In Busybox hush, '<' and '>' are used as redirection operators. For example, cat foo > bar will write content of file foo inside file bar. In U-Boot, we do not have file system, so we can hardly redirect command output inside a file.
But, in actual U-Boot hush, these operators ('<' and '>') are used as string compare operators. For example, test aaa < bbb returns 0 as aaa is before bbb in the dictionary. Busybox hush also permits this, but operators need to be escaped ('<' and '>'). Indeed, if escaping is needed it permits the developer to think about its code, as in a lot of case, we want to compare integers (using '-lt' or '-gt') rather than strings.
As testing in U-Boot is handled by the test command, we will stick with the original behaviour and not adapt to Busybox one.
Nonetheless, if one day we decide to implement test with '[[ ]]', we will then stick to upstream Busybox behavior.
Signed-off-by: Francis Laniel francis.laniel@amarulasolutions.com Reviewed-by: Simon Glass sjg@chromium.org --- common/cli_hush_upstream.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/common/cli_hush_upstream.c b/common/cli_hush_upstream.c index 11870c51e8..a56ea6c5c8 100644 --- a/common/cli_hush_upstream.c +++ b/common/cli_hush_upstream.c @@ -6159,7 +6159,28 @@ static struct pipe *parse_stream(char **pstring, if (parse_redirect(&ctx, redir_fd, redir_style, input)) goto parse_error_exitcode1; continue; /* get next char */ -#endif /* !__U_BOOT__ */ +#else /* __U_BOOT__ */ + /* + * In U-Boot, '<' and '>' can be used in test command to test if + * a string is, alphabetically, before or after another. + * In 2021 Busybox hush, we will keep the same behavior and so not treat + * them as redirection operator. + * + * Indeed, in U-Boot, tests are handled by the test command and not by the + * shell code. + * So, better to give this character as input to test command. + * + * NOTE In my opinion, when you use '<' or '>' I am almost sure + * you wanted to use "-gt" or "-lt" in place, so thinking to + * escape these will make you should check your code (sh syntax + * at this level is, for me, error prone). + */ + case '>': + fallthrough; + case '<': + o_addQchr(&ctx.word, ch); + continue; +#endif /* __U_BOOT__ */ case '#': if (ctx.word.length == 0 && !ctx.word.has_quoted_part) { /* skip "#comment" */