Add util function to parse a list of integers

This will help parsing arguments like '1234:5678' into a list of
integers.

app/src/util/str_util.c

@@ -81,6 +81,35 @@ parse_integer(const char *s, long *out) {
     return true;
 }
 
+size_t
+parse_integers(const char *s, const char sep, size_t max_items, long *out) {
+    size_t count = 0;
+    char *endptr;
+    do {
+        errno = 0;
+        long value = strtol(s, &endptr, 0);
+        if (errno == ERANGE) {
+            return 0;
+        }
+
+        if (endptr == s || (*endptr != sep && *endptr != '\0')) {
+            return 0;
+        }
+
+        out[count++] = value;
+        if (*endptr == sep) {
+            if (count >= max_items) {
+                // max items already reached, could not accept a new item
+                return 0;
+            }
+            // parse the next token during the next iteration
+            s = endptr + 1;
+        }
+    } while (*endptr != '\0');
+
+    return count;
+}
+
 bool
 parse_integer_with_suffix(const char *s, long *out) {
     char *endptr;

app/src/util/str_util.h

@@ -31,6 +31,11 @@ strquote(const char *src);
 bool
 parse_integer(const char *s, long *out);
 
+// parse s as integers separated by sep (for example '1234:2000')
+// returns the number of integers on success, 0 on failure
+size_t
+parse_integers(const char *s, const char sep, size_t max_items, long *out);
+
 // parse s as an integer into value
 // like parse_integer(), but accept 'k'/'K' (x1000) and 'm'/'M' (x1000000) as
 // suffix

app/tests/test_strutil.c

@@ -187,6 +187,55 @@ static void test_parse_integer(void) {
     assert(!ok); // out-of-range
 }
 
+static void test_parse_integers(void) {
+    long values[5];
+
+    size_t count = parse_integers("1234", ':', 5, values);
+    assert(count == 1);
+    assert(values[0] == 1234);
+
+    count = parse_integers("1234:5678", ':', 5, values);
+    assert(count == 2);
+    assert(values[0] == 1234);
+    assert(values[1] == 5678);
+
+    count = parse_integers("1234:5678", ':', 2, values);
+    assert(count == 2);
+    assert(values[0] == 1234);
+    assert(values[1] == 5678);
+
+    count = parse_integers("1234:-5678", ':', 2, values);
+    assert(count == 2);
+    assert(values[0] == 1234);
+    assert(values[1] == -5678);
+
+    count = parse_integers("1:2:3:4:5", ':', 5, values);
+    assert(count == 5);
+    assert(values[0] == 1);
+    assert(values[1] == 2);
+    assert(values[2] == 3);
+    assert(values[3] == 4);
+    assert(values[4] == 5);
+
+    count = parse_integers("1234:5678", ':', 1, values);
+    assert(count == 0); // max_items == 1
+
+    count = parse_integers("1:2:3:4:5", ':', 3, values);
+    assert(count == 0); // max_items == 3
+
+    count = parse_integers(":1234", ':', 5, values);
+    assert(count == 0); // invalid
+
+    count = parse_integers("1234:", ':', 5, values);
+    assert(count == 0); // invalid
+
+    count = parse_integers("1234:", ':', 1, values);
+    assert(count == 0); // invalid, even when max_items == 1
+
+    count = parse_integers("1234::5678", ':', 5, values);
+    assert(count == 0); // invalid
+}
+
 static void test_parse_integer_with_suffix(void) {
     long value;
     bool ok = parse_integer_with_suffix("1234", &value);
@@ -249,6 +298,7 @@ int main(void) {
     test_strquote();
     test_utf8_truncate();
     test_parse_integer();
+    test_parse_integers();
     test_parse_integer_with_suffix();
     return 0;
 }