User's Guide
Reference Manual
Release Notes
PDF
Top

STDLIB
Reference Manual
Version 1.16.5

Expand All
Contract All

Table of Contents

# zip

### MODULE

zip

### MODULE SUMMARY

Utility for reading and creating 'zip' archives.

### DESCRIPTION

The zip module archives and extract files to and from a zip archive. The zip format is specified by the "ZIP Appnote.txt" file available on PKWare's website www.pkware.com.

The zip module supports zip archive versions up to 6.1. However, password-protection and Zip64 is not supported.

By convention, the name of a zip file should end in ".zip". To abide to the convention, you'll need to add ".zip" yourself to the name.

Zip archives are created with the zip/2 or the zip/3 function. (They are also available as create, to resemble the erl_tar module.)

To extract files from a zip archive, use the unzip/1 or the unzip/2 function. (They are also available as extract.)

To return a list of the files in a zip archive, use the list_dir/1 or the list_dir/2 function. (They are also available as table.)

To print a list of files to the Erlang shell, use either the t/1 or tt/1 function.

In some cases, it is desirable to open a zip archive, and to unzip files from it file by file, without having to reopen the archive. The functions zip_open, zip_get, zip_list_dir and zip_close do this.

### LIMITATIONS

Zip64 archives are not currently supported.

Password-protected and encrypted archives are not currently supported

Only the DEFLATE (zlib-compression) and the STORE (uncompressed data) zip methods are supported.

The size of the archive is limited to 2 G-byte (32 bits).

Comments for individual files is not supported when creating zip archives. The zip archive comment for the whole zip archive is supported.

There is currently no support for altering an existing zip archive. To add or remove a file from an archive, the whole archive must be recreated.

### DATA TYPES

    zip_file()

The record zip_file contains the following fields.

name = string()

  the name of the file

info = file_info()

  file info as in file:read_file_info/1

comment = string()

  the comment for the file in the zip archive

offset = integer()

  the offset of the file in the zip archive (used internally)

comp_size = integer()

  the compressed size of the file (the uncompressed size is found in info)

    zip_comment

The record zip_comment just contains the archive comment for a zip archive

comment = string()

  the comment for the zip archive

### EXPORTS

zip(Name, FileList) -> RetValue
zip(Name, FileList, Options) -> RetValue
create(Name, FileList) -> RetValue
create(Name, FileList, Options) -> RetValue

Types:

Name = filename()
FileList = [FileSpec]
FileSpec = filename() | {filename(), binary()}
Options = [Option]
Option = memory | cooked | verbose | {comment, Comment} | {cwd, CWD} | {compress, What} | {uncompress, What}
What = all | [Extension] | {add, [Extension]} | {del, [Extension]}
Extension = string()
Comment = CWD = string()
RetValue = {ok, Name} | {ok, {Name, binary()}} | {error, Reason}
Reason = term()

The zip function creates a zip archive containing the files specified in FileList.

As synonyms, the functions create/2 and create/3 are provided, to make it resemble the erl_tar module.

The file-list is a list of files, with paths relative to the current directory, they will be stored with this path in the archive. Files may also be specified with data in binaries, to create an archive directly from data.

Files will be compressed using the DEFLATE compression, as described in the Appnote.txt file. However, files will be stored without compression if they already are compressed. The zip/2 and zip/3 checks the file extension to see whether the file should be stored without compression. Files with the following extensions are not compressed: .Z, .zip, .zoo, .arc, .lzh, .arj.

It is possible to override the default behavior and explicitly control what types of files that should be compressed by using the {compress, What} and {uncompress, What} options. It is possible to have several compress and uncompress options. In order to trigger compression of a file, its extension must match with the compress condition and must not match the uncompress condition. For example if compress is set to ["gif", "jpg"] and uncompress is set to ["jpg"], only files with "gif" as extension will be compressed. No other files will be compressed.

The following options are available:

cooked

  By default, the open/2 function will open the zip file in raw mode, which is faster but does not allow a remote (erlang) file server to be used. Adding cooked to the mode list will override the default and open the zip file without the raw option. The same goes for the files added.

verbose

  Print an informational message about each file being added.

memory

  The output will not be to a file, but instead as a tuple {FileName, binary()}. The binary will be a full zip archive with header, and can be extracted with for instance unzip/2.

{comment, Comment}

  Add a comment to the zip-archive.

{cwd, CWD}

  Use the given directory as current directory, it will be prepended to file names when adding them, although it will not be in the zip-archive. (Acting like a file:set_cwd/1, but without changing the global cwd property.)

{compress, What}

  Controls what types of files that will be compressed. It is by default set to all. The following values of What are allowed:

  all

    means that all files will be compressed (as long as they pass the uncompress condition).

  [Extension]

    means that only files with exactly these extensions will be compressed.

  {add,[Extension]}

    adds these extensions to the list of compress extensions.

  {del,[Extension]}

    deletes these extensions from the list of compress extensions.

{uncompress, What}

  Controls what types of files that will be uncompressed. It is by default set to [".Z",".zip",".zoo",".arc",".lzh",".arj"]. The following values of What are allowed:

  all

    means that no files will be compressed.

  [Extension]

    means that files with these extensions will be uncompressed.

  {add,[Extension]}

    adds these extensions to the list of uncompress extensions.

  {del,[Extension]}

    deletes these extensions from the list of uncompress extensions.

unzip(Archive) -> RetValue
unzip(Archive, Options) -> RetValue
extract(Archive) -> RetValue
extract(Archive, Options) -> RetValue

Types:

Archive = filename() | binary()
Options = [Option]
Option = {file_list, FileList} | keep_old_files | verbose | memory | {file_filter, FileFilter} | {cwd, CWD}
FileList = [filename()]
FileBinList = [{filename(),binary()}]
FileFilter = fun(ZipFile) -> true | false
CWD = string()
ZipFile = zip_file()
RetValue = {ok,FileList} | {ok,FileBinList} | {error, Reason} | {error, {Name, Reason}}
Reason = term()

The unzip/1 function extracts all files from a zip archive. The unzip/2 function provides options to extract some files, and more.

If the Archive argument is given as a binary, the contents of the binary is assumed to be a zip archive, otherwise it should be a filename.

The following options are available:

{file_list, FileList}

  By default, all files will be extracted from the zip archive. With the {file_list,FileList} option, the unzip/2 function will only extract the files whose names are included in FileList. The full paths, including the names of all sub directories within the zip archive, must be specified.

cooked

  By default, the open/2 function will open the zip file in raw mode, which is faster but does not allow a remote (erlang) file server to be used. Adding cooked to the mode list will override the default and open zip file without the raw option. The same goes for the files extracted.

keep_old_files

  By default, all existing files with the same name as file in the zip archive will be overwritten. With the keep_old_files option, the unzip/2 function will not overwrite any existing files. Not that even with the memory option given, which means that no files will be overwritten, files existing will be excluded from the result.

verbose

  Print an informational message as each file is being extracted.

memory

  Instead of extracting to the current directory, the memory option will give the result as a list of tuples {Filename, Binary}, where Binary is a binary containing the extracted data of the file named Filename in the zip archive.

{cwd, CWD}

  Use the given directory as current directory, it will be prepended to file names when extracting them from the zip-archive. (Acting like a file:set_cwd/1, but without changing the global cwd property.)

list_dir(Archive) -> RetValue
list_dir(Archive, Options)
table(Archive) -> RetValue
table(Archive, Options)

Types:

Archive = filename() | binary()
RetValue = {ok, [Comment, Files]} | {error, Reason}
Comment = zip_comment()
Files = [zip_file()]
Options = [Option]
Option = cooked
Reason = term()

The list_dir/1 function retrieves the names of all files in the zip archive Archive. The list_dir/2 function provides options.

As synonyms, the functions table/2 and table/3 are provided, to make it resemble the erl_tar module.

The result value is the tuple {ok, List}, where List contains the zip archive comment as the first element.

The following options are available:

cooked

  By default, the open/2 function will open the zip file in raw mode, which is faster but does not allow a remote (erlang) file server to be used. Adding cooked to the mode list will override the default and open zip file without the raw option.

t(Archive)

Types:

Archive = filename() | binary() | ZipHandle
ZipHandle = pid()

The t/1 function prints the names of all files in the zip archive Archive to the Erlang shell. (Similar to "tar t".)

tt(Archive)

Types:

Archive = filename() | binary()

The tt/1 function prints names and information about all files in the zip archive Archive to the Erlang shell. (Similar to "tar tv".)

zip_open(Archive) -> {ok, ZipHandle} | {error, Reason}
zip_open(Archive, Options) -> {ok, ZipHandle} | {error, Reason}

Types:

Archive = filename() | binary()
Options = [Option]
Options = cooked | memory | {cwd, CWD}
CWD = string()
ZipHandle = pid()

The zip_open function opens a zip archive, and reads and saves its directory. This means that subsequently reading files from the archive will be faster than unzipping files one at a time with unzip.

The archive must be closed with zip_close/1.

zip_list_dir(ZipHandle) -> Result | {error, Reason}

Types:

Result = [ZipComment, ZipFile...]
ZipComment = #zip_comment{}
ZipFile = #zip_file{}
ZipHandle = pid()

The zip_list_dir/1 function returns the file list of an open zip archive.

zip_get(ZipHandle) -> {ok, [Result]} | {error, Reason}
zip_get(FileName, ZipHandle) -> {ok, Result} | {error, Reason}

Types:

FileName = filename()
ZipHandle = pid()
Result = filename() | {filename(), binary()}

The zip_get function extracts one or all files from an open archive.

The files will be unzipped to memory or to file, depending on the options given to the zip_open function when the archive was opened.

zip_close(ZipHandle) -> ok | {error, einval}

Types:

ZipHandle = pid()

The zip_close/1 function closes a zip archive, previously opened with zip_open. All resources are closed, and the handle should not be used after closing.