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Convey mongoc_grigfs_cnv_file_t wrapper

The new functionality provided by this fork allows to compress/uncompress and/or encrypt/decrypt file on the fly while reading/writing from the mongo. Original src mongoc-grigfs-file.c modified to provide hooks: right before chunk write in mongo collection and right after read. mongoc_grigfs_cnv_file_t wrapper uses mongoc_grigfs_file_t internally(object composition) so interface is the same.

Additional functions provided:

  • mongoc_gridfs_cnv_file_is_compressed()
  • mongoc_gridfs_cnv_file_is_encrypted()
  • mongoc_gridfs_cnv_file_get_compressed_length()
  • mongoc_gridfs_cnv_file_set_aes_key()
  • mongoc_gridfs_cnv_file_set_aes_key_from_password()

Instance of mongoc_grigfs_cnv_file_t can be created using functions (similar to mongoc_grigfs_file_t creation functions):

  • mongoc_gridfs_create_cnv_file_from_stream()
  • mongoc_gridfs_create_cnv_file()
  • mongoc_gridfs_find_one_cnv()
  • mongoc_gridfs_find_one_cnv_by_filename()
  • mongoc_gridfs_cnv_file_from_file() // additional function to create from mongoc_grigfs_file_t

this functions accepts additional flags parameter to specify compress/uncompress/encrypt/decrypt behavior

See example-cnv-gridfs example to see how to read/write files using cnv gridfs file(example similar to original example-gridfs). Tests for new functionality available in test-mongoc-gridfs-cnv-file.c

zlib is used for compress/decompress, Brian Gladman's AES implementation(with EAX mode) used for encrypt/decpypt

Data encrypted/compressed chunk-by-chunk, so actual chunk size can be greater or less than file.chunk_size, however because mongoc logic uses file.chunk_size(not actual written chunk size) to calculate offset, seek() function works(even if file size changed due to compression) over compressed file like it's not compressed. Notice that length of compressed file is saved as original(uncompressed) file length, compressed length saved in metadata. Because of tricks with file size and chunks size and implementation of mongoc_grigfs_cnv_file_t that depends on those sizes, it's not possible to read compressed file using mongoc_grigfs_cnv_file_t, you should use mongoc_grigfs_cnv_file_t with MONGOC_CNV_NONE flag.


mongo-c-driver is a client library written in C for MongoDB.

There are absolutely no guarantees of API/ABI stability at this point. But generally, we won't break API/ABI unless we have good reason.

mongo-c-driver depends on Libbson. Libbson will automatically be built if you do not have it installed on your system.

If you are looking for the legacy C driver, it can be found in the legacy branch.

Documentation / Support / Feedback

The documentation is available at For issues with, questions about, or feedback for libmongoc, please look into our support channels. Please do not email any of the libmongoc developers directly with issues or questions - you're more likely to get an answer on the mongodb-user list on Google Groups.

Bugs / Feature Requests

Think you’ve found a bug? Want to see a new feature in libmongoc? Please open a case in our issue management tool, JIRA:

Bug reports in JIRA for all driver projects (i.e. CDRIVER, CSHARP, JAVA) and the Core Server (i.e. SERVER) project are public.

How To Ask For Help

If you are having difficulty building the driver after reading the below instructions, please email the mongodb-user list to ask for help. Please include in your email all of the following information:

  • The version of the driver you are trying to build (branch or tag).
    • Examples: master branch, 1.0.2 tag
  • Host OS, version, and architecture.
    • Examples: Windows 8 64-bit x86, Ubuntu 12.04 32-bit x86, OS X Mavericks
  • C Compiler and version.
    • Examples: GCC 4.8.2, MSVC 2013 Express, clang 3.4, XCode 5
  • The output of ./ or ./configure (depending on whether you are building from a repository checkout or from a tarball). The output starting from "libbson was configured with the following options" is sufficient.

  • The text of the error you encountered.

Failure to include the relevant information will result in additional round-trip communications to ascertain the necessary details, delaying a useful response. Here is a made-up example of a help request that provides the relevant information:

Hello, I'm trying to build the C driver with SSL, from mongo-c-driver-1.1.4.tar.gz. I'm on Ubuntu 14.04, 64-bit Intel, with gcc 4.8.2. I run configure like:

$ ./configure --enable-sasl=yes
checking for gcc... gcc
checking whether the C compiler works... yes

... SNIPPED OUTPUT, but when you ask for help, include full output without any omissions ...

checking for pkg-config... no
checking for SASL... no
checking for sasl_client_init in -lsasl2... no
checking for sasl_client_init in -lsasl... no
configure: error: You must install the Cyrus SASL libraries and development headers to enable SASL support.

Can you tell me what I need to install? Thanks!

Security Vulnerabilities

If you’ve identified a security vulnerability in a driver or any other MongoDB project, please report it according to the instructions here.

Building from Release Tarball

Unless you intend on contributing to the mongo-c-driver, you will want to build from a release tarball.

The most current release is 1.1.4 which you can download here. mongo-c-driver-1.1.4.tar.gz.

To build on UNIX-like systems, do the following:

$ tar xzf mongo-c-driver-1.1.4.tar.gz
$ cd mongo-c-driver-1.1.4
$ ./configure
$ make
$ sudo make install

To see all of the options available to you during configuration, run:

$ ./configure --help

To build on Windows Vista or newer with Visual Studio 2010, do the following:

cd mongo-c-driver-1.1.4
cd src\libbson
cmake -DCMAKE_INSTALL_PREFIX=C:\usr -G "Visual Studio 10 Win64" .
msbuild.exe ALL_BUILD.vcxproj
msbuild.exe INSTALL.vcxproj
cd ..\..
cmake -DCMAKE_INSTALL_PREFIX=C:\usr -DBSON_ROOT_DIR=C:\usr -G "Visual Studio 10 Win64" .
msbuild.exe ALL_BUILD.vcxproj
msbuild.exe INSTALL.vcxproj

Building From Git

mongo-c-driver contains a copy of libbson in the case that your system does not already have libbson installed. The configure script will detect if libbson is not installed and install it too.



$ sudo yum install git gcc automake autoconf libtool


$ sudo apt-get install git gcc automake autoconf libtool


$ su -c 'pkg install git gcc automake autoconf libtool'

Fetch Sources and Build

You can use the following to checkout and build mongo-c-driver:

git clone
cd mongo-c-driver
sudo make install

In standard automake fasion, ./ only needs to be run once. You can use ./configure directly going forward. Also, see ./configure --help for all configure options.

Building on Windows

Currently, the cmake build system for mongo-c-driver does not build the libbson package as well. This needs to be done manually with cmake.

SSL is supported through the use of OpenSSL. SASL is not currently supported but is planned. To enable OpenSSL support, install the appropriate OpenSSL for Windows from here. The instructions below assume 64-bit builds, so you would want to get the version for "Win64 OpenSSL 1.0.1f" which includes libraries and headers.

If you are building from git, and not a release tarball, you also need to initialize the git submodule for libbson:

git submodule init
git submodule update

Then proceed to build and install libbson using cmake and Visual Studio's command line tool, msbuild.exe. You can of course open these project files from Visual Studio as well:

cd src\libbson
cmake -DCMAKE_INSTALL_PREFIX=C:\usr -G "Visual Studio 10 Win64" .
msbuild.exe ALL_BUILD.vcxproj
msbuild.exe INSTALL.vcxproj
cd ..\..
cmake -DCMAKE_INSTALL_PREFIX=C:\usr -DBSON_ROOT_DIR=C:\usr -G "Visual Studio 10 Win64" .
msbuild.exe ALL_BUILD.vcxproj
msbuild.exe INSTALL.vcxproj

Generating the Docs

To generate the documentation you must install the yelp-tools package. On Linux this package can be found in the package manager for your distribution, on OSX we recommend using TingPing's homebrew-gnome tap.

Then use the following ./configure options:

  • --enable-html-docs - builds the HTML documentation
  • --enable-man-pages - builds and installs the man-pages.
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