
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va_list *ap)
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{
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const char *errmsg;
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for (;;) {
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guide = parse_arrelem(buffer, tok, guide, ap);
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if (!guide)
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return NULL;
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if (*guide != ',')
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errmsg = parse_arrelem(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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if (**guide != ',')
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break;
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guide++;
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guide_consume_one(guide);
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}
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return guide;
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return NULL;
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}
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static const char *parse_arr(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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const char **guide,
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va_list *ap)
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{
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assert(*guide == '[');
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const char *errmsg;
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if (tok->type != JSMN_ARRAY)
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return NULL;
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guide_must_be(guide, '[');
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guide = parse_arrlist(buffer, tok, guide + 1, ap);
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if (!guide)
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return NULL;
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return guide;
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if (tok->type != JSMN_ARRAY) {
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return tal_fmt(tmpctx, "token is not an array: %.*s",
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json_tok_full_len(tok),
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json_tok_full(buffer, tok));
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}
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errmsg = parse_arrlist(buffer, tok, guide, ap);
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if (errmsg)
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return errmsg;
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guide_must_be(guide, ']');
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return NULL;
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}
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bool json_scanv(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list ap)
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const char *json_scanv(const tal_t *ctx,
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const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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va_list ap)
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{
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va_list cpy;
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const char *orig_guide = guide, *errmsg;
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/* We need this, since &ap doesn't work on some platforms... */
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va_copy(cpy, ap);
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guide = parse_guide(buffer, tok, guide, &cpy);
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errmsg = parse_guide(buffer, tok, &guide, &cpy);
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va_end(cpy);
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if (!guide)
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return false;
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if (errmsg) {
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return tal_fmt(ctx, "Parsing '%.*s': %s",
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(int)(guide - orig_guide), orig_guide,
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errmsg);
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}
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assert(guide[0] == '\0');
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return true;
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return NULL;
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}
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bool json_scan(const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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...)
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const char *json_scan(const tal_t *ctx,
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const char *buffer,
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const jsmntok_t *tok,
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const char *guide,
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...)
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{
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va_list ap;
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bool ret;
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const char *ret;
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va_start(ap, guide);
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ret = json_scanv(buffer, tok, guide, ap);
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ret = json_scanv(ctx, buffer, tok, guide, ap);
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va_end(ap);
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return ret;
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}
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