1 files changed, 60 insertions, 0 deletions
diff --git a/build/macros.go b/build/macros.go
new file mode 100644
index 0000000..5d3422e
--- /dev/null
+++ b/build/macros.go
@@ -0,0 +1,60 @@
+package build
+
+import (
+	"fmt"
+)
+
+// ApplyUser wraps any build.Copy instructions as build.CopyAs using the given
+// UID/GID.
+//
+func ApplyUser(uid uint, gid uint, instructions []Instruction) []Instruction {
+	applied := make([]Instruction, len(instructions))
+
+	for i, instruction := range instructions {
+		if copy, iscopy := instruction.(Copy); iscopy {
+			applied[i] = CopyAs{uid, gid, copy}
+		} else {
+			applied[i] = instruction
+		}
+	}
+
+	return applied
+}
+
+// Chown returns a build.Run instruction for setting ownership on the given
+// path.
+//
+func Chown(uid uint, gid uint, path string) Run {
+	return Run{"chown %s:%s", []string{fmt.Sprint(uid), fmt.Sprint(gid), path}}
+}
+
+// CreateDirectory returns a build.Run instruction for creating the given
+// directory.
+//
+func CreateDirectory(path string) Run {
+	return Run{"mkdir -p", []string{path}}
+}
+
+// CreateUser returns build.Run instructions for creating the given user
+// account and group.
+//
+func CreateUser(name string, uid uint, gid uint) []Run {
+	return []Run{
+		{"groupadd -o -g %s -r", []string{fmt.Sprint(gid), name}},
+		{"useradd -o -m -d %s -r -g %s -u %s", []string{homeDir(name), name, fmt.Sprint(uid), name}},
+	}
+}
+
+// Home returns a build.Env instruction for setting the user's home directory.
+//
+func Home(name string) Env {
+	return Env{map[string]string{"HOME": homeDir(name)}}
+}
+
+func homeDir(name string) string {
+	if name == "root" {
+		return "/root"
+	}
+
+	return "/home/" + name
+}