shell: allow spaces in arguments via quoting (#8157) (#8165)

* shell: allow spaces in arguments via quoting (#8157)

- updated argument splitting regex to handle quoted segments
- added robust quote stripping to remove matching quotes from flags
- added unit tests for regex splitting and flag parsing

* shell: use robust state machine parser for command line arguments

- replaced regex-based splitter with splitCommandLine state machine
- added escape character support in splitCommandLine and stripQuotes
- updated unit tests to include escaped quotes and single-quote literals
- addressed feedback regarding escaped quotes handling (#8157)

* shell: detect unbalanced quotes in stripQuotes

- modified stripQuotes to return the original string if quotes are unbalanced
- added test cases for unbalanced quotes in shell_liner_test.go

* shell: refactor shared parsing logic into parseShellInput helper

- unified splitting and unquoting logic into a single state machine
- splitCommandLine now returns unquoted tokens directly
- simplified processEachCmd by removing redundant unquoting loop
- improved maintainability by eliminating code duplication

* shell: detect trailing backslash in stripQuotes

- updated parseShellInput to include escaped state in unbalanced flag
- stripQuotes now returns original string if it ends with an unescaped backslash
- added test case for trailing backslash in shell_liner_test.go

weed/shell/shell_liner_test.go

@@ -0,0 +1,105 @@
+package shell
+
+import (
+	"flag"
+	"reflect"
+	"testing"
+)
+
+func TestSplitCommandLine(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected []string
+	}{
+		{
+			input:    `s3.configure -user=test`,
+			expected: []string{`s3.configure`, `-user=test`},
+		},
+		{
+			input:    `s3.configure -user=Test_number_004 -account_display_name="Test number 004" -actions=write -apply`,
+			expected: []string{`s3.configure`, `-user=Test_number_004`, `-account_display_name=Test number 004`, `-actions=write`, `-apply`},
+		},
+		{
+			input:    `s3.configure -user=Test_number_004 -account_display_name='Test number 004' -actions=write -apply`,
+			expected: []string{`s3.configure`, `-user=Test_number_004`, `-account_display_name=Test number 004`, `-actions=write`, `-apply`},
+		},
+		{
+			input:    `s3.configure -flag="a b"c'd e'`,
+			expected: []string{`s3.configure`, `-flag=a bcd e`},
+		},
+		{
+			input:    `s3.configure -name="a\"b"`,
+			expected: []string{`s3.configure`, `-name=a"b`},
+		},
+		{
+			input:    `s3.configure -path='a\ b'`,
+			expected: []string{`s3.configure`, `-path=a\ b`},
+		},
+	}
+
+	for _, tt := range tests {
+		got := splitCommandLine(tt.input)
+		if !reflect.DeepEqual(got, tt.expected) {
+			t.Errorf("input: %s\ngot:  %v\nwant: %v", tt.input, got, tt.expected)
+		}
+	}
+}
+
+func TestStripQuotes(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{input: `"Test number 004"`, expected: `Test number 004`},
+		{input: `'Test number 004'`, expected: `Test number 004`},
+		{input: `-account_display_name="Test number 004"`, expected: `-account_display_name=Test number 004`},
+		{input: `-flag="a"b'c'`, expected: `-flag=abc`},
+		{input: `-name="a\"b"`, expected: `-name=a"b`},
+		{input: `-path='a\ b'`, expected: `-path=a\ b`},
+		{input: `"unbalanced`, expected: `"unbalanced`},
+		{input: `'unbalanced`, expected: `'unbalanced`},
+		{input: `-name="a\"b`, expected: `-name="a\"b`},
+		{input: `trailing\`, expected: `trailing\`},
+	}
+
+	for _, tt := range tests {
+		got := stripQuotes(tt.input)
+		if got != tt.expected {
+			t.Errorf("input: %s, got: %s, want: %s", tt.input, got, tt.expected)
+		}
+	}
+}
+
+func TestFlagParsing(t *testing.T) {
+	fs := flag.NewFlagSet("test", flag.ContinueOnError)
+	displayName := fs.String("account_display_name", "", "display name")
+
+	rawArg := `-account_display_name="Test number 004"`
+	args := []string{stripQuotes(rawArg)}
+	err := fs.Parse(args)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := "Test number 004"
+	if *displayName != expected {
+		t.Errorf("got: [%s], want: [%s]", *displayName, expected)
+	}
+}
+
+func TestEscapedFlagParsing(t *testing.T) {
+	fs := flag.NewFlagSet("test", flag.ContinueOnError)
+	name := fs.String("name", "", "name")
+
+	rawArg := `-name="a\"b"`
+	args := []string{stripQuotes(rawArg)}
+	err := fs.Parse(args)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := `a"b`
+	if *name != expected {
+		t.Errorf("got: [%s], want: [%s]", *name, expected)
+	}
+}