1 files changed, 170 insertions, 0 deletions
diff --git a/config/typed.go b/config/typed.go
new file mode 100644
index 00000000..39eeb767
--- /dev/null
+++ b/config/typed.go
@@ -0,0 +1,170 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+
+	"codeberg.org/lindenii/furgit/internal/intconv"
+)
+
+// ValueKind describes the presence and form of a config value.
+type ValueKind uint8
+
+const (
+	// ValueMissing means the queried key does not exist.
+	ValueMissing ValueKind = iota
+	// ValueValueless means the key exists but has no "= <value>" part.
+	ValueValueless
+	// ValueString means the key exists and has an explicit value (possibly "").
+	ValueString
+)
+
+func isValidSection(s string) bool {
+	if len(s) == 0 {
+		return false
+	}
+
+	for i := range len(s) {
+		ch := s[i]
+		if !isLetter(ch) && !isDigit(ch) && ch != '-' && ch != '.' {
+			return false
+		}
+	}
+
+	return true
+}
+
+func isKeyChar(ch byte) bool {
+	return isLetter(ch) || isDigit(ch) || ch == '-'
+}
+
+func parseBool(value string) (bool, error) {
+	switch {
+	case strings.EqualFold(value, "true"),
+		strings.EqualFold(value, "yes"),
+		strings.EqualFold(value, "on"):
+		return true, nil
+	case strings.EqualFold(value, "false"),
+		strings.EqualFold(value, "no"),
+		strings.EqualFold(value, "off"),
+		value == "":
+		return false, nil
+	}
+
+	n, err := parseInt32(value)
+	if err != nil {
+		return false, fmt.Errorf("invalid boolean value %q", value)
+	}
+
+	return n != 0, nil
+}
+
+func parseInt32(value string) (int32, error) {
+	n64, err := parseInt64WithMax(value, math.MaxInt32)
+	if err != nil {
+		return 0, err
+	}
+
+	return intconv.Int64ToInt32(n64)
+}
+
+func parseInt(value string) (int, error) {
+	n64, err := parseInt64WithMax(value, int64(int(^uint(0)>>1)))
+	if err != nil {
+		return 0, err
+	}
+
+	return int(n64), nil
+}
+
+func parseInt64(value string) (int64, error) {
+	return parseInt64WithMax(value, int64(^uint64(0)>>1))
+}
+
+func parseInt64WithMax(value string, maxValue int64) (int64, error) {
+	if value == "" {
+		return 0, errors.New("empty value")
+	}
+
+	trimmed := strings.TrimLeft(value, " \t\n\r\f\v")
+	if trimmed == "" {
+		return 0, errors.New("empty value")
+	}
+
+	numPart := trimmed
+	factor := int64(1)
+
+	if last := trimmed[len(trimmed)-1]; last == 'k' || last == 'K' || last == 'm' || last == 'M' || last == 'g' || last == 'G' {
+		switch toLower(last) {
+		case 'k':
+			factor = 1024
+		case 'm':
+			factor = 1024 * 1024
+		case 'g':
+			factor = 1024 * 1024 * 1024
+		}
+
+		numPart = trimmed[:len(trimmed)-1]
+	}
+
+	if numPart == "" {
+		return 0, errors.New("missing integer value")
+	}
+
+	n, err := strconv.ParseInt(numPart, 0, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	intMax := maxValue
+	intMin := -maxValue - 1
+
+	if n > 0 && n > intMax/factor {
+		return 0, errors.New("integer overflow")
+	}
+
+	if n < 0 && n < intMin/factor {
+		return 0, errors.New("integer overflow")
+	}
+
+	n *= factor
+
+	return n, nil
+}
+
+func truncateAtNUL(value string) string {
+	for i := range len(value) {
+		if value[i] == 0 {
+			return value[:i]
+		}
+	}
+
+	return value
+}
+
+func isSpace(ch byte) bool {
+	return ch == ' ' || ch == '\t'
+}
+
+func isWhitespace(ch byte) bool {
+	return ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r' || ch == '\v' || ch == '\f'
+}
+
+func isLetter(ch byte) bool {
+	return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')
+}
+
+func isDigit(ch byte) bool {
+	return ch >= '0' && ch <= '9'
+}
+
+func toLower(ch byte) byte {
+	if ch >= 'A' && ch <= 'Z' {
+		return ch + ('a' - 'A')
+	}
+
+	return ch
+}