ash: parser: Fix alias expansion after heredoc or newlines

Upstream commit:

    Date: Wed, 29 Apr 2020 00:19:59 +1000
    parser: Fix alias expansion after heredoc or newlines

    This script should print OK:

        alias a="case x in " b=x
        a
        b) echo BAD;; esac

        alias BEGIN={ END=}
        BEGIN
    	cat <<- EOF > /dev/null
    		$(:)
    	EOF
        END
        : <<- EOF &&
    		$(:)
        EOF
        BEGIN
    	echo OK
        END

    However, because the value of checkkwd is either zeroed when it
    shouldn't, or isn't zeroed when it should, dash currently gets
    it wrong in every case.

    This patch fixes it by saving checkkwd and zeroing it where needed.

function                                             old     new   delta
readtoken                                            157     176     +19

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

5 files changed, 31 insertions, 2 deletions

diff --git a/shell/ash.c b/shell/ash.c
index f1c21188e..5a001b004 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -13265,10 +13265,14 @@ readtoken(void)
         if (kwd & CHKNL) {
                 while (t == TNL) {
                         parseheredoc();
+                        checkkwd = 0;
                         t = xxreadtoken();
                 }
         }
 
+        kwd |= checkkwd;
+        checkkwd = 0;
+
         if (t != TWORD || quoteflag) {
                 goto out;
         }
@@ -13287,7 +13291,7 @@ readtoken(void)
                 }
         }
 
-        if (checkkwd & CHKALIAS) {
+        if (kwd & CHKALIAS) {
 #if ENABLE_ASH_ALIAS
                 struct alias *ap;
                 ap = lookupalias(wordtext, 1);
@@ -13300,7 +13304,6 @@ readtoken(void)
 #endif
         }
  out:
-        checkkwd = 0;
 #if DEBUG
         if (!alreadyseen)
                 TRACE(("token '%s' %s\n", tokname_array[t], t == TWORD ? wordtext : ""));
diff --git a/shell/ash_test/ash-alias/alias_brace.right b/shell/ash_test/ash-alias/alias_brace.right
new file mode 100644
index 000000000..7326d9603
--- /dev/null
+++ b/shell/ash_test/ash-alias/alias_brace.right
@@ -0,0 +1 @@
+Ok
diff --git a/shell/ash_test/ash-alias/alias_brace.tests b/shell/ash_test/ash-alias/alias_brace.tests
new file mode 100755
index 000000000..7571b64ac
--- /dev/null
+++ b/shell/ash_test/ash-alias/alias_brace.tests
@@ -0,0 +1,16 @@
+# Note: bash would need:
+#shopt -s expand_aliases
+# to enable aliases in non-interactive mode
+alias BEGIN={ END=}
+BEGIN
+        cat <<- EOF > /dev/null
+                $(:)
+        EOF
+END
+
+: <<- EOF &&
+        $(:)
+EOF
+BEGIN
+        echo Ok
+END
diff --git a/shell/ash_test/ash-alias/alias_case.right b/shell/ash_test/ash-alias/alias_case.right
new file mode 100644
index 000000000..7326d9603
--- /dev/null
+++ b/shell/ash_test/ash-alias/alias_case.right
@@ -0,0 +1 @@
+Ok
diff --git a/shell/ash_test/ash-alias/alias_case.tests b/shell/ash_test/ash-alias/alias_case.tests
new file mode 100755
index 000000000..ed8275875
--- /dev/null
+++ b/shell/ash_test/ash-alias/alias_case.tests
@@ -0,0 +1,8 @@
+# Note: bash would need:
+#shopt -s expand_aliases
+# to enable aliases in non-interactive mode
+alias a="case x in " b=x
+a
+b) echo BAD;;
+*) echo Ok;;
+esac