Fix locale-dependent JSON float parsing in fvec_from_value

.github/workflows/test.yaml

@@ -11,6 +11,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: astral-sh/setup-uv@v7
+      - run: sudo locale-gen fr_FR.UTF-8
       - run: ./scripts/vendor.sh
       - run: make loadable static
       - run: uv sync --directory tests
@@ -75,6 +76,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: astral-sh/setup-uv@v7
+      - run: sudo locale-gen fr_FR.UTF-8
       - run: ./scripts/vendor.sh
       - run: make loadable static
       - run: uv sync --directory tests

sqlite-vec.c

@@ -69,6 +69,80 @@ typedef size_t usize;
 #define countof(x) (sizeof(x) / sizeof((x)[0]))
 #define min(a, b) (((a) <= (b)) ? (a) : (b))
 
+// Locale-independent strtod for parsing JSON floats.
+// strtod(3) respects LC_NUMERIC, so "1.5" fails in French/German locales
+// where the decimal separator is a comma. This parser always uses '.'.
+static double strtod_c(const char *str, char **endptr) {
+  const char *p = str;
+  double result = 0.0;
+  int sign = 1;
+  int has_digits = 0;
+
+  while (*p == ' ' || *p == '\t' || *p == '\n' || *p == '\r') {
+    p++;
+  }
+
+  if (*p == '-') {
+    sign = -1;
+    p++;
+  } else if (*p == '+') {
+    p++;
+  }
+
+  while (*p >= '0' && *p <= '9') {
+    result = result * 10.0 + (*p - '0');
+    p++;
+    has_digits = 1;
+  }
+
+  if (*p == '.') {
+    double fraction = 0.0;
+    double divisor = 1.0;
+    p++;
+    while (*p >= '0' && *p <= '9') {
+      fraction = fraction * 10.0 + (*p - '0');
+      divisor *= 10.0;
+      p++;
+      has_digits = 1;
+    }
+    result += fraction / divisor;
+  }
+
+  if ((*p == 'e' || *p == 'E') && has_digits) {
+    int exp_sign = 1;
+    int exponent = 0;
+    p++;
+    if (*p == '-') {
+      exp_sign = -1;
+      p++;
+    } else if (*p == '+') {
+      p++;
+    }
+    while (*p >= '0' && *p <= '9') {
+      exponent = exponent * 10 + (*p - '0');
+      p++;
+    }
+    if (exponent > 0) {
+      double exp_mult = pow(10.0, (double)exponent);
+      if (exp_sign == 1) {
+        result *= exp_mult;
+      } else {
+        result /= exp_mult;
+      }
+    }
+  }
+
+  if (endptr) {
+    *endptr = (char *)(has_digits ? p : str);
+  }
+
+  if (result == HUGE_VAL || result == -HUGE_VAL) {
+    errno = ERANGE;
+  }
+
+  return sign * result;
+}
+
 #ifndef SQLITE_VEC_ENABLE_RESCORE
 #define SQLITE_VEC_ENABLE_RESCORE 1
 #endif
@@ -1043,7 +1117,7 @@ static int fvec_from_value(sqlite3_value *value, f32 **vector,
       char *endptr;
 
       errno = 0;
-      double result = strtod(ptr, &endptr);
+      double result = strtod_c(ptr, &endptr);
       if ((errno != 0 && result == 0) // some interval error?
           || (errno == ERANGE &&
               (result == HUGE_VAL || result == -HUGE_VAL)) // too big / smalls

tests/test-locale.py

@@ -0,0 +1,46 @@
+"""Tests for locale-independent JSON float parsing (issue #241).
+
+strtod(3) respects LC_NUMERIC, so locales like fr_FR or de_DE that use ','
+as the decimal separator would cause vec0 to reject valid JSON vectors like
+'[0.1, 0.2, 0.3]'. The fix replaces strtod with a custom locale-independent
+parser (strtod_c) that always treats '.' as the decimal separator.
+"""
+
+import locale
+import struct
+import pytest
+from helpers import _f32
+
+
+def test_vec0_locale_independent(db):
+    db.execute("create virtual table v using vec0(embedding float[3])")
+
+    original = locale.setlocale(locale.LC_NUMERIC)
+    locale_changed = False
+
+    for candidate in ("fr_FR.UTF-8", "de_DE.UTF-8", "it_IT.UTF-8", "fr_FR", "de_DE"):
+        try:
+            locale.setlocale(locale.LC_NUMERIC, candidate)
+            locale_changed = True
+            break
+        except locale.Error:
+            continue
+
+    try:
+        db.execute("insert into v(rowid, embedding) values (1, '[0.1, 0.2, 0.3]')")
+        db.execute("insert into v(rowid, embedding) values (2, '[1.23, 4.56, 7.89]')")
+        db.execute("insert into v(rowid, embedding) values (3, '[1e-3, 2.5e2, -0.75]')")
+
+        row = db.execute("select embedding from v where rowid = 1").fetchone()
+        assert row[0] == _f32([0.1, 0.2, 0.3])
+
+        row = db.execute("select embedding from v where rowid = 2").fetchone()
+        assert row[0] == _f32([1.23, 4.56, 7.89])
+
+        row = db.execute("select embedding from v where rowid = 3").fetchone()
+        assert row[0] == _f32([1e-3, 2.5e2, -0.75])
+    finally:
+        locale.setlocale(locale.LC_NUMERIC, original)
+
+    if not locale_changed:
+        pytest.skip("No non-C locale available to test locale independence")