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[cmdline] Fix multi-layer variable expansion (again) 

Expansion of the (admittedly perverse) "aaa}bbb${ccc" will currently
fail because expand_command() does not check that the closing "}"
occurs later than the opening "${".

Fix by ensuring that the most recent opening "${" is used to match
against the first *subsequent* closing "}".

Total cost of this change: -12 bytes, bringing the overall cost of
this feature to -4 bytes.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2010-11-23 00:18:11 +00:00
parent c1327e43ab
commit 66679fe7df
1 changed files with 3 additions and 3 deletions
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6
src/core/exec.c
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@ -121,12 +121,12 @@ static char * expand_command ( const char *command ) {
for ( tmp = expcmd ; *tmp ; tmp++ ) {
if ( ( tmp[0] == '$' ) && ( tmp[1] == '{' ) )
start = tmp;
if ( tmp[0] == '}' )
if ( start && ( tmp[0] == '}' ) ) {
end = tmp;
if ( start && end )
break;
}
}
if ( ! ( start && end ) )
if ( ! end )
break;
*start = '\0';
name = ( start + 2 );