Fix/improve handling of escaping in ini parser

Quoting from UPGRADING:

- A leading dollar in a quoted string can now be escaped: "\${" will now be
  interpreted as a string with contents `${`.

- Backslashes in double quoted strings are now more consistently treated as
  escape characters. Previously, "foo\\" followed by something other than a
  newline was not considered as a teminated string. It is now interpreted as a
  string with contents `foo\`. However, as an exception, the string "foo\"
  followed by a newline will continue to be treated as a valid string with
  contents `foo\` rather than an unterminated string. This exception exists to
  support naive uses of Windows file pahts as "C:\foo\".

Closes GH-7420.

Author: dryabov

Zend/zend_ini_scanner.l

@@ -591,31 +591,35 @@ end_raw_value_chars:
 		return 0;
 	}
 
-	while (YYCURSOR < YYLIMIT) {
-		switch (*YYCURSOR++) {
+	unsigned char *s = SCNG(yy_text);
+
+	while (s < YYLIMIT) {
+		switch (*s++) {
 			case '"':
-				if (YYCURSOR < YYLIMIT && YYCURSOR[-2] == '\\' && *YYCURSOR != '\r' && *YYCURSOR != '\n') {
-					continue;
-				}
 				break;
 			case '$':
-				if (*YYCURSOR == '{') {
+				if (s < YYLIMIT && *s == '{') {
 					break;
 				}
 				continue;
 			case '\\':
-				if (YYCURSOR < YYLIMIT && *YYCURSOR != '"') {
-					YYCURSOR++;
+				if (s < YYLIMIT) {
+					unsigned char escaped = *s++;
+					/* A special case for Windows paths, e.g. key="C:\path\" */
+					if (escaped == '"' && (s >= YYLIMIT || *s == '\n' || *s == '\r')) {
+						break;
+					}
 				}
 				ZEND_FALLTHROUGH;
 			default:
 				continue;
 		}
 
-		YYCURSOR--;
+		s--;
 		break;
 	}
 
+	YYCURSOR = s;
 	yyleng = YYCURSOR - SCNG(yy_text);
 
 	zend_ini_escape_string(ini_lval, yytext, yyleng, '"');

ext/standard/tests/general_functions/parse_ini_basic.data

@@ -130,3 +130,14 @@ ini-with.hyphen = hyphen and dot
 [windows paths]
 winpath1="c:\some windows\path\test\new\r\quote \" here\single ' quote\some more"
 winpath2="special case\"
+
+[characters escaping]
+; Note: single-quoted strings don't support characters escaping, and the line below
+;       is single-quoted string, followed by unquoted text, followed by single-quoted '.'
+single_quoted = 'She said \'Exactly my point\'.'
+double_quoted = "She said \"Exactly my point\"."
+double_quoted_2 = "Use \\\" to escape double quote"
+double_quoted_multiline = "Lorem \"ipsum\"""
+ dolor"
+dollar_test = "\${test}"
+unescaped ="\n\r\t"

ext/standard/tests/general_functions/parse_ini_basic.phpt

@@ -15,7 +15,7 @@ var_dump(parse_ini_file($ini_file, 1));
 echo "Done.\n";
 ?>
 --EXPECT--
-array(26) {
+array(27) {
   ["basic"]=>
   array(15) {
     ["basicval"]=>
@@ -279,5 +279,21 @@ array(26) {
     ["winpath2"]=>
     string(13) "special case\"
   }
+  ["characters escaping"]=>
+  array(6) {
+    ["single_quoted"]=>
+    string(28) "She said \Exactly my point\."
+    ["double_quoted"]=>
+    string(28) "She said "Exactly my point"."
+    ["double_quoted_2"]=>
+    string(29) "Use \" to escape double quote"
+    ["double_quoted_multiline"]=>
+    string(20) "Lorem "ipsum"
+ dolor"
+    ["dollar_test"]=>
+    string(7) "${test}"
+    ["unescaped"]=>
+    string(6) "\n\r\t"
+  }
 }
 Done.