getopt_long: accept prefix match of long options containing equals signs

Consider the first equals sign found in the option to be the delimiter
between it and its argument, even if it matches an equals sign in the
option name. This avoids consuming the equals sign, which would prevent
finding the argument. Instead, it forces a partial match of the part of
the option name before the equals sign.

Maintainer's note: GNU getopt_long does not explicitly document this
behavior, but it can be seen as a consequence of how partial matches
are specified, and at least GNU (bfd) ld is known to make use of it.

diff --git a/src/misc/getopt_long.c b/src/misc/getopt_long.c
index 0d1501d457c11c9072b3beb124a3b11ab2954863..008b747c551f2a9eef42c6d30a76e096ad65dcee 100644 (file)
--- a/src/misc/getopt_long.c
+++ b/src/misc/getopt_long.c
@@ -63,7 +63,8 @@ static int __getopt_long_core(int argc, char *const *argv, const char *optstring
                        const char *name = longopts[i].name;
                        opt = argv[optind]+1;
                        if (*opt == '-') opt++;
-                       for (; *name && *name == *opt; name++, opt++);
+                       while (*opt && *opt != '=' && *opt == *name)
+                               name++, opt++;
                        if (*opt && *opt != '=') continue;
                        arg = opt;
                        match = i;