qemu-io: Add generic function for reinitializing optind.
On FreeBSD 11.2:
$ nbdkit memory size=1M --run './qemu-io -f raw -c "aio_write 0 512" $nbd'
Parsing error: non-numeric argument, or extraneous/unrecognized suffix -- aio_write
After main option parsing, we reinitialize optind so we can parse each
command. However reinitializing optind to 0 does not work on FreeBSD.
What happens when you do this is optind remains 0 after the option
parsing loop, and the result is we try to parse argv[optind] ==
argv[0] == "aio_write" as if it was the first parameter.
The FreeBSD manual page says:
In order to use getopt() to evaluate multiple sets of arguments, or to
evaluate a single set of arguments multiple times, the variable optreset
must be set to 1 before the second and each additional set of calls to
getopt(), and the variable optind must be reinitialized.
(From the rest of the man page it is clear that optind must be
reinitialized to 1).
The glibc man page says:
A program that scans multiple argument vectors, or rescans the same
vector more than once, and wants to make use of GNU extensions such as
'+' and '-' at the start of optstring, or changes the value of
POSIXLY_CORRECT between scans, must reinitialize getopt() by resetting
optind to 0, rather than the traditional value of 1. (Resetting to 0
forces the invocation of an internal initialization routine that
rechecks POSIXLY_CORRECT and checks for GNU extensions in optstring.)
This commit introduces an OS-portability function called
qemu_reset_optind which provides a way of resetting optind that works
on FreeBSD and platforms that use optreset, while keeping it the same
as now on other platforms.
Note that the qemu codebase sets optind in many other places, but in
those other places it's setting a local variable and not using getopt.
This change is only needed in places where we are using getopt and the
associated global variable optind.
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Message-id: 20190118101114.11759-2-rjones@redhat.com
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 2c39124..ee8f56e 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -114,7 +114,7 @@
}
}
- optind = 0;
+ qemu_reset_optind();
return ct->cfunc(blk, argc, argv);
}
