hush: treat ${#?} as "length of $?"

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

shell/ash_test/ash-vars/param_expand_indicate_error.right

@@ -0,0 +1,43 @@
+SHELL: line 1: syntax error: bad substitution
+1
+0
+====
+_
+SHELL: line 1: 1: parameter not set
+SHELL: line 1: 1: parameter not set or null
+SHELL: line 1: 1: message1
+SHELL: line 1: 1: message1
+SHELL: line 1: 1: unset!
+SHELL: line 1: 1: null or unset!
+====
+_aaaa
+_aaaa
+_aaaa
+_aaaa
+_aaaa
+_aaaa
+_aaaa
+====
+_
+SHELL: line 1: f: parameter not set
+SHELL: line 1: f: parameter not set or null
+SHELL: line 1: f: message3
+SHELL: line 1: f: message3
+SHELL: line 1: f: unset!
+SHELL: line 1: f: null or unset!
+====
+_
+_
+SHELL: line 1: f: parameter not set or null
+_
+SHELL: line 1: f: message4
+_
+SHELL: line 1: f: null or unset!
+====
+_fff
+_fff
+_fff
+_fff
+_fff
+_fff
+_fff

shell/ash_test/ash-vars/param_expand_indicate_error.tests

@@ -0,0 +1,61 @@
+# do all of these in subshells since it's supposed to error out
+# (set argv0 to "SHELL" to avoid "/path/to/shell: blah" in error messages)
+
+# first try some invalid patterns
+#"$THIS_SH" -c 'echo ${?}' SHELL -- this is valid as it's the same as $?
+"$THIS_SH" -c 'echo ${:?}' SHELL
+
+# then some funky ones
+# note: bash prints 1 - treats it as "length of $#"
+"$THIS_SH" -c 'echo ${#?}' SHELL
+# bash prints 0
+"$THIS_SH" -c 'echo ${#:?}' SHELL
+
+# now some valid ones
+export msg_unset="unset!"
+export msg_null_or_unset="null or unset!"
+
+echo ====
+"$THIS_SH" -c 'set --; echo _$1' SHELL
+"$THIS_SH" -c 'set --; echo _${1?}' SHELL
+"$THIS_SH" -c 'set --; echo _${1:?}' SHELL
+"$THIS_SH" -c 'set --; echo _${1?message1}' SHELL
+"$THIS_SH" -c 'set --; echo _${1:?message1}' SHELL
+"$THIS_SH" -c 'set --; echo _${1?$msg_unset}' SHELL
+"$THIS_SH" -c 'set --; echo _${1:?$msg_null_or_unset}' SHELL
+
+echo ====
+"$THIS_SH" -c 'set -- aaaa; echo _$1' SHELL
+"$THIS_SH" -c 'set -- aaaa; echo _${1?}' SHELL
+"$THIS_SH" -c 'set -- aaaa; echo _${1:?}' SHELL
+"$THIS_SH" -c 'set -- aaaa; echo _${1?word}' SHELL
+"$THIS_SH" -c 'set -- aaaa; echo _${1:?word}' SHELL
+"$THIS_SH" -c 'set -- aaaa; echo _${1?$msg_unset}' SHELL
+"$THIS_SH" -c 'set -- aaaa; echo _${1:?$msg_null_or_unset}' SHELL
+
+echo ====
+"$THIS_SH" -c 'unset f; echo _$f' SHELL
+"$THIS_SH" -c 'unset f; echo _${f?}' SHELL
+"$THIS_SH" -c 'unset f; echo _${f:?}' SHELL
+"$THIS_SH" -c 'unset f; echo _${f?message3}' SHELL
+"$THIS_SH" -c 'unset f; echo _${f:?message3}' SHELL
+"$THIS_SH" -c 'unset f; echo _${f?$msg_unset}' SHELL
+"$THIS_SH" -c 'unset f; echo _${f:?$msg_null_or_unset}' SHELL
+
+echo ====
+"$THIS_SH" -c 'f=; echo _$f' SHELL
+"$THIS_SH" -c 'f=; echo _${f?}' SHELL
+"$THIS_SH" -c 'f=; echo _${f:?}' SHELL
+"$THIS_SH" -c 'f=; echo _${f?word}' SHELL
+"$THIS_SH" -c 'f=; echo _${f:?message4}' SHELL
+"$THIS_SH" -c 'f=; echo _${f?$msg_unset}' SHELL
+"$THIS_SH" -c 'f=; echo _${f:?$msg_null_or_unset}' SHELL
+
+echo ====
+"$THIS_SH" -c 'f=fff; echo _$f' SHELL
+"$THIS_SH" -c 'f=fff; echo _${f?}' SHELL
+"$THIS_SH" -c 'f=fff; echo _${f:?}' SHELL
+"$THIS_SH" -c 'f=fff; echo _${f?word}' SHELL
+"$THIS_SH" -c 'f=fff; echo _${f:?word}' SHELL
+"$THIS_SH" -c 'f=fff; echo _${f?$msg_unset}' SHELL
+"$THIS_SH" -c 'f=fff; echo _${f:?$msg_null_or_unset}' SHELL

shell/hush.c

@@ -5559,8 +5559,10 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
 	first_char = arg[0] = arg0 & 0x7f;
 	exp_op = 0;
 
-	if (first_char == '#'      /* ${#... */
+	if (first_char == '#' && arg[1] /* ${#... but not ${#} */
-	 && arg[1] && !exp_saveptr /* not ${#} and not ${#<op_char>...} */
+	 && (!exp_saveptr               /* and (not ${#<op_char>...} */
+	    || (arg[1] == '?' && arg[2] == '\0') /* or ${#?} - "len of $?") */
+	    )
 	) {
 		/* It must be length operator: ${#var} */
 		var++;
@@ -5797,7 +5799,11 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
 					/* mimic bash message */
 					die_if_script("%s: %s",
 						var,
-						exp_word[0] ? exp_word : "parameter null or not set"
+						exp_word[0]
+						? exp_word
+						: "parameter null or not set"
+						/* ash has more specific messages, a-la: */
+						/*: (exp_save == ':' ? "parameter null or not set" : "parameter not set")*/
 					);
 //TODO: how interactive bash aborts expansion mid-command?
 				} else {

shell/hush_test/hush-vars/param_expand_indicate_error.right

@@ -1,5 +1,5 @@
 hush: syntax error: unterminated ${name}
-0
+1
 0
 ====
 _

shell/hush_test/hush-vars/param_expand_indicate_error.tests

@@ -5,7 +5,7 @@
 "$THIS_SH" -c 'echo ${:?}'
 
 # then some funky ones
-# note: bash prints 1 - treats it as "length of $#"? We print 0
+# note: bash prints 1 - treats it as "length of $#"
 "$THIS_SH" -c 'echo ${#?}'
 # bash prints 0
 "$THIS_SH" -c 'echo ${#:?}'