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json: Use state machine and fix 1E10 parsing

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Use a state machine to check for valid numbers and fix the 1E10
parsing case.

With help from Claude.
This commit is contained in:
Wim Taymans 2026-03-09 18:17:04 +01:00
parent c745582ef5
commit f6939a1cf0
2 changed files with 24 additions and 34 deletions
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57
spa/include/spa/utils/json-core.h
View file

@ -476,40 +476,29 @@ SPA_API_JSON bool spa_json_is_int(const char *val, int len)
SPA_API_JSON bool spa_json_is_json_number(const char *val, int len)
{
int pos = 0, first;
/* integer */
if (len == 0)
return 0;
if (pos < len && val[pos] == '-')
pos++;
first = pos;
while(pos < len && val[pos] >= '0' && val[pos] <= '9')
pos++;
if (pos == first || (first + 1 < pos && val[first] == '0'))
return 0;
/* fraction */
if (pos == len)
return 1;
if (val[pos++] != '.')
return 0;
first = pos;
while(pos < len && val[pos] >= '0' && val[pos] <= '9')
pos++;
if (pos == first)
return 0;
/* exponent */
if (pos == len)
return 1;
if (val[pos] != 'e' && val[pos] != 'E')
return 0;
pos++;
if (val[pos] == '-' || val[pos] == '+')
pos++;
while(pos < len && val[pos] >= '0' && val[pos] <= '9')
pos++;
if (pos != len)
return 0;
return 1;
static const int8_t trans[9][7] = {
/* '1-9' '0' '-' '+' '.' 'eE' other */
/* 0 */ {-1, -1, -1, -1, 6, 7, -1 }, /* after '0' */
/* 1 */ { 1, 1, -1, -1, 6, 7, -1 }, /* in integer */
/* 2 */ { 2, 2, -1, -1, -1, 7, -1 }, /* in fraction */
/* 3 */ { 3, 3, -1, -1, -1, -1, -1 }, /* in exponent */
/* 4 */ { 1, 0, 5, -1, -1, -1, -1 }, /* start */
/* 5 */ { 1, 0, -1, -1, -1, -1, -1 }, /* after '-' */
/* 6 */ { 2, 2, -1, -1, -1, -1, -1 }, /* after '.' */
/* 7 */ { 3, 3, 8, 8, -1, -1, -1 }, /* after 'e'/'E' */
/* 8 */ { 3, 3, -1, -1, -1, -1, -1 }, /* after exp sign */
};
int i, state = 4;
for (i = 0; i < len; i++) {
char v = val[i];
int cls = (v >= '1' && v <= '9') ? 0 : v == '0' ? 1 :
v == '-' ? 2 : v == '+' ? 3 : v == '.' ? 4 :
(v == 'e' || v == 'E') ? 5 : 6;
if ((state = trans[state][cls]) < 0)
return false;
}
return state < 4;
}
/* bool */

1
test/test-spa-json.c
View file

@ -740,6 +740,7 @@ PWTEST(json_float_check)
{ "-1.", 1, 0 },
{ "-.0", 1, 0 },
{ "-1E10", 1, 1 },
};
unsigned i;