A deep dive into git internals.
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git-guts-fs/git-guts/Utils.fs

229 lines
8.6 KiB

namespace git_guts
open System
open System.Text
open System.IO
open System.Diagnostics
open Spectre.Console
// --------------------------------------------------------------------
type CaptureStdout () =
// Temporarily capture output sent to stdout.
// set up a buffer to capture stdout
let _writer = new StringWriter()
let _prevOut = System.Console.Out
let _prevAnsiConsole = AnsiConsole.Console.Profile.Out
do
System.Console.SetOut( _writer )
AnsiConsole.Console.Profile.Out <- new AnsiConsoleOutput( _writer )
interface IDisposable with
member this.Dispose() =
// clean up
System.Console.SetOut( _prevOut )
AnsiConsole.Console.Profile.Out <- _prevAnsiConsole
_writer.Dispose()
member this.getOutput =
// return the captured output
_writer.ToString()
// --------------------------------------------------------------------
type StringBuilderBuf () =
// Allow messages to be built up in a StringBuilder.
// initialize
let _buf = new StringBuilder()
member this.printf fmt =
// generate the message, then add it to the buffer
let writeBuf (msg: string) =
_buf.Append( msg ) |> ignore
Printf.kprintf writeBuf fmt
member this.endOfLine =
_buf.AppendLine() |> ignore
override this.ToString() =
_buf.ToString()
// --------------------------------------------------------------------
[<AutoOpen>]
module Utils =
let runGit repoDir cmd args =
// run git and capture the output
let gitPath = "git" // nb: we assume this is on the PATH
let gitDir = Path.Combine( repoDir, ".git" )
let startInfo = ProcessStartInfo( FileName=gitPath, RedirectStandardOutput=true, UseShellExecute=false )
let addArg arg = startInfo.ArgumentList.Add( arg )
Seq.iter addArg [| "--git-dir"; gitDir; cmd |]
Seq.iter addArg args
let proc = Process.Start( startInfo )
let getBytes = Seq.initInfinite ( fun _ -> proc.StandardOutput.BaseStream.ReadByte() )
let output = getBytes |> Seq.takeWhile ( fun b -> b <> -1 ) |> Seq.map ( fun b -> byte(b) ) |> Seq.toArray
proc.WaitForExit()
if proc.ExitCode <> 0 then
failwithf "git failure: rc=%d" proc.ExitCode
output
let runGitText repoDir cmd args =
// run git and capture the output as text
Encoding.UTF8.GetString( runGit repoDir cmd args )
let runGitGc repoDir =
// run git garbage collection
runGit repoDir "gc" [] |> ignore
let disableSpectreCapabilities () =
// disable colors (and other capabilities) in Spectre.Console
AnsiConsole.Profile.Capabilities.ColorSystem <- ColorSystem.NoColors
AnsiConsole.Profile.Capabilities.Ansi <- false
AnsiConsole.Profile.Capabilities.Links <- false
// FUDGE! Spectre.Console wraps output?!?!
AnsiConsole.Profile.Width <- 99999
let safeSpectreString (str: string) =
// escape characters that have meaning for Spectre
str.Replace( "[", "[[" ).Replace( "]", "]]" )
let changeExtn (fname: string) newExtn =
// change the filename's extension
let dirName = Path.GetDirectoryName( fname )
let fname2 = Path.GetFileNameWithoutExtension( fname ) + newExtn
if dirName = String.Empty then
fname2
else
Path.Join( dirName, fname2 )
let makeHeader (caption: string) (caption2: string) =
// generate a header string
let buf = StringBuilderBuf()
let nChars = 3 + 1 + caption.Length + ( if caption2 <> "" then 1+caption2.Length else 0 )
buf.printf "--- [cyan]%s[/] " (safeSpectreString caption)
if caption2 <> "" then
buf.printf "%s " caption2
buf.printf "%s" ( String( '-', Math.Max( 79-nChars, 3 ) ) )
buf.ToString()
let dumpBytes (data: byte[]) startIndex nBytes prefix =
let buf = StringBuilderBuf()
let endIndex = startIndex + nBytes - 1
let startIndex0 = int( startIndex / 16 ) * 16
for byteNoStart in [ startIndex0 .. 16 .. endIndex ] do
buf.printf "%s%05x |" prefix byteNoStart
for i = 0 to 15 do
let byteNo = byteNoStart + i
buf.printf " %s" (
if byteNo >= startIndex && byteNo <= endIndex then
sprintf "%02x" data.[byteNo]
else
".."
)
buf.printf " | "
for i = 0 to 15 do
let byteNo = byteNoStart + i
buf.printf "%c" (
if byteNo >= startIndex && byteNo <= endIndex then
if data.[byteNo] >= 32uy && data.[byteNo] < 127uy then
Convert.ToChar( data.[byteNo] )
else
'.'
else
' '
)
buf.endOfLine
buf.ToString()
let blobStr blobData snip =
// return the blob display string
let enc = System.Text.Encoding.GetEncoding( "UTF-8", EncoderFallback.ExceptionFallback, DecoderFallback.ExceptionFallback )
let textVal =
try
// try to convert the blob a string
enc.GetString( blobData, 0, blobData.Length )
with
| :? DecoderFallbackException ->
// couldn't convert the blob to a string - dump it
dumpBytes blobData 0 blobData.Length ""
// NOTE: If there is a lot of content, we show only the first and last few lines (to avoid
// overwhelming the output), but this won't work too well if those lines are very long... :-/
let lines = textVal.Split( "\n" )
if lines.Length <= 10 || not snip then
textVal
else
let getLines = seq {
yield! Seq.take 5 lines
yield String.Format( " ...{0} lines snipped...", lines.Length-8 )
yield! lines.[ lines.Length-5 .. lines.Length-1 ]
}
String.Join( "\n", getLines )
let objNameStr objName =
// return the object name display string
"[yellow]" + objName + "[/]"
let refStr ref =
// return the ref display string
"[green]" + ref + "[/]"
let pathStr path =
// return the path display string
match path with
| "" -> "(empty)"
| _ -> "[green]" + (if path.Substring(0,2) = "./" then path.Substring(2) else path) + "[/]"
let bitflagString (flags: uint) nBytes (flagNames: Map<uint,string>) =
// convert the bitflags to a formatted string
let fmt = sprintf "0x{0:x%d}" (2 * nBytes)
let flagsStr = String.Format( fmt, flags )
let checkBitflag (bflag, flagName) =
flags &&& bflag <> 0u
let fnames = Map.toSeq flagNames |> Seq.filter checkBitflag |> Seq.map snd |> Seq.toArray
if fnames.Length = 0 then
flagsStr
else
sprintf "%s (%s)" (String.Join( ", ", fnames )) flagsStr
let permsString (perms: uint16) =
// convert the file permission flags to a formatted string
let permNames = "rwxrwxrwx"
let permsStr = String.Join( "", seq {
for flagNo = 0 to permNames.Length-1 do
let bmask = uint16( 1 <<< (8 - flagNo) )
yield if perms &&& bmask <> 0us then permNames.[flagNo] else '-'
} )
sprintf "%s (0x%x)" permsStr perms
let readBytes (inp: Stream) nBytes =
// read the specified number of bytes from the stream
let buf = Array.zeroCreate nBytes
let nBytesRead = inp.Read( buf, 0, nBytes )
if nBytesRead <> nBytes then
failwithf "Unexpected number of bytes read: %d/%d" nBytesRead nBytes
buf
let parseTimestamp tstamp =
// parse a timestamp
let epoch = DateTime( 1970, 1, 1, 0, 0, 0, DateTimeKind.Utc )
epoch.AddSeconds( float( tstamp ) )
let plural n val1 val2 =
// return a pluralized string
sprintf "%d %s" n ( if n = 1 then val1 else val2 )
let friendlyByteCount nBytes =
// return a friendly byte-count string
if nBytes < 1024L then
plural (int nBytes) "byte" "bytes"
else if nBytes < 1024L * 1024L then
sprintf "%.1f KB" ( float( nBytes ) / 1024.0 )
else if nBytes < 1024L * 1024L * 1024L then
sprintf "%.1f MB" ( float( nBytes ) / 1024.0 / 1024.0 )
else
sprintf "%.1f GB" ( float( nBytes ) / 1024.0 / 1024.0 / 1024.0 )