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hush: fix a case where "$@" must expand to no word at all

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This commit is contained in:
Denis Vlasenko 2008-07-05 17:40:04 +00:00
parent a60f84ebf0
commit afdcd12ed7
3 changed files with 36 additions and 6 deletions
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16
shell/hush.c
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@ -2380,6 +2380,9 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
p = strchr(p, SPECIAL_VAR_SYMBOL);
first_ch = arg[0] | or_mask; /* forced to "quoted" if or_mask = 0x80 */
/* "$@" is special. Even if quoted, it can still
* expand to nothing (not even an empty string) */
if ((first_ch & 0x7f) != '@')
ored_ch |= first_ch;
val = NULL;
switch (first_ch & 0x7f) {
@ -2401,6 +2404,7 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
i = 1;
if (!global_argv[i])
break;
ored_ch |= first_ch; /* do it for "$@" _now_, when we know it's not empty */
if (!(first_ch & 0x80)) { /* unquoted $* or $@ */
smallint sv = output->o_quote;
/* unquoted var's contents should be globbed, so don't quote */
@ -2932,16 +2936,26 @@ static int done_word(o_string *word, struct p_context *ctx)
}
}
#endif
if (word->nonnull /* we saw "xx" or 'xx' */
if (word->nonnull /* word had "xx" or 'xx' at least as part of it */
/* optimization: and if it's ("" or '') or ($v... or `cmd`...): */
&& (word->data[0] == '\0' || word->data[0] == SPECIAL_VAR_SYMBOL)
/* (otherwise it's "abc".... and is already safe) */
) {
/* but exclude "$@"! it expands to no word despite "" */
char *p = word->data;
while (p[0] == SPECIAL_VAR_SYMBOL
&& (p[1] & 0x7f) == '@'
&& p[2] == SPECIAL_VAR_SYMBOL
) {
p += 3;
}
if (p == word->data || p[0] != '\0') {
/* Insert "empty variable" reference, this makes
* e.g. "", $empty"" etc to not disappear */
o_addchr(word, SPECIAL_VAR_SYMBOL);
o_addchr(word, SPECIAL_VAR_SYMBOL);
}
}
child->argv = add_malloced_string_to_strings(child->argv, xstrdup(word->data));
debug_print_strings("word appended to argv", child->argv);
}

2
shell/hush_test/hush-parsing/starquoted2.right Normal file
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@ -0,0 +1,2 @@
Should be printed
Should be printed

14
shell/hush_test/hush-parsing/starquoted2.tests Executable file
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@ -0,0 +1,14 @@
if test $# != 0; then
exec "$THIS_SH" "$0"
fi
# No params!
for a in "$*"; do echo Should be printed; done
for a in "$@"; do echo Should not be printed; done
# Yes, believe it or not, bash is mesmerized by "$@" and stops
# treating "" as "this word cannot be expanded to nothing,
# but must be at least null string". Now it can be expanded to nothing.
for a in "$@"""; do echo Should not be printed; done
for a in """$@"; do echo Should not be printed; done
for a in """$@"''"$@"''; do echo Should not be printed; done
for a in ""; do echo Should be printed; done