Commands/Get-SqlMigrationHash.ps1
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<# Copyright (C) 2020 Jeffrey Sharp Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. #> function Get-SqlMigrationHash { <# .SYNOPSIS Computes a hash value for a SQL migration. The hash value is adequate for change detection, but not for cryptography. #> param ( # Path of the directory containing the SQL migration. [string] $Path ) # Generate file list $Files = [ordered] @{} # ... first, using explicit file list, if one is provided # NOTE: This _Files.lst capability is a compatibility hack for an existing # user and will be removed as soon as they don't need it. Join-Path $Path _Files.lst ` | Get-Item -ErrorAction SilentlyContinue ` | Get-Content -Encoding utf8 ` | ForEach-Object { Join-Path $Path $_ } ` | Get-Item ` | ForEach-Object { $Files[$_.FullName] = $_ } # ... then, using sorted order Get-ChildItem $Path *.sql -Recurse ` | Where-Object { -not $Files.Contains($_.FullName) } ` | Sort-Object FullName ` | ForEach-Object { $Files[$_.FullName] = $_ } # Compute a hash for each file $Hashes = $Files.Values ` | Get-FileHash -Algorithm SHA1 ` | ForEach-Object Hash ` | Out-String # Prep a stream to read the hashes as binary $Bytes = $Hashes | ConvertFrom-Hex $Stream = New-Object System.IO.MemoryStream @(,$Bytes) # Compute a single hash from the per-file hashes Get-FileHash -InputStream $Stream -Algorithm SHA1 | % Hash } function ConvertFrom-Hex { <# .SYNOPSIS Converts from a string of hex digits (1-9, a-f, A-F) to a byte array. Non-hex-digit characters are ignored. #> [OutputType([byte[]])] param ( # String of hex digits to convert. [Parameter(Mandatory, Position=0, ValueFromPipeline)] [string] $Hex ) [byte[]] ( $Hex ` -replace '[^0-9a-fA-F]', '' ` -split '(?<=\G..)(?=..)' ` | % { [Convert]::ToByte($_, 16) } ) } |