ash: parser: Add syntax stack for recursive parsing

This closes 10821.

Upstream patch:

    From: Herbert Xu <herbert@gondor.apana.org.au>
    Date: Fri, 9 Mar 2018 00:14:02 +0800
    parser: Add syntax stack for recursive parsing

    Without a stack of syntaxes we cannot correctly these two cases
    together:

            "${a#'$$'}"
            "${a#"${b-'$$'}"}"

    A recursive parser also helps in some other corner cases such
    as nested arithmetic expansion with paratheses.

    This patch adds a syntax stack allocated from the stack using
    alloca.  As a side-effect this allows us to remove the naked
    backslashes for patterns within double-quotes, which means that
    EXP_QPAT also has to go.

    This patch also fixes removes any backslashes that precede right
    braces when they are present within a parameter expansion context,
    and backslashes that precede double quotes within inner double
    quotes inside a parameter expansion in a here-document context.

    The idea of a recursive parser is based on a patch by Harald van
    Dijk.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

var_bash3, var_bash4 and var_bash6 tests are updated
with the output given by bash-4.3.43

With this patch, the following tests now pass for ash:

    dollar_repl_slash_bash2.tests
    squote_in_varexp2.tests
    squote_in_varexp.tests
    var_bash4.tests

function                                             old     new   delta
readtoken1                                          2615    2874    +259
synstack_push                                          -      54     +54
evalvar                                              574     571      -3
rmescapes                                            330     310     -20
subevalvar                                          1279    1258     -21
argstr                                              1146    1107     -39
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/4 up/down: 313/-83)           Total: 230 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

19 files changed, 168 insertions, 121 deletions

diff --git a/shell/ash.c b/shell/ash.c
index cf1d062fb..97379cd92 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -5888,10 +5888,9 @@ static int substr_atoi(const char *s)
  * performs globbing, and thus diverges from what we do).
  */
 #define EXP_CASE        0x10    /* keeps quotes around for CASE pattern */
-#define EXP_QPAT        0x20    /* pattern in quoted parameter expansion */
-#define EXP_VARTILDE2   0x40    /* expand tildes after colons only */
-#define EXP_WORD        0x80    /* expand word in parameter expansion */
-#define EXP_QUOTED      0x100   /* expand word in double quotes */
+#define EXP_VARTILDE2   0x20    /* expand tildes after colons only */
+#define EXP_WORD        0x40    /* expand word in parameter expansion */
+#define EXP_QUOTED      0x80    /* expand word in double quotes */
 /*
  * rmescape() flags
  */
@@ -5901,7 +5900,7 @@ static int substr_atoi(const char *s)
 #define RMESCAPE_HEAP   0x10    /* Malloc strings instead of stalloc */
 
 /* Add CTLESC when necessary. */
-#define QUOTES_ESC     (EXP_FULL | EXP_CASE | EXP_QPAT)
+#define QUOTES_ESC     (EXP_FULL | EXP_CASE)
 /* Do not skip NUL characters. */
 #define QUOTES_KEEPNUL EXP_TILDE
 
@@ -6090,7 +6089,6 @@ rmescapes(char *str, int flag, int *slash_position)
                 IF_BASH_PATTERN_SUBST('/',) CTLESC, CTLQUOTEMARK, '\0' };
 
         char *p, *q, *r;
-        unsigned inquotes;
         unsigned protect_against_glob;
         unsigned globbing;
 
@@ -6121,18 +6119,21 @@ rmescapes(char *str, int flag, int *slash_position)
                 }
         }
 
-        inquotes = 0;
         globbing = flag & RMESCAPE_GLOB;
         protect_against_glob = globbing;
         while (*p) {
                 if ((unsigned char)*p == CTLQUOTEMARK) {
-// Note: both inquotes and protect_against_glob only affect whether
+// Note: protect_against_glob only affect whether
 // CTLESC,<ch> gets converted to <ch> or to \<ch>
-                        inquotes = ~inquotes;
                         p++;
                         protect_against_glob = globbing;
                         continue;
                 }
+                if (*p == '\\') {
+                        /* naked back slash */
+                        protect_against_glob = 0;
+                        goto copy;
+                }
                 if ((unsigned char)*p == CTLESC) {
                         p++;
 #if DEBUG
@@ -6168,10 +6169,6 @@ rmescapes(char *str, int flag, int *slash_position)
                                         *q++ = '\\';
                                 }
                         }
-                } else if (*p == '\\' && !inquotes) {
-                        /* naked back slash */
-                        protect_against_glob = 0;
-                        goto copy;
                 }
 #if BASH_PATTERN_SUBST
                 else if (slash_position && p == str + *slash_position) {
@@ -6669,16 +6666,6 @@ argstr(char *p, int flags)
                 case CTLESC:
                         startloc++;
                         length++;
-
-                        /*
-                         * Quoted parameter expansion pattern: remove quote
-                         * unless inside inner quotes or we have a literal
-                         * backslash.
-                         */
-                        if (((flags | inquotes) & (EXP_QPAT | EXP_QUOTED)) ==
-                            EXP_QPAT && *p != '\\')
-                                break;
-
                         goto addquote;
                 case CTLVAR:
                         TRACE(("argstr: evalvar('%s')\n", p));
@@ -6869,15 +6856,24 @@ subevalvar(char *p, char *varname, int strloc, int subtype,
         }
 #endif
         argstr_flags = EXP_TILDE;
-        if (subtype != VSASSIGN && subtype != VSQUESTION)
-                argstr_flags |= (flag & (EXP_QUOTED | EXP_QPAT) ? EXP_QPAT : EXP_CASE);
+        if (subtype != VSASSIGN
+         && subtype != VSQUESTION
+#if BASH_SUBSTR
+         && subtype != VSSUBSTR
+#endif
+        ) {
+                /* EXP_CASE keeps CTLESC's */
+                argstr_flags = EXP_TILDE | EXP_CASE;
+        }
         argstr(p, argstr_flags);
+        //bb_error_msg("str0:'%s'", (char *)stackblock() + strloc);
 #if BASH_PATTERN_SUBST
         slash_pos = -1;
         if (repl) {
                 slash_pos = expdest - ((char *)stackblock() + strloc);
                 STPUTC('/', expdest);
-                argstr(repl + 1, argstr_flags);
+                //bb_error_msg("repl+1:'%s'", repl + 1);
+                argstr(repl + 1, EXP_TILDE); /* EXP_TILDE: echo "${v/x/~}" expands ~ ! */
                 *repl = '/';
         }
 #endif
@@ -10669,6 +10665,34 @@ pgetc_eatbnl(void)
         return c;
 }
 
+struct synstack {
+        smalluint syntax;
+        uint8_t innerdq   :1;
+        uint8_t varpushed :1;
+        uint8_t dblquote  :1;
+        int varnest;            /* levels of variables expansion */
+        int dqvarnest;          /* levels of variables expansion within double quotes */
+        int parenlevel;         /* levels of parens in arithmetic */
+        struct synstack *prev;
+        struct synstack *next;
+};
+
+static void
+synstack_push(struct synstack **stack, struct synstack *next, int syntax)
+{
+        memset(next, 0, sizeof(*next));
+        next->syntax = syntax;
+        next->next = *stack;
+        (*stack)->prev = next;
+        *stack = next;
+}
+
+static ALWAYS_INLINE void
+synstack_pop(struct synstack **stack)
+{
+        *stack = (*stack)->next;
+}
+
 /*
  * To handle the "." command, a stack of input files is used.  Pushfile
  * adds a new entry to the stack and popfile restores the previous level.
@@ -11928,19 +11952,13 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
         size_t len;
         struct nodelist *bqlist;
         smallint quotef;
-        smallint dblquote;
         smallint oldstyle;
-        IF_FEATURE_SH_MATH(smallint prevsyntax;) /* syntax before arithmetic */
         smallint pssyntax;   /* we are expanding a prompt string */
-        int varnest;         /* levels of variables expansion */
-        IF_FEATURE_SH_MATH(int arinest;)    /* levels of arithmetic expansion */
-        IF_FEATURE_SH_MATH(int parenlevel;) /* levels of parens in arithmetic */
-        int dqvarnest;       /* levels of variables expansion within double quotes */
         IF_BASH_DOLLAR_SQUOTE(smallint bash_dollar_squote = 0;)
+        /* syntax stack */
+        struct synstack synbase = { .syntax = syntax };
+        struct synstack *synstack = &synbase;
 
-        bqlist = NULL;
-        quotef = 0;
-        IF_FEATURE_SH_MATH(prevsyntax = 0;)
 #if ENABLE_ASH_EXPAND_PRMT
         pssyntax = (syntax == PSSYNTAX);
         if (pssyntax)
@@ -11948,11 +11966,10 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
 #else
         pssyntax = 0; /* constant */
 #endif
-        dblquote = (syntax == DQSYNTAX);
-        varnest = 0;
-        IF_FEATURE_SH_MATH(arinest = 0;)
-        IF_FEATURE_SH_MATH(parenlevel = 0;)
-        dqvarnest = 0;
+        if (syntax == DQSYNTAX)
+                synstack->dblquote = 1;
+        quotef = 0;
+        bqlist = NULL;
 
         STARTSTACKSTR(out);
  loop:
@@ -11960,9 +11977,9 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
         CHECKEND();     /* set c to PEOF if at end of here document */
         for (;;) {      /* until end of line or end of word */
                 CHECKSTRSPACE(4, out);  /* permit 4 calls to USTPUTC */
-                switch (SIT(c, syntax)) {
+                switch (SIT(c, synstack->syntax)) {
                 case CNL:       /* '\n' */
-                        if (syntax == BASESYNTAX)
+                        if (synstack->syntax == BASESYNTAX)
                                 goto endword;   /* exit outer loop */
                         USTPUTC(c, out);
                         nlprompt();
@@ -11982,13 +11999,13 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
                                 if (c & 0x100) {
                                         /* Unknown escape. Encode as '\z' */
                                         c = (unsigned char)c;
-                                        if (eofmark == NULL || dblquote)
+                                        if (eofmark == NULL || synstack->dblquote)
                                                 USTPUTC(CTLESC, out);
                                         USTPUTC('\\', out);
                                 }
                         }
 #endif
-                        if (eofmark == NULL || dblquote)
+                        if (eofmark == NULL || synstack->dblquote)
                                 USTPUTC(CTLESC, out);
                         USTPUTC(c, out);
                         break;
@@ -12008,20 +12025,13 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
                                 /* Backslash is retained if we are in "str"
                                  * and next char isn't dquote-special.
                                  */
-                                if (dblquote
+                                if (synstack->dblquote
                                  && c != '\\'
                                  && c != '`'
                                  && c != '$'
-                                 && (c != '"' || eofmark != NULL)
+                                 && (c != '"' || (eofmark != NULL && !synstack->varnest))
+                                 && (c != '}' || !synstack->varnest)
                                 ) {
-//dash survives not doing USTPUTC(CTLESC), but merely by chance:
-//Example: "\z" gets encoded as "\<CTLESC>z".
-//rmescapes() then emits "\", "\z", protecting z from globbing.
-//But it's wrong, should protect _both_ from globbing:
-//everything in double quotes is not globbed.
-//Unlike dash, we have a fix in rmescapes() which emits bare "z"
-//for "<CTLESC>z" since "z" is not glob-special (else unicode may break),
-//and glob would see "\z" and eat "\". Thus:
                                         USTPUTC(CTLESC, out); /* protect '\' from glob */
                                         USTPUTC('\\', out);
                                 }
@@ -12031,56 +12041,62 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
                         }
                         break;
                 case CSQUOTE:
-                        syntax = SQSYNTAX;
+                        synstack->syntax = SQSYNTAX;
  quotemark:
                         if (eofmark == NULL) {
                                 USTPUTC(CTLQUOTEMARK, out);
                         }
                         break;
                 case CDQUOTE:
-                        syntax = DQSYNTAX;
-                        dblquote = 1;
+                        synstack->syntax = DQSYNTAX;
+                        synstack->dblquote = 1;
+ toggledq:
+                        if (synstack->varnest)
+                                synstack->innerdq ^= 1;
                         goto quotemark;
                 case CENDQUOTE:
                         IF_BASH_DOLLAR_SQUOTE(bash_dollar_squote = 0;)
-                        if (eofmark != NULL && varnest == 0) {
+                        if (eofmark != NULL && synstack->varnest == 0) {
                                 USTPUTC(c, out);
-                        } else {
-                                if (dqvarnest == 0) {
-                                        syntax = BASESYNTAX;
-                                        dblquote = 0;
-                                }
-                                quotef = 1;
-                                goto quotemark;
+                                break;
                         }
-                        break;
+
+                        if (synstack->dqvarnest == 0) {
+                                synstack->syntax = BASESYNTAX;
+                                synstack->dblquote = 0;
+                        }
+
+                        quotef = 1;
+
+                        if (c == '"')
+                                goto toggledq;
+
+                        goto quotemark;
                 case CVAR:      /* '$' */
                         PARSESUB();             /* parse substitution */
                         break;
                 case CENDVAR:   /* '}' */
-                        if (varnest > 0) {
-                                varnest--;
-                                if (dqvarnest > 0) {
-                                        dqvarnest--;
-                                }
+                        if (!synstack->innerdq && synstack->varnest > 0) {
+                                if (!--synstack->varnest && synstack->varpushed)
+                                        synstack_pop(&synstack);
+                                else if (synstack->dqvarnest > 0)
+                                        synstack->dqvarnest--;
                                 c = CTLENDVAR;
                         }
                         USTPUTC(c, out);
                         break;
 #if ENABLE_FEATURE_SH_MATH
                 case CLP:       /* '(' in arithmetic */
-                        parenlevel++;
+                        synstack->parenlevel++;
                         USTPUTC(c, out);
                         break;
                 case CRP:       /* ')' in arithmetic */
-                        if (parenlevel > 0) {
-                                parenlevel--;
+                        if (synstack->parenlevel > 0) {
+                                synstack->parenlevel--;
                         } else {
                                 if (pgetc_eatbnl() == ')') {
                                         c = CTLENDARI;
-                                        if (--arinest == 0) {
-                                                syntax = prevsyntax;
-                                        }
+                                        synstack_pop(&synstack);
                                 } else {
                                         /*
                                          * unbalanced parens
@@ -12106,7 +12122,7 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
                 case CIGN:
                         break;
                 default:
-                        if (varnest == 0) {
+                        if (synstack->varnest == 0) {
 #if BASH_REDIR_OUTPUT
                                 if (c == '&') {
 //Can't call pgetc_eatbnl() here, this requires three-deep pungetc()
@@ -12125,12 +12141,12 @@ readtoken1(int c, int syntax, char *eofmark, int striptabs)
  endword:
 
 #if ENABLE_FEATURE_SH_MATH
-        if (syntax == ARISYNTAX)
+        if (synstack->syntax == ARISYNTAX)
                 raise_error_syntax("missing '))'");
 #endif
-        if (syntax != BASESYNTAX && eofmark == NULL)
+        if (synstack->syntax != BASESYNTAX && eofmark == NULL)
                 raise_error_syntax("unterminated quoted string");
-        if (varnest != 0) {
+        if (synstack->varnest != 0) {
                 /* { */
                 raise_error_syntax("missing '}'");
         }
@@ -12312,7 +12328,7 @@ parsesub: {
          || (c != '(' && c != '{' && !is_name(c) && !is_special(c))
         ) {
 #if BASH_DOLLAR_SQUOTE
-                if (syntax != DQSYNTAX && c == '\'')
+                if (synstack->syntax != DQSYNTAX && c == '\'')
                         bash_dollar_squote = 1;
                 else
 #endif
@@ -12332,6 +12348,8 @@ parsesub: {
                 }
         } else {
                 /* $VAR, $<specialchar>, ${...}, or PEOA/PEOF */
+                smalluint newsyn = synstack->syntax;
+
                 USTPUTC(CTLVAR, out);
                 typeloc = out - (char *)stackblock();
                 STADJUST(1, out);
@@ -12390,6 +12408,8 @@ parsesub: {
                         static const char types[] ALIGN1 = "}-+?=";
                         /* ${VAR...} but not $VAR or ${#VAR} */
                         /* c == first char after VAR */
+                        int cc = c;
+
                         switch (c) {
                         case ':':
                                 c = pgetc_eatbnl();
@@ -12414,21 +12434,24 @@ parsesub: {
                                 break;
                         }
                         case '%':
-                        case '#': {
-                                int cc = c;
+                        case '#':
                                 subtype = (c == '#' ? VSTRIMLEFT : VSTRIMRIGHT);
                                 c = pgetc_eatbnl();
-                                if (c != cc)
-                                        goto badsub;
-                                subtype++;
+                                if (c == cc)
+                                        subtype++;
+                                else
+                                        pungetc();
+
+                                newsyn = BASESYNTAX;
                                 break;
-                        }
 #if BASH_PATTERN_SUBST
                         case '/':
                                 /* ${v/[/]pattern/repl} */
 //TODO: encode pattern and repl separately.
-// Currently ${v/$var_with_slash/repl} is horribly broken
+// Currently cases like: v=1;echo ${v/$((1/1))/ONE}
+// are broken (should print "ONE")
                                 subtype = VSREPLACE;
+                                newsyn = BASESYNTAX;
                                 c = pgetc_eatbnl();
                                 if (c != '/')
                                         goto badsub;
@@ -12440,11 +12463,24 @@ parsesub: {
  badsub:
                         pungetc();
                 }
+
+                if (newsyn == ARISYNTAX && subtype > VSNORMAL)
+                        newsyn = DQSYNTAX;
+
+                if (newsyn != synstack->syntax) {
+                        synstack_push(&synstack,
+                                synstack->prev ?: alloca(sizeof(*synstack)),
+                                newsyn);
+
+                        synstack->varpushed = 1;
+                        synstack->dblquote = newsyn != BASESYNTAX;
+                }
+
                 ((unsigned char *)stackblock())[typeloc] = subtype;
                 if (subtype != VSNORMAL) {
-                        varnest++;
-                        if (dblquote)
-                                dqvarnest++;
+                        synstack->varnest++;
+                        if (synstack->dblquote)
+                                synstack->dqvarnest++;
                 }
                 STPUTC('=', out);
         }
@@ -12501,7 +12537,7 @@ parsebackq: {
                         case '\\':
                                 pc = pgetc(); /* or pgetc_eatbnl()? why (example)? */
                                 if (pc != '\\' && pc != '`' && pc != '$'
-                                 && (!dblquote || pc != '"')
+                                 && (!synstack->dblquote || pc != '"')
                                 ) {
                                         STPUTC('\\', pout);
                                 }
@@ -12576,10 +12612,11 @@ parsebackq: {
  * Parse an arithmetic expansion (indicate start of one and set state)
  */
 parsearith: {
-        if (++arinest == 1) {
-                prevsyntax = syntax;
-                syntax = ARISYNTAX;
-        }
+
+        synstack_push(&synstack,
+                        synstack->prev ?: alloca(sizeof(*synstack)),
+                        ARISYNTAX);
+        synstack->dblquote = 1;
         USTPUTC(CTLARI, out);
         goto parsearith_return;
 }
diff --git a/shell/ash_test/ash-arith/arith_nested1.right b/shell/ash_test/ash-arith/arith_nested1.right
new file mode 100644
index 000000000..d00491fd7
--- /dev/null
+++ b/shell/ash_test/ash-arith/arith_nested1.right
@@ -0,0 +1 @@
+1
diff --git a/shell/ash_test/ash-arith/arith_nested1.tests b/shell/ash_test/ash-arith/arith_nested1.tests
new file mode 100755
index 000000000..28571b833
--- /dev/null
+++ b/shell/ash_test/ash-arith/arith_nested1.tests
@@ -0,0 +1 @@
+echo $(( ( $((1)) ) ))
diff --git a/shell/ash_test/ash-quoting/squote_in_varexp3.right b/shell/ash_test/ash-quoting/squote_in_varexp3.right
new file mode 100644
index 000000000..223b7836f
--- /dev/null
+++ b/shell/ash_test/ash-quoting/squote_in_varexp3.right
@@ -0,0 +1 @@
+B
diff --git a/shell/ash_test/ash-quoting/squote_in_varexp3.tests b/shell/ash_test/ash-quoting/squote_in_varexp3.tests
new file mode 100755
index 000000000..028a88fd9
--- /dev/null
+++ b/shell/ash_test/ash-quoting/squote_in_varexp3.tests
@@ -0,0 +1 @@
+x=\'B; echo "${x#\'}"
diff --git a/shell/ash_test/ash-vars/var_bash3.right b/shell/ash_test/ash-vars/var_bash3.right
index a97c850ea..8899d981c 100644
--- a/shell/ash_test/ash-vars/var_bash3.right
+++ b/shell/ash_test/ash-vars/var_bash3.right
@@ -1,6 +1,6 @@
 1 a041#c
 2 a041#c
-3 a\041#c
+3 a041#c
 4 a\041#c
 5 a\041#c
 6 a\041#c
@@ -17,4 +17,4 @@
 17 a\tc
 18 a\tc
 19 atc
-20 a\tc
+20 atc
diff --git a/shell/ash_test/ash-vars/var_bash4.right b/shell/ash_test/ash-vars/var_bash4.right
index 0ef1bf661..9067e58e6 100644
--- a/shell/ash_test/ash-vars/var_bash4.right
+++ b/shell/ash_test/ash-vars/var_bash4.right
@@ -3,26 +3,26 @@ Replace str:   _\\_\z_
 Pattern:       single backslash and star: "replace literal star"
 Unquoted:      a_\_z_b\*c
 Unquoted =:    a_\_z_b\*c
-Quoted:        a_\_\z_b\*c
-Quoted =:      a_\_\z_b\*c
+Quoted:        a_\_z_b\*c
+Quoted =:      a_\_z_b\*c
 Pattern:       double backslash and star: "replace backslash and everything after it"
 Unquoted:      a*b_\_z_
 Unquoted =:    a*b_\_z_
-Quoted:        a*b_\_\z_
-Quoted =:      a*b_\_\z_
+Quoted:        a*b_\_z_
+Quoted =:      a*b_\_z_
 
 Source:        a\bc
 Replace str:   _\\_\z_
 Pattern:       single backslash and b: "replace b"
 Unquoted:      a\_\_z_c
 Unquoted =:    a\_\_z_c
-Quoted:        a\_\_\z_c
-Quoted =:      a\_\_\z_c
+Quoted:        a\_\_z_c
+Quoted =:      a\_\_z_c
 Pattern:       double backslash and b: "replace backslash and b"
 Unquoted:      a_\_z_c
 Unquoted =:    a_\_z_c
-Quoted:        a_\_\z_c
-Quoted =:      a_\_\z_c
+Quoted:        a_\_z_c
+Quoted =:      a_\_z_c
 
 Source:        a\bc
 Replace str:   _\\_\z_ (as variable $s)
diff --git a/shell/ash_test/ash-vars/var_bash6.right b/shell/ash_test/ash-vars/var_bash6.right
index 63fc23df8..115ff8b04 100644
--- a/shell/ash_test/ash-vars/var_bash6.right
+++ b/shell/ash_test/ash-vars/var_bash6.right
@@ -1,5 +1,5 @@
 Expected Actual
 a*z    : a*z
-\z     : \z
+z      : z
 a1z a2z: a1z a2z
 z      : z
diff --git a/shell/ash_test/ash-vars/var_bash6.tests b/shell/ash_test/ash-vars/var_bash6.tests
index cf2e4f020..686834177 100755
--- a/shell/ash_test/ash-vars/var_bash6.tests
+++ b/shell/ash_test/ash-vars/var_bash6.tests
@@ -3,7 +3,7 @@
 >a1z; >a2z;
           echo 'Expected' 'Actual'
 v='a bz'; echo 'a*z    :' "${v/a*z/a*z}"
-v='a bz'; echo '\z     :' "${v/a*z/\z}"
+v='a bz'; echo 'z      :' "${v/a*z/\z}"
 v='a bz'; echo 'a1z a2z:' ${v/a*z/a*z}
 v='a bz'; echo 'z      :' ${v/a*z/\z}
 rm a1z a2z
diff --git a/shell/ash_test/ash-vars/var_bash7.right b/shell/ash_test/ash-vars/var_bash7.right
new file mode 100644
index 000000000..223b7836f
--- /dev/null
+++ b/shell/ash_test/ash-vars/var_bash7.right
@@ -0,0 +1 @@
+B
diff --git a/shell/ash_test/ash-vars/var_bash7.tests b/shell/ash_test/ash-vars/var_bash7.tests
new file mode 100755
index 000000000..c4ce03f7f
--- /dev/null
+++ b/shell/ash_test/ash-vars/var_bash7.tests
@@ -0,0 +1 @@
+x=AB; echo "${x#$'\x41'}"
diff --git a/shell/hush_test/hush-arith/arith_nested1.right b/shell/hush_test/hush-arith/arith_nested1.right
new file mode 100644
index 000000000..d00491fd7
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith_nested1.right
@@ -0,0 +1 @@
+1
diff --git a/shell/hush_test/hush-arith/arith_nested1.tests b/shell/hush_test/hush-arith/arith_nested1.tests
new file mode 100755
index 000000000..28571b833
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith_nested1.tests
@@ -0,0 +1 @@
+echo $(( ( $((1)) ) ))
diff --git a/shell/hush_test/hush-quoting/squote_in_varexp3.right b/shell/hush_test/hush-quoting/squote_in_varexp3.right
new file mode 100644
index 000000000..223b7836f
--- /dev/null
+++ b/shell/hush_test/hush-quoting/squote_in_varexp3.right
@@ -0,0 +1 @@
+B
diff --git a/shell/hush_test/hush-quoting/squote_in_varexp3.tests b/shell/hush_test/hush-quoting/squote_in_varexp3.tests
new file mode 100755
index 000000000..028a88fd9
--- /dev/null
+++ b/shell/hush_test/hush-quoting/squote_in_varexp3.tests
@@ -0,0 +1 @@
+x=\'B; echo "${x#\'}"
diff --git a/shell/hush_test/hush-vars/var_bash3.right b/shell/hush_test/hush-vars/var_bash3.right
index a97c850ea..8899d981c 100644
--- a/shell/hush_test/hush-vars/var_bash3.right
+++ b/shell/hush_test/hush-vars/var_bash3.right
@@ -1,6 +1,6 @@
 1 a041#c
 2 a041#c
-3 a\041#c
+3 a041#c
 4 a\041#c
 5 a\041#c
 6 a\041#c
@@ -17,4 +17,4 @@
 17 a\tc
 18 a\tc
 19 atc
-20 a\tc
+20 atc
diff --git a/shell/hush_test/hush-vars/var_bash4.right b/shell/hush_test/hush-vars/var_bash4.right
index 0ef1bf661..9067e58e6 100644
--- a/shell/hush_test/hush-vars/var_bash4.right
+++ b/shell/hush_test/hush-vars/var_bash4.right
@@ -3,26 +3,26 @@ Replace str:   _\\_\z_
 Pattern:       single backslash and star: "replace literal star"
 Unquoted:      a_\_z_b\*c
 Unquoted =:    a_\_z_b\*c
-Quoted:        a_\_\z_b\*c
-Quoted =:      a_\_\z_b\*c
+Quoted:        a_\_z_b\*c
+Quoted =:      a_\_z_b\*c
 Pattern:       double backslash and star: "replace backslash and everything after it"
 Unquoted:      a*b_\_z_
 Unquoted =:    a*b_\_z_
-Quoted:        a*b_\_\z_
-Quoted =:      a*b_\_\z_
+Quoted:        a*b_\_z_
+Quoted =:      a*b_\_z_
 
 Source:        a\bc
 Replace str:   _\\_\z_
 Pattern:       single backslash and b: "replace b"
 Unquoted:      a\_\_z_c
 Unquoted =:    a\_\_z_c
-Quoted:        a\_\_\z_c
-Quoted =:      a\_\_\z_c
+Quoted:        a\_\_z_c
+Quoted =:      a\_\_z_c
 Pattern:       double backslash and b: "replace backslash and b"
 Unquoted:      a_\_z_c
 Unquoted =:    a_\_z_c
-Quoted:        a_\_\z_c
-Quoted =:      a_\_\z_c
+Quoted:        a_\_z_c
+Quoted =:      a_\_z_c
 
 Source:        a\bc
 Replace str:   _\\_\z_ (as variable $s)
diff --git a/shell/hush_test/hush-vars/var_bash6.right b/shell/hush_test/hush-vars/var_bash6.right
index 63fc23df8..115ff8b04 100644
--- a/shell/hush_test/hush-vars/var_bash6.right
+++ b/shell/hush_test/hush-vars/var_bash6.right
@@ -1,5 +1,5 @@
 Expected Actual
 a*z    : a*z
-\z     : \z
+z      : z
 a1z a2z: a1z a2z
 z      : z
diff --git a/shell/hush_test/hush-vars/var_bash6.tests b/shell/hush_test/hush-vars/var_bash6.tests
index cf2e4f020..686834177 100755
--- a/shell/hush_test/hush-vars/var_bash6.tests
+++ b/shell/hush_test/hush-vars/var_bash6.tests
@@ -3,7 +3,7 @@
 >a1z; >a2z;
           echo 'Expected' 'Actual'
 v='a bz'; echo 'a*z    :' "${v/a*z/a*z}"
-v='a bz'; echo '\z     :' "${v/a*z/\z}"
+v='a bz'; echo 'z      :' "${v/a*z/\z}"
 v='a bz'; echo 'a1z a2z:' ${v/a*z/a*z}
 v='a bz'; echo 'z      :' ${v/a*z/\z}
 rm a1z a2z