ash: document where we accept invalid syntax. no code changes

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

1 files changed, 17 insertions, 1 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 444a6961b..9f1f8a4de 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -6371,6 +6371,16 @@ subevalvar(char *p, char *str, int strloc, int subtype,
 
 /*
  * Add the value of a specialized variable to the stack string.
+ * name parameter (examples):
+ * ash -c 'echo $1'      name:'1='
+ * ash -c 'echo $qwe'    name:'qwe='
+ * ash -c 'echo $$'      name:'$='
+ * ash -c 'echo ${$}'    name:'$='
+ * ash -c 'echo ${$##q}' name:'$=q'
+ * ash -c 'echo ${#$}'   name:'$='
+ * note: examples with bad shell syntax:
+ * ash -c 'echo ${#$1}'  name:'$=1'
+ * ash -c 'echo ${#1#}'  name:'1=#'
  */
 static ssize_t
 varvalue(char *name, int varflags, int flags, struct strlist *var_str_list)
@@ -6407,7 +6417,7 @@ varvalue(char *name, int varflags, int flags, struct strlist *var_str_list)
                         return -1;
  numvar:
                 len = cvtnum(num);
-                break;
+                goto check_1char_name;
         case '-':
                 expdest = makestrspace(NOPTS, expdest);
                 for (i = NOPTS - 1; i >= 0; i--) {
@@ -6416,6 +6426,12 @@ varvalue(char *name, int varflags, int flags, struct strlist *var_str_list)
                                 len++;
                         }
                 }
+ check_1char_name:
+#if 0
+                /* handles cases similar to ${#$1} */
+                if (name[2] != '\0')
+                        raise_error_syntax("bad substitution");
+#endif
                 break;
         case '@':
                 if (sep)