1 files changed, 550 insertions, 0 deletions

diff --git a/src/json.c b/src/json.c
new file mode 100644
index 0000000..ee1382c
--- /dev/null
+++ b/src/json.c
@@ -0,0 +1,550 @@
+#include "json.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+        const char *p;
+        const char *end;
+        int depth;
+} json_parser_t;
+
+static json_value_t *parse_value(json_parser_t *ps);
+
+static json_value_t *value_new(json_type_t type)
+{
+        json_value_t *v = calloc(1, sizeof(*v));
+        if (v != NULL)
+                v->type = type;
+        return v;
+}
+
+void json_free(json_value_t *value)
+{
+        size_t i;
+
+        if (value == NULL)
+                return;
+        switch (value->type) {
+        case JSON_STRING:
+                free(value->as.string);
+                break;
+        case JSON_ARRAY:
+                for (i = 0; i < value->as.array.count; i++)
+                        json_free(value->as.array.items[i]);
+                free(value->as.array.items);
+                break;
+        case JSON_OBJECT:
+                for (i = 0; i < value->as.object.count; i++) {
+                        free(value->as.object.keys[i]);
+                        json_free(value->as.object.values[i]);
+                }
+                free(value->as.object.keys);
+                free(value->as.object.values);
+                break;
+        default:
+                break;
+        }
+        free(value);
+}
+
+static void skip_ws(json_parser_t *ps)
+{
+        while (ps->p < ps->end) {
+                char c = *ps->p;
+                if (c != ' ' && c != '\t' && c != '\n' && c != '\r')
+                        return;
+                ps->p++;
+        }
+}
+
+static bool at(const json_parser_t *ps, char c)
+{
+        return ps->p < ps->end && *ps->p == c;
+}
+
+static bool literal(json_parser_t *ps, const char *word)
+{
+        size_t n = strlen(word);
+
+        if ((size_t)(ps->end - ps->p) < n)
+                return false;
+        if (memcmp(ps->p, word, n) != 0)
+                return false;
+        ps->p += n;
+        return true;
+}
+
+static int hex_digit(char c)
+{
+        if (c >= '0' && c <= '9')
+                return c - '0';
+        if (c >= 'a' && c <= 'f')
+                return c - 'a' + 10;
+        if (c >= 'A' && c <= 'F')
+                return c - 'A' + 10;
+        return -1;
+}
+
+static bool read_hex4(json_parser_t *ps, unsigned *out)
+{
+        unsigned value = 0;
+        int i;
+
+        if (ps->end - ps->p < 4)
+                return false;
+        for (i = 0; i < 4; i++) {
+                int digit = hex_digit(ps->p[i]);
+                if (digit < 0)
+                        return false;
+                value = (value << 4) | (unsigned)digit;
+        }
+        ps->p += 4;
+        *out = value;
+        return true;
+}
+
+static size_t utf8_encode(unsigned cp, char *out)
+{
+        if (cp < 0x80) {
+                out[0] = (char)cp;
+                return 1;
+        }
+        if (cp < 0x800) {
+                out[0] = (char)(0xC0 | (cp >> 6));
+                out[1] = (char)(0x80 | (cp & 0x3F));
+                return 2;
+        }
+        if (cp < 0x10000) {
+                out[0] = (char)(0xE0 | (cp >> 12));
+                out[1] = (char)(0x80 | ((cp >> 6) & 0x3F));
+                out[2] = (char)(0x80 | (cp & 0x3F));
+                return 3;
+        }
+        out[0] = (char)(0xF0 | (cp >> 18));
+        out[1] = (char)(0x80 | ((cp >> 12) & 0x3F));
+        out[2] = (char)(0x80 | ((cp >> 6) & 0x3F));
+        out[3] = (char)(0x80 | (cp & 0x3F));
+        return 4;
+}
+
+typedef struct {
+        char *data;
+        size_t len;
+        size_t cap;
+} strbuf_t;
+
+static bool strbuf_push(strbuf_t *sb, const char *data, size_t n)
+{
+        if (sb->len + n + 1 > sb->cap) {
+                size_t cap = sb->cap ? sb->cap : 32;
+                char *grown;
+                while (sb->len + n + 1 > cap)
+                        cap *= 2;
+                grown = realloc(sb->data, cap);
+                if (grown == NULL)
+                        return false;
+                sb->data = grown;
+                sb->cap = cap;
+        }
+        memcpy(sb->data + sb->len, data, n);
+        sb->len += n;
+        sb->data[sb->len] = '\0';
+        return true;
+}
+
+static bool parse_escape(json_parser_t *ps, strbuf_t *sb)
+{
+        char encoded[4];
+        unsigned cp;
+        char c;
+
+        if (ps->p >= ps->end)
+                return false;
+        c = *ps->p++;
+        switch (c) {
+        case '"':
+                return strbuf_push(sb, "\"", 1);
+        case '\\':
+                return strbuf_push(sb, "\\", 1);
+        case '/':
+                return strbuf_push(sb, "/", 1);
+        case 'b':
+                return strbuf_push(sb, "\b", 1);
+        case 'f':
+                return strbuf_push(sb, "\f", 1);
+        case 'n':
+                return strbuf_push(sb, "\n", 1);
+        case 'r':
+                return strbuf_push(sb, "\r", 1);
+        case 't':
+                return strbuf_push(sb, "\t", 1);
+        case 'u':
+                break;
+        default:
+                return false;
+        }
+
+        if (!read_hex4(ps, &cp))
+                return false;
+        if (cp >= 0xD800 && cp <= 0xDBFF) {
+                unsigned low;
+                const char *save = ps->p;
+                if (ps->end - ps->p >= 2 && ps->p[0] == '\\' &&
+                    ps->p[1] == 'u') {
+                        ps->p += 2;
+                        if (!read_hex4(ps, &low))
+                                return false;
+                        if (low >= 0xDC00 && low <= 0xDFFF) {
+                                cp = 0x10000 + ((cp - 0xD800) << 10) +
+                                     (low - 0xDC00);
+                        } else {
+                                ps->p = save;
+                                cp = 0xFFFD;
+                        }
+                } else {
+                        cp = 0xFFFD;
+                }
+        } else if (cp >= 0xDC00 && cp <= 0xDFFF) {
+                cp = 0xFFFD;
+        }
+        return strbuf_push(sb, encoded, utf8_encode(cp, encoded));
+}
+
+static char *parse_raw_string(json_parser_t *ps)
+{
+        strbuf_t sb = {NULL, 0, 0};
+
+        if (!at(ps, '"'))
+                return NULL;
+        ps->p++;
+        if (!strbuf_push(&sb, "", 0))
+                return NULL;
+
+        while (ps->p < ps->end) {
+                char c = *ps->p;
+                if (c == '"') {
+                        ps->p++;
+                        return sb.data;
+                }
+                if (c == '\\') {
+                        ps->p++;
+                        if (!parse_escape(ps, &sb))
+                                break;
+                        continue;
+                }
+                if ((unsigned char)c < 0x20)
+                        break;
+                ps->p++;
+                if (!strbuf_push(&sb, &c, 1))
+                        break;
+        }
+        free(sb.data);
+        return NULL;
+}
+
+static json_value_t *parse_string(json_parser_t *ps)
+{
+        char *text = parse_raw_string(ps);
+        json_value_t *v;
+
+        if (text == NULL)
+                return NULL;
+        v = value_new(JSON_STRING);
+        if (v == NULL) {
+                free(text);
+                return NULL;
+        }
+        v->as.string = text;
+        return v;
+}
+
+static json_value_t *parse_number(json_parser_t *ps)
+{
+        const char *start = ps->p;
+        json_value_t *v;
+        char *stop = NULL;
+        char token[64];
+        size_t n;
+        double number;
+
+        if (at(ps, '-'))
+                ps->p++;
+        if (ps->p >= ps->end)
+                return NULL;
+        if (*ps->p == '0')
+                ps->p++;
+        else if (*ps->p >= '1' && *ps->p <= '9')
+                while (ps->p < ps->end && *ps->p >= '0' && *ps->p <= '9')
+                        ps->p++;
+        else
+                return NULL;
+        if (at(ps, '.')) {
+                ps->p++;
+                if (ps->p >= ps->end || *ps->p < '0' || *ps->p > '9')
+                        return NULL;
+                while (ps->p < ps->end && *ps->p >= '0' && *ps->p <= '9')
+                        ps->p++;
+        }
+        if (at(ps, 'e') || at(ps, 'E')) {
+                ps->p++;
+                if (at(ps, '+') || at(ps, '-'))
+                        ps->p++;
+                if (ps->p >= ps->end || *ps->p < '0' || *ps->p > '9')
+                        return NULL;
+                while (ps->p < ps->end && *ps->p >= '0' && *ps->p <= '9')
+                        ps->p++;
+        }
+
+        n = (size_t)(ps->p - start);
+        if (n == 0 || n >= sizeof(token))
+                return NULL;
+        memcpy(token, start, n);
+        token[n] = '\0';
+
+        errno = 0;
+        number = strtod(token, &stop);
+        if (stop != token + n)
+                return NULL;
+
+        v = value_new(JSON_NUMBER);
+        if (v == NULL)
+                return NULL;
+        v->as.number = number;
+        return v;
+}
+
+static bool grow_slots(void ***slots, size_t count, size_t *cap, size_t size)
+{
+        void **grown;
+        size_t next;
+
+        if (count < *cap)
+                return true;
+        next = *cap ? *cap * 2 : 8;
+        grown = realloc(*slots, next * size);
+        if (grown == NULL)
+                return false;
+        memset((char *)grown + count * size, 0, (next - count) * size);
+        *slots = grown;
+        *cap = next;
+        return true;
+}
+
+static json_value_t *parse_array(json_parser_t *ps)
+{
+        json_value_t *v = value_new(JSON_ARRAY);
+        size_t cap = 0;
+
+        if (v == NULL)
+                return NULL;
+        ps->p++;
+        skip_ws(ps);
+        if (at(ps, ']')) {
+                ps->p++;
+                return v;
+        }
+        for (;;) {
+                json_value_t *item;
+                if (!grow_slots((void ***)&v->as.array.items, v->as.array.count,
+                                &cap, sizeof(json_value_t *)))
+                        break;
+                item = parse_value(ps);
+                if (item == NULL)
+                        break;
+                v->as.array.items[v->as.array.count++] = item;
+                skip_ws(ps);
+                if (at(ps, ',')) {
+                        ps->p++;
+                        continue;
+                }
+                if (at(ps, ']')) {
+                        ps->p++;
+                        return v;
+                }
+                break;
+        }
+        json_free(v);
+        return NULL;
+}
+
+static json_value_t *parse_object(json_parser_t *ps)
+{
+        json_value_t *v = value_new(JSON_OBJECT);
+        size_t cap_keys = 0;
+        size_t cap_values = 0;
+
+        if (v == NULL)
+                return NULL;
+        ps->p++;
+        skip_ws(ps);
+        if (at(ps, '}')) {
+                ps->p++;
+                return v;
+        }
+        for (;;) {
+                char *key;
+                json_value_t *item;
+
+                skip_ws(ps);
+                if (!grow_slots((void ***)&v->as.object.keys,
+                                v->as.object.count, &cap_keys, sizeof(char *)))
+                        break;
+                if (!grow_slots((void ***)&v->as.object.values,
+                                v->as.object.count, &cap_values,
+                                sizeof(json_value_t *)))
+                        break;
+                key = parse_raw_string(ps);
+                if (key == NULL)
+                        break;
+                skip_ws(ps);
+                if (!at(ps, ':')) {
+                        free(key);
+                        break;
+                }
+                ps->p++;
+                item = parse_value(ps);
+                if (item == NULL) {
+                        free(key);
+                        break;
+                }
+                v->as.object.keys[v->as.object.count] = key;
+                v->as.object.values[v->as.object.count] = item;
+                v->as.object.count++;
+
+                skip_ws(ps);
+                if (at(ps, ',')) {
+                        ps->p++;
+                        continue;
+                }
+                if (at(ps, '}')) {
+                        ps->p++;
+                        return v;
+                }
+                break;
+        }
+        json_free(v);
+        return NULL;
+}
+
+static json_value_t *parse_value(json_parser_t *ps)
+{
+        json_value_t *v;
+
+        if (ps->depth >= JSON_MAX_DEPTH)
+                return NULL;
+        skip_ws(ps);
+        if (ps->p >= ps->end)
+                return NULL;
+
+        switch (*ps->p) {
+        case '"':
+                return parse_string(ps);
+        case '{':
+                ps->depth++;
+                v = parse_object(ps);
+                ps->depth--;
+                return v;
+        case '[':
+                ps->depth++;
+                v = parse_array(ps);
+                ps->depth--;
+                return v;
+        case 't':
+                if (!literal(ps, "true"))
+                        return NULL;
+                v = value_new(JSON_BOOL);
+                if (v != NULL)
+                        v->as.boolean = true;
+                return v;
+        case 'f':
+                if (!literal(ps, "false"))
+                        return NULL;
+                v = value_new(JSON_BOOL);
+                if (v != NULL)
+                        v->as.boolean = false;
+                return v;
+        case 'n':
+                if (!literal(ps, "null"))
+                        return NULL;
+                return value_new(JSON_NULL);
+        default:
+                return parse_number(ps);
+        }
+}
+
+json_value_t *json_parse(const char *text, size_t len)
+{
+        json_parser_t ps;
+        json_value_t *root;
+
+        if (text == NULL)
+                return NULL;
+        ps.p = text;
+        ps.end = text + len;
+        ps.depth = 0;
+
+        if (len >= 3 && memcmp(text, "\xEF\xBB\xBF", 3) == 0)
+                ps.p += 3;
+
+        root = parse_value(&ps);
+        if (root == NULL)
+                return NULL;
+        skip_ws(&ps);
+        if (ps.p != ps.end) {
+                json_free(root);
+                return NULL;
+        }
+        return root;
+}
+
+const json_value_t *json_object_get(const json_value_t *object, const char *key)
+{
+        size_t i;
+
+        if (object == NULL || object->type != JSON_OBJECT || key == NULL)
+                return NULL;
+        for (i = 0; i < object->as.object.count; i++)
+                if (strcmp(object->as.object.keys[i], key) == 0)
+                        return object->as.object.values[i];
+        return NULL;
+}
+
+const char *json_as_string(const json_value_t *value)
+{
+        if (value == NULL || value->type != JSON_STRING)
+                return NULL;
+        return value->as.string;
+}
+
+bool json_as_double(const json_value_t *value, double *out)
+{
+        char *stop = NULL;
+        double parsed;
+
+        if (value == NULL)
+                return false;
+        if (value->type == JSON_NUMBER) {
+                *out = value->as.number;
+                return true;
+        }
+        if (value->type != JSON_STRING || value->as.string[0] == '\0')
+                return false;
+        errno = 0;
+        parsed = strtod(value->as.string, &stop);
+        if (stop == NULL || *stop != '\0' || errno == ERANGE)
+                return false;
+        *out = parsed;
+        return true;
+}
+
+bool json_as_llong(const json_value_t *value, long long *out)
+{
+        double parsed;
+
+        if (!json_as_double(value, &parsed))
+                return false;
+        *out = (long long)parsed;
+        return true;
+}