From 579d34c39c6d26661403eb210850686a677080b2 Mon Sep 17 00:00:00 2001
From: Nate Maninger <me@n8m.us>
Date: Tue, 16 Apr 2024 14:12:44 -0700
Subject: [PATCH 1/2] disk: support openbsd

---
 internal/disk/usage_default.go |  2 +-
 internal/disk/usage_openbsd.go | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 internal/disk/usage_openbsd.go

diff --git a/internal/disk/usage_default.go b/internal/disk/usage_default.go
index 68b4ab53..4b0e27c0 100644
--- a/internal/disk/usage_default.go
+++ b/internal/disk/usage_default.go
@@ -1,4 +1,4 @@
-//go:build !windows
+//go:build !windows && !openbsd
 
 package disk
 
diff --git a/internal/disk/usage_openbsd.go b/internal/disk/usage_openbsd.go
new file mode 100644
index 00000000..b53ee23d
--- /dev/null
+++ b/internal/disk/usage_openbsd.go
@@ -0,0 +1,20 @@
+//go:build openbsd
+
+package disk
+
+import "golang.org/x/sys/unix"
+
+// Usage returns the free and total bytes on the filesystem containing the
+// specified path.
+func Usage(p string) (free, total uint64, err error) {
+	var stat unix.Statfs_t
+	if err := unix.Statfs(p, &stat); err != nil {
+		return 0, 0, err
+	}
+	return stat.F_bfree * uint64(stat.F_bsize), stat.F_blocks * uint64(stat.F_bsize), nil
+}
+
+// Drives returns the paths of all drives on Windows. It is a no-op on other systems
+func Drives() ([]string, error) {
+	return nil, nil
+}

From fcf2857a2a2fc42082da6d3f3a7f85a3307d77d2 Mon Sep 17 00:00:00 2001
From: Nate Maninger <me@n8m.us>
Date: Wed, 17 Apr 2024 13:08:56 -0700
Subject: [PATCH 2/2] disk: add comment about syscall differences

---
 internal/disk/usage_default.go | 3 +++
 internal/disk/usage_openbsd.go | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/internal/disk/usage_default.go b/internal/disk/usage_default.go
index 4b0e27c0..748bc176 100644
--- a/internal/disk/usage_default.go
+++ b/internal/disk/usage_default.go
@@ -11,6 +11,9 @@ func Usage(p string) (free, total uint64, err error) {
 	if err := unix.Statfs(p, &stat); err != nil {
 		return 0, 0, err
 	}
+	// Linux-based systems and Darwin use bfree and blocks to represent the
+	// number of free and total blocks in the filesystem. Multiplying by f_bsize
+	// converts that to the number of free and total bytes of a filesystem.
 	return stat.Bfree * uint64(stat.Bsize), stat.Blocks * uint64(stat.Bsize), nil
 }
 
diff --git a/internal/disk/usage_openbsd.go b/internal/disk/usage_openbsd.go
index b53ee23d..8411fc7e 100644
--- a/internal/disk/usage_openbsd.go
+++ b/internal/disk/usage_openbsd.go
@@ -11,6 +11,9 @@ func Usage(p string) (free, total uint64, err error) {
 	if err := unix.Statfs(p, &stat); err != nil {
 		return 0, 0, err
 	}
+	// OpenBSD uses f_bfree and f_blocks to represent the number of free and
+	// total blocks in the filesystem. Multiplying by f_bsize converts that to
+	// the number of free and total bytes of a filesystem.
 	return stat.F_bfree * uint64(stat.F_bsize), stat.F_blocks * uint64(stat.F_bsize), nil
 }