ash: add support for bash 'function' keyword

Where the POSIX shell allows functions to be defined as:

   name () compound-command [ redirections ]

bash adds the alternative syntax:

   function name [()] compound-command [ redirections ]

Implement this in ash's bash compatibility mode.  Most compound
commands work (for/while/until/if/case/[[]]/{}); one exception is:

   function f (echo "no way!")

The other two variants work:

   f() (echo "ok")
   function f() (echo "also ok")

function                                             old     new   delta
parse_command                                       1555    1744    +189
tokname_array                                        232     240      +8
.rodata                                           155612  155566     -46
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 197/-46)           Total: 151 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 110 insertions, 31 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 84502636a..e7a867f52 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -7726,36 +7726,40 @@ changepath(const char *new)
         clearcmdentry(firstchange);
         builtinloc = idx_bltin;
 }
-
-#define TEOF 0
-#define TNL 1
-#define TREDIR 2
-#define TWORD 3
-#define TSEMI 4
-#define TBACKGND 5
-#define TAND 6
-#define TOR 7
-#define TPIPE 8
-#define TLP 9
-#define TRP 10
-#define TENDCASE 11
-#define TENDBQUOTE 12
-#define TNOT 13
-#define TCASE 14
-#define TDO 15
-#define TDONE 16
-#define TELIF 17
-#define TELSE 18
-#define TESAC 19
-#define TFI 20
-#define TFOR 21
-#define TIF 22
-#define TIN 23
-#define TTHEN 24
-#define TUNTIL 25
-#define TWHILE 26
-#define TBEGIN 27
-#define TEND 28
+enum {
+        TEOF,
+        TNL,
+        TREDIR,
+        TWORD,
+        TSEMI,
+        TBACKGND,
+        TAND,
+        TOR,
+        TPIPE,
+        TLP,
+        TRP,
+        TENDCASE,
+        TENDBQUOTE,
+        TNOT,
+        TCASE,
+        TDO,
+        TDONE,
+        TELIF,
+        TELSE,
+        TESAC,
+        TFI,
+        TFOR,
+#if ENABLE_ASH_BASH_COMPAT
+        TFUNCTION,
+#endif
+        TIF,
+        TIN,
+        TTHEN,
+        TUNTIL,
+        TWHILE,
+        TBEGIN,
+        TEND
+};
 typedef smallint token_id_t;
 
 /* first char is indicating which tokens mark the end of a list */
@@ -7784,6 +7788,9 @@ static const char *const tokname_array[] = {
         "\1esac",
         "\1fi",
         "\0for",
+#if ENABLE_ASH_BASH_COMPAT
+        "\0function",
+#endif
         "\0if",
         "\0in",
         "\1then",
@@ -10762,6 +10769,7 @@ simplecmd(void)
         int savecheckkwd;
 #if ENABLE_ASH_BASH_COMPAT
         smallint double_brackets_flag = 0;
+        smallint function_flag = 0;
 #endif
 
         args = NULL;
@@ -10778,6 +10786,11 @@ simplecmd(void)
                 t = readtoken();
                 switch (t) {
 #if ENABLE_ASH_BASH_COMPAT
+                case TFUNCTION:
+                        if (peektoken() != TWORD)
+                                raise_error_unexpected_syntax(TWORD);
+                        function_flag = 1;
+                        break;
                 case TAND: /* "&&" */
                 case TOR: /* "||" */
                         if (!double_brackets_flag) {
@@ -10806,6 +10819,29 @@ simplecmd(void)
                                 app = &n->narg.next;
                                 savecheckkwd = 0;
                         }
+#if ENABLE_ASH_BASH_COMPAT
+                        if (function_flag) {
+                                checkkwd = CHKNL | CHKKWD;
+                                switch (peektoken()) {
+                                case TBEGIN:
+                                case TIF:
+                                case TCASE:
+                                case TUNTIL:
+                                case TWHILE:
+                                case TFOR:
+                                        goto do_func;
+                                case TLP:
+                                        function_flag = 0;
+                                        break;
+                                case TWORD:
+                                        if (strcmp("[[", wordtext) == 0)
+                                                goto do_func;
+                                        /* fall through */
+                                default:
+                                        raise_error_unexpected_syntax(-1);
+                                }
+                        }
+#endif
                         break;
                 case TREDIR:
                         *rpp = n = redirnode;
@@ -10813,6 +10849,7 @@ simplecmd(void)
                         parsefname();   /* read name of redirection file */
                         break;
                 case TLP:
+ IF_ASH_BASH_COMPAT(do_func:)
                         if (args && app == &args->narg.next
                          && !vars && !redir
                         ) {
@@ -10820,7 +10857,7 @@ simplecmd(void)
                                 const char *name;
 
                                 /* We have a function */
-                                if (readtoken() != TRP)
+                                if (IF_ASH_BASH_COMPAT(!function_flag &&) readtoken() != TRP)
                                         raise_error_unexpected_syntax(TRP);
                                 name = n->narg.text;
                                 if (!goodname(name)
@@ -10833,6 +10870,7 @@ simplecmd(void)
                                 n->narg.next = parse_command();
                                 return n;
                         }
+                        IF_ASH_BASH_COMPAT(function_flag = 0;)
                         /* fall through */
                 default:
                         tokpushback = 1;
@@ -11013,6 +11051,7 @@ parse_command(void)
                 n1 = list(0);
                 t = TEND;
                 break;
+        IF_ASH_BASH_COMPAT(case TFUNCTION:)
         case TWORD:
         case TREDIR:
                 tokpushback = 1;
diff --git a/shell/ash_test/ash-misc/func_bash1.right b/shell/ash_test/ash-misc/func_bash1.right
new file mode 100644
index 000000000..41bf8828c
--- /dev/null
+++ b/shell/ash_test/ash-misc/func_bash1.right
@@ -0,0 +1,12 @@
+1
+2
+3
+1
+2
+3
+1
+2
+3
+1
+2
+3
diff --git a/shell/ash_test/ash-misc/func_bash1.tests b/shell/ash_test/ash-misc/func_bash1.tests
new file mode 100755
index 000000000..2cc0970e8
--- /dev/null
+++ b/shell/ash_test/ash-misc/func_bash1.tests
@@ -0,0 +1,28 @@
+function f() { echo $1; }
+f 1
+
+function f() ( echo $1; )
+f 2
+
+function f() ( echo $1 )
+f 3
+
+function f() for i in 1 2 3; do
+        echo $i
+done
+f
+
+function f { echo $1; }
+f 1
+
+# the next two don't work
+#function f ( echo $1; )
+f 2
+
+#function f ( echo $1 )
+f 3
+
+function f for i in 1 2 3; do
+        echo $i
+done
+f