misc: Add Openat2

1 files changed, 22 insertions, 0 deletions

diff --git a/misc/misc.go b/misc/misc.go
index 5526797..572651f 100644
--- a/misc/misc.go
+++ b/misc/misc.go
@@ -1,8 +1,30 @@
 // Package misc provides miscellaneous functions.
 package misc
 
+import (
+	"errors"
+	"strings"
+)
+
+// Copy_map the map src to dst without clearing existing items in dst.
 func Copy_map[K comparable, V any](dst map[K]V, src map[K]V) {
 	for k, v := range src {
 		dst[k] = v
 	}
 }
+
+// String_to_byte_ptr returns a pointer to the first byte of a string. It
+// ensures that the returned pointer is null-terminated.
+func String_to_byte_ptr(s string) (*byte, error) {
+	// If the string already contains a null then whoever attempts to
+	// interpret this as a null-terminated string won't be able to see the
+	// whole string. This is probably not expected by the caller.
+	if strings.IndexByte(s, 0) != -1 {
+		return nil, Err_null_byte
+	}
+	buf := make([]byte, len(s)+1) // Zeros them out...
+	copy(buf, s)                  // ... so the last byte would be null.
+	return &buf[0], nil
+}
+
+var Err_null_byte = errors.New("string contains null byte")