commit f3062b422ebd9cdbf9b51f3beb44df3831e0c6b6 Author: starainrt Date: Sat Feb 4 17:52:28 2023 +0800 init diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..85e7c1d --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +/.idea/ diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..14e2f77 --- /dev/null +++ b/LICENSE @@ -0,0 +1,373 @@ +Mozilla Public License Version 2.0 +================================== + +1. Definitions +-------------- + +1.1. "Contributor" + means each individual or legal entity that creates, contributes to + the creation of, or owns Covered Software. + +1.2. "Contributor Version" + means the combination of the Contributions of others (if any) used + by a Contributor and that particular Contributor's Contribution. + +1.3. "Contribution" + means Covered Software of a particular Contributor. + +1.4. "Covered Software" + means Source Code Form to which the initial Contributor has attached + the notice in Exhibit A, the Executable Form of such Source Code + Form, and Modifications of such Source Code Form, in each case + including portions thereof. + +1.5. "Incompatible With Secondary Licenses" + means + + (a) that the initial Contributor has attached the notice described + in Exhibit B to the Covered Software; or + + (b) that the Covered Software was made available under the terms of + version 1.1 or earlier of the License, but not also under the + terms of a Secondary License. + +1.6. "Executable Form" + means any form of the work other than Source Code Form. + +1.7. "Larger Work" + means a work that combines Covered Software with other material, in + a separate file or files, that is not Covered Software. + +1.8. "License" + means this document. + +1.9. "Licensable" + means having the right to grant, to the maximum extent possible, + whether at the time of the initial grant or subsequently, any and + all of the rights conveyed by this License. + +1.10. "Modifications" + means any of the following: + + (a) any file in Source Code Form that results from an addition to, + deletion from, or modification of the contents of Covered + Software; or + + (b) any new file in Source Code Form that contains any Covered + Software. + +1.11. "Patent Claims" of a Contributor + means any patent claim(s), including without limitation, method, + process, and apparatus claims, in any patent Licensable by such + Contributor that would be infringed, but for the grant of the + License, by the making, using, selling, offering for sale, having + made, import, or transfer of either its Contributions or its + Contributor Version. + +1.12. "Secondary License" + means either the GNU General Public License, Version 2.0, the GNU + Lesser General Public License, Version 2.1, the GNU Affero General + Public License, Version 3.0, or any later versions of those + licenses. + +1.13. "Source Code Form" + means the form of the work preferred for making modifications. + +1.14. "You" (or "Your") + means an individual or a legal entity exercising rights under this + License. For legal entities, "You" includes any entity that + controls, is controlled by, or is under common control with You. For + purposes of this definition, "control" means (a) the power, direct + or indirect, to cause the direction or management of such entity, + whether by contract or otherwise, or (b) ownership of more than + fifty percent (50%) of the outstanding shares or beneficial + ownership of such entity. + +2. License Grants and Conditions +-------------------------------- + +2.1. Grants + +Each Contributor hereby grants You a world-wide, royalty-free, +non-exclusive license: + +(a) under intellectual property rights (other than patent or trademark) + Licensable by such Contributor to use, reproduce, make available, + modify, display, perform, distribute, and otherwise exploit its + Contributions, either on an unmodified basis, with Modifications, or + as part of a Larger Work; and + +(b) under Patent Claims of such Contributor to make, use, sell, offer + for sale, have made, import, and otherwise transfer either its + Contributions or its Contributor Version. + +2.2. Effective Date + +The licenses granted in Section 2.1 with respect to any Contribution +become effective for each Contribution on the date the Contributor first +distributes such Contribution. + +2.3. Limitations on Grant Scope + +The licenses granted in this Section 2 are the only rights granted under +this License. No additional rights or licenses will be implied from the +distribution or licensing of Covered Software under this License. +Notwithstanding Section 2.1(b) above, no patent license is granted by a +Contributor: + +(a) for any code that a Contributor has removed from Covered Software; + or + +(b) for infringements caused by: (i) Your and any other third party's + modifications of Covered Software, or (ii) the combination of its + Contributions with other software (except as part of its Contributor + Version); or + +(c) under Patent Claims infringed by Covered Software in the absence of + its Contributions. + +This License does not grant any rights in the trademarks, service marks, +or logos of any Contributor (except as may be necessary to comply with +the notice requirements in Section 3.4). + +2.4. Subsequent Licenses + +No Contributor makes additional grants as a result of Your choice to +distribute the Covered Software under a subsequent version of this +License (see Section 10.2) or under the terms of a Secondary License (if +permitted under the terms of Section 3.3). + +2.5. Representation + +Each Contributor represents that the Contributor believes its +Contributions are its original creation(s) or it has sufficient rights +to grant the rights to its Contributions conveyed by this License. + +2.6. Fair Use + +This License is not intended to limit any rights You have under +applicable copyright doctrines of fair use, fair dealing, or other +equivalents. + +2.7. Conditions + +Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted +in Section 2.1. + +3. Responsibilities +------------------- + +3.1. Distribution of Source Form + +All distribution of Covered Software in Source Code Form, including any +Modifications that You create or to which You contribute, must be under +the terms of this License. You must inform recipients that the Source +Code Form of the Covered Software is governed by the terms of this +License, and how they can obtain a copy of this License. You may not +attempt to alter or restrict the recipients' rights in the Source Code +Form. + +3.2. Distribution of Executable Form + +If You distribute Covered Software in Executable Form then: + +(a) such Covered Software must also be made available in Source Code + Form, as described in Section 3.1, and You must inform recipients of + the Executable Form how they can obtain a copy of such Source Code + Form by reasonable means in a timely manner, at a charge no more + than the cost of distribution to the recipient; and + +(b) You may distribute such Executable Form under the terms of this + License, or sublicense it under different terms, provided that the + license for the Executable Form does not attempt to limit or alter + the recipients' rights in the Source Code Form under this License. + +3.3. Distribution of a Larger Work + +You may create and distribute a Larger Work under terms of Your choice, +provided that You also comply with the requirements of this License for +the Covered Software. If the Larger Work is a combination of Covered +Software with a work governed by one or more Secondary Licenses, and the +Covered Software is not Incompatible With Secondary Licenses, this +License permits You to additionally distribute such Covered Software +under the terms of such Secondary License(s), so that the recipient of +the Larger Work may, at their option, further distribute the Covered +Software under the terms of either this License or such Secondary +License(s). + +3.4. Notices + +You may not remove or alter the substance of any license notices +(including copyright notices, patent notices, disclaimers of warranty, +or limitations of liability) contained within the Source Code Form of +the Covered Software, except that You may alter any license notices to +the extent required to remedy known factual inaccuracies. + +3.5. Application of Additional Terms + +You may choose to offer, and to charge a fee for, warranty, support, +indemnity or liability obligations to one or more recipients of Covered +Software. However, You may do so only on Your own behalf, and not on +behalf of any Contributor. You must make it absolutely clear that any +such warranty, support, indemnity, or liability obligation is offered by +You alone, and You hereby agree to indemnify every Contributor for any +liability incurred by such Contributor as a result of warranty, support, +indemnity or liability terms You offer. You may include additional +disclaimers of warranty and limitations of liability specific to any +jurisdiction. + +4. Inability to Comply Due to Statute or Regulation +--------------------------------------------------- + +If it is impossible for You to comply with any of the terms of this +License with respect to some or all of the Covered Software due to +statute, judicial order, or regulation then You must: (a) comply with +the terms of this License to the maximum extent possible; and (b) +describe the limitations and the code they affect. Such description must +be placed in a text file included with all distributions of the Covered +Software under this License. Except to the extent prohibited by statute +or regulation, such description must be sufficiently detailed for a +recipient of ordinary skill to be able to understand it. + +5. Termination +-------------- + +5.1. The rights granted under this License will terminate automatically +if You fail to comply with any of its terms. However, if You become +compliant, then the rights granted under this License from a particular +Contributor are reinstated (a) provisionally, unless and until such +Contributor explicitly and finally terminates Your grants, and (b) on an +ongoing basis, if such Contributor fails to notify You of the +non-compliance by some reasonable means prior to 60 days after You have +come back into compliance. Moreover, Your grants from a particular +Contributor are reinstated on an ongoing basis if such Contributor +notifies You of the non-compliance by some reasonable means, this is the +first time You have received notice of non-compliance with this License +from such Contributor, and You become compliant prior to 30 days after +Your receipt of the notice. + +5.2. If You initiate litigation against any entity by asserting a patent +infringement claim (excluding declaratory judgment actions, +counter-claims, and cross-claims) alleging that a Contributor Version +directly or indirectly infringes any patent, then the rights granted to +You by any and all Contributors for the Covered Software under Section +2.1 of this License shall terminate. + +5.3. In the event of termination under Sections 5.1 or 5.2 above, all +end user license agreements (excluding distributors and resellers) which +have been validly granted by You or Your distributors under this License +prior to termination shall survive termination. + +************************************************************************ +* * +* 6. Disclaimer of Warranty * +* ------------------------- * +* * +* Covered Software is provided under this License on an "as is" * +* basis, without warranty of any kind, either expressed, implied, or * +* statutory, including, without limitation, warranties that the * +* Covered Software is free of defects, merchantable, fit for a * +* particular purpose or non-infringing. The entire risk as to the * +* quality and performance of the Covered Software is with You. * +* Should any Covered Software prove defective in any respect, You * +* (not any Contributor) assume the cost of any necessary servicing, * +* repair, or correction. This disclaimer of warranty constitutes an * +* essential part of this License. No use of any Covered Software is * +* authorized under this License except under this disclaimer. * +* * +************************************************************************ + +************************************************************************ +* * +* 7. Limitation of Liability * +* -------------------------- * +* * +* Under no circumstances and under no legal theory, whether tort * +* (including negligence), contract, or otherwise, shall any * +* Contributor, or anyone who distributes Covered Software as * +* permitted above, be liable to You for any direct, indirect, * +* special, incidental, or consequential damages of any character * +* including, without limitation, damages for lost profits, loss of * +* goodwill, work stoppage, computer failure or malfunction, or any * +* and all other commercial damages or losses, even if such party * +* shall have been informed of the possibility of such damages. This * +* limitation of liability shall not apply to liability for death or * +* personal injury resulting from such party's negligence to the * +* extent applicable law prohibits such limitation. Some * +* jurisdictions do not allow the exclusion or limitation of * +* incidental or consequential damages, so this exclusion and * +* limitation may not apply to You. * +* * +************************************************************************ + +8. Litigation +------------- + +Any litigation relating to this License may be brought only in the +courts of a jurisdiction where the defendant maintains its principal +place of business and such litigation shall be governed by laws of that +jurisdiction, without reference to its conflict-of-law provisions. +Nothing in this Section shall prevent a party's ability to bring +cross-claims or counter-claims. + +9. Miscellaneous +---------------- + +This License represents the complete agreement concerning the subject +matter hereof. If any provision of this License is held to be +unenforceable, such provision shall be reformed only to the extent +necessary to make it enforceable. Any law or regulation which provides +that the language of a contract shall be construed against the drafter +shall not be used to construe this License against a Contributor. + +10. Versions of the License +--------------------------- + +10.1. New Versions + +Mozilla Foundation is the license steward. Except as provided in Section +10.3, no one other than the license steward has the right to modify or +publish new versions of this License. Each version will be given a +distinguishing version number. + +10.2. Effect of New Versions + +You may distribute the Covered Software under the terms of the version +of the License under which You originally received the Covered Software, +or under the terms of any subsequent version published by the license +steward. + +10.3. Modified Versions + +If you create software not governed by this License, and you want to +create a new license for such software, you may create and use a +modified version of this License if you rename the license and remove +any references to the name of the license steward (except to note that +such modified license differs from this License). + +10.4. Distributing Source Code Form that is Incompatible With Secondary +Licenses + +If You choose to distribute Source Code Form that is Incompatible With +Secondary Licenses under the terms of this version of the License, the +notice described in Exhibit B of this License must be attached. + +Exhibit A - Source Code Form License Notice +------------------------------------------- + + This Source Code Form is subject to the terms of the Mozilla Public + License, v. 2.0. If a copy of the MPL was not distributed with this + file, You can obtain one at http://mozilla.org/MPL/2.0/. + +If it is not possible or desirable to put the notice in a particular +file, then You may include the notice in a location (such as a LICENSE +file in a relevant directory) where a recipient would be likely to look +for such a notice. + +You may add additional accurate notices of copyright ownership. + +Exhibit B - "Incompatible With Secondary Licenses" Notice +--------------------------------------------------------- + + This Source Code Form is "Incompatible With Secondary Licenses", as + defined by the Mozilla Public License, v. 2.0. diff --git a/README.md b/README.md new file mode 100644 index 0000000..289f5ec --- /dev/null +++ b/README.md @@ -0,0 +1,36 @@ +# asar [![GoDoc](https://godoc.org/layeh.com/asar?status.svg)](https://godoc.org/layeh.com/asar) + +Package asar reads and writes ASAR (Atom-Shell Archive) archives + + import ( + "os" + + "layeh.com/asar" + ) + + + f, err := os.Open("sample.asar") + if err != nil { + panic(err) + } + defer f.Close() + + archive, err := asar.Decode(f) + if err != nil { + panic(err) + } + + test := archive.Find("test", "file.txt") + if test == nil { + panic("file not found") + } + // print contents of test/file.txt in sample.asar + fmt.Println(test.String()) + +## License + +MPL 2.0 + +## Author + +Tim Cooper (tim.cooper@layeh.com) diff --git a/builder.go b/builder.go new file mode 100644 index 0000000..82761d8 --- /dev/null +++ b/builder.go @@ -0,0 +1,80 @@ +package asar // import "b612.me/asar" + +import ( + "io" + "strings" +) + +// Builder helps construct an Entry. +// +// A builder keeps track of the root Entry and the active Entry. When entries +// are added using the Add* methods, they are added as children to the active +// Entry. +type Builder struct { + root, current *Entry +} + +// Root returns the root Entry. +func (b *Builder) Root() *Entry { + return b.root +} + +func (b *Builder) init() { + if b.root == nil { + b.root = &Entry{ + Flags: FlagDir, + } + b.current = b.root + } +} + +// Parent sets the active entry to the parent of the active Entry (i.e. moves up +// a level). +// +// The function panics if called on the root Entry. +func (b *Builder) Parent() *Builder { + if b.current == b.root { + panic("root has no parent") + } + b.current = b.current.Parent + return b +} + +// AddString adds a new file Entry whose contents are the given string. +func (b *Builder) AddString(name, contents string, flags Flag) *Builder { + return b.Add(name, strings.NewReader(contents), int64(len(contents)), flags) +} + +// Add adds a new file Entry. +func (b *Builder) Add(name string, ra io.ReaderAt, size int64, flags Flag) *Builder { + b.init() + + child := &Entry{ + Name: name, + Size: size, + Flags: flags, + Parent: b.current, + + r: ra, + } + b.current.Children = append(b.current.Children, child) + + return b +} + +// AddDir adds a new directory Entry. The active Entry is switched to this newly +// added Entry. +func (b *Builder) AddDir(name string, flags Flag) *Builder { + b.init() + + child := &Entry{ + Name: name, + Flags: flags | FlagDir, + Parent: b.current, + } + + b.current.Children = append(b.current.Children, child) + b.current = child + + return b +} diff --git a/cmd/asar/main.go b/cmd/asar/main.go new file mode 100644 index 0000000..59cdc0a --- /dev/null +++ b/cmd/asar/main.go @@ -0,0 +1,97 @@ +package main // import "b612.me/cmd/asar" + +import ( + "flag" + "fmt" + "os" + "path/filepath" + + "b612.me/asar" +) + +func main() { + flag.Usage = func() { + fmt.Fprintf(os.Stderr, "usage: %s [options] [command]\n", os.Args[0]) + fmt.Fprintf(os.Stderr, "Commands:\n") + fmt.Fprintf(os.Stderr, "\n") + fmt.Fprintf(os.Stderr, " l|list \n") + fmt.Fprintf(os.Stderr, " list contents of asar archive\n") + fmt.Fprintf(os.Stderr, " x|extract \n") + fmt.Fprintf(os.Stderr, " extract contents of asar archive to directory\n") + fmt.Fprintf(os.Stderr, "\n") + flag.PrintDefaults() + } + flag.Parse() + + if flag.NArg() < 2 { + flag.Usage() + os.Exit(3) + } + + file, err := os.Open(flag.Arg(1)) + if err != nil { + fmt.Fprintf(os.Stderr, "asar: %s\n", err) + os.Exit(1) + } + defer file.Close() + + root, err := asar.Decode(file) + if err != nil { + fmt.Fprintf(os.Stderr, "asar: %s\n", err) + os.Exit(1) + } + + switch command := flag.Arg(0); command { + case "l", "list": + root.Walk(func(path string, _ os.FileInfo, _ error) error { + fmt.Println("/" + path) + return nil + }) + + case "x", "extract": + if flag.NArg() < 3 { + flag.Usage() + os.Exit(1) + } + + target := flag.Arg(2) + + err := root.Walk(func(path string, info os.FileInfo, _ error) error { + entry := info.Sys().(*asar.Entry) + + realPath := filepath.Join(target, path) + if entry.Flags&asar.FlagDir != 0 { + return os.MkdirAll(realPath, 0755) + } + if entry.Flags&asar.FlagUnpacked != 0 { + return nil + } + + perm := os.FileMode(0644) + if entry.Flags&asar.FlagExecutable != 0 { + perm |= 0111 + } + + f, err := os.OpenFile(realPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, perm) + if err != nil { + return err + } + + _, err = entry.WriteTo(f) + if err != nil { + f.Close() + return err + } + + if err := f.Close(); err != nil { + return err + } + + return nil + }) + if err != nil { + fmt.Fprintf(os.Stderr, "asar: %s\n", err) + os.Exit(1) + } + } +} diff --git a/decoder.go b/decoder.go new file mode 100644 index 0000000..e2bacc2 --- /dev/null +++ b/decoder.go @@ -0,0 +1,64 @@ +package asar // import "b612.me/asar" + +import ( + "encoding/binary" + "errors" + "io" +) + +var ( + errMalformed = errors.New("asar: malformed archive") +) + +// Decode decodes the ASAR archive in ra. +// +// Returns the root element and nil on success. nil and an error is returned on +// failure. +func Decode(ra io.ReaderAt) (*Entry, error) { + headerSize := uint32(0) + headerStringSize := uint32(0) + + // [pickle object header (4 bytes) == 4] + // [pickle uint32 = $header_object_size] + { + var buff [8]byte + if n, _ := ra.ReadAt(buff[:], 0); n != 8 { + return nil, errMalformed + } + + dataSize := binary.LittleEndian.Uint32(buff[:4]) + if dataSize != 4 { + return nil, errMalformed + } + headerSize = binary.LittleEndian.Uint32(buff[4:8]) + } + + // [pickle object header (4 bytes)] + // [pickle data header (4 bytes) == $string_size] + // [pickle string ($string_size bytes)] + { + var buff [8]byte + if n, _ := ra.ReadAt(buff[:], 8); n != 8 { + return nil, errMalformed + } + + headerObjectSize := binary.LittleEndian.Uint32(buff[:4]) + if headerObjectSize != headerSize-4 { + return nil, errMalformed + } + + headerStringSize = binary.LittleEndian.Uint32(buff[4:8]) + } + + // read header string + headerSection := io.NewSectionReader(ra, 8+8, int64(headerStringSize)) + baseOffset := 8 + int64(headerSize) + baseOffset += baseOffset % 4 // pickle objects are uint32 aligned + + root, err := decodeHeader(ra, headerSection, baseOffset) + if err != nil { + return nil, err + } + + return root, nil +} diff --git a/decoder_test.go b/decoder_test.go new file mode 100644 index 0000000..551684e --- /dev/null +++ b/decoder_test.go @@ -0,0 +1,91 @@ +package asar // import "b612.me/asar" + +import ( + "bytes" + "io/ioutil" + "os" + "path/filepath" + "testing" +) + +func TestExtractThis(t *testing.T) { + f, err := os.Open("testdata/extractthis.asar") + if err != nil { + t.Fatal(err) + } + defer f.Close() + + root, err := Decode(f) + if err != nil { + t.Fatal(err) + } + + if root.Flags&FlagDir == 0 { + t.Fatal("expecting root directory to have FlagDir") + } + + { + f1 := root.Find("dir1", "file1.txt") + if f1 == nil { + t.Fatal("could not find dir1/file1.txt") + } + if f1.Path() != "dir1/file1.txt" { + t.Fatal("unexpected path") + } + body, err := ioutil.ReadAll(f1.Open()) + if err != nil { + t.Fatal(err) + } + if !bytes.Equal(body, []byte(`file one.`)) { + t.Fatalf("dir1/file1.txt body is incorrect (got %s)", body) + } + } + + { + f2 := root.Find("dir2").Find("file3.txt") + if f2 == nil { + t.Fatal("could not find dir2/file3.txt") + } + s := f2.String() + if s != `123` { + t.Fatalf("dir2/file3.txt body is incorrect (got %s)", s) + } + } + + { + empty := root.Find("emptyfile.txt") + if empty == nil { + t.Fatal("could not find emptyfile.txt") + } + if len(empty.Bytes()) != 0 { + t.Fatal("expecting emptyfile.txt to be empty") + } + } + + { + var i int + root.Walk(func(_ string, _ os.FileInfo, _ error) error { + i++ + return nil + }) + + if i != 7 { + t.Fatalf("expected to walk over 7 items, got %d", i) + } + } + + { + var i int + root.Walk(func(_ string, fi os.FileInfo, _ error) error { + i++ + if fi.IsDir() { + return filepath.SkipDir + } + return nil + }) + + if i != 4 { + t.Fatalf("expected to walk over 4 items, got %d", i) + } + } +} diff --git a/doc.go b/doc.go new file mode 100644 index 0000000..537cfb9 --- /dev/null +++ b/doc.go @@ -0,0 +1,2 @@ +// Package asar reads and writes ASAR (Atom-Shell Archive) archives. +package asar // import "b612.me/asar" diff --git a/encoder.go b/encoder.go new file mode 100644 index 0000000..6a16864 --- /dev/null +++ b/encoder.go @@ -0,0 +1,131 @@ +package asar // import "b612.me/asar" + +import ( + "bytes" + "encoding/binary" + "encoding/json" + "io" + "strconv" +) + +type entryEncoder struct { + Contents []io.Reader + CurrentOffset int64 + Header bytes.Buffer + Encoder *json.Encoder +} + +func (enc *entryEncoder) Write(v interface{}) { + enc.Encoder.Encode(v) + enc.Header.Truncate(enc.Header.Len() - 1) // cut off trailing new line +} + +func (enc *entryEncoder) WriteField(key string, v interface{}) { + enc.Write(key) + enc.Header.WriteByte(':') + enc.Write(v) +} + +func (enc *entryEncoder) Encode(e *Entry) error { + enc.Header.WriteByte('{') + if e.Flags&FlagDir != 0 { + if e.Flags&FlagUnpacked != 0 { + enc.WriteField("unpacked", true) + enc.Header.WriteByte(',') + } + enc.Write("files") + enc.Header.WriteString(":{") + for i, child := range e.Children { + if i > 0 { + enc.Header.WriteByte(',') + } + if !validFilename(child.Name) { + panic(errHeader) + } + enc.Write(child.Name) + enc.Header.WriteByte(':') + if err := enc.Encode(child); err != nil { + return err + } + } + enc.Header.WriteByte('}') + } else { + enc.Write("size") + enc.Header.WriteByte(':') + enc.Write(e.Size) + + if e.Flags&FlagExecutable != 0 { + enc.Header.WriteByte(',') + enc.WriteField("executable", true) + } + + enc.Header.WriteByte(',') + if e.Flags&FlagUnpacked == 0 { + enc.WriteField("offset", strconv.FormatInt(enc.CurrentOffset, 10)) + enc.CurrentOffset += e.Size + enc.Contents = append(enc.Contents, io.NewSectionReader(e.r, e.Offset+e.baseOffset, e.Size)) + } else { + enc.WriteField("unpacked", true) + } + } + enc.Header.WriteByte('}') + return nil +} + +// EncodeTo writes an ASAR archive containing Entry's descendants. This function +// is usally called on the root entry. +func (e *Entry) EncodeTo(w io.Writer) (n int64, err error) { + + defer func() { + if r := recover(); r != nil { + if e := r.(error); e != nil { + err = e + } else { + panic(r) + } + } + + }() + + encoder := entryEncoder{} + { + var reserve [16]byte + encoder.Header.Write(reserve[:]) + } + encoder.Encoder = json.NewEncoder(&encoder.Header) + if err = encoder.Encode(e); err != nil { + return + } + + length := encoder.Header.Len() - 16 + var newLen int + { + var padding [3]byte + if mod := length % 4; mod != 0 { + encoder.Header.Write(padding[:4-mod]) + } + newLen = encoder.Header.Len() - 16 + } + + header := encoder.Header.Bytes() + binary.LittleEndian.PutUint32(header[:4], 4) + binary.LittleEndian.PutUint32(header[4:8], 8+uint32(newLen)) + binary.LittleEndian.PutUint32(header[8:12], 4+uint32(newLen)) + binary.LittleEndian.PutUint32(header[12:16], uint32(length)) + + n, err = encoder.Header.WriteTo(w) + if err != nil { + return + } + + for _, chunk := range encoder.Contents { + var written int64 + written, err = io.Copy(w, chunk) + n += written + if err != nil { + return + } + } + + return +} diff --git a/encoder_test.go b/encoder_test.go new file mode 100644 index 0000000..52b825c --- /dev/null +++ b/encoder_test.go @@ -0,0 +1,29 @@ +package asar // import "b612.me/asar" + +import ( + "io/ioutil" + "strings" + "testing" +) + +func TestEncodeInvalidName(t *testing.T) { + root := New(".", nil, 0, 0, FlagDir) + root.Children = append( + root.Children, + New(".", strings.NewReader("test"), 4, 0, FlagNone), + ) + if _, err := root.EncodeTo(ioutil.Discard); err == nil { + t.Fatal("we should have had an error") + } +} + +func TestEncodeUnpacked(t *testing.T) { + root := New(".", nil, 0, 0, FlagDir) + root.Children = append( + root.Children, + New("sample", nil, 0, 0, FlagUnpacked), + ) + if _, err := root.EncodeTo(ioutil.Discard); err != nil { + t.Fatalf("err: %s", err) + } +} diff --git a/entry.go b/entry.go new file mode 100644 index 0000000..7b3198d --- /dev/null +++ b/entry.go @@ -0,0 +1,231 @@ +package asar // import "b612.me/asar" + +import ( + "errors" + "io" + "io/ioutil" + "os" + "path/filepath" + "strings" + "time" +) + +// Flag is a bit field of Entry flags. +type Flag uint32 + +const ( + // FlagNone denotes an entry with no flags. + FlagNone Flag = 0 + // FlagDir denotes a directory entry. + FlagDir Flag = 1 << iota + // FlagExecutable denotes a file with the executable bit set. + FlagExecutable + // FlagUnpacked denotes that the entry's contents are not included in + // the archive. + FlagUnpacked +) + +// Entry is a file or a folder in an ASAR archive. +type Entry struct { + Name string + Size int64 + Offset int64 + Flags Flag + Parent *Entry + Children []*Entry + + r io.ReaderAt + baseOffset int64 +} + +// New creates a new Entry. +func New(name string, ra io.ReaderAt, size, offset int64, flags Flag) *Entry { + return &Entry{ + Name: name, + Size: size, + Offset: offset, + Flags: flags, + + r: ra, + } +} + +// FileInfo returns the os.FileInfo information about the entry. +func (e *Entry) FileInfo() os.FileInfo { + return fileInfo{e} +} + +type fileInfo struct { + e *Entry +} + +func (f fileInfo) Name() string { + return f.e.Name +} + +func (f fileInfo) Size() int64 { + return f.e.Size +} + +func (f fileInfo) Mode() os.FileMode { + if f.e.Flags&FlagDir != 0 { + return 0555 | os.ModeDir + } + + if f.e.Flags&FlagExecutable != 0 { + return 0555 + } + + return 0444 +} + +func (f fileInfo) ModTime() time.Time { + return time.Time{} +} + +func (f fileInfo) IsDir() bool { + return f.e.Flags&FlagDir != 0 +} + +func (f fileInfo) Sys() interface{} { + return f.e +} + +// Path returns the file path to the entry. +// +// For example, given the following tree structure: +// +// root +// - sub1 +// - sub2 +// - file2.jpg +// +// file2.jpg's path would be: +// +// sub2/file2.jpg +func (e *Entry) Path() string { + if e.Parent == nil { + return "" + } + + var p []string + + for e != nil && e.Parent != nil { + p = append(p, e.Name) + e = e.Parent + } + + l := len(p) / 2 + for i := 0; i < l; i++ { + j := len(p) - i - 1 + p[i], p[j] = p[j], p[i] + } + + return strings.Join(p, "/") +} + +// Open returns an *io.SectionReader of the entry's contents. nil is returned if +// the entry cannot be opened (e.g. because it is a directory). +func (e *Entry) Open() *io.SectionReader { + if e.Flags&FlagDir != 0 || e.Flags&FlagUnpacked != 0 { + return nil + } + return io.NewSectionReader(e.r, e.baseOffset+e.Offset, e.Size) +} + +// WriteTo writes the entry's contents to the given writer. nil is returned if the entry cannot +// be opened (e.g. if the entry is a directory). +func (e *Entry) WriteTo(w io.Writer) (n int64, err error) { + r := e.Open() + if r == nil { + return 0, errors.New("asar: entry cannot be opened") + } + return io.Copy(w, r) +} + +// Bytes returns the entry's contents as a byte slice. nil is returned if the +// entry cannot be read. +func (e *Entry) Bytes() []byte { + body := e.Open() + if body == nil { + return nil + } + b, err := ioutil.ReadAll(body) + if err != nil { + return nil + } + return b +} + +// Bytes returns the entry's contents as a string. nil is returned if the entry +// cannot be read. +func (e *Entry) String() string { + body := e.Bytes() + if body == nil { + return "" + } + return string(body) +} + +// Find searches for a sub-entry of the current entry. nil is returned if the +// requested sub-entry cannot be found. +// +// For example, given the following tree structure: +// +// root +// - sub1 +// - sub2 +// - sub2.1 +// - file2.jpg +// +// The following expression would return the .jpg *Entry: +// +// root.Find("sub2", "sub2.1", "file2.jpg") +func (e *Entry) Find(path ...string) *Entry { +pathLoop: + for _, name := range path { + for _, child := range e.Children { + if child.Name == name { + e = child + continue pathLoop + } + } + return nil + } + return e +} + +// Walk recursively walks over the entry's children. See filepath.Walk and +// filepath.WalkFunc for more information. +func (e *Entry) Walk(walkFn filepath.WalkFunc) error { + return walk(e, "", walkFn) +} + +func walk(e *Entry, parentPath string, walkFn filepath.WalkFunc) error { + for i := 0; i < len(e.Children); i++ { + child := e.Children[i] + childPath := parentPath + child.Name + + err := walkFn(childPath, child.FileInfo(), nil) + if err == filepath.SkipDir { + continue + } + if err != nil { + return err + } + if child.Flags&FlagDir == 0 { + continue + } + if err := walk(child, childPath+"/", walkFn); err != nil { + return err + } + } + return nil +} + +func validFilename(filename string) bool { + if filename == "." || filename == ".." { + return false + } + return strings.IndexAny(filename, "\x00\\/") == -1 +} diff --git a/go.mod b/go.mod new file mode 100644 index 0000000..77f9fb5 --- /dev/null +++ b/go.mod @@ -0,0 +1,3 @@ +module b612.me/asar + +go 1.17 diff --git a/header.go b/header.go new file mode 100644 index 0000000..8ee9df9 --- /dev/null +++ b/header.go @@ -0,0 +1,212 @@ +package asar // import "b612.me/asar" + +import ( + "encoding/json" + "errors" + "io" +) + +var ( + errHeader = errors.New("asar: invalid file header") +) + +type jsonReader struct { + ASAR io.ReaderAt + BaseOffset int64 + D *json.Decoder + Token json.Token +} + +func (j *jsonReader) Peek() json.Token { + if j.Token != nil { + return j.Token + } + tkn, err := j.D.Token() + if err != nil { + if err == io.EOF { + return nil + } + panic(err) + } + j.Token = tkn + return tkn +} + +func (j *jsonReader) HasDelimRune(r rune) bool { + peek := j.Peek() + ru, ok := peek.(json.Delim) + if !ok { + return false + } + if rune(ru) != r { + return false + } + return true +} + +func (j *jsonReader) Next() json.Token { + if j.Token != nil { + t := j.Token + j.Token = nil + return t + } + + tkn, err := j.D.Token() + if err != nil { + if err == io.EOF { + return nil + } + panic(err) + } + return tkn +} + +func (j *jsonReader) NextDelimRune() rune { + tkn := j.Next() + r, ok := tkn.(json.Delim) + if !ok { + panic(errHeader) + } + return rune(r) +} + +func (j *jsonReader) ExpectDelim(r rune) { + next := j.NextDelimRune() + if next != r { + panic(errHeader) + } +} + +func (j *jsonReader) ExpectBool() bool { + tkn := j.Next() + b, ok := tkn.(bool) + if !ok { + panic(errHeader) + } + return b +} + +func (j *jsonReader) ExpectString() string { + next := j.Next() + str, ok := next.(string) + if !ok { + panic(errHeader) + } + return str +} + +func (j *jsonReader) ExpectStringVal(val string) { + str := j.ExpectString() + if str != val { + panic(errHeader) + } +} + +func (j *jsonReader) ExpectInt64() int64 { + var number json.Number + switch j.Peek().(type) { + case string: + number = json.Number(j.ExpectString()) + case json.Number: + number = j.Next().(json.Number) + default: + panic(errHeader) + } + val, err := number.Int64() + if err != nil { + panic(errHeader) + } + return val +} + +func parseRoot(r *jsonReader) *Entry { + entry := &Entry{ + Flags: FlagDir, + } + + r.ExpectDelim('{') + r.ExpectStringVal("files") + parseFiles(r, entry) + r.ExpectDelim('}') + if r.Next() != nil { + panic(errHeader) + } + return entry +} + +func parseFiles(r *jsonReader, parent *Entry) { + r.ExpectDelim('{') + for !r.HasDelimRune('}') { + parseEntry(r, parent) + } + r.ExpectDelim('}') +} + +func parseEntry(r *jsonReader, parent *Entry) { + name := r.ExpectString() + if name == "" { + panic(errHeader) + } + if !validFilename(name) { + panic(errHeader) + } + + r.ExpectDelim('{') + + child := &Entry{ + Name: name, + Parent: parent, + } + + for !r.HasDelimRune('}') { + switch r.ExpectString() { + case "files": + child.Flags |= FlagDir + parseFiles(r, child) + case "size": + child.Size = r.ExpectInt64() + case "offset": + child.Offset = r.ExpectInt64() + case "unpacked": + if r.ExpectBool() { + child.Flags |= FlagUnpacked + } + case "executable": + if r.ExpectBool() { + child.Flags |= FlagExecutable + } + default: + panic(errHeader) + } + } + + if child.Flags&FlagDir == 0 { + child.r = r.ASAR + child.baseOffset = r.BaseOffset + } + + parent.Children = append(parent.Children, child) + r.ExpectDelim('}') +} + +func decodeHeader(asar io.ReaderAt, header *io.SectionReader, offset int64) (entry *Entry, err error) { + decoder := json.NewDecoder(header) + decoder.UseNumber() + reader := jsonReader{ + ASAR: asar, + BaseOffset: offset, + D: decoder, + } + defer func() { + if r := recover(); r != nil { + if e := r.(error); e != nil { + err = e + } else { + panic(r) + } + } + + }() + entry = parseRoot(&reader) + return +} diff --git a/testdata/LICENSE b/testdata/LICENSE new file mode 100644 index 0000000..4d231b4 --- /dev/null +++ b/testdata/LICENSE @@ -0,0 +1,20 @@ +Copyright (c) 2014 GitHub Inc. + +Permission is hereby granted, free of charge, to any person obtaining +a copy of this software and associated documentation files (the +"Software"), to deal in the Software without restriction, including +without limitation the rights to use, copy, modify, merge, publish, +distribute, sublicense, and/or sell copies of the Software, and to +permit persons to whom the Software is furnished to do so, subject to +the following conditions: + +The above copyright notice and this permission notice shall be +included in all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE +LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. diff --git a/testdata/extractthis-unpack-dir.asar b/testdata/extractthis-unpack-dir.asar new file mode 100644 index 0000000..02cbd14 Binary files /dev/null and b/testdata/extractthis-unpack-dir.asar differ diff --git a/testdata/extractthis-unpack.asar b/testdata/extractthis-unpack.asar new file mode 100644 index 0000000..82ffbfa Binary files /dev/null and b/testdata/extractthis-unpack.asar differ diff --git a/testdata/extractthis.asar b/testdata/extractthis.asar new file mode 100644 index 0000000..1f4934a Binary files /dev/null and b/testdata/extractthis.asar differ diff --git a/testdata/extractthis/dir1/file1.txt b/testdata/extractthis/dir1/file1.txt new file mode 100644 index 0000000..2649b94 --- /dev/null +++ b/testdata/extractthis/dir1/file1.txt @@ -0,0 +1 @@ +file one. \ No newline at end of file diff --git a/testdata/extractthis/dir2/file2.png b/testdata/extractthis/dir2/file2.png new file mode 100644 index 0000000..a3986de Binary files /dev/null and b/testdata/extractthis/dir2/file2.png differ diff --git a/testdata/extractthis/dir2/file3.txt b/testdata/extractthis/dir2/file3.txt new file mode 100644 index 0000000..d800886 --- /dev/null +++ b/testdata/extractthis/dir2/file3.txt @@ -0,0 +1 @@ +123 \ No newline at end of file diff --git a/testdata/extractthis/emptyfile.txt b/testdata/extractthis/emptyfile.txt new file mode 100644 index 0000000..e69de29 diff --git a/testdata/extractthis/file0.txt b/testdata/extractthis/file0.txt new file mode 100644 index 0000000..2f993a3 --- /dev/null +++ b/testdata/extractthis/file0.txt @@ -0,0 +1 @@ +file0 content \ No newline at end of file