krino: foundation — sexp reader, config language, init/new/check

1 files changed, 71 insertions, 0 deletions

diff --git a/internal/config/units.go b/internal/config/units.go
new file mode 100644
index 0000000..ea61dee
--- /dev/null
+++ b/internal/config/units.go
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package config
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"strconv"
+	"time"
+)
+
+// ParseSize reads a size: a whole number with an optional K, M, G or T
+// suffix, in powers of 1024.
+func ParseSize(s string) (int64, error) {
+	num, mult := s, int64(1)
+	if n := len(s); n > 0 {
+		switch s[n-1] {
+		case 'K':
+			mult = 1 << 10
+		case 'M':
+			mult = 1 << 20
+		case 'G':
+			mult = 1 << 30
+		case 'T':
+			mult = 1 << 40
+		}
+		if mult > 1 {
+			num = s[:n-1]
+		}
+	}
+	v, err := parseCount(num)
+	if err != nil || v > math.MaxInt64/mult {
+		return 0, fmt.Errorf("bad size %q: want a whole number with an optional K, M, G or T, like 50M", s)
+	}
+	return v * mult, nil
+}
+
+var durationUnits = map[byte]time.Duration{
+	's': time.Second, 'm': time.Minute, 'h': time.Hour, 'd': 24 * time.Hour, 'w': 7 * 24 * time.Hour,
+}
+
+// ParseDuration reads a duration: a whole number followed by s, m, h, d or w.
+func ParseDuration(s string) (time.Duration, error) {
+	bad := fmt.Errorf("bad duration %q: want a whole number followed by s, m, h, d or w, like 30d", s)
+	if len(s) < 2 {
+		return 0, bad
+	}
+	unit, ok := durationUnits[s[len(s)-1]]
+	if !ok {
+		return 0, bad
+	}
+	v, err := parseCount(s[:len(s)-1])
+	if err != nil || v > int64(math.MaxInt64/unit) {
+		return 0, bad
+	}
+	return time.Duration(v) * unit, nil
+}
+
+// parseCount reads a non-empty run of ASCII digits.
+func parseCount(s string) (int64, error) {
+	if s == "" {
+		return 0, errors.New("empty number")
+	}
+	for _, c := range s {
+		if c < '0' || c > '9' {
+			return 0, errors.New("not a whole number")
+		}
+	}
+	return strconv.ParseInt(s, 10, 64)
+}