hush: fix globbing+backslashes in unquoted $var expansion

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

shell/hush_test/hush-glob/glob2.right

@@ -0,0 +1,18 @@
+Expected Actual
+Z\*    : Z\*
+Z*     : Z*
+Z\f    : Z\f
+Z\*    : Z\*
+
+Z\z    : Z\z
+Zz     : Zz
+Z\z    : Z\z
+Z\z    : Z\z
+
+Z\     : Z\
+Z\     : Z\
+
+Z\f Zf : Z\f Zf
+Z\f Zf : Z\f Zf
+
+Done: 0

shell/hush_test/hush-glob/glob2.tests

@@ -0,0 +1,27 @@
+# This test demonstrates that in unquoted $v, backslashes expand by this rule:
+# \z -> \\\z; \<eol> -> \\<eol> (for any z, special or not),
+# and subsequently globbing converts \\ to \ and treats \z as literal z
+# even if it is a special char.
+
+>'Zf'
+>'Z\f'
+	echo 'Expected' 'Actual'
+v='\*'; echo 'Z\*    :' Z$v
+        echo 'Z*     :' Z\*
+        echo 'Z\f    :' Z\\*
+        echo 'Z\*    :' Z\\\*  # NB! only this matches Z$v output
+echo
+v='\z'; echo 'Z\z    :' Z$v
+        echo 'Zz     :' Z\z
+        echo 'Z\z    :' Z\\z
+        echo 'Z\z    :' Z\\\z
+echo
+v='\';  echo 'Z\     :' Z$v
+        echo 'Z\     :' Z\\
+echo
+v='*';  echo 'Z\f Zf :' Z$v
+        echo 'Z\f Zf :' Z*
+echo
+
+rm 'Z\f' 'Zf'
+echo Done: $?

shell/hush_test/hush-vars/var_bash4.right

@@ -1,23 +1,40 @@
 Source:        a*b\*c
 Replace str:   _\\_\z_
 Pattern:       single backslash and star: "replace literal star"
-In assignment: a_\_z_b\*c
 Unquoted:      a_\_z_b\*c
+Unquoted =:    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"
-In assignment: a*b_\_z_
 Unquoted:      a*b_\_z_
+Unquoted =:    a*b_\_z_
 Quoted:        a*b_\_\z_
+Quoted =:      a*b_\_\z_
 
 Source:        a\bc
 Replace str:   _\\_\z_
 Pattern:       single backslash and b: "replace b"
-In assignment: a\_\_z_c
 Unquoted:      a\_\_z_c
+Unquoted =:    a\_\_z_c
 Quoted:        a\_\_\z_c
+Quoted =:      a\_\_\z_c
 Pattern:       double backslash and b: "replace backslash and b"
-In assignment: a_\_z_c
 Unquoted:      a_\_z_c
+Unquoted =:    a_\_z_c
 Quoted:        a_\_\z_c
+Quoted =:      a_\_\z_c
+
+Source:        a\bc
+Replace str:   _\\_\z_ (as variable $s)
+Pattern:       single backslash and b: "replace b"
+Unquoted:      a\_\\_\z_c
+Unquoted =:    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
 
 Done: 0

shell/hush_test/hush-vars/var_bash4.tests

@@ -6,23 +6,30 @@
 # even in quotes.
 #
 # bash4 (and probably bash3 too): "Quoted:" results are different from
-# unquoted and assignment expansions - they have a backslash before z.
+# unquoted expansions - they have a backslash before z.
+#
+# The difference only exists if repl is a literal. If it is a variable:
+# ${v/.../$s}, then all backslashes are preserved in both cases.
 
 v='a*b\*c'
 echo 'Source:       ' "$v"
 echo 'Replace str:  ' '_\\_\z_'
 
 echo 'Pattern:      ' 'single backslash and star: "replace literal star"'
-r=${v/\*/_\\_\z_}
-echo 'In assignment:' "$r"
 echo 'Unquoted:     ' ${v/\*/_\\_\z_}
+r=${v/\*/_\\_\z_}
+echo 'Unquoted =:   ' "$r"
 echo 'Quoted:       ' "${v/\*/_\\_\z_}"
+r="${v/\*/_\\_\z_}"
+echo 'Quoted =:     ' "$r"
 
 echo 'Pattern:      ' 'double backslash and star: "replace backslash and everything after it"'
-r=${v/\\*/_\\_\z_}
-echo 'In assignment:' "$r"
 echo 'Unquoted:     '  ${v/\\*/_\\_\z_}
+r=${v/\\*/_\\_\z_}
+echo 'Unquoted =:   ' "$r"
 echo 'Quoted:       ' "${v/\\*/_\\_\z_}"
+r="${v/\\*/_\\_\z_}"
+echo 'Quoted =:     ' "$r"
 
 echo
 
@@ -31,16 +38,43 @@ echo 'Source:       ' "$v"
 echo 'Replace str:  ' '_\\_\z_'
 
 echo 'Pattern:      ' 'single backslash and b: "replace b"'
-r=${v/\b/_\\_\z_}
-echo 'In assignment:' "$r"
 echo 'Unquoted:     '  ${v/\b/_\\_\z_}
+r=${v/\b/_\\_\z_}
+echo 'Unquoted =:   ' "$r"
 echo 'Quoted:       ' "${v/\b/_\\_\z_}"
+r="${v/\b/_\\_\z_}"
+echo 'Quoted =:     ' "$r"
 
 echo 'Pattern:      ' 'double backslash and b: "replace backslash and b"'
-r=${v/\\b/_\\_\z_}
-echo 'In assignment:' "$r"
 echo 'Unquoted:     '  ${v/\\b/_\\_\z_}
+r=${v/\\b/_\\_\z_}
+echo 'Unquoted =:   ' "$r"
 echo 'Quoted:       ' "${v/\\b/_\\_\z_}"
+r="${v/\\b/_\\_\z_}"
+echo 'Quoted =:     ' "$r"
+
+echo
+
+v='a\bc'
+s='_\\_\z_'
+echo 'Source:       ' "$v"
+echo 'Replace str:  ' "$s" '(as variable $s)'
+
+echo 'Pattern:      ' 'single backslash and b: "replace b"'
+echo 'Unquoted:     '  ${v/\b/$s}
+r=${v/\b/$s}
+echo 'Unquoted =:   ' "$r"
+echo 'Quoted:       ' "${v/\b/$s}"
+r="${v/\b/$s}"
+echo 'Quoted =:     ' "$r"
+
+echo 'Pattern:      ' 'double backslash and b: "replace backslash and b"'
+echo 'Unquoted:     '  ${v/\\b/$s}
+r=${v/\\b/$s}
+echo 'Unquoted =:   ' "$r"
+echo 'Quoted:       ' "${v/\\b/$s}"
+r="${v/\\b/$s}"
+echo 'Quoted =:     ' "$r"
 
 echo