mkfatfsimg

Updated: May 06, 2022

Build a FAT filesystem image (QNX)

Syntax:

mkfatfsimg [option...]* [buildfile] [directory] [outputfile]

mkxfs -t fatfsimg [option...]* [buildfile] [directory] [outputfile]

Runs on:

Linux, Mac, Microsoft Windows

Options:

-?
(QNX Neutrino 7.0 or later) Display some help information.
-D
Treat undeclared intermediate directories as errors. If there's a target filesystem entry of /x/y, and /x has never occurred explicitly in the buildfile, the patch file, the input directory, or as a child of a recursively included directory, then /x is considered an undeclared intermediate directory.
-d
Display warnings for undeclared intermediate directories.
-l inputline
(“el”) Process inputline before interpreting the buildfile. Input lines given to mkfatfsimg should be quoted to prevent interpretation by the shell. Multiple -l options are processed in the order specified. This option is especially useful for setting global attributes when the input is a directory only.
-n[n..]
Don't use timestamps in the files. Using the -n option permits identical images in binary format. One n strips timestamps from files that vary from run to run. More than one strips ALL time information, which is necessary on Windows NTFS with daylight saving time.
-o directory
(“oh”) Specify a directory to be used for all permanent build artifacts, other than the output image itself.
-p patchfile
Apply patching instructions from this file (see Patch files,” below).
-r rootdir

This option doesn't immediately affect where mkfatfsimg searches for host files; it only adds standard search paths under rootdir to the MKIFS_PATH environment variable. Because this variable isn't used as the default value for the search attribute (unlike with mkifs), you must do the following to make mkfatfsimg behave like mkifs when searching for files:

  1. Add the line [search=${MKIFS_PATH}] near the beginning of your buildfile. For more information, see the search attribute and the MKIFS_PATH description.
  2. Set the PROCESSOR and PROCESSOR_BASE environment variables based on the target platform.

Then, when searching for files, mkfatfsimg will search the default paths used for storing binaries within the rootdir directory before searching the default paths within ${QNX_TARGET}.

You can define multiple -r options; each adds a set of paths to search for files. For an explanation of how multiple -r options are handled, see the mkifs -r option.

-v[v..]
Operate verbosely. Specifying additional v options increases the verbosity. The default is quiet operation.

Description:

The mkfatfsimg utility reads a text buildfile and/or a specified directory and produces a binary image file containing a FAT (fs-dos.so) filesystem created from the given input. You can copy this file to target media at a later stage.

Note: Don't confuse this command with mkdosfs, which initializes an empty FAT filesystem and is available for Neutrino hosts only.
You specify the input and output with these parameters:
buildfile
The filename of the buildfile that describes the contents of the FAT filesystem. Use a hyphen (-) to specify standard input (the default) instead of a buildfile.
directory
The root of a directory hierarchy to be appended to the file list specified in buildfile (if any). The default is no directory.
outputfile
The filename of the image file containing the FAT filesystem. Use a hyphen (-) to write image-file data to standard output (the default). Note that you can specify the output file only if you specified either a buildfile or a directory.

If you don't define buildfile or directory, a buildfile is expected as input from standard input. If you don't define outputfile, image-file data will be produced on standard output.

This utility supports long filenames (VFAT).

By default, the FAT type (12, 16, or 32) is derived from the volume size and other geometry parameters. You can use the fat attribute to override this.

Note:
  • The FAT filesystem supports only file sizes less than 4 GB.
  • There's only very limited support for permissions in FAT filesystems. A file or directory can be flagged as “read-only”; mkfatfsimg sets this flag when it encounters a file or directory without write permissions for anybody.
  • There's no support for hard or symbolic links in FAT filesystems. If you explicitly add a file link or implicitly include one as part of a directory in your buildfile, mkfatfsimg either prints a warning and skips the item or prints an error and exits in failure, depending on the optional attribute setting.
  • FAT filesystems have no concept of ownership. If you use the uid or gid attribute in the buildfile, it's silently ignored.

License checking

The mkfatfsimg utility checks for a valid QNX license key before performing any operation. If the license check fails, the utility stops running and displays a diagnostic message. A license check may fail if the license key is expired, missing, or not currently activated, or if the key doesn’t contain the permissions needed to run the utility.

Buildfiles

The mkfatfsimg command uses the same buildfile grammar as mkifs, but supports a different set of attributes. The buildfile is basically just a list of files that you want to be included in the FAT image file when it's built by mkfatfsimg. As well as identifying the files to be included, you can specify various attributes that are used to set parameters of the filesystem and the files in it. For example, you can specify the maximum size of the filesystem, or make individual files read-only.

Note:

You can't use a backslash (\) to break long lines into smaller pieces.

You can use forward slashes (/) as directory delimiters in mkfatfsimg buildfiles, even on Windows. It is strongly recommended to do so, because backslashes may adversely affect the functionality of your buildfile.

In a buildfile, a pound sign (#) indicates a comment; anything between it and the end of the line is ignored. There must be a space between a buildfile command and the pound sign.

Each line is in the form:

[attributes] file_specification

where the attributes (with the enclosing square brackets) and the file specification are both optional.

You can use an attribute:

Attributes provide information about the file following the attribute. They are enclosed in square brackets; when combining attributes (e.g., to specify the search path on the host system and declare the file as mandatory), enclose both attribute tokens in the same pair of square brackets. For example:

# correct way
[search=/tmp -optional] filename
# incorrect way
[search=/tmp] [-optional] filename
There are two types of attributes:
boolean attributes
Those prefixed with a plus (+) or minus (-) sign.
value attributes
Those ending with an equals sign (=) followed by a value. Don't put any spaces around the equals sign.
A question mark (?) before an attribute makes the setting conditional. The attribute is set only if it hasn't already been set. For example:
?+followlink 
sets the +followlink attribute only if +followlink or -followlink hasn't been specified.

The file_specification that follows the attributes takes one of these forms:

path

The file is copied from the host to the location in the image defined by the prefix attribute. If path starts with a slash (“/”) on a Linux or Mac development host, or a disk volume label (i.e., drive letter and a colon) followed by a backslash (“\”) on a Windows host, the path is absolute and mkfatfsimg looks for the file at that exact host location. (On Windows, any path starting with a backslash but no disk label is absolute within the disk volume of the current directory (e.g., the C: drive) but not across all volumes. To make the path completely absolute, the disk label must be given.)

If path contains a slash or backslash character that's not at the start, the path is relative and mkfatfsimg tries to resolve it relative to the current working directory (CWD). If path does not contain a directory separator or the file could not be found relative to the CWD, mkfatfsimg tries to resolve it relative to all directories given in the search attribute, in succession.

target_path=host_path
The specified file or contents of the specified directory are fetched from the host filesystem and placed into the image at the specified target location. The search for the host_path file or directory contents proceeds in the same way as it does with the first file specification form, meaning it depends on whether the path is absolute or relative (see the previous paragraph for details).
target_path={contents}
An inline definition. The contents of the file are listed within the buildfile itself, enclosed in braces ({ }); the file doesn't exist on the host system anywhere. The contents of the inline file can't be on the same line as the opening or closing brace.
Note:

The mkfatfsimg utility doesn't parse the contents of an inline file for anything but the closing brace. For example, mkfatfsimg doesn't interpret a pound sign (#) in an inline file as the beginning of a comment. The syntax of the inline file depends on what it's used for on the target system.

Closing braces (}) and backslashes (\) in an inline file must be escaped with a backslash.

You can enclose a filename in double quotes (") if it includes spaces or unusual characters.

Attributes

In mkfatfsimg buildfiles, the following attributes are supported:

The following attributes are recognized, but not semantically supported by mkfatfsimg:

The following attributes are recognized, but are only partly supported by mkfatfsimg:

Since the default values will generate only a 1,44MB FAT12 image, you should explicitly specify at least the image size by specifying num_sectors, to make sure that the image produced will be large enough to hold all specified files and that it will be compatible with your specific target device.

An OR-bar indicates that either the first element or the second element must be present, but not both (e.g., +|-followlink means either +followlink or -followlink, but not +-followlink).

cd attribute

cd=pathname

Set the current working directory to the specified pathname before attempting to open the host file. The default is the directory from which you invoked mkfatfsimg.

You can specify variables in the attribute's value. For information on how they're expanded (i.e., evaluated to a value used in their place), see the mkxfs section on processing variables.

In the pathname, you can use forward slashes (/) as directory delimiters, even on Windows. It is strongly recommended to do so, because backslashes may adversely affect the functionality of your buildfile.

cksum attribute

cksum=number

Specify the expected checksum (as calculated by the cksum utility) of the file that the attribute applies to. If you specify this attribute, mkfatfsimg calculates the checksum of the host file imported into the image and compares it to the expected value; if a mismatch is detected, the program terminates with an error.

dperms attribute

Note: FAT filesystems don't support permissions; they have only a read-only attribute. You can still use the perms attribute, but the only effect is that if the permissions indicate that the directory should not be writeable for anyone, then the read-only attribute is set.
dperms=dperms_spec

Set the access permissions of the directory. The dperms_spec can be one of the following:

The default dperms_spec is *.

drop attribute

drop=[pattern[|pattern]...]

(QNX Neutrino 7.1 or later) Specify patterns of file names that you want to ignore when recursively importing host directories. Each pattern is a simple filename wildcard pattern that can include the following meta-characters:

?
Match exactly one arbitrary character.
*
Match zero or more arbitrary characters.
\
Treat the next character literally.

For example:

[drop=*.sym] bin
[drop=*.a|*.dll] lib

Note the following:

Specifying the drop attribute without a pattern turns off exclusion in subsequent directories (unless you specify another drop attribute).

fat attribute

fat=type

Set the FAT type of the target filesystem. The type must be one of 12, 16, or 32. Note that by defining a specific target FAT type, you may limit the parameter choices so far that no valid filesystem can be constructed. It's usually best to leave this as the default, which is to auto-determine a reasonable FAT type. See the sec_per_clus attribute for how this works.

filter attribute

filter=filter_spec

Run the host file through the filter program specified, presenting the host file data as standard input to the program and using the standard output from the program as the data to be placed into the FAT filesystem. Default is no filter. You can specify a filter_spec of none. This is useful if you need to override a global filter specification.

[+|-followlink]

Whether to resolve any symbolic links and include the target files or directories instead of the links.

If you specify +followlink (enable the attribute), whenever an item taken from the host filesystem is a symbolic link, mkfatfsimg follows the link and includes its target. If you omit the attribute, this is the default behavior.

If you specify -followlink (disable it):

gid attribute

gid=id_spec

This attribute is supposed to set the group ID number for the file. Since FAT filesystems have no provision to store file ownership information, this attribute is silently disregarded.

include attribute (boolean)

+|-include

(QNX Neutrino 7.1 or later) Include files as part of the buildfile being processed. You can apply this attribute to a single file:

[+include] buildfile_path

or as a global attribute:

[+include]
buildfile_path_1
buildfile_path_2
...
buildfile_path_n
[-include]

You can specify variables in the attribute's value. For information on how they're expanded (i.e., evaluated to a value used in their place), see the mkxfs section on processing variables.

Each buildfile_path can be an absolute or a relative path. If buildfile_path starts with a slash (“/”) on a Linux or Mac development host, or a disk volume label followed by a backslash (“\”) on a Windows host, it's absolute and mkfatfsimg searches for the file in that exact host location. For more details on specifying absolute paths, see the buildfile path description above. If the path starts with another character sequence, it's a relative path, and mkfatfsimg searches the following directories (in this order):

Note that you can't use the target=host notation for the paths.

If an include file can't be found, the result depends on the optional attribute. If +optional is set, the missing file is skipped; otherwise, mkfatfsimg terminates with an error.

Buildfiles are processed top-down, and buildfile inclusion happens in place: when an include attribute is found, the included buildfile is loaded and processed; when processing is completed, mkfatfsimg returns to the including buildfile.

You can nest buildfile inclusions, but any circular inclusion is treated as an error. For example, the inclusion hierarchy A(B(D),C(E,F)) is valid, but A(A) and A(B(C(B))) aren't. If you include a buildfile more than once (which could easily happen with nested include files), the repeated inclusion is ignored, and mkfatfsimg issues a diagnostic message.

Note: The top buildfile together with its included buildfiles effectively form one large “buildfile stream” that's processed as a single buildfile would be. This means that all attribute settings in effect before an inclusion remain in effect inside the included files, and everything set in an included file is carried over into the parent buildfile.

The default is -include, which causes files (if found) to be added to the filesystem, not to the buildfile.

media attribute

media=number

Specify a media indicator code. The default value is 0xF8.

mountperms attribute

This attribute is supposed to set the access permissions for the filesystem mountpoint. Since the FAT filesystem has no provision to store mount information, this attribute is silently disregarded.

mtime attribute

mtime=time_spec

Set the timestamps of the files or directories to the specified time. The time_spec must be either:

Timestamps specified with the mtime attribute aren't affected by the -n option.

num_sectors attribute

num_sectors=count

Set the number of sectors on the volume. The count argument is an integer, optionally followed by K, M, or G (the case doesn't matter). The default value is 2880. Note that the sector size is controlled by a different attribute, sector_size.

optional attribute (boolean)

+|-optional

If this attribute is enabled and the host file can't be found, output a warning and continue building the embedded filesystem. If it's disabled and the host file can't be found, output an error message and exit. The default setting is enabled.

This attribute applies only to those items explicitly included in the buildfile.

Note: If you specify [+optional] and [+followlink] (or don't specify one or both of them and use their default setting) and a broken symbolic link is implicitly included from a directory, mkfatfsimg returns an error and exits. This is because when followlink is enabled, symbolic links should never be imported into the image.

perms attribute

perms=perms_spec

Set the access permissions of the file. The perms_spec can be one of the following:

The default perms_spec is *.

FAT filesystems don't support permissions; they have only a read-only attribute. If the combination of permissions indicates that the file shouldn't be writeable for anyone, the read-only attribute is set.

prefix attribute

prefix=path

Set the prefix on the target file names. The default is the empty string.

You can specify variables in the attribute's value. For information on how they're expanded (i.e., evaluated to a value used in their place), see the mkxfs section on processing variables.

In the prefix path, you can use forward slashes (/) as directory delimiters, even on Windows. It is strongly recommended to do so, because backslashes may adversely affect the functionality of your buildfile.

search=path[:path...]

This attribute specifies that mkfatfsimg should search for the file in the named path locations on the host system. The search directory portion of the host file name isn't included in the name that's stored in the FAT filesystem. The default setting is empty, meaning only the current working directory will be searched for the host files. To make mkfatfsimg include the directories named in the MKIFS_PATH variable in the host locations that it searches, see the -r rootdir explanation above.

You can specify variables in the attribute's value. For information on how they're expanded (i.e., evaluated to a value used in their place), see the mkxfs section on processing variables.

Note:

To ensure that your search paths work without modification on all supported host OSs, you can use:

  • forward slashes (“/”), which are now recognized by Windows as well as Linux and macOS; it is strongly recommended to use forward slashes as directory delimiters, because backslashes may adversely affect the functionality of your buildfile
  • the PFS environment variable instead of “;” or “:” to separate multiple paths in path lists (see PFS under “Environment variables:” below)

sec_per_clus attribute

sec_per_clus=number

Define the number of sectors assigned per each cluster. This must be one of 1, 2, 4, 8, 16, 32, or 64. Note that while “officially” allowed, you can't choose a value of 128 because it would necessarily result in a cluster size > 32K and would likely be incompatible with many systems.

The default is to auto-detect a reasonable sectors/cluster ratio. The built-in algorithm tries to use as few sectors per cluster as possible and use the smallest-possible FAT type. This strategy is meant to minimize allocation overhead (the average over-allocation is 1/2 cluster per each file). Of course, small clusters will go along with large FATs which also take up some space. If you know that your filesystem will contain only few files, you may choose a larger sectors/cluster ratio to keep the FATs smaller.

sector_size attribute

sector_size=size_spec

Specify the sector size of the filesystem's target device. The size_spec argument is an integer, optionally followed by k (the case doesn't matter). The default value is 512; valid values are 512, 1k, 2k, 4k, 8k, 16k, and 32k. Note that any sector size greater than 4k may be incompatible with some operating systems and will cause a warning to be issued.

sha256 attribute

sha256=hex_string

Specify the expected SHA256 hash of the file that the attribute applies to. If you specify this attribute, mkfatfsimg calculates the SHA256 hash of the host file imported into the image and compares it to the expected value; if a mismatch is detected, the program terminates with an error.

You must specify the expected hash as a string of 64 hexadecimal digits, without a prefix or any delimiters. For example, instead of specifying 0xaa,0xbb,0xcc,..., specify aabbcc....

type attribute

type=file_type
Sets the type of the file being created in the FAT filesystem. Allowable types are:
  • file—a regular, everyday file (the default)
  • dir—a directory
Note: You don't need to specify the type when you're copying the contents of a directory. For example, this command:
[type=dir]/usr/bin=/usr/nto/x86_64/bin
creates an empty directory named /usr/bin, with the same owner and permissions as for the host directory. To recursively copy /usr/nto/x86_64/bin to /usr/bin, you just need to specify:
/usr/bin=/usr/nto/x86_64/bin

Although link is an accepted type, FAT filesystems don't support symbolic links, so you shouldn't use this setting with mkfatfsimg. If you do, it either prints a warning message (if +optional is specified), or prints an error message and exits in failure (if -optional is specified).

uid attribute

uid=id_spec

This attribute is supposed to set the user ID number for the file. Since FAT filesystems have no provision to store file ownership information, this attribute is silently disregarded.

vol_lbl attribute

vol_lbl=string

Set the volume label to the given string. The default is no label.

Patch files

Patch files let you override the user ID, group ID, and permissions of certain files, depending on their location and filename pattern. Patches are applied after all files have been collected (from the buildfile and/or the specified directory). Consequently, patch files can override settings specified in the buildfile.

Patch files must contain only lines of the form:

#comment

or:

type:path:pattern:uid:gid:perms

In comment lines, # must be the first character. The entire line is treated as a comment and is ignored.

The type is either d or f, optionally followed by r. Type d patches are applied only to directories, and type f patches are applied only to files. An r indicates that the patch should be applied recursively within path; without r, the patch is applied to path only.

The pattern is a filename pattern that specifies which files to apply the patch to. The uid and gid must be decimal numbers, while perms must be an octal number (see chmod). Note that it isn't possible to set only the user ID, group ID, or permissions; for each match, all three are affected. As mentioned above, the FAT filesystem ignores any settings for the user ID and group ID.

Examples:

To create a FAT filesystem to copy onto a target system's hard-disk partition:

  1. Create a buildfile, my_fatfs.bld:
    # A sample buildfile for mkfatfsimg
    [num_sectors=512k]
    /home/thaupt
    

    In this example, we've specified a sector count of 512*1024, which relates to an image size of 128 MB. The files and subdirectories from the /home/thaupt directory on the host system are to be recursively copied into the root directory of the FAT filesystem.

  2. Create a FAT filesystem image file, my_fatfs.img, using the above buildfile:
    mkfatfsimg my_fatfs.bld my_fatfs.img
    
  3. Copy the image file to a target system's hard-disk partition as follows:
    dd if=my_fatfs.img of=/dev/hd0t7 count=524288
    

To create a GPT disk image:

  1. Create a buildfile, fat.bld, for the FAT filesystem:
    [num_sectors=16k]
    tst.txt={
    hello!
    }
    
  2. Generate a FAT filesystem image:
    mkfatfsimg fat.bld fat.fsi
    
  3. Create a configuration file, disk.cfg, for the disk image:
    [cylinders=80 heads=16 sectors_per_track=16 start_at_cylinder=1]
    [partition=1 type_guid="ms" name="FAT"] "fat.fsi"
    
  4. Create the disk image:
    diskimage -g -c disk.cfg -o disk.img
    
  5. Transfer the disk.img image onto the target system, copy the image onto the disk, and reboot. You can then use pted to get information about the partitions:
    # ls /dev/hd1*
    /dev/hd1         /dev/hd1.ms.0
    # pted /dev/hd1 show -vv
         Partition   1: 
            Attributes: 
                  Type: Microsoft File System
             Type GUID: EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
           Unique GUID: 2DA3EE00-5103-4A5A-A780-C70C2202867A
          Starting LBA: 256
            Ending LBA: 16639
               Sectors: 16384
                  Name: FAT
    

Environment variables:

PFS
Specifies the Path Field Separator (PFS). The mkfatfsimg utility automatically sets this variable to the character used to separate paths in path lists. That is, mkfatfsimg sets the variable to “;” on a Windows host and to “:” on a Linux or macOS host.

To keep buildfiles host OS-independent, use this environment variable instead of the OS-specific characters; for example, instead of writing:

[search=/a/b:/x/y/z]

write:

[search=/a/b${PFS}/x/y/z]

The mkfatfsimg utility will set the environment variable to the path separator appropriate for the host platform.

Exit status:

0
Successful completion.
1
An error occurred.