A portable (OSX/Linux/Windows/Android/iOS), simple zip library written in C

This is done by hacking awesome miniz library and layering functions on top of the miniz v3.1.2 API.

The Idea

... Some day, I was looking for zip library written in C for my project, but I could not find anything simple enough and lightweight. Everything what I tried required 'crazy mental gymnastics' to integrate or had some limitations or was too heavy. I hate frameworks, factories and adding new dependencies. If I must to install all those dependencies and link new library, I'm getting almost sick. I wanted something powerful and small enough, so I could add just a few files and compile them into my project. And finally I found miniz. Miniz is a lossless, high performance data compression library in a single source file. I only needed simple interface to append buffers or files to the current zip-entry. Thanks to this feature I'm able to merge many files/buffers and compress them on-the-fly.

It was the reason, why I decided to write zip module on top of the miniz. It required a little bit hacking and wrapping some functions, but I kept simplicity. So, you can grab these 3 files and compile them into your project. I hope that interface is also extremely simple, so you will not have any problems to understand it.

Examples

• Create a new zip archive with default compression level.

struct zip_t *zip = zip_open("foo.zip", ZIP_DEFAULT_COMPRESSION_LEVEL, 'w');
{
    zip_entry_open(zip, "foo-1.txt");
    {
        const char *buf = "Some data here...\0";
        zip_entry_write(zip, buf, strlen(buf));
    }
    zip_entry_close(zip);

    zip_entry_open(zip, "foo-2.txt");
    {
        // merge 3 files into one entry and compress them on-the-fly.
        zip_entry_fwrite(zip, "foo-2.1.txt");
        zip_entry_fwrite(zip, "foo-2.2.txt");
        zip_entry_fwrite(zip, "foo-2.3.txt");
    }
    zip_entry_close(zip);
}
zip_close(zip);

• Append to the existing zip archive.

struct zip_t *zip = zip_open("foo.zip", ZIP_DEFAULT_COMPRESSION_LEVEL, 'a');
{
    zip_entry_open(zip, "foo-3.txt");
    {
        const char *buf = "Append some data here...\0";
        zip_entry_write(zip, buf, strlen(buf));
    }
    zip_entry_close(zip);
}
zip_close(zip);

• Extract a zip archive into a folder.

int on_extract_entry(const char *filename, void *arg) {
    static int i = 0;
    int n = *(int *)arg;
    printf("Extracted: %s (%d of %d)\n", filename, ++i, n);

    return 0;
}

// From "foo.zip" on disk
int arg = 2;
zip_extract("foo.zip", "/tmp", on_extract_entry, &arg);

// Or from memory
arg = 2;
zip_stream_extract(zipstream, zipstreamsize, "/tmp", on_extract_entry, &arg);

• Extract a zip entry into memory.

void *buf = NULL;
size_t bufsize;

struct zip_t *zip = zip_open("foo.zip", 0, 'r');
{
    zip_entry_open(zip, "foo-1.txt");
    {
        zip_entry_read(zip, &buf, &bufsize);
    }
    zip_entry_close(zip);
}
zip_close(zip);

free(buf);

• Extract a zip entry into memory (no internal allocation).

unsigned char *buf;
size_t bufsize;

struct zip_t *zip = zip_open("foo.zip", 0, 'r');
{
    zip_entry_open(zip, "foo-1.txt");
    {
        bufsize = zip_entry_size(zip);
        buf = calloc(sizeof(unsigned char), bufsize);

        zip_entry_noallocread(zip, (void *)buf, bufsize);
    }
    zip_entry_close(zip);
}
zip_close(zip);

free(buf);

• Extract a zip entry into memory using callback.

struct buffer_t {
    char *data;
    size_t size;
};

static size_t on_extract(void *arg, unsigned long long offset, const void *data, size_t size) {
    struct buffer_t *buf = (struct buffer_t *)arg;
    buf->data = realloc(buf->data, buf->size + size + 1);
    assert(NULL != buf->data);

    memcpy(&(buf->data[buf->size]), data, size);
    buf->size += size;
    buf->data[buf->size] = 0;

    return size;
}

struct buffer_t buf = {0};
struct zip_t *zip = zip_open("foo.zip", 0, 'r');
{
    zip_entry_open(zip, "foo-1.txt");
    {
        zip_entry_extract(zip, on_extract, &buf);
    }
    zip_entry_close(zip);
}
zip_close(zip);

free(buf.data);

• Extract a zip entry into a file.

struct zip_t *zip = zip_open("foo.zip", 0, 'r');
{
    zip_entry_open(zip, "foo-2.txt");
    {
        zip_entry_fread(zip, "foo-2.txt");
    }
    zip_entry_close(zip);
}
zip_close(zip);

• Create a new zip archive in memory (stream API).

char *outbuf = NULL;
size_t outbufsize = 0;

const char *inbuf = "Append some data here...\0";
struct zip_t *zip = zip_stream_open(NULL, 0, ZIP_DEFAULT_COMPRESSION_LEVEL, 'w');
{
    zip_entry_open(zip, "foo-1.txt");
    {
        zip_entry_write(zip, inbuf, strlen(inbuf));
    }
    zip_entry_close(zip);

    /* copy compressed stream into outbuf */
    zip_stream_copy(zip, (void **)&outbuf, &outbufsize);
}
zip_stream_close(zip);

free(outbuf);

• Extract a zip entry into memory (stream API).

char *buf = NULL;
size_t bufsize = 0;

struct zip_t *zip = zip_stream_open(zipstream, zipstreamsize, 0, 'r');
{
    zip_entry_open(zip, "foo-1.txt");
    {
        zip_entry_read(zip, (void **)&buf, &bufsize);
    }
    zip_entry_close(zip);
}
zip_stream_close(zip);

free(buf);

• Extract a partial zip entry

Reads up to size bytes of the entry starting at offset into a caller-owned buffer (no internal allocation). size is clamped to the bytes remaining after offset, so it is safe to pass a size larger than what is left in the entry. The call returns the number of bytes actually written, or a negative error code (for example when offset is past the end of the entry).

unsigned char buf[16];
size_t bufsize = sizeof(buf);

struct zip_t *zip = zip_open("foo.zip", 0, 'r');
{
    zip_entry_open(zip, "foo-1.txt");
    {
        size_t offset = 4;
        ssize_t nread = zip_entry_noallocreadwithoffset(zip, offset, bufsize, (void *)buf);
        if (nread < 0) {
            // offset out of range or read error
        }
    }

    zip_entry_close(zip);
}
zip_close(zip);

• List of all zip entries

struct zip_t *zip = zip_open("foo.zip", 0, 'r');
int i, n = zip_entries_total(zip);
for (i = 0; i < n; ++i) {
    zip_entry_openbyindex(zip, i);
    {
        const char *name = zip_entry_name(zip);
        int isdir = zip_entry_isdir(zip);
        int issymlink = zip_entry_issymlink(zip);
        unsigned long long size = zip_entry_size(zip);
        unsigned int crc32 = zip_entry_crc32(zip);
    }
    zip_entry_close(zip);
}
zip_close(zip);

• Compress folder (recursively)

void zip_walk(struct zip_t *zip, const char *path) {
    DIR *dir;
    struct dirent *entry;
    char fullpath[MAX_PATH];
    struct stat s;

    memset(fullpath, 0, MAX_PATH);
    dir = opendir(path);
    assert(dir);

    while ((entry = readdir(dir))) {
      // skip "." and ".."
      if (!strcmp(entry->d_name, ".\0") || !strcmp(entry->d_name, "..\0"))
        continue;

      snprintf(fullpath, sizeof(fullpath), "%s/%s", path, entry->d_name);
      stat(fullpath, &s);
      if (S_ISDIR(s.st_mode))
        zip_walk(zip, fullpath);
      else {
        zip_entry_open(zip, fullpath);
        zip_entry_fwrite(zip, fullpath);
        zip_entry_close(zip);
      }
    }

    closedir(dir);
}

• Delete zip archive entries.

char *entries[] = {"unused.txt", "remove.ini", "delete.me"};
// size_t indices[] = {0, 1, 2};

struct zip_t *zip = zip_open("foo.zip", 0, 'd');
{
    zip_entries_delete(zip, entries, 3);

    // you can also delete by index, instead of by name
    // zip_entries_deletebyindex(zip, indices, 3);
}
zip_close(zip);

• Create a password-protected zip archive (Traditional PKWARE Encryption).

struct zip_t *zip = zip_open_with_password("secret.zip", ZIP_DEFAULT_COMPRESSION_LEVEL, 'w', "password");
{
    zip_entry_open(zip, "secret-1.txt");
    {
        const char *buf = "Classified data...\0";
        zip_entry_write(zip, buf, strlen(buf));
    }
    zip_entry_close(zip);
}
zip_close(zip);

• Extract a password-protected zip archive.

void *buf = NULL;
size_t bufsize;

struct zip_t *zip = zip_open_with_password("secret.zip", 0, 'r', "password");
{
    zip_entry_open(zip, "secret-1.txt");
    {
        zip_entry_read(zip, &buf, &bufsize);
    }
    zip_entry_close(zip);
}
zip_close(zip);

free(buf);

• Password-protected archive in memory (stream API).

char *outbuf = NULL;
size_t outbufsize = 0;

struct zip_t *zip = zip_stream_open_with_password(NULL, 0, ZIP_DEFAULT_COMPRESSION_LEVEL, 'w', "password");
{
    zip_entry_open(zip, "secret-1.txt");
    {
        const char *buf = "Classified data...\0";
        zip_entry_write(zip, buf, strlen(buf));
    }
    zip_entry_close(zip);

    zip_stream_copy(zip, (void **)&outbuf, &outbufsize);
}
zip_stream_close(zip);

/* read it back */
void *readbuf = NULL;
size_t readsize = 0;

zip = zip_stream_open_with_password(outbuf, outbufsize, 0, 'r', "password");
{
    zip_entry_open(zip, "secret-1.txt");
    {
        zip_entry_read(zip, &readbuf, &readsize);
    }
    zip_entry_close(zip);
}
zip_stream_close(zip);

free(readbuf);
free(outbuf);

• Delete entries from a password-protected archive.

char *entries[] = {"obsolete.txt", "remove-me.dat"};

struct zip_t *zip = zip_open_with_password("secret.zip", 0, 'd', "password");
{
    zip_entries_delete(zip, entries, 2);
}
zip_close(zip);

Bindings

Compile zip library as a dynamic library.

$ mkdir build
$ cd build
$ cmake -DBUILD_SHARED_LIBS=true ..
$ cmake --build .

Go (cgo)

Third party binding: kuba--/c-go-zip

package main

/*
#cgo CFLAGS: -I../src
#cgo LDFLAGS: -L. -lzip
#include <zip.h>
*/
import "C"
import "unsafe"

func main() {
    path := C.CString("/tmp/go.zip")
    zip := C.zip_open(path, 6, 'w')

    entryname := C.CString("test")
    C.zip_entry_open(zip, entryname)

    content := "test content"
    buf := unsafe.Pointer(C.CString(content))
    bufsize := C.size_t(len(content))
    C.zip_entry_write(zip, buf, bufsize)

    C.zip_entry_close(zip)

    C.zip_close(zip)
}

Rust (ffi)

extern crate libc;
use std::ffi::CString;

#[repr(C)]
pub struct Zip {
    _private: [u8; 0],
}

#[link(name = "zip")]
extern "C" {
    fn zip_open(path: *const libc::c_char, level: libc::c_int, mode: libc::c_char) -> *mut Zip;
    fn zip_close(zip: *mut Zip) -> libc::c_void;

    fn zip_entry_open(zip: *mut Zip, entryname: *const libc::c_char) -> libc::c_int;
    fn zip_entry_close(zip: *mut Zip) -> libc::c_int;
    fn zip_entry_write(
        zip: *mut Zip,
        buf: *const libc::c_void,
        bufsize: libc::size_t,
    ) -> libc::c_int;
}

fn main() {
    let path = CString::new("/tmp/rust.zip").unwrap();
    let mode: libc::c_char = 'w' as libc::c_char;

    let entryname = CString::new("test.txt").unwrap();
    let content = "test content\0";

    unsafe {
        let zip: *mut Zip = zip_open(path.as_ptr(), 5, mode);
        {
            zip_entry_open(zip, entryname.as_ptr());
            {
                let buf = content.as_ptr() as *const libc::c_void;
                let bufsize = content.len() as libc::size_t;
                zip_entry_write(zip, buf, bufsize);
            }
            zip_entry_close(zip);
        }
        zip_close(zip);
    }
}

Ruby (ffi)

Install ffi gem.

$ gem install ffi

Bind in your module.

require 'ffi'

module Zip
  extend FFI::Library
  ffi_lib "./libzip.#{::FFI::Platform::LIBSUFFIX}"

  attach_function :zip_open, [:string, :int, :char], :pointer
  attach_function :zip_close, [:pointer], :void

  attach_function :zip_entry_open, [:pointer, :string], :int
  attach_function :zip_entry_close, [:pointer], :void
  attach_function :zip_entry_write, [:pointer, :string, :int], :int
end

ptr = Zip.zip_open("/tmp/ruby.zip", 6, "w" )

status = Zip.zip_entry_open(ptr, "test")

content = "test content"
status = Zip.zip_entry_write(ptr, content, content.size())

Zip.zip_entry_close(ptr)
Zip.zip_close(ptr)

Python (cffi)

Install cffi package

$ pip install cffi

Bind in your package.

import ctypes.util
from cffi import FFI

ffi = FFI()
ffi.cdef("""
    struct zip_t *zip_open(const char *zipname, int level, char mode);
    void zip_close(struct zip_t *zip);

    int zip_entry_open(struct zip_t *zip, const char *entryname);
    int zip_entry_close(struct zip_t *zip);
    int zip_entry_write(struct zip_t *zip, const void *buf, size_t bufsize);
"""
)

Zip = ffi.dlopen(ctypes.util.find_library("zip"))

ptr = Zip.zip_open("/tmp/python.zip", 6, 'w')

status = Zip.zip_entry_open(ptr, "test")

content = "test content"
status = Zip.zip_entry_write(ptr, content, len(content))

Zip.zip_entry_close(ptr)
Zip.zip_close(ptr)

Never (ffi)

extern "libzip.so" func zip_open(zipname: string, level: int, mode: char) -> c_ptr
extern "libzip.so" func zip_close(zip: c_ptr) -> void

extern "libzip.so" func zip_entry_open(zip: c_ptr, entryname: string) -> int
extern "libzip.so" func zip_entry_close(zip: c_ptr) -> int
extern "libzip.so" func zip_entry_write(zip: c_ptr, buf: string, bufsize: int) -> int
extern "libzip.so" func zip_entry_fwrite(zip: c_ptr, filename: string) -> int

func main() -> int
{
    let content = "Test content"

    let zip = zip_open("/tmp/never.zip", 6, 'w');

    zip_entry_open(zip, "test.file");
    zip_entry_fwrite(zip, "/tmp/test.txt");
    zip_entry_close(zip);

    zip_entry_open(zip, "test.content");
    zip_entry_write(zip, content, length(content));
    zip_entry_close(zip);

    zip_close(zip);
    0
}

Ring

The language comes with RingZip based on this library

load "ziplib.ring"

new Zip {
    setFileName("myfile.zip")
    open("w")
    newEntry() {
        open("test.c")
        writefile("test.c")
        close()
    }
    close()
}

Zig

$ zig build-exe main.zig -lc -lzip

const c = @cImport({
    @cInclude("zip.h");
});

pub fn main() void {
    var zip = c.zip_open("/tmp/zig.zip", 6, 'w');
    defer c.zip_close(zip);

    _ = c.zip_entry_open(zip, "test");
    defer _ = c.zip_entry_close(zip);

    const content = "test content";
    _ = c.zip_entry_write(zip, content, content.len);
}

Odin

Third party binding: thechampagne/zip-odin

package main

foreign import lib "system:zip"

import "core:c"

foreign lib {
    zip_open :: proc(zipname : cstring, level : c.int, mode : c.char) -> rawptr ---

    zip_close :: proc(zip : rawptr) ---

    zip_entry_open :: proc(zip : rawptr, entryname : cstring) -> c.int ---

    zip_entry_close :: proc(zip : rawptr) -> c.int ---

    zip_entry_write :: proc(zip : rawptr, buf : rawptr, bufsize : c.size_t) -> c.int ---
}

main :: proc() {
    zip_file := zip_open("odin.zip", 6, 'w')
    defer zip_close(zip_file)

    zip_entry_open(zip_file, "test")
    defer zip_entry_close(zip_file)

    content := "test content";
    zip_entry_write(zip_file, &content, len(content))
}

Nim

Third party binding: thechampagne/nimzip

$ nim c --passL:-lzip main.nim

proc zip_open(zipname: cstring, level: cint, mode: char): pointer {.importc.}
proc zip_close(zip: pointer) {.importc.}
proc zip_entry_open(zip: pointer, entryname: cstring): cint {.importc.}
proc zip_entry_close(zip: pointer): cint {.importc.}
proc zip_entry_write(zip: pointer, buf: pointer, bufsize: csize_t): cint {.importc.}

when isMainModule:
  var zip = zip_open("/tmp/nim.zip", 6, 'w')

  discard zip_entry_open(zip, "test")

  let content: cstring = "test content";
  discard zip_entry_write(zip, content, csize_t(len(content)))

  discard zip_entry_close(zip)
  zip_close(zip)

D

Third party binding: thechampagne/zip-d

$ dmd -L-lzip main.d

extern(C) void* zip_open(const(char)* zipname, int level, char mode);
extern(C) void zip_close(void* zip);
extern(C) int zip_entry_open(void* zip, const(char)* entryname);
extern(C) int zip_entry_close(void* zip);
extern(C) int zip_entry_write(void* zip, const(void)* buf, size_t bufsize);

void main()
{
  void* zip = zip_open("/tmp/d.zip", 6, 'w');
  scope(exit) zip_close(zip);

  zip_entry_open(zip, "test");
  scope(exit) zip_entry_close(zip);

  string content = "test content";
  zip_entry_write(zip, content.ptr, content.length);
}

Pascal

Third party binding: thechampagne/zip-pascal

program main;

{$linklib c}
{$linklib zip}

uses ctypes;

function zip_open(zipname:Pchar; level:longint; mode:char):pointer;cdecl;external;
procedure zip_close(zip:pointer);cdecl;external;
function zip_entry_open(zip:pointer; entryname:Pchar):longint;cdecl;external;
function zip_entry_close(zip:pointer):longint;cdecl;external;
function zip_entry_write(zip:pointer; buf:pointer; bufsize:csize_t):longint;cdecl;external;

const
   content: Pchar = 'test content';
var
   zip : pointer;

begin
   zip := zip_open('/tmp/pascal.zip', 6, 'w');

   zip_entry_open(zip, 'test');

   zip_entry_write(zip, content, strlen(content));
   zip_entry_close(zip);
   zip_close(zip);
end.

lua

Third party binding: gynt/luamemzip

-- Loads the luamemzip.dll
zip = require("luamemzip")

content = "Test content"

z = zip.zip_stream_open(nil, 6, 'w')

zip.zip_entry_open(z, "test.content")
zip.zip_entry_write(z, content)
zip.zip_entry_close(z)

data = zip.zip_stream_copy(z)

zip.zip_close(z)

Optional features

The library supports three compile-time flags to strip unused functionality and reduce binary size. All features are enabled by default -- if you just drop the source files into your project and compile, everything works as before.

With CMake:

# Extract-only build (no compression)
cmake .. -DZIP_ENABLE_DEFLATE=OFF

# Compress-only build (no extraction)
cmake .. -DZIP_ENABLE_INFLATE=OFF

# Disable symlink support
cmake .. -DZIP_HAVE_SYMLINK=OFF

Without CMake (compiler flags):

cc -DZIP_ENABLE_DEFLATE=0 -c zip.c

Or define before including the header:

#define ZIP_ENABLE_DEFLATE 0
#include "zip.h"

No ZIP64

By default, opening an archive for writing with the literal mode character 'w' will enable ZIP64 output. Internally the library sets a write flag when the mode equals the literal 'w':

mz_uint wflags = (mode == 'w') ? MZ_ZIP_FLAG_WRITE_ZIP64 : 0;

To ensure the produced ZIP archive is NOT ZIP64, use the alternate mode value that selects the same semantic mode but does not compare equal to the literal 'w'. The implementation accepts an alternate value in the switch labels (so the same behavior is selected), but only the literal 'w' triggers the automatic ZIP64 flag.

Convention:

• Use 'w' - 64 (integer value 55) when calling zip_open, zip_stream_open, etc., to select write mode without enabling ZIP64.
• The same pattern applies to other modes: use 'r' - 64, 'a' - 64, 'd' - 64 to pick the non-ZIP64 variants.

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