[gparted] Fix reading FAT16/32 FS labels on Alpine Linux (!104)

[Curtis Gedak <gedakc src gnome org>]

commit a48b29ba197232f694424c749976701fb0a607fc
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Fri Jun 17 11:16:43 2022 +0100

    Fix reading FAT16/32 FS labels on Alpine Linux (!104)
    
    Several of the FAT16/32 file system unit tests fail on Alpine Linux.  In
    this commit we are just looking at the failure to read the label.  The
    test fails like this:
        $ ./test_SupportedFileSystems --gtest_filter='*CreateAndReadLabel/fat16'
        ...
        [ RUN      ] My/SupportedFileSystemsTest.CreateAndReadLabel/fat16
        test_SupportedFileSystems.cc:551: Failure
        Expected equality of these values:
          fs_label
            Which is: "TEST_LABEL"
          m_partition.get_filesystem_label().c_str()
            Which is: ""
        test_SupportedFileSystems.cc:554: Failure
        Value of: m_partition.get_messages().empty()
          Actual: false
        Expected: true
        Partition messages:
        Mtools version 4.0.39, dated April 10th, 2022
        Usage: mlabel [-vscVn] [-N serial] drive:
    
        [  FAILED  ] My/SupportedFileSystemsTest.CreateAndReadLabel/fat16, where GetParam() = 13 (21 ms)
    
    The same error can be seen by using GParted to display a FAT16 or FAT32
    file system on Alpine Linux.  The Partition Information dialog displays
    this warning:
        Mtools version 4.0.39, dated April 10th, 2022
        Usage: mlabel [-vscVn] [-N serial] drive:
    
    Reproduce this on the command line:
        # mkfs.fat -F 16 -v -I -n TEST_LABEL /dev/sdb1
        # mlabel -s :: -i /dev/sdb1
        Mtools version 4.0.39, dated April 10th, 2022
        Usage: mlabel [-vscVn] [-N serial] drive:
        # echo $?
        1
    
    The mlabel.c source [1] uses getopt(3) to parse the command line
    arguments.  musl libc's [2] getopt(3) must be strictly POSIX compliant
    [3][4] and stops reading options at the first non-option argument, '::'
    in this case.  Move the non-option argument to the end of the command
    line and it works:
        # mlabel -s -i /dev/sdb1 ::
         Volume label is TEST_LABEL
    
    Where as GNU Libc's getopt(3) [5] says that by default it reorders argv
    eventually moving all non-option arguments to the end, hence why this
    has worked on every Linux distribution using GNU Libc.  This can be
    broken on any Linux distribution using GNU Libc by enforcing strict
    POSIX behaviour from getopt(3).  For example on Fedora 36:
        # mkfs.fat -F 16 -v -I -n TEST_LABEL /dev/sdb1
        # export POSIXLY_CORRECT=1
        # mlabel -s :: -i /dev/sdb1
        Mtools version 4.0.39, dated April 10th, 2022
        Usage: mlabel [-vscVn] [-N serial] drive:
        # echo $?
        1
        # mlabel -s -i /dev/sdb1 ::
        Hidden (2048) does not match sectors (63)
         Volume label is TEST_LABEL
        # echo $?
        0
    
    Fix by moving the non-option (image file drive specification) '::' to
    the end of the mlabel command line.
    
    [1] Mtools
        https://www.gnu.org/software/mtools/
    [2] musl libc
        https://musl.libc.org/
        "musl is an implementation of the C standard library built on top of
        the Linux system call API, including interfaces defined in the base
        language standard, POSIX, and widely agreed-upon extensions.
        "
    [3] POSIX.1-2017, Functions, getopt
        https://pubs.opengroup.org/onlinepubs/9699919799/functions/getopt.html
    [4] getopt(3p)
        https://man7.org/linux/man-pages/man3/getopt.3p.html
    [5] getopt(3)
        https://www.man7.org/linux/man-pages/man3/getopt.3.html
        "By default, getopt() permutes the contents of argv as it scans, so
        that eventually all the nonoptions are at the end.  Two other
        scanning modes are also implemented.  If the first character of
        optstring is '+' or the environment variable POSIXLY_CORRECT is set,
        then option processing stops as soon as a nonoption argument is
        encountered.
        "
    
    Closes !104 - Add Alpine Linux CI jobs and resolve label and UUID issues
                  with FAT16/32

 src/fat16.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/fat16.cc b/src/fat16.cc
index 530630c1..bf37c195 100644
--- a/src/fat16.cc
+++ b/src/fat16.cc
@@ -192,7 +192,7 @@ void fat16::set_used_sectors( Partition & partition )
 
 void fat16::read_label(Partition& partition)
 {
-       exit_status = Utils::execute_command("mlabel -s :: -i " + Glib::shell_quote(partition.get_path()),
+       exit_status = Utils::execute_command("mlabel -s -i " + Glib::shell_quote(partition.get_path()) + " 
::",
                                             output, error, true);
        if (exit_status != 0)
        {