hush: propagate (output,n) parameters into expand_one_var()

This is necessary since expand_one_var() for ${var:+ARG} must create more than one
output word, and thus can't simply return a char*.

function                                             old     new   delta
expand_one_var                                      1610    1643     +33
expand_vars_to_list                                 1139    1125     -14
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 33/-14)             Total: 19 bytes

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

1 files changed, 49 insertions, 14 deletions

diff --git a/shell/hush.c b/shell/hush.c
index b738d2fd8..ea259f53c 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -5976,7 +5976,8 @@ static int append_str_maybe_ifs_split(o_string *output, int *ended_in_ifs, int n
 /* Helper:
  * Handles <SPECIAL_VAR_SYMBOL>varname...<SPECIAL_VAR_SYMBOL> construct.
  */
-static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, char **pp)
+static NOINLINE int expand_one_var(o_string *output,
+        int *ended_in_ifs, int n, int first_ch, char *arg, char **pp)
 {
         const char *val;
         char *to_be_freed;
@@ -6038,9 +6039,9 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
         /* Look up the variable in question */
         if (isdigit(var[0])) {
                 /* parse_dollar should have vetted var for us */
-                int n = xatoi_positive(var);
-                if (n < G.global_argc)
-                        val = G.global_argv[n];
+                int nn = xatoi_positive(var);
+                if (nn < G.global_argc)
+                        val = G.global_argv[nn];
                 /* else val remains NULL: $N with too big N */
         } else {
                 switch (var[0]) {
@@ -6236,6 +6237,34 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
                          * Colon forms (${var:-word}, ${var:=word} etc) do the same,
                          * but also treat null var as if it is unset.
                          */
+/*
+ * Word-splitting and squote behavior of bash:
+ * $ f() { for i; do echo "|$i|"; done; };
+ *
+ * $ x=; f ${x:?'x y' z}
+ * bash: x: x y z
+ * $ x=; f "${x:?'x y' z}"
+ * bash: x: x y z       # dash prints: dash: x: 'x y' z
+ *
+ * $ x=; f ${x:='x y' z}
+ * |x|
+ * |y|
+ * |z|
+ * $ x=; f "${x:='x y' z}"
+ * |'x y' z|
+ *
+ * $ x=x; f ${x:+'x y' z}
+ * |x y|
+ * |z|
+ * $ x=x; f "${x:+'x y' z}"
+ * |'x y' z|
+ *
+ * $ x=; f ${x:-'x y' z}
+ * |x y|
+ * |z|
+ * $ x=; f "${x:-'x y' z}"
+ * |'x y' z|
+ */
                         int use_word = (!val || ((exp_save == ':') && !val[0]));
                         if (exp_op == '+')
                                 use_word = !use_word;
@@ -6244,7 +6273,10 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
                         if (use_word) {
 //FIXME: unquoted ${x:+"b c" d} and ${x:+'b c' d} should expand to two words
 //currently it expands to three.
-                                to_be_freed = encode_then_expand_vararg(exp_word, /*handle_squotes:*/ !(arg0 & 0x80), /*unbackslash:*/ 0);
+                                to_be_freed = encode_then_expand_vararg(exp_word,
+                                                /*handle_squotes:*/ !(arg0 & 0x80),
+                                                /*unbackslash:*/ 0
+                                );
                                 if (to_be_freed)
                                         exp_word = to_be_freed;
                                 if (exp_op == '?') {
@@ -6258,6 +6290,11 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
                                                 /*: (exp_save == ':' ? "parameter null or not set" : "parameter not set")*/
                                         );
 //TODO: how interactive bash aborts expansion mid-command?
+//It aborts the entire line:
+// $ f() { for i; do echo "|$i|"; done; }; x=; f "${x:?'x y' z}"; echo YO
+// bash: x: x y z
+// $
+// ("echo YO" is not executed, neither the f function call)
                                 } else {
                                         val = exp_word;
                                 }
@@ -6280,10 +6317,12 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
         } /* if (exp_op) */
 
         arg[0] = arg0;
-
         *pp = p;
-        *to_be_freed_pp = to_be_freed;
-        return val;
+
+        n = append_str_maybe_ifs_split(output, ended_in_ifs, n, first_ch, val);
+
+        free(to_be_freed);
+        return n;
 }
 
 /* Expand all variable references in given string, adding words to list[]
@@ -6427,13 +6466,9 @@ static NOINLINE int expand_vars_to_list(o_string *output, int n, char *arg)
                         break;
                 }
 #endif
-                default: {
-                        char *to_be_freed;
-                        val = expand_one_var(&to_be_freed, arg, &p);
-                        n = append_str_maybe_ifs_split(output, &ended_in_ifs, n, first_ch, val);
-                        free(to_be_freed);
+                default:
+                        n = expand_one_var(output, &ended_in_ifs, n, first_ch, arg, &p);
                         goto restore;
-                } /* default: */
                 } /* switch (char after <SPECIAL_VAR_SYMBOL>) */
 
                 if (val && val[0]) {