Accept short git revs

Short revisions are fine, SHA1 is broken anyway.

lock.json

@@ -1 +1 @@
-{"depends":[{"method":"fetchzip","packages":["npeg"],"path":"/nix/store/ffkxmjmigfs7zhhiiqm0iw2c34smyciy-source","ref":"1.2.1","rev":"26d62fdc40feb84c6533956dc11d5ee9ea9b6c09","sha256":"0xpzifjkfp49w76qmaylan8q181bs45anmp46l4bwr3lkrr7bpwh","srcDir":"src","url":"https://github.com/zevv/npeg/archive/26d62fdc40feb84c6533956dc11d5ee9ea9b6c09.tar.gz"},{"method":"fetchzip","packages":["preserves"],"path":"/nix/store/nrxd0z8mxmdphw49c6p4n9lmmq0iq5pq-source","ref":"20231019","rev":"a2dc5becc0596d52ab205d869b7c167c0b562fb4","sha256":"09jygr7ynzh6vp2p54dgq2qz651d3lgvypkjwjp74zzp3jgwz7g5","srcDir":"src","url":"https://git.syndicate-lang.org/ehmry/preserves-nim/archive/a2dc5becc0596d52ab205d869b7c167c0b562fb4.tar.gz"}]}
+{"depends":[{"method":"fetchzip","packages":["npeg"],"path":"/nix/store/ffkxmjmigfs7zhhiiqm0iw2c34smyciy-source","ref":"1.2.1","rev":"26d62fdc40feb84c6533956dc11d5ee9ea9b6c09","sha256":"0xpzifjkfp49w76qmaylan8q181bs45anmp46l4bwr3lkrr7bpwh","srcDir":"src","url":"https://github.com/zevv/npeg/archive/26d62fdc40feb84c6533956dc11d5ee9ea9b6c09.tar.gz"},{"method":"fetchzip","packages":["preserves"],"path":"/nix/store/nrcpzf9hx70kry3gwhrdzcs3qicjncjh-source","ref":"20231021","rev":"edece399be70818208bf2263c30cb2bcf435bbff","sha256":"0xmw35wmw3a4lja9q4qvlvpxv3xk0hnkjg4fwfw6f3inh6zfiqki","srcDir":"src","url":"https://git.syndicate-lang.org/ehmry/preserves-nim/archive/edece399be70818208bf2263c30cb2bcf435bbff.tar.gz"}]}

nim_lk.nimble

@@ -3,6 +3,6 @@ bin = @["nim_lk"]
 description = "Tool for generating Nim lockfiles"
 license = "BSD-3-Clause"
 srcDir = "src"
-version = "20231021"
+version = "20231031"
 
 requires "nim >= 2.0.0", "preserves >= 20231021"

src/nim_lk.nim

@@ -7,7 +7,7 @@ import nimblepkg/common,
   nimblepkg/packageparser,
   nimblepkg/version
 
-import std/[algorithm, deques, httpclient, json, os, osproc, parseutils, streams, strutils, uri]
+import std/[algorithm, cmdline, deques, httpclient, json, os, osproc, parseutils, streams, strutils, uri]
 import preserves
 
 const githubPackagesUrl =
@@ -64,8 +64,8 @@ proc gitLsRemote(url: string; withTags: bool): seq[tuple[tag: string, rev: strin
 proc matchRev(url: string; wanted: VersionRange): tuple[tag: string, rev: string] =
   if wanted.kind == verSpecial:
     let special = string(wanted.spe)
-    if special.len == 41 and special[0] == '#':
-      result[1] = special[1..39]
+    if special[0] == '#':
+      result[1] = special[1..special.high]
     else:
       quit("unhandled version " & url & " " & $wanted)
   else:
@@ -120,9 +120,7 @@ proc prefetchGit(uri: Uri; version: VersionRange): Preserve =
   var archiveUri = uri
   archiveUri.scheme = "https"
   archiveUri.path.removeSuffix ".git"
-  archiveUri.path.add "/archive/"
-  archiveUri.path.add rev
-  archiveUri.path.add ".tar.gz"
+  archiveUri.path = archiveUri.path / "archive"/ rev & ".tar.gz"
   let client = newHttpClient()
   defer: close(client)
   let
@@ -217,12 +215,12 @@ proc getPackgeUri(name: string): tuple[uri: string, meth: string] =
           quit("Failed to parse shit JSON " & $e)
     inc i
 
-proc generateLockfile(): Preserve =
+proc generateLockfile(directoryPath: string): Preserve =
   result = initDictionary()
   var
     deps = initSequence()
     pending: Deque[PkgTuple]
-  collectRequires(pending, getCurrentDir())
+  collectRequires(pending, directoryPath)
   while pending.len > 0:
     let batchLen = pending.len
     for i in 1..batchLen:
@@ -259,9 +257,16 @@ proc generateLockfile(): Preserve =
   result["depends".toPreserve] = deps
 
 proc main =
+  var packagePath = getCurrentDir()
+  case paramCount()
+  of 0: discard
+  of 1:
+    packagePath = commandLineParams()[0]
+  else:
+    quit "no more than a single package path may be specified"
   var
     stream = newFileStream(stdout)
-    lockInfo = generateLockfile()
+    lockInfo = generateLockfile(packagePath)
   cannonicalize(lockInfo)
   writeText(stream, lockInfo, textJson)
   writeLine(stream)