rabbit_env: Fix Bourne shell concatenated literal parsing

The parser didn't handle literals of the form:
    'single-quoted'unquoted'single-quoted-again'"or-even-double-quoted"

In particular, the unquoted parsing assumed that nothing else could
follow it. The testsuite is extended with the issue reporter's case.

While here, improve escaped characters handling. They used to be not
parsed specifically at all.

Fixes #2969.

2 files changed, 148 insertions, 6 deletions

diff --git a/deps/rabbit_common/src/rabbit_env.erl b/deps/rabbit_common/src/rabbit_env.erl
index cdd708a63e..97c575bb9f 100644
--- a/deps/rabbit_common/src/rabbit_env.erl
+++ b/deps/rabbit_common/src/rabbit_env.erl
@@ -1727,14 +1727,35 @@ is_sh_function(Line, Lines) ->
     andalso
     re:run(hd(Lines), "^\\s*\\{\\s*$", [{capture, none}]) =:= match.
 
-parse_sh_literal("'" ++ SingleQuoted, Lines, Literal) ->
+parse_sh_literal([$' | SingleQuoted], Lines, Literal) ->
     parse_single_quoted_literal(SingleQuoted, Lines, Literal);
-parse_sh_literal("\"" ++ DoubleQuoted, Lines, Literal) ->
+parse_sh_literal([$" | DoubleQuoted], Lines, Literal) ->
     parse_double_quoted_literal(DoubleQuoted, Lines, Literal);
-parse_sh_literal("$'" ++ DollarSingleQuoted, Lines, Literal) ->
+parse_sh_literal([$$, $' | DollarSingleQuoted], Lines, Literal) ->
     parse_dollar_single_quoted_literal(DollarSingleQuoted, Lines, Literal);
+parse_sh_literal([], Lines, Literal) ->
+    %% We reached the end of the literal.
+    {lists:reverse(Literal), Lines};
 parse_sh_literal(Unquoted, Lines, Literal) ->
-    {lists:reverse(Literal) ++ Unquoted, Lines}.
+    parse_unquoted_literal(Unquoted, Lines, Literal).
+
+parse_unquoted_literal([$\\], [Line | Lines], Literal) ->
+    %% The newline character is escaped: it means line continuation.
+    parse_unquoted_literal(Line, Lines, Literal);
+parse_unquoted_literal([$\\, C | Rest], Lines, Literal) ->
+    %% This is an escaped character, so we "eat" the two characters but append
+    %% only the escaped one.
+    parse_unquoted_literal(Rest, Lines, [C | Literal]);
+parse_unquoted_literal([C | _] = Rest, Lines, Literal)
+  when C =:= $' orelse C =:= $" ->
+    %% We reached the end of the unquoted literal and the beginning of a quoted
+    %% literal. Both are concatenated.
+    parse_sh_literal(Rest, Lines, Literal);
+parse_unquoted_literal([C | Rest], Lines, Literal) ->
+    parse_unquoted_literal(Rest, Lines, [C | Literal]);
+parse_unquoted_literal([], Lines, Literal) ->
+    %% We reached the end of the unquoted literal.
+    parse_sh_literal([], Lines, Literal).
 
 parse_single_quoted_literal([$' | Rest], Lines, Literal) ->
     %% We reached the closing single quote.
@@ -1747,6 +1768,14 @@ parse_single_quoted_literal([], [Line | Lines], Literal) ->
 parse_single_quoted_literal([C | Rest], Lines, Literal) ->
     parse_single_quoted_literal(Rest, Lines, [C | Literal]).
 
+parse_double_quoted_literal([$\\], [Line | Lines], Literal) ->
+    %% The newline character is escaped: it means line continuation.
+    parse_double_quoted_literal(Line, Lines, Literal);
+parse_double_quoted_literal([$\\, C | Rest], Lines, Literal)
+  when C =:= $$ orelse C =:= $` orelse C =:= $" orelse C =:= $\\ ->
+    %% This is an escaped character, so we "eat" the two characters but append
+    %% only the escaped one.
+    parse_double_quoted_literal(Rest, Lines, [C | Literal]);
 parse_double_quoted_literal([$" | Rest], Lines, Literal) ->
     %% We reached the closing double quote.
     parse_sh_literal(Rest, Lines, Literal);
@@ -1758,6 +1787,59 @@ parse_double_quoted_literal([], [Line | Lines], Literal) ->
 parse_double_quoted_literal([C | Rest], Lines, Literal) ->
     parse_double_quoted_literal(Rest, Lines, [C | Literal]).
 
+-define(IS_OCTAL(C), C >= $0 andalso C < $8).
+-define(IS_HEX(C),
+        (C >= $0 andalso C =< $9) orelse
+        (C >= $a andalso C =< $f) orelse
+        (C >= $A andalso C =< $F)).
+
+parse_dollar_single_quoted_literal([$\\, C1, C2, C3 | Rest], Lines, Literal)
+  when ?IS_OCTAL(C1) andalso ?IS_OCTAL(C2) andalso ?IS_OCTAL(C3) ->
+    %% An octal-based escaped character.
+    C = octal_to_character([C1, C2, C3]),
+    parse_dollar_single_quoted_literal(Rest, Lines, [C | Literal]);
+parse_dollar_single_quoted_literal([$\\, $x, C1, C2 | Rest], Lines, Literal)
+  when ?IS_HEX(C1) andalso ?IS_HEX(C2) ->
+    %% A hex-based escaped character.
+    C = hex_to_character([C1, C2]),
+    parse_dollar_single_quoted_literal(Rest, Lines, [C | Literal]);
+parse_dollar_single_quoted_literal([$\\, $u,
+                                    C1, C2, C3, C4 | Rest],
+                                   Lines, Literal)
+  when ?IS_HEX(C1) andalso ?IS_HEX(C2) andalso
+       ?IS_HEX(C3) andalso ?IS_HEX(C4) ->
+    %% A hex-based escaped character.
+    C = hex_to_character([C1, C2, C3, C4]),
+    parse_dollar_single_quoted_literal(Rest, Lines, [C | Literal]);
+parse_dollar_single_quoted_literal([$\\, $U,
+                                    C1, C2, C3, C4,
+                                    C5, C6, C7, C8 | Rest],
+                                   Lines, Literal)
+  when ?IS_HEX(C1) andalso ?IS_HEX(C2) andalso
+       ?IS_HEX(C3) andalso ?IS_HEX(C4) andalso
+       ?IS_HEX(C5) andalso ?IS_HEX(C6) andalso
+       ?IS_HEX(C7) andalso ?IS_HEX(C8) ->
+    %% A hex-based escaped character.
+    C = hex_to_character([C1, C2, C3, C4, C5, C6, C7, C8]),
+    parse_dollar_single_quoted_literal(Rest, Lines, [C | Literal]);
+parse_dollar_single_quoted_literal([$\\, C1 | Rest], Lines, Literal)
+  when C1 =:= $a orelse
+       C1 =:= $b orelse
+       C1 =:= $e orelse
+       C1 =:= $E orelse
+       C1 =:= $f orelse
+       C1 =:= $n orelse
+       C1 =:= $r orelse
+       C1 =:= $t orelse
+       C1 =:= $v orelse
+       C1 =:= $\\ orelse
+       C1 =:= $' orelse
+       C1 =:= $" orelse
+       C1 =:= $? ->
+    %% This is an escaped character, so we "eat" the two characters but append
+    %% only the escaped one.
+    C = esc_to_character(C1),
+    parse_dollar_single_quoted_literal(Rest, Lines, [C | Literal]);
 parse_dollar_single_quoted_literal([$'], Lines, Literal) ->
     %% We reached the closing single quote.
     {lists:reverse(Literal), Lines};
@@ -1769,6 +1851,37 @@ parse_dollar_single_quoted_literal([], [Line | Lines], Literal) ->
 parse_dollar_single_quoted_literal([C | Rest], Lines, Literal) ->
     parse_dollar_single_quoted_literal(Rest, Lines, [C | Literal]).
 
+octal_to_character(List) ->
+    octal_to_character(List, 0).
+
+octal_to_character([D | Rest], C) when ?IS_OCTAL(D) ->
+    octal_to_character(Rest, C * 8 + D - $0);
+octal_to_character([], C) ->
+    C.
+
+hex_to_character(List) ->
+    hex_to_character(List, 0).
+
+hex_to_character([D | Rest], C) ->
+    hex_to_character(Rest, C * 16 + hex_to_int(D));
+hex_to_character([], C) ->
+    C.
+
+hex_to_int(C) when C >= $0 andalso C =< $9 -> C - $0;
+hex_to_int(C) when C >= $a andalso C =< $f -> 10 + C - $a;
+hex_to_int(C) when C >= $A andalso C =< $F -> 10 + C - $A.
+
+esc_to_character($a) -> 7;   % Bell
+esc_to_character($b) -> 8;   % Backspace
+esc_to_character($e) -> 27;  % Esc
+esc_to_character($E) -> 27;  % Esc
+esc_to_character($f) -> 12;  % Form feed
+esc_to_character($n) -> $\n; % Newline
+esc_to_character($r) -> 13;  % Carriage return
+esc_to_character($t) -> 9;   % Horizontal tab
+esc_to_character($v) -> 11;  % Vertical tab
+esc_to_character(C)  -> C.
+
 skip_sh_function(["}" | Lines], Vars) ->
     parse_conf_env_file_output2(Lines, Vars);
 skip_sh_function([_ | Lines], Vars) ->
diff --git a/deps/rabbit_common/test/rabbit_env_SUITE.erl b/deps/rabbit_common/test/rabbit_env_SUITE.erl
index daee0e2ab7..bc1b463d79 100644
--- a/deps/rabbit_common/test/rabbit_env_SUITE.erl
+++ b/deps/rabbit_common/test/rabbit_env_SUITE.erl
@@ -1087,13 +1087,42 @@ check_parse_conf_env_file_output(_) ->
          #{}
         )),
     ?assertEqual(
+       #{"DOUBLE_QUOTED" => "\\' \" \\v",
+         "SINGLE_DOLLAR" => "' \" \\ \007 z z z z"},
+       rabbit_env:parse_conf_env_file_output2(
+         ["DOUBLE_QUOTED=\"\\' \\\" \\v\"",
+          "SINGLE_DOLLAR=$'\\' \\\" \\\\ \\a \\172 \\x7a \\u007A \\U0000007a'"
+         ],
+         #{}
+        )),
+    ?assertEqual(
        #{"A" => "a",
          "B" => "b",
-         "MULTI_LINE" => "\n'foobar'"},
+         "SINGLE_QUOTED_MULTI_LINE" => "\n'foobar'",
+         "DOUBLE_QUOTED_MULTI_LINE" => "Line1\nLine2"},
        rabbit_env:parse_conf_env_file_output2(
          ["A=a",
-          "MULTI_LINE='",
+          "SINGLE_QUOTED_MULTI_LINE='",
           "'\"'\"'foobar'\"'\"",
+          "DOUBLE_QUOTED_MULTI_LINE=\"Line1",
+          "Line\\",
+          "2\"",
           "B=b"],
          #{}
+        )),
+    ?assertEqual(
+       #{"shellHook" =>
+         "\n"
+         "function isShellInteractive {\n"
+         "  # shell is interactive if $- contains 'i'\n"
+         "  [[ $- == *i* ]]\n"
+         "}\n"},
+       rabbit_env:parse_conf_env_file_output2(
+         ["shellHook='",
+          "function isShellInteractive {",
+          "  # shell is interactive if $- contains '\\''i'\\''",
+          "  [[ $- == *i* ]]",
+          "}",
+          "'"],
+         #{}
         )).