ash: use pgetc_eatbnl() in more places

Part of upstream commit:

    Date:   Thu Mar 8 08:37:11 2018 +0100
    Author: Harald van Dijk <harald@gigawatt.nl>
    parser: use pgetc_eatbnl() in more places

    dash has a pgetc_eatbnl function in parser.c which skips any
    backslash-newline combinations. It's not used everywhere it could be.
    There is also some duplicated backslash-newline handling elsewhere in
    parser.c. Replace most of the calls to pgetc() with calls to
    pgetc_eatbnl() and remove the duplicated backslash-newline handling.

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

Not adding "readtoken1(pgetc_eatbnl(), DQSYNTAX..." changes, since
readtoken1() handles the "starts with backslash + newline" case itself.

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

shell/ash_test/ash-heredoc/heredoc_backslash1.right

@@ -0,0 +1,43 @@
+Quoted heredoc:
+a\
+	b
+a\\
+	b
+ 123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-')
+c\
+
+Unquoted heredoc:
+a	b
+a\
+	b
+ 123456 -qwerty-\t-\-\"-\'-`-\--\z-\*-\?-
+	-qwerty-\t-\-\"-\'-`-\--\z-\*-\?-
+ 123456 v-$a-\t-\-\"-\x-`-\--\z-\*-\?-
+ 123456 v-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-
+cEOF2
+
+Quoted -heredoc:
+a\
+b
+a\\
+b
+ 123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-')
+c\
+
+Unquoted -heredoc:
+a	b
+a\
+b
+ 123456 -qwerty-\t-\-\"-\'-`-\--\z-\*-\?-
+-qwerty-\t-\-\"-\'-`-\--\z-\*-\?-
+ 123456 v-$a-\t-\-\"-\x-`-\--\z-\*-\?-
+ 123456 v-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-
+cEOF4
+
+Done: 0

shell/ash_test/ash-heredoc/heredoc_backslash1.tests

@@ -0,0 +1,70 @@
+# Test for correct handling of backslashes.
+# Note that some lines in each heredoc start with a tab.
+
+a=qwerty
+
+echo Quoted heredoc:
+cat <<"EOF1"
+a\
+	b
+a\\
+	b
+ 123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-')
+c\
+EOF1
+echo
+
+echo Unquoted heredoc:
+cat <<EOF2
+a\
+	b
+a\\
+	b
+ 123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-')
+c\
+EOF2
+EOF2
+echo
+
+echo Quoted -heredoc:
+cat <<-"EOF3"
+a\
+	b
+a\\
+	b
+ 123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-')
+c\
+	EOF3
+# In -heredoc case the marker is detected even if it is indented.
+echo
+
+echo Unquoted -heredoc:
+cat <<-EOF4
+a\
+	b
+a\\
+	b
+ 123456 -$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+	-$a-\t-\\-\"-\'-\`-\--\z-\*-\?-
+ 123456 `echo  v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-'`
+ 123456 $(echo v'-$a-\t-\\-\"-\x-\`-\--\z-\*-\?-')
+c\
+EOF4
+	EOF4
+# The marker is not detected if preceding line ends in backslash.
+# TODO: marker should be detected even if it is split by line continuation:
+# EOF\
+# 4
+# but currently hush doesn't do it. (Tab before "4" is not allowed, though.)
+echo
+
+echo "Done: $?"

shell/ash_test/ash-heredoc/heredoc_bkslash_newline1.right

@@ -0,0 +1,8 @@
+heredoc0
+Ok0:0
+heredoc1
+Ok1:0
+heredoc2
+Ok2:0
+heredoc3
+Ok4:0

shell/ash_test/ash-heredoc/heredoc_bkslash_newline1.tests

@@ -0,0 +1,25 @@
+cat <\
+<\
+EOF
+heredoc0
+EOF
+echo Ok0:$?
+
+cat <<\
+ EOF
+heredoc1
+EOF
+echo Ok1:$?
+
+cat <<\
+- EOF
+heredoc2
+	EOF
+echo Ok2:$?
+
+cat <\
+<\
+- EOF
+heredoc3
+	EOF
+echo Ok4:$?