Join-PathSafely.ps1

function Join-PathSafely {
    # .SYNOPSIS
    # Joins two path parts together and suppresses any errors that may occur.
    #
    # .DESCRIPTION
    # Combines two paths parts (parent and child) into a single path. This
    # function is intended to be used in situations where the Join-Path cmdlet
    # may fail due to a variety of reasons. This function is designed to
    # suppress errors and return a boolean value indicating whether the
    # operation was successful.
    #
    # .PARAMETER ReferenceToJoinedPath
    # This parameter is required; it is a reference to a string object that
    # will be populated with the joined path (parent path + child path). If the
    # operation was successful, the referenced string object will be populated
    # with the joined path. If the operation was unsuccessful, the referenced
    # string is undefined.
    #
    # .PARAMETER ParentPath
    # This parameter is required; it is a string representing the parent part
    # of the path.
    #
    # .PARAMETER ChildPath
    # This parameter is required; it is the child part of the path.
    #
    # .EXAMPLE
    # $strParentPartOfPath = 'Z:'
    # $strChildPartOfPath = '####FAKE####'
    # $strJoinedPath = $null
    # $boolSuccess = Join-PathSafely -ReferenceToJoinedPath ([ref]$strJoinedPath) -ParentPath $strParentPartOfPath -ChildPath $strChildPartOfPath
    #
    # .EXAMPLE
    # $strParentPartOfPath = 'Z:'
    # $strChildPartOfPath = '####FAKE####'
    # $strJoinedPath = $null
    # $boolSuccess = Join-PathSafely ([ref]$strJoinedPath) $strParentPartOfPath $strChildPartOfPath
    #
    # .INPUTS
    # None. You can't pipe objects to Join-PathSafely.
    #
    # .OUTPUTS
    # System.Boolean. Join-PathSafely returns a boolean value indiciating
    # whether the process completed successfully. $true means the process
    # completed successfully; $false means there was an error.
    #
    # .NOTES
    # This function also supports the use of positional parameters instead of
    # named parameters. If positional parameters are used instead of named
    # parameters, then three positional parameters are required:
    #
    # The first positional parameter is a reference to a string object that
    # will be populated with the joined path (parent path + child path). If the
    # operation was successful, the referenced string object will be populated
    # with the joined path. If the operation was unsuccessful, the referenced
    # string is undefined.
    #
    # The second positional parameter is a string representing the parent part
    # of the path.
    #
    # The third positional parameter is the child part of the path.
    #
    # Version: 2.0.20250215.0

    #region License ########################################################
    # Copyright (c) 2025 Frank Lesniak
    #
    # Permission is hereby granted, free of charge, to any person obtaining a
    # copy of this software and associated documentation files (the
    # "Software"), to deal in the Software without restriction, including
    # without limitation the rights to use, copy, modify, merge, publish,
    # distribute, sublicense, and/or sell copies of the Software, and to permit
    # persons to whom the Software is furnished to do so, subject to the
    # following conditions:
    #
    # The above copyright notice and this permission notice shall be included
    # in all copies or substantial portions of the Software.
    #
    # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
    # OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
    # NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
    # DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
    # OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
    # USE OR OTHER DEALINGS IN THE SOFTWARE.
    #endregion License ########################################################

    param (
        [ref]$ReferenceToJoinedPath = ([ref]$null),
        [string]$ParentPath = '',
        [string]$ChildPath = ''
    )

    #region FunctionsToSupportErrorHandling ################################
    function Get-ReferenceToLastError {
        # .SYNOPSIS
        # Gets a reference (memory pointer) to the last error that
        # occurred.
        #
        # .DESCRIPTION
        # Returns a reference (memory pointer) to $null ([ref]$null) if no
        # errors on on the $error stack; otherwise, returns a reference to
        # the last error that occurred.
        #
        # .EXAMPLE
        # # Intentionally empty trap statement to prevent terminating
        # # errors from halting processing
        # trap { }
        #
        # # Retrieve the newest error on the stack prior to doing work:
        # $refLastKnownError = Get-ReferenceToLastError
        #
        # # Store current error preference; we will restore it after we do
        # # some work:
        # $actionPreferenceFormerErrorPreference = $global:ErrorActionPreference
        #
        # # Set ErrorActionPreference to SilentlyContinue; this will suppress
        # # error output. Terminating errors will not output anything, kick
        # # to the empty trap statement and then continue on. Likewise, non-
        # # terminating errors will also not output anything, but they do not
        # # kick to the trap statement; they simply continue on.
        # $global:ErrorActionPreference = [System.Management.Automation.ActionPreference]::SilentlyContinue
        #
        # # Do something that might trigger an error
        # Get-Item -Path 'C:\MayNotExist.txt'
        #
        # # Restore the former error preference
        # $global:ErrorActionPreference = $actionPreferenceFormerErrorPreference
        #
        # # Retrieve the newest error on the error stack
        # $refNewestCurrentError = Get-ReferenceToLastError
        #
        # $boolErrorOccurred = $false
        # if (($null -ne $refLastKnownError.Value) -and ($null -ne $refNewestCurrentError.Value)) {
        #     # Both not $null
        #     if (($refLastKnownError.Value) -ne ($refNewestCurrentError.Value)) {
        #         $boolErrorOccurred = $true
        #     }
        # } else {
        #     # One is $null, or both are $null
        #     # NOTE: $refLastKnownError could be non-null, while
        #     # $refNewestCurrentError could be null if $error was cleared;
        #     # this does not indicate an error.
        #     #
        #     # So:
        #     # If both are null, no error.
        #     # If $refLastKnownError is null and $refNewestCurrentError is
        #     # non-null, error.
        #     # If $refLastKnownError is non-null and $refNewestCurrentError
        #     # is null, no error.
        #     #
        #     if (($null -eq $refLastKnownError.Value) -and ($null -ne $refNewestCurrentError.Value)) {
        #         $boolErrorOccurred = $true
        #     }
        # }
        #
        # .INPUTS
        # None. You can't pipe objects to Get-ReferenceToLastError.
        #
        # .OUTPUTS
        # System.Management.Automation.PSReference ([ref]).
        # Get-ReferenceToLastError returns a reference (memory pointer) to
        # the last error that occurred. It returns a reference to $null
        # ([ref]$null) if there are no errors on on the $error stack.
        #
        # .NOTES
        # Version: 2.0.20250215.0

        #region License ################################################
        # Copyright (c) 2025 Frank Lesniak
        #
        # Permission is hereby granted, free of charge, to any person
        # obtaining a copy of this software and associated documentation
        # files (the "Software"), to deal in the Software without
        # restriction, including without limitation the rights to use,
        # copy, modify, merge, publish, distribute, sublicense, and/or sell
        # copies of the Software, and to permit persons to whom the
        # Software is furnished to do so, subject to the following
        # conditions:
        #
        # The above copyright notice and this permission notice shall be
        # included in all copies or substantial portions of the Software.
        #
        # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
        # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
        # OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
        # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
        # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
        # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
        # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
        # OTHER DEALINGS IN THE SOFTWARE.
        #endregion License ################################################

        if ($Error.Count -gt 0) {
            return ([ref]($Error[0]))
        } else {
            return ([ref]$null)
        }
    }

    function Test-ErrorOccurred {
        # .SYNOPSIS
        # Checks to see if an error occurred during a time period, i.e.,
        # during the execution of a command.
        #
        # .DESCRIPTION
        # Using two references (memory pointers) to errors, this function
        # checks to see if an error occurred based on differences between
        # the two errors.
        #
        # To use this function, you must first retrieve a reference to the
        # last error that occurred prior to the command you are about to
        # run. Then, run the command. After the command completes, retrieve
        # a reference to the last error that occurred. Pass these two
        # references to this function to determine if an error occurred.
        #
        # .PARAMETER ReferenceToEarlierError
        # This parameter is required; it is a reference (memory pointer) to
        # a System.Management.Automation.ErrorRecord that represents the
        # newest error on the stack earlier in time, i.e., prior to running
        # the command for which you wish to determine whether an error
        # occurred.
        #
        # If no error was on the stack at this time,
        # ReferenceToEarlierError must be a reference to $null
        # ([ref]$null).
        #
        # .PARAMETER ReferenceToLaterError
        # This parameter is required; it is a reference (memory pointer) to
        # a System.Management.Automation.ErrorRecord that represents the
        # newest error on the stack later in time, i.e., after to running
        # the command for which you wish to determine whether an error
        # occurred.
        #
        # If no error was on the stack at this time, ReferenceToLaterError
        # must be a reference to $null ([ref]$null).
        #
        # .EXAMPLE
        # # Intentionally empty trap statement to prevent terminating
        # # errors from halting processing
        # trap { }
        #
        # # Retrieve the newest error on the stack prior to doing work
        # if ($Error.Count -gt 0) {
        #     $refLastKnownError = ([ref]($Error[0]))
        # } else {
        #     $refLastKnownError = ([ref]$null)
        # }
        #
        # # Store current error preference; we will restore it after we do
        # # some work:
        # $actionPreferenceFormerErrorPreference = $global:ErrorActionPreference
        #
        # # Set ErrorActionPreference to SilentlyContinue; this will
        # # suppress error output. Terminating errors will not output
        # # anything, kick to the empty trap statement and then continue
        # # on. Likewise, non- terminating errors will also not output
        # # anything, but they do not kick to the trap statement; they
        # # simply continue on.
        # $global:ErrorActionPreference = [System.Management.Automation.ActionPreference]::SilentlyContinue
        #
        # # Do something that might trigger an error
        # Get-Item -Path 'C:\MayNotExist.txt'
        #
        # # Restore the former error preference
        # $global:ErrorActionPreference = $actionPreferenceFormerErrorPreference
        #
        # # Retrieve the newest error on the error stack
        # if ($Error.Count -gt 0) {
        #     $refNewestCurrentError = ([ref]($Error[0]))
        # } else {
        #     $refNewestCurrentError = ([ref]$null)
        # }
        #
        # if (Test-ErrorOccurred -ReferenceToEarlierError $refLastKnownError -ReferenceToLaterError $refNewestCurrentError) {
        #     # Error occurred
        # } else {
        #     # No error occurred
        # }
        #
        # .INPUTS
        # None. You can't pipe objects to Test-ErrorOccurred.
        #
        # .OUTPUTS
        # System.Boolean. Test-ErrorOccurred returns a boolean value
        # indicating whether an error occurred during the time period in
        # question. $true indicates an error occurred; $false indicates no
        # error occurred.
        #
        # .NOTES
        # This function also supports the use of positional parameters
        # instead of named parameters. If positional parameters are used
        # instead of named parameters, then two positional parameters are
        # required:
        #
        # The first positional parameter is a reference (memory pointer) to
        # a System.Management.Automation.ErrorRecord that represents the
        # newest error on the stack earlier in time, i.e., prior to running
        # the command for which you wish to determine whether an error
        # occurred. If no error was on the stack at this time, the first
        # positional parameter must be a reference to $null ([ref]$null).
        #
        # The second positional parameter is a reference (memory pointer)
        # to a System.Management.Automation.ErrorRecord that represents the
        # newest error on the stack later in time, i.e., after to running
        # the command for which you wish to determine whether an error
        # occurred. If no error was on the stack at this time,
        # ReferenceToLaterError must be a reference to $null ([ref]$null).
        #
        # Version: 2.0.20250215.0

        #region License ################################################
        # Copyright (c) 2025 Frank Lesniak
        #
        # Permission is hereby granted, free of charge, to any person
        # obtaining a copy of this software and associated documentation
        # files (the "Software"), to deal in the Software without
        # restriction, including without limitation the rights to use,
        # copy, modify, merge, publish, distribute, sublicense, and/or sell
        # copies of the Software, and to permit persons to whom the
        # Software is furnished to do so, subject to the following
        # conditions:
        #
        # The above copyright notice and this permission notice shall be
        # included in all copies or substantial portions of the Software.
        #
        # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
        # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
        # OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
        # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
        # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
        # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
        # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
        # OTHER DEALINGS IN THE SOFTWARE.
        #endregion License ################################################
        param (
            [ref]$ReferenceToEarlierError = ([ref]$null),
            [ref]$ReferenceToLaterError = ([ref]$null)
        )

        # TODO: Validate input

        $boolErrorOccurred = $false
        if (($null -ne $ReferenceToEarlierError.Value) -and ($null -ne $ReferenceToLaterError.Value)) {
            # Both not $null
            if (($ReferenceToEarlierError.Value) -ne ($ReferenceToLaterError.Value)) {
                $boolErrorOccurred = $true
            }
        } else {
            # One is $null, or both are $null
            # NOTE: $ReferenceToEarlierError could be non-null, while
            # $ReferenceToLaterError could be null if $error was cleared;
            # this does not indicate an error.
            # So:
            # - If both are null, no error.
            # - If $ReferenceToEarlierError is null and
            #   $ReferenceToLaterError is non-null, error.
            # - If $ReferenceToEarlierError is non-null and
            #   $ReferenceToLaterError is null, no error.
            if (($null -eq $ReferenceToEarlierError.Value) -and ($null -ne $ReferenceToLaterError.Value)) {
                $boolErrorOccurred = $true
            }
        }

        return $boolErrorOccurred
    }
    #endregion FunctionsToSupportErrorHandling ################################

    trap {
        # Intentionally left empty to prevent terminating errors from halting
        # processing
    }

    #region Process Input ##################################################
    if ([string]::IsNullOrEmpty($ParentPath)) {
        Write-Warning "In the function Join-PathSafely(), the ParentPath parameter is required and cannot be null or empty."
        return $false
    }
    #endregion Process Input ##################################################

    # Retrieve the newest error on the stack prior to doing work
    $refLastKnownError = Get-ReferenceToLastError

    # Store current error preference; we will restore it after we do the work
    # of this function
    $actionPreferenceFormerErrorPreference = $global:ErrorActionPreference

    # Set ErrorActionPreference to SilentlyContinue; this will suppress error
    # output. Terminating errors will not output anything, kick to the empty
    # trap statement and then continue on. Likewise, non-terminating errors
    # will also not output anything, but they do not kick to the trap
    # statement; they simply continue on.
    $global:ErrorActionPreference = [System.Management.Automation.ActionPreference]::SilentlyContinue

    # Attempt to join the path
    ($ReferenceToJoinedPath.Value) = Join-Path -Path $ParentPath -ChildPath $ChildPath

    # Restore the former error preference
    $global:ErrorActionPreference = $actionPreferenceFormerErrorPreference

    # Retrieve the newest error on the error stack
    $refNewestCurrentError = Get-ReferenceToLastError

    if (Test-ErrorOccurred -ReferenceToEarlierError $refLastKnownError -ReferenceToLaterError $refNewestCurrentError) {
        # Error occurred; return failure indicator:
        return $false
    } else {
        # No error occurred; return success indicator:
        return $true
    }
}