add os.readfile()

compiler/stdlib/os.go

@@ -2,6 +2,7 @@ package stdlib
 
 import (
 	"io"
+	"io/ioutil"
 	"os"
 	"os/exec"
 
@@ -78,6 +79,25 @@ var osModule = map[string]objects.Object{
 	"exec_look_path":      FuncASRSE(exec.LookPath),                     // exec_look_path(file) => string/error
 	"exec":                &objects.UserFunction{Value: osExec},         // exec(name, args...) => command
 	"stat":                &objects.UserFunction{Value: osStat},         // stat(name) => imap(fileinfo)/error
+	"read_file":           &objects.UserFunction{Value: osReadFile},     // readfile(name) => array(byte)/error
+}
+
+func osReadFile(args ...objects.Object) (ret objects.Object, err error) {
+	if len(args) != 1 {
+		return nil, objects.ErrWrongNumArguments
+	}
+
+	fname, ok := objects.ToString(args[0])
+	if !ok {
+		return nil, objects.ErrInvalidTypeConversion
+	}
+
+	bytes, err := ioutil.ReadFile(fname)
+	if err != nil {
+		return wrapError(err), nil
+	}
+
+	return &objects.Bytes{Value: bytes}, nil
 }
 
 func osStat(args ...objects.Object) (ret objects.Object, err error) {

compiler/stdlib/os_test.go

@@ -8,6 +8,29 @@ import (
 	"github.com/d5/tengo/objects"
 )
 
+func TestReadFile(t *testing.T) {
+	content := []byte("the quick brown fox jumps over the lazy dog")
+	tf, err := ioutil.TempFile("", "test")
+	if err != nil {
+		t.Logf("could not open tempfile: %s", err)
+		return
+	}
+	defer os.Remove(tf.Name())
+
+	_, err = tf.Write(content)
+	if err != nil {
+		t.Logf("could not write temp content: %s", err)
+		return
+	}
+
+	tf.Close()
+
+	module(t, "os").call("read_file", tf.Name()).expect(&objects.Bytes{Value: content})
+}
+
+func TestReadFileArgs(t *testing.T) {
+	module(t, "os").call("read_file").expectError()
+}
 func TestFileStatArgs(t *testing.T) {
 	module(t, "os").call("stat").expectError()
 }

docs/stdlib-os.md

@@ -63,6 +63,7 @@ os := import("os")
 - `lookup_env(key string) => string/false`: retrieves the value of the environment variable named by the key.
 - `mkdir(name string, perm int) => error `: creates a new directory with the specified name and permission bits (before umask).
 - `mkdir_all(name string, perm int) => error `: creates a directory named path, along with any necessary parents, and returns nil, or else returns an error.
+- `read_file(name string) => bytes/error `: reads the contents of a file into a byte array
 - `readlink(name string) => string/error `: returns the destination of the named symbolic link.
 - `remove(name string) => error `: removes the named file or (empty) directory.
 - `remove_all(name string) => error `: removes path and any children it contains.