Fix parsing of double-quoted values with backslash continuations (#373)

Co-authored-by: ᴊᴏᴇ ᴄʜᴇɴ <jc@unknwon.io>

Author: felipecrs

ini_test.go

@@ -567,6 +567,31 @@ key = test value <span style="color: %s\; background: %s">more text</span>
 			assert.Equal(t, `test value <span style="color: %s; background: %s">more text</span>`, f.Section("").Key("key").String())
 		})
 
+		t.Run("unescape double quotes with backslash continuation", func(t *testing.T) {
+			f, err := LoadSources(LoadOptions{
+				UnescapeValueDoubleQuotes: true,
+			}, []byte(`hello = "!f() { \
+  echo "hello world"; \
+};f"`))
+			require.NoError(t, err)
+			require.NotNil(t, f)
+
+			expected := `!f() { \
+  echo "hello world"; \
+};f`
+			assert.Equal(t, expected, f.Section("").Key("hello").String())
+
+			t.Run("inverse case", func(t *testing.T) {
+				_, err := LoadSources(LoadOptions{
+					UnescapeValueDoubleQuotes: true,
+					IgnoreContinuation:        true,
+				}, []byte(`hello = "!f() { \
+  echo "hello world"; \
+};f"`))
+				require.Error(t, err)
+			})
+		})
+
 		t.Run("can parse small python-compatible INI files", func(t *testing.T) {
 			f, err := LoadSources(LoadOptions{
 				AllowPythonMultilineValues: true,

parser.go

@@ -182,6 +182,13 @@ func (p *parser) readMultilines(line, val, valQuote string) (string, error) {
 
 		pos := strings.LastIndex(next, valQuote)
 		if pos > -1 {
+			// Check if the line ends with backslash continuation after the quote
+			restOfLine := strings.TrimRight(next[pos+len(valQuote):], "\r\n")
+			if !p.options.IgnoreContinuation && strings.HasSuffix(strings.TrimSpace(restOfLine), `\`) {
+				val += next
+				continue
+			}
+
 			val += next[:pos]
 
 			comment, has := cleanComment([]byte(next[pos:]))