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| -rw-r--r-- | shell/hush.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/shell/hush.c b/shell/hush.c index 3c19bceaa..4b46752a3 100644 --- a/shell/hush.c +++ b/shell/hush.c @@ -3151,6 +3151,41 @@ static int o_get_last_ptr(o_string *o, int n) return ((int)(uintptr_t)list[n-1]) + string_start; } +/* + * Globbing routines. + * + * Most words in commands need to be globbed, even ones which are + * (single or double) quoted. This stems from the possiblity of + * constructs like "abc"* and 'abc'* - these should be globbed. + * Having a different code path for fully-quoted strings ("abc", + * 'abc') would only help performance-wise, but we still need + * code for partially-quoted strings. + * + * Unfortunately, if we want to match bash and ash behavior in all cases, + * the logic can't be see as "shell-syntax argument is first transformed + * to a string, then globbed, and if globbing does not match anything, + * it is used verbatim". Here are two examples where it fails: + * + * echo 'b\*'? + * + * The globbing can't be avoided (because of '?' at the end). + * The glob pattern is: b\\\*? - IOW, both \ and * are literals + * and are glob-escaped. If this does not match, bash/ash print b\*? + * - IOW: they "unbackslash" the pattern. + * Now, look at this: + * + * v='\\\*'; echo b$v? + * + * The glob pattern is the same here: b\\\*? - an unquoted $var expansion + * should be used as glob pattern with no changes. However, if glob + * does not match, bash/ash print b\\\*? - NOT THE SAME as 1st example! + * + * ash implements this by having an encoded representation of the word + * to glob, which IS NOT THE SAME as the glob pattern - it has more data. + * Glob pattern is derived from it. If glob fails, the decision what result + * should be is made using that encoded representation. Not glob pattern. + */ + #if ENABLE_HUSH_BRACE_EXPANSION /* There in a GNU extension, GLOB_BRACE, but it is not usable: * first, it processes even {a} (no commas), second, |