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hush: do fewer strdups in % and hash expansions

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function                                             old     new   delta
builtin_umask                                        133     132      -1
expand_one_var                                      1552    1543      -9

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko 2010-09-10 11:06:01 +02:00
parent d98e5c65c3
commit 4f870496e7
3 changed files with 30 additions and 13 deletions
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29
shell/hush.c
View File

@ -3800,8 +3800,8 @@ static int encode_string(o_string *as_string,
ch = i_getch(input); /* eat next */
if (ch == '\n')
goto again; /* skip \<newline> */
} /* else: ch remains == '\\', and we double it */
o_addqchr(dest, ch); /* \c if c is s glob char, else just c */
} /* else: ch remains == '\\', and we double it below: */
o_addqchr(dest, ch); /* \c if c is a glob char, else just c */
nommu_addchr(as_string, ch);
goto again;
}
@ -4618,26 +4618,29 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
* Then var's value is matched to it and matching part removed.
*/
if (val && val[0]) {
char *t;
char *exp_exp_word;
char *loc;
unsigned scan_flags = pick_scan(exp_op, *exp_word);
if (exp_op == *exp_word) /* ## or %% */
exp_word++;
//TODO: avoid xstrdup unless needed
// (see HACK ALERT below for an example)
val = to_be_freed = xstrdup(val);
exp_exp_word = encode_then_expand_string(exp_word, /*process_bkslash:*/ 1, /*unbackslash:*/ 1);
if (exp_exp_word)
exp_word = exp_exp_word;
loc = scan_and_match(to_be_freed, exp_word, scan_flags);
/* HACK ALERT. We depend here on the fact that
* G.global_argv and results of utoa and get_local_var_value
* are actually in writable memory:
* scan_and_match momentarily stores NULs there. */
t = (char*)val;
loc = scan_and_match(t, exp_word, scan_flags);
//bb_error_msg("op:%c str:'%s' pat:'%s' res:'%s'",
// exp_op, to_be_freed, exp_word, loc);
// exp_op, t, exp_word, loc);
free(exp_exp_word);
if (loc) { /* match was found */
if (scan_flags & SCAN_MATCH_LEFT_HALF) /* #[#] */
val = loc;
val = loc; /* take right part */
else /* %[%] */
*loc = '\0';
val = to_be_freed = xstrndup(val, loc - val); /* left */
}
}
}
@ -4646,13 +4649,13 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
/* It's ${var/[/]pattern[/repl]} thing.
* Note that in encoded form it has TWO parts:
* var/pattern<SPECIAL_VAR_SYMBOL>repl<SPECIAL_VAR_SYMBOL>
* and if // is used, it is encoded as \:
* var\pattern<SPECIAL_VAR_SYMBOL>repl<SPECIAL_VAR_SYMBOL>
*/
/* Empty variable always gives nothing: */
// "v=''; echo ${v/*/w}" prints "", not "w"
if (val && val[0]) {
/* It's ${var/[/]pattern[/repl]} thing */
/*
* Pattern is taken literally, while
/* pattern uses non-standard expansion.
* repl should be unbackslashed and globbed
* by the usual expansion rules:
* >az; >bz;
@ -7339,7 +7342,7 @@ int hush_main(int argc, char **argv)
/* Deal with HUSH_VERSION */
G.shell_ver.flg_export = 1;
G.shell_ver.flg_read_only = 1;
/* Code which handles ${var/P/R} needs writable values for all variables,
/* Code which handles ${var<op>...} needs writable values for all variables,
* therefore we xstrdup: */
G.shell_ver.varstr = xstrdup(hush_version_str),
G.top_var = &G.shell_ver;

5
shell/hush_test/hush-vars/var_bash6.right Normal file
View File

@ -0,0 +1,5 @@
Expected Actual
a*z : a*z
\z : \z
a1z a2z: a1z a2z
z : z

9
shell/hush_test/hush-vars/var_bash6.tests Executable file
View File

@ -0,0 +1,9 @@
# This testcase checks globbing correctness in ${v/a/b}
>a1z; >a2z;
echo 'Expected' 'Actual'
v='a bz'; echo 'a*z :' "${v/a*z/a*z}"
v='a bz'; echo '\z :' "${v/a*z/\z}"
v='a bz'; echo 'a1z a2z:' ${v/a*z/a*z}
v='a bz'; echo 'z :' ${v/a*z/\z}
rm a1z a2z