pussuw commented on code in PR #1654:
URL: https://github.com/apache/nuttx-apps/pull/1654#discussion_r1143779202
##########
nshlib/nsh.h:
##########
@@ -715,6 +715,25 @@ struct nsh_parser_s
#endif
};
+#ifdef CONFIG_NSH_ALIAS
+struct nsh_alias_s
+{
+ FAR struct nsh_alias_s *next; /* Single link list for traversing */
+ FAR char *name; /* Name of the alias */
+ FAR char *value; /* Value behind the name */
+ union
+ {
+ struct
+ {
+ uint8_t exp : 1; /* Already expanded ? */
Review Comment:
It is a POSIX requirement, a once expanded alias shall not be expanded again
within a single tokenized string.
```
$ alias foo=bar
$ foo foo <- this will expand to bar foo
```
I just realized only the *command* should be expanded, not the argument
list, thus the comment above is not correct. The recursive protection is
against even more insane aliases that would really end in infinite recursion.
LIke:
```
$ alias echo=echo
$ echo
```
> To prevent infinite loops in recursive aliasing, if the shell is not
currently processing an alias of the same name, the word shall be replaced by
the value of the alias; otherwise, it shall not be replaced.
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_03_01
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