1 files changed, 53 insertions, 5 deletions
diff --git a/lib/libutil/expand_number.3 b/lib/libutil/expand_number.3
index 1b932400de69..b1833cedf406 100644
--- a/lib/libutil/expand_number.3
+++ b/lib/libutil/expand_number.3
@@ -24,11 +24,12 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd July 25, 2025
+.Dd August 6, 2025
 .Dt EXPAND_NUMBER 3
 .Os
 .Sh NAME
-.Nm expand_number
+.Nm expand_number ,
+.Nm expand_unsigned
 .Nd parse a number from human readable form
 .Sh LIBRARY
 .Lb libutil
@@ -38,6 +39,10 @@
 .Fo expand_number
 .Fa "const char *buf" "int64_t *num"
 .Fc
+.Ft int
+.Fo expand_unsigned
+.Fa "const char *buf" "uint64_t *num"
+.Fc
 .Sh DESCRIPTION
 The
 .Fn expand_number
@@ -48,6 +53,17 @@ quantity in the location pointed to by its
 .Fa *num
 argument.
 .Pp
+The
+.Fn expand_unsigned
+function is similar to
+.Fn expand_number ,
+but accepts only positive numbers in the range
+.Bq 0, Ns Dv UINT64_MAX .
+.Pp
+Both functions interpret the input
+.Dq -0
+as 0.
+.Pp
 The input string must consist of a decimal number, optionally preceded
 by a
 .Sq +
@@ -81,20 +97,38 @@ is interpreted as 5, and
 .Dq 5kb
 is interpreted as 5,120).
 However, the usage of this suffix is discouraged.
+.Pp
+For backward compatibility reasons, if the compiler supports generic
+selection, a macro is provided which automatically replaces calls to
+.Fn expand_number
+with calls to
+.Fn expand_unsigned
+if the type of the actual
+.Va num
+argument is compatible with
+.Vt uint64_t * .
 .Sh RETURN VALUES
 .Rv -std
 .Sh ERRORS
 The
 .Fn expand_number
-function will fail if:
+and
+.Fn expand_unsigned
+functions will fail if:
 .Bl -tag -width Er
 .It Bq Er EINVAL
 The given string does not contain a valid number.
 .It Bq Er EINVAL
 An unrecognized suffix was encountered.
 .It Bq Er ERANGE
-The given string represents a number which does not fit into a
-.Vt int64_t .
+The given string represents a number which does not fit into an
+.Vt int64_t
+(for
+.Fn expand_number )
+or
+.Vt uint64_t
+(for
+.Fn expand_unsigned ) .
 .El
 .Sh SEE ALSO
 .Xr humanize_number 3
@@ -103,3 +137,17 @@ The
 .Fn expand_number
 function first appeared in
 .Fx 6.3 .
+The original implementation did not handle negative numbers correctly,
+and it was switched to taking a
+.Vt uint64_t *
+and accepting only positive numbers in
+.Fx 9.0 .
+The
+.Fn expand_unsigned
+function was added,
+and
+.Fn expand_number
+switched back to
+.Vt int64_t * ,
+in
+.Fx 15.0 .