Examples

.github/workflows/ci.yml

@@ -50,3 +50,11 @@ jobs:
       - name: Test Dub package
         run: dub run --arch=x86_64
         working-directory: .github/dub_test
+
+      - name: Test download_unbox Example
+        run: ./download_unbox.d
+        working-directory: examples
+
+      - name: Test box_upload Example
+        run: ./box_upload.d
+        working-directory: examples

ReadMe.md

@@ -226,6 +226,75 @@ dirEntries(root, SpanMode.breadth, false)
     .writeBinaryFile(filename);
 ```
 
+### Download, list and extract archive
+
+This examples uses [`requests`](https://github.com/ikod/dlang-requests) to download
+an archive from the web, list the archive content and extract it with a single expression.
+(`std.net.curl.byChunk` would also work and woudn't require the const casting)
+
+Thanks to D ranges laziness, the archive is extracted as the data download progresses.
+As such, it is possible to download and extract very large archives with minimal memory footprint
+(and without creating an intermediate file on disk).
+
+```d
+import squiz_box;
+import requests;
+
+const url = "https://github.com/dlang/dmd/archive/master.tar.gz";
+const dest = ".";
+
+// Algorithm matched at runtime with url (using extension)
+auto algo = boxAlgo(url);
+
+size_t downloadSz;
+
+auto rq = Request();
+rq.useStreaming = true;
+rq.get(url).receiveAsRange()
+    .map!(c => cast(const(ubyte)[])c)             // type-casting to const is necessary
+    .tee!(c => downloadSz += c.length)            // trace download size
+    .unbox(algo)
+    .tee!(e => writeln(buildPath(dest, e.path)))  // list archive content
+    .each!(e => e.extractTo(dest));               // extract
+```
+
+### Create archive, list and upload to web
+
+This examples creates an archive and uses [`requests`](https://github.com/ikod/dlang-requests) to upload
+it on the web.
+As in the previous example, the data is uploaded as the archive creation progresses.
+
+```d
+import squiz_box;
+import requests;
+
+const postTo = "https://httpbin.org/post";
+const fmt = ".tar.xz";
+const src = "...";
+const prefix;
+
+size_t uploadSz;
+
+// Algorithm matched at runtime (using extension)
+auto algo = boxAlgo(fmt);
+
+const exclusion = [".git", ".dub", ".vscode", "libsquiz-box.a", "build"];
+
+auto archiveChunks = dirEntries(src, SpanMode.breadth, false)
+    .filter!(e => !e.isDir)
+    .filter!(e => !exclusion.any!(ex => e.name.canFind(ex)))
+    .tee!(e => writeln(e.name))
+    .map!(e => fileEntry(e.name, src, prefix))
+    .box(algo)
+    .tee!(c => uploadSz += c.length);
+
+auto rq = Request();
+auto resp = rq.post(postTo, archiveChunks, algo.mimetype);
+enforce(resp.code < 300, format!"%s responded %s"(postTo, resp.code));
+
+writefln!"POST %s - status %s (posted %s bytes)"(postTo, resp.code, uploadSz);
+```
+
 ### Full control over the streaming process
 
 Sometimes, D ranges are not practical. Think of a receiver thread that

examples/box_upload.d

@@ -0,0 +1,66 @@
+#!/usr/bin/env dub
+/+ dub.sdl:
+    name "box_upload"
+    description "an example for squiz-box: create archive and upload to the web"
+    dependency "squiz-box" path=".."
+    dependency "requests" version="~>2.1.1"
++/
+
+module examples.box_upload;
+
+import squiz_box;
+import requests;
+
+import std.algorithm;
+import std.exception;
+import std.getopt;
+import std.format;
+import std.file;
+import std.path;
+import std.range;
+import std.stdio;
+
+void main(string[] args)
+{
+    string postTo = "https://httpbin.org/post";
+    string fmt = ".tar.xz";
+    string src = "..";
+    string prefix;
+
+    auto opts = getopt(args,
+        "post-to", &postTo,
+        "format", &fmt,
+        "src", &src,
+        "prefix", &prefix,
+    );
+
+    if (opts.helpWanted)
+    {
+        defaultGetoptPrinter("Squiz-box example, create archive, list and upload", opts.options);
+    }
+
+    // Algorithm matched at runtime (using extension)
+    auto algo = boxAlgo(fmt);
+
+    size_t numFiles;
+    size_t dataSz;
+
+    const exclusion = [".git", ".dub", ".vscode", "libsquiz-box.a", "build"];
+
+    auto archiveChunks = dirEntries(src, SpanMode.breadth, false)
+        .filter!(e => !e.isDir)
+        .filter!(e => !exclusion.any!(ex => e.name.canFind(ex)))
+        .tee!(e => stdout.writeln(e.name))
+        .tee!(e => numFiles += 1)
+        .map!(e => fileEntry(e.name, src, prefix))
+        .box(algo)
+        .tee!(c => stderr.writefln!"uploaded %s bytes"(c.length))
+        .tee!(c => dataSz += c.length);
+
+    auto rq = Request();
+    auto resp = rq.post(postTo, archiveChunks, algo.mimetype);
+    enforce(resp.code < 300, format!"%s responded %s"(postTo, resp.code));
+
+    writefln!"POST %s - status %s"(postTo, resp.code);
+    writefln!"Archived %s files. Uploaded %s bytes"(numFiles, dataSz);
+}

examples/download_unbox.d

@@ -0,0 +1,67 @@
+#!/usr/bin/env dub
+/+ dub.sdl:
+    name "download_unbox"
+    description "an example for squiz-box: download, list and extract archive"
+    dependency "squiz-box" path=".."
+    dependency "requests" version="~>2.1.1"
++/
+
+module examples.download_unbox;
+
+import squiz_box;
+import requests;
+
+import std.algorithm;
+import std.getopt;
+import std.file;
+import std.path;
+import std.range;
+import std.stdio;
+
+void main(string[] args)
+{
+    string url = "https://github.com/dlang/dmd/archive/master.tar.gz";
+    string dest;
+
+    auto opts = getopt(args,
+        "url", "URL of archive to download", &url,
+        "dest", "The destination directory. Extracted files will disappear if not specified.", &dest,
+    );
+
+    if (opts.helpWanted)
+    {
+        defaultGetoptPrinter("Squiz-box, download, list and extract archive", opts.options);
+    }
+
+    const outDir = dest.length ? dest : buildPath(tempDir, "squiz-box-example");
+
+    if (!exists(outDir))
+        mkdirRecurse(outDir);
+
+    scope(success)
+    {
+        if (!dest)
+            rmdirRecurse(outDir);
+    }
+
+    // Algorithm matched at runtime with url (using extension)
+    auto algo = boxAlgo(url);
+
+    writefln!"GET %s"(url);
+
+    size_t dataSz;
+    size_t numFiles;
+
+    auto rq = Request();
+    rq.useStreaming = true;
+    rq.get(url).receiveAsRange()
+        .map!(c => cast(const(ubyte)[])c)
+        .tee!(c => stderr.writefln!"received %s bytes"(c.length))
+        .tee!(c => dataSz += c.length)
+        .unbox(algo)
+        .tee!(e => stdout.writeln(buildPath(dest, e.path)))
+        .tee!(e => numFiles += 1)
+        .each!(e => e.extractTo(outDir));
+
+    writefln!"Downloaded %s bytes. Extracted %s files."(dataSz, numFiles);
+}

src/squiz_box/box/package.d

@@ -46,6 +46,7 @@ template isBoxAlgo(A)
                 BoxEntry[] boxEntries;
                 const(ubyte)[] bytes = algo.box(boxEntries).join();
                 UnboxEntry[] unboxEntries = algo.unbox(only(bytes), No.removePrefix).array;
+                string mt = algo.mimetype;
             }));
 }
 
@@ -56,7 +57,7 @@ interface BoxAlgo
     ByteRange box(BoxEntryRange entries, size_t chunkSize = defaultChunkSize);
 
     /// ditto
-    ByteRange box(I)(I entries, size_t chunkSize = defaultChunkSize)
+    final ByteRange box(I)(I entries, size_t chunkSize = defaultChunkSize)
             if (isBoxEntryRange!I && !is(I == BoxEntryRange))
     {
         return box(inputRangeObject(entries), chunkSize);
@@ -66,11 +67,24 @@ interface BoxAlgo
     UnboxEntryRange unbox(ByteRange bytes, Flag!"removePrefix" removePrefix = No.removePrefix);
 
     /// ditto
-    UnboxEntryRange unbox(I)(I bytes, Flag!"removePrefix" removePrefix = No.removePrefix)
-            if (isByteRange!I && !is(I == ByteRange))
-    {
+    final UnboxEntryRange unbox(I)(I bytes, Flag!"removePrefix" removePrefix = No.removePrefix)
+            if (isByteRange!I && !is(I : ByteRange))
+    {
+        // It is necessary to disambiguate `!is(I : ByteRange) with non-const `ubyte[]` range.
+        // Otherwise we can have infinite recursion and stack overflow at runtime.
+        // The assertion could be in the template constraints, but the static assertion gives
+        // opportunity of a helpful message.
+        // TODO: add an overload accepting a non-const `ubyte[]` range. Can be tested with
+        // requests `ReceiveAsRange`
+        enum message = "Squiz-Box requires range of `const(ubyte)[]` but received `ubyte[]`. "
+            ~ "Consider typecasting your range with `.map!(c => cast(const(ubyte)[])c)`";
+        static assert(!is(ElementType!I == ubyte[]), message);
+
         return unbox(inputRangeObject(bytes), removePrefix);
     }
+
+    /// The mimetype of the compressed archive
+    @property string mimetype() const;
 }
 
 static assert(isBoxAlgo!BoxAlgo);
@@ -94,6 +108,11 @@ private class CBoxAlgo(A) : BoxAlgo if (isBoxAlgo!A)
     {
         return inputRangeObject(algo.unbox(bytes, removePrefix));
     }
+
+    @property string mimetype() const
+    {
+        return algo.mimetype;
+    }
 }
 
 /// Build a BoxAlgo interface from a compile-time known box algo structure.
@@ -355,7 +374,8 @@ interface UnboxEntry : ArchiveEntry
         import std.stdio : File;
         import std.string : startsWith;
 
-        assert(exists(baseDirectory) && isDir(baseDirectory));
+        assert(exists(baseDirectory) && isDir(baseDirectory),
+            "extracting to " ~ baseDirectory ~ ": must be a directory");
 
         enforce(
             !this.isBomb,
@@ -678,8 +698,7 @@ class InfoBoxEntry : BoxEntry
 
 /// Create a BoxEntry from the provided info.
 /// This allows to create archives out of generated data, without any backing file on disk.
-InfoBoxEntry infoEntry(I)(BoxEntryInfo info, I data)
-if (isByteRange!I)
+InfoBoxEntry infoEntry(I)(BoxEntryInfo info, I data) if (isByteRange!I)
 in (info.type == EntryType.regular || data.empty, "symlinks and directories can't have data")
 {
     import std.datetime : Clock;

src/squiz_box/box/tar.d

@@ -25,6 +25,8 @@ struct TarAlgo
         auto dataInput = new ByteRangeCursor!I(input);
         return TarUnbox(dataInput, removePrefix);
     }
+
+    enum mimetype = "application/x-tar";
 }
 
 static assert(isBoxAlgo!TarAlgo);
@@ -46,6 +48,8 @@ struct TarGzAlgo
         auto dataInput = new ByteRangeCursor!II(ii);
         return TarUnbox(dataInput, removePrefix);
     }
+
+    enum mimetype = "application/x-gtar";
 }
 
 static assert(isBoxAlgo!TarGzAlgo);
@@ -69,6 +73,8 @@ version (HaveSquizBzip2)
             auto dataInput = new ByteRangeCursor!II(ii);
             return TarUnbox(dataInput, removePrefix);
         }
+
+        enum mimetype = "application/x-gtar";
     }
 
     static assert(isBoxAlgo!TarBzip2Algo);
@@ -93,6 +99,8 @@ version (HaveSquizLzma)
             auto dataInput = new ByteRangeCursor!II(ii);
             return TarUnbox(dataInput, removePrefix);
         }
+
+        enum mimetype = "application/x-gtar";
     }
 
     static assert(isBoxAlgo!TarXzAlgo);
@@ -183,8 +191,8 @@ enum Typeflag : ubyte
     directory = '5',
     fifo = '6',
     contiguousFile = '7',
-    posixExtended = 'g',
-    extended = 'x',
+    extendedGlobal = 'g',
+    extendedFile = 'x',
     gnuLongname = 'L',
     gnuLonglink = 'K',
 }
@@ -564,9 +572,10 @@ struct TarInfo
         case Typeflag.directory:
         case Typeflag.fifo:
         case Typeflag.contiguousFile:
-        case Typeflag.posixExtended:
-        case Typeflag.extended:
             return decodeHeader(blk);
+        case Typeflag.extendedGlobal:
+        case Typeflag.extendedFile:
+            return skipExtendedDecodeHeader(cursor, blk);
         case Typeflag.gnuLongname:
         case Typeflag.gnuLonglink:
             return decodeGnuLongHeader(cursor, blk);
@@ -612,6 +621,14 @@ struct TarInfo
         return info;
     }
 
+    private static TarInfo skipExtendedDecodeHeader(Cursor cursor, scope ref BlockInfo blk)
+    {
+        const sz = next512(blk.size);
+        cursor.ffw(sz);
+
+        return TarInfo.decode(cursor);
+    }
+
     private static TarInfo decodeGnuLongHeader(Cursor cursor, scope ref BlockInfo blk)
     {
         auto data = new char[next512(blk.size)];

src/squiz_box/box/zip.d

@@ -27,6 +27,8 @@ struct ZipAlgo
         auto stream = new ByteRangeCursor!I(input);
         return ZipUnbox!Cursor(stream, removePrefix);
     }
+
+    enum mimetype = "application/zip";
 }
 
 static assert(isBoxAlgo!ZipAlgo);