Modified module ziparchives to alternatively open zip files as byte strings.

src/test_ziparchives_inmem.nim

@@ -0,0 +1,21 @@
+import zippy/ziparchives
+
+proc test_case() =
+  var archive = open_zip_archive("inner_test.zip")
+  defer: archive.close()
+
+  for fname in archive.walk_files:
+    let inner_bytes = archive.extract_file(fname)
+
+    # First test scenario: Extract file-by-file
+    # var inner_archive = open_zip_archive_bytes(bytes)
+    # defer: inner_archive.close()
+
+    # for ifname in inner_archive.walk_files:
+    #   let ifbytes = inner_archive.extract_file(ifname)
+    #   writeFile(ifname, ifbytes)
+
+    # Second test scenario: Extract whole inner archives
+    extractAllBytes(inner_bytes, fname & ".d")
+
+test_case()

src/zippy/ziparchives.nim

@@ -16,6 +16,9 @@ type
   ZipArchiveRecordKind = enum
     FileRecord, DirectoryRecord
 
+  ZipArchiveReaderMode = enum
+    MemfileMode, StringMode
+
   ZipArchiveRecord = object
     kind: ZipArchiveRecordKind
     fileHeaderOffset: int
@@ -26,7 +29,9 @@ type
     filePermissions: set[FilePermission]
 
   ZipArchiveReader* = ref object
+    mode: ZipArchiveReaderMode
     memFile: MemFile
+    byteString: string
     records: OrderedTable[string, ZipArchiveRecord]
 
 iterator walkFiles*(reader: ZipArchiveReader): string =
@@ -36,6 +41,16 @@ iterator walkFiles*(reader: ZipArchiveReader): string =
     if record.kind == FileRecord:
       yield record.path
 
+proc getDataPtr(reader: ZipArchiveReader): ptr UncheckedArray[uint8] =
+  case reader.mode
+  of MemfileMode:   cast[ptr UncheckedArray[uint8]](reader.memFile.mem)
+  of StringMode:    cast[ptr UncheckedArray[uint8]](reader.byteString[0].addr)
+
+proc getDataLen(reader: ZipArchiveReader): int =
+  case reader.mode
+  of MemfileMode:   reader.memFile.size
+  of StringMode:    reader.byteString.len
+
 proc extractFile*(
   reader: ZipArchiveReader, path: string
 ): string {.raises: [ZippyError].} =
@@ -44,7 +59,7 @@ proc extractFile*(
     raise newException(ZippyError, "No file record found for " & path)
 
   let
-    src = cast[ptr UncheckedArray[uint8]](reader.memFile.mem)
+    src = reader.getDataPtr()
     record =
       try:
         reader.records[path]
@@ -53,7 +68,7 @@ proc extractFile*(
 
   var pos = record.fileHeaderOffset
 
-  if pos + fileHeaderLen > reader.memFile.size:
+  if pos + fileHeaderLen > reader.getDataLen():
     failArchiveEOF()
 
   if read32(src, pos) != fileHeaderSignature:
@@ -73,7 +88,7 @@ proc extractFile*(
 
   pos += fileHeaderLen + fileNameLen + extraFieldLen
 
-  if pos + record.compressedSize > reader.memFile.size:
+  if pos + record.compressedSize > reader.getDataLen():
     failArchiveEOF()
 
   case record.kind:
@@ -93,7 +108,8 @@ proc extractFile*(
     raise newException(ZippyError, "Verifying crc32 failed")
 
 proc close*(reader: ZipArchiveReader) {.raises: [OSError].} =
-  reader.memFile.close()
+  if reader.mode == MemfileMode:
+    reader.memFile.close()
 
 proc parseMsDosDateTime(time, date: uint16): Time =
   let
@@ -155,9 +171,9 @@ proc utf8ify(fileName: string): string =
   $runes
 
 proc findEndOfCentralDirectory(reader: ZipArchiveReader): int =
-  let src = cast[ptr UncheckedArray[uint8]](reader.memFile.mem)
+  let src = reader.getDataPtr()
 
-  result = reader.memFile.size - 22 # Work backwards in the file starting here
+  result = reader.getDataLen() - 22 # Work backwards in the file starting here
   while true:
     if result < 0:
       failArchiveEOF()
@@ -170,7 +186,7 @@ proc findStartOfCentralDirectory(
   reader: ZipArchiveReader,
   start, numRecordEntries: int
 ): int =
-  let src = cast[ptr UncheckedArray[uint8]](reader.memFile.mem)
+  let src = reader.getDataPtr()
 
   result = start # Work backwards in the file starting here
   var numRecordsFound: int
@@ -183,17 +199,16 @@ proc findStartOfCentralDirectory(
         return
     dec result
 
-proc openZipArchive*(
-  zipPath: string
-): ZipArchiveReader {.raises: [IOError, OSError, ZippyError].} =
-  result = ZipArchiveReader()
-  result.memFile = memfiles.open(zipPath)
 
+proc openZipArchiveInternal(
+  reader: ZipArchiveReader
+): ZipArchiveReader {.raises: [IOError, OSError, ZippyError].} =
+  result = reader
   try:
-    let src = cast[ptr UncheckedArray[uint8]](result.memFile.mem)
+    let src = result.getDataPtr()
 
     let eocd = result.findEndOfCentralDirectory()
-    if eocd + 22 > result.memFile.size:
+    if eocd + 22 > result.getDataLen():
       failArchiveEOF()
 
     var zip64 = false
@@ -217,7 +232,7 @@ proc openZipArchive*(
         raise newException(ZippyError, "Unsupported archive, num disks")
 
       var pos = zip64EndOfCentralDirectoryStart
-      if pos + 64 > result.memFile.size:
+      if pos + 64 > result.getDataLen():
         failArchiveEOF()
 
       if read32(src, pos) != zip64EndOfCentralDirectorySignature:
@@ -268,11 +283,11 @@ proc openZipArchive*(
 
     var pos = socdOffset + centralDirectoryStart
 
-    if eocd + 22 > result.memFile.size:
+    if eocd + 22 > result.getDataLen():
       failArchiveEOF()
 
     for _ in 0 ..< numCentralDirectoryRecords:
-      if pos + 46 > result.memFile.size:
+      if pos + 46 > result.getDataLen():
         failArchiveEOF()
 
       if read32(src, pos) != centralDirectoryFileHeaderSignature:
@@ -306,7 +321,7 @@ proc openZipArchive*(
 
       pos += 46
 
-      if pos + fileNameLen > result.memFile.size:
+      if pos + fileNameLen > result.getDataLen():
         failArchiveEOF()
 
       var fileName = newString(fileNameLen)
@@ -321,7 +336,7 @@ proc openZipArchive*(
         var extraFieldsOffset = pos
 
         while extraFieldsOffset < pos + extraFieldLen:
-          if pos + 4 > result.memFile.size:
+          if pos + 4 > result.getDataLen():
             failArchiveEOF()
 
           let
@@ -395,10 +410,24 @@ proc openZipArchive*(
     result.close()
     raise e
 
-proc extractAll*(
-  zipPath, dest: string
-) {.raises: [IOError, OSError, ZippyError].} =
-  ## Extracts the files stored in archive to the destination directory.
+proc openZipArchive*(
+  zipPath: string
+): ZipArchiveReader {.raises: [IOError, OSError, ZippyError].} =
+  result = ZipArchiveReader()
+  result.mode = MemfileMode
+  result.memFile = memfiles.open(zipPath)
+  return openZipArchiveInternal(result)
+
+proc openZipArchiveBytes*(
+  byteString: string
+): ZipArchiveReader {.raises: [IOError, OSError, ZippyError].} =
+  result = ZipArchiveReader()
+  result.mode = StringMode
+  result.byteString = byteString
+  return openZipArchiveInternal(result)
+
+
+proc checkExtractDestination(dest: string) {.raises: [IOError, OSError, ZippyError].} =
   ## The path to the destination directory must exist.
   ## The destination directory itself must not exist (it is not overwitten).
   if dest == "" or dirExists(dest):
@@ -410,9 +439,10 @@ proc extractAll*(
   if head != "" and not dirExists(head):
     raise newException(ZippyError, "Path to " & dest & " does not exist")
 
-  let
-    reader = openZipArchive(zipPath)
-    src = cast[ptr UncheckedArray[uint8]](reader.memFile.mem)
+proc extractAllInternal(
+  reader: ZipArchiveReader, dest: string
+) {.raises: [IOError, OSError, ZippyError].} =
+  let src = reader.getDataPtr()
 
   # Verify some things before attempting to write the files
   for _, record in reader.records:
@@ -452,6 +482,22 @@ proc extractAll*(
   finally:
     reader.close()
 
+proc extractAll*(
+  zipPath, dest: string
+) {.raises: [IOError, OSError, ZippyError].} =
+  ## Extracts the files stored in archive to the destination directory.
+  checkExtractDestination(dest)
+  let reader = openZipArchive(zipPath)
+  extractAllInternal(reader, dest)
+
+proc extractAllBytes*(
+  zipBytes, dest: string
+) {.raises: [IOError, OSError, ZippyError].} =
+  ## Extracts the files stored in byte-string archive to the destination directory.
+  checkExtractDestination(dest)
+  let reader = openZipArchiveBytes(zipBytes)
+  extractAllInternal(reader, dest)
+
 when (NimMajor, NimMinor, NimPatch) >= (1, 6, 0):
   # For some reason `sink Table | OrderedTable` does not work, so work around:
   template createZipArchiveImpl(