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[libc] Print "<NULL>" for wide-character NULL strings
The existing code intends to print NULL strings as "<NULL>" (for the
sake of debug messages), but the logic is incorrect when handling
wide-character strings.  Fix the logic and add applicable unit tests.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
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mcb30 committed Apr 12, 2016
1 parent 320488d commit cc8824a
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Showing 2 changed files with 8 additions and 2 deletions.
6 changes: 4 additions & 2 deletions src/core/vsprintf.c
Expand Up @@ -257,11 +257,13 @@ size_t vcprintf ( struct printf_context *ctx, const char *fmt, va_list args ) {
} else if ( *fmt == 's' ) {
if ( length < &type_sizes[LONG_LEN] ) {
ptr = va_arg ( args, char * );
if ( ! ptr )
ptr = "<NULL>";
} else {
wptr = va_arg ( args, wchar_t * );
if ( ! wptr )
ptr = "<NULL>";
}
if ( ( ptr == NULL ) && ( wptr == NULL ) )
ptr = "<NULL>";
} else if ( *fmt == 'p' ) {
intptr_t ptrval;

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4 changes: 4 additions & 0 deletions src/tests/vsprintf_test.c
Expand Up @@ -108,6 +108,10 @@ static void vsprintf_test_exec ( void ) {
snprintf_ok ( 64, "PCI 00:1f.3", "PCI %02x:%02x.%x", 0x00, 0x1f, 0x03 );
snprintf_ok ( 64, "Region [1000000,3f000000)", "Region [%llx,%llx)",
0x1000000ULL, 0x3f000000ULL );

/* Null string (used for debug messages) */
snprintf_ok ( 16, "<NULL>", "%s", ( ( char * ) NULL ) );
snprintf_ok ( 16, "<NULL>", "%ls", ( ( wchar_t * ) NULL ) );
}

/** vsprintf() self-test */
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