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[settings] Eliminate call to fetchf_named_setting() in expand_settings() 

Use parse_setting_name() and fetchf_setting_copy() in
expand_settings(), to eliminate the call to fetchf_named_setting().

This change also eliminates the potentially large stack-allocated
buffer in expand_settings().

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/598/head
Michael Brown 2013-07-18 14:47:42 +01:00
parent a5be7c4f29
commit 129a70631a
1 changed files with 25 additions and 22 deletions
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47
src/core/settings.c
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@ -2014,15 +2014,18 @@ struct setting_type setting_type_busdevfn __setting_type = {
* eventually free() it.
*/
char * expand_settings ( const char *string ) {
struct settings *settings;
struct setting setting;
char *expstr;
char *start;
char *end;
char *head;
char *name;
char *tail;
int setting_len;
int new_len;
char *value;
char *tmp;
int new_len;
int rc;
/* Obtain temporary modifiable copy of string */
expstr = strdup ( string );
@ -2052,27 +2055,27 @@ char * expand_settings ( const char *string ) {
*end = '\0';
tail = ( end + 1 );
/* Determine setting length */
setting_len = fetchf_named_setting ( name, NULL, 0, NULL, 0 );
if ( setting_len < 0 )
setting_len = 0; /* Treat error as empty setting */
/* Read setting into temporary buffer */
{
char setting_buf[ setting_len + 1 ];
setting_buf[0] = '\0';
fetchf_named_setting ( name, NULL, 0, setting_buf,
sizeof ( setting_buf ) );
/* Construct expanded string and discard old string */
tmp = expstr;
new_len = asprintf ( &expstr, "%s%s%s",
head, setting_buf, tail );
free ( tmp );
if ( new_len < 0 )
return NULL;
/* Expand setting */
if ( ( rc = parse_setting_name ( name, find_child_settings,
&settings,
&setting ) ) != 0 ) {
/* Treat invalid setting names as empty */
value = NULL;
} else {
/* Fetch and format setting value. Ignore
* errors; treat non-existent settings as empty.
*/
fetchf_setting_copy ( settings, &setting, &value );
}
/* Construct expanded string and discard old string */
tmp = expstr;
new_len = asprintf ( &expstr, "%s%s%s",
head, ( value ? value : "" ), tail );
free ( value );
free ( tmp );
if ( new_len < 0 )
return NULL;
}
return expstr;