package cstruct-lwt

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Access C-like structures directly from OCaml


Dune Dependency





v6.2.0 2023-02-20

  • Add sub_copy function (@c-cube, #305)

  • Fix documentation (@MisterDA, #304)

  • Add to_hex_string function (@c-cube, #306)

  • Fix documentation and use Cstruct.length instead of Cstruct.len (@reynir, #307)

  • Deprecate copy function (alias of to_string) (will be removed at the next minor release) (@reynir, #308)

v6.1.1 2022-07-24

  • ppx_cstruct: remove superfluous stdlib-shims dependency (@hannesm #300)

v6.1.0 2022-03-29

breaking changes

  • The deprecated functions Cstruct.len, Cstruct.add_len, Cstruct.set_len, and Cstruct.blit_to_string have been removed (@hannesm #291)

  • Implement host_endian (@haesbaert #292, fixes #72)

  • Compatibility with OCaml 5.0.0 (@dinosaure #294)

  • Drop support of OCaml < 4.08.0, remove bigarray-compat dependency (@hannesm #298)

  • Fix year in changes of 6.0.1 (@reynir #297)

v6.0.1 2021-06-25

breaking changes

  • Cstruct.len is deprecated, it will be deleted at the next release. You should use Cstruct.length instead. (@dinosaure, @hannesm, #284)

  • Remove color from ppx's binary to replicate diff of errors in any contexts (@dinosaure, @sternenseemann, #285)

  • Add shiftv (@talex5, @avsm, @dinosaure, #287)

  • Use Bytes_val if available (@hannesm, @avsm, @dinosaure, #286)

v6.0.0 2020-09-10

breaking changes

  • Add the function Cstruct.length, Cstruct.len will be deprecated to next release (@dinosaure, @hannesm, @avsm, #279)

  • Cstruct.to_string requires 2 optional arguments ?off and ?len (@hannesm, @cfcs, @talex5, @dinosaure, #262)

  • Use ppxlib instead ppx_tools_versioned (@pveber, @avsm, @dinosaure, #280)

  • Delete the support of old version of OCaml (< 4.07.0) for ppx_cstruct (@avsm, @dinosaure, #280)

  • Add useful functions to be able to parse some contents with Cstruct.t like the astring library (#227, @dinosaure, @avsm, @samoht, @hannesm).

  • Improve the interface of Cstruct.t with capabilities (@hannesm, @cfcs, @talex5, @dinosaure, #262)

v5.2.0 2020-06-10

Upgrade the ppx_cstruct library to use the OCaml 4.11 AST rather than than OCaml 4.04, which in turn should make it easier to port to ppxlib in the future and improve interoperability with other PPXs (@bikallem #275).

Also upgrades build files to use dune 2.0 (@bikallem #275) and fixes the GitHub Actions versions (@smorimoto #273) and also test OCaml 4.10.0 (@avsm).

v5.1.1 2019-11-23

This is a point release to fix a regression in 5.1.0 on compilers earlier than 4.07.

The release also fixes the test suite and CI on compilers greater than 4.07.

v5.1.0 2019-11-23

  • Do not issue deprecation warnings when using OCaml 4.08.0 and cstruct-ppx with enums due to Pervasives (#269 @cypheon @hannesm)

  • Tighten parsing of the [@len] attribute to ensure it is a valid, positive integer (#265 @emillon)

  • Update JavaScript bindings to latest Js_of_ocaml 3.5.0 interfaces (@hhugo #268)

v5.0.0 2019-04-19

Security: This release tightens bounds checks to ensure that data outside a given view (but still inside the underlying buffer) cannot be accessed.

  • sub does more checks (#244 #245 @hannesm @talex5 review by @dinosaure)

  • add_len and set_len are now deprecated and will be removed in a future release. (#251 @hannesm)

  • do not add user-provided data for bounds checks (#253 @hannesm, report and review by @talex5)

  • improve CI to add fuzzing (#255 #252 @avsm @yomimono @talex5)

Remove Unix dependency: cstruct now uses the new bigarray-compat library instead of Bigarray directly, to avoid a dependency on Unix when using OCaml compilers less than 4.06.0. This will break downstream libraries that do not have a direct dependency on Bigarray. Simply fix it in your library by adding a bigarray dependency in your dune file. (#247 @TheLortex)

Capability module: To improve the safety of future code with stronger type checking, this release introduces a new Cstruct_cap module which makes the underlying Cstruct an abstract type instead of a record. In return for this extra abstraction, the module can enforce read-only, write only, and read/write buffers by tracking them as phantom type variables. Although this library shares an implementation internally with classic Cstruct, it is a significant revision and so we will be gradually migrating to it. Feedback on it is welcome! (#237 @dinosaure and many excited reviewers)

Ppx compare functions: A new compare_X function is generated for cenum declarations. This respects custom ids supplied in the cenum declaration and so is more robust than polymorphic compare (#248 @emillon)

The CI has also been switched over to both Azure Pipelines and Drone in addition to Travis, and as a result the tests all run on Windows, macOS, various Linux distributions, on x86 and arm64 machines, and runs AFL fuzz tests on the Drone cloud (#255 @avsm).

v4.0.0 2019-03-25

  • Sexplib is now an optional library for the base Cstruct module. A new Cstruct_sexp module has been introduced with the serialiser functions, contained within the cstruct-sexp opam package.

    To convert old code, simply use Cstruct_sexp.t instead of Cstruct.t in a record type for which you are using [@@deriving sexp]. This is a type alias to Cstruct.t but also has the right sexp-conversion functions in scope. There is an example of this in the ppx_test/with-sexp directory in the source repo.

    When you have converted and released your library, add an opam constraint of cstruct {>="4.0.0"} to your own opam packages to ensure that they pick up this version of the library. (fixes #222, @avsm)

  • JavaScript stubs are now installed using the jsoo mechanism rather than a manual specification (#241 @jonludlam)

  • Use computed versions in opam files to ensure that dependent opam packages such as cstruct-async get the same base version of cstruct to avoid mismatches. (@avsm)

  • Add a ppx test suite to checks that all error paths in ppx handling are reachable and have meaningful location info (#238 @emillon)

v3.7.0 2019-03-10

  • Improve performance by not doing redundant bounds checks in both the Bigarray and Cstruct level (#236 @Reperator @chambart)

  • Ignore fields starting wih _ by skipping code generation but still respecting the space usage of that field. This was a convention before but is now enforced by the code generator to save space in the output (#233 @emillon)

  • More warnings suppression for sizeof and enums (#231 @emillon)

v3.6.0 2019-03-01

  • A [%%cstruct type ...] declaration generates many values that are potentially unused. The code generator in ppx_cstruct now guarantees that there will be no more "unused value" (warning 32) statements from use of the ppx form. (#228 @emillon)

  • Actually run the ppx tests instead of just building them. (#227 @emillon to fix #226 from @XVilka)

v3.5.0 2019-02-26

  • Remove trailing spaces in hexdump output (#219 @emillon)

  • Add Cstruct.rev to allocate a reversed cstruct (#221 @emillon)

  • Cstruct_unix now uses the post-OCaml 4.06 Unix.map_file instead of the deprecated Bigarray map_file that was removed in OCaml 4.08 (@avsm, see ocaml/ocaml#2263)

  • Remove unnecessary (wrapped false) in the build system (@avsm)

  • Correct ocamldoc to the right cstruct-ppx package pointer (@avsm)

v3.4.0 2019-02-02

  • Remove old compatibility packages for cstruct.lwt, cstruct.async, cstruct.ppx and cstruct.unix. These were deprecated in cstruct.3.0.0 in favour of counter part libraries with a dash in the name (cstruct-lwt, cstruct-async, cstruct.unix) or ppx_cstruct for the PPX extension. (@avsm)

v3.3.0 2019-01-22

  • Support for bi-endian cstructs that generate both sets of accessor functions (#212 by @XVilka). This generates both BE and LE modules to use as needed.

  • Modify of_string and of_bytes to have an option ?off offset argument into the source bytes. (#208 by @XVilka)

  • Improve tests to work on 32-bit architectures and handle Gc better (@samoht)

  • Do not depend explicitly on deprecated ppx_driver. This was primarily there for older compilers, and new uses should be based around ppxlib. (#201 by @edwintorok).

  • Upgrade opam metadata to 2.0 format. (#217 by @XVilka @avsm)

  • Upgrade to dune from jbuilder and support dune-release instead of topkg (@avsm)

v3.2.1 2017-12-13

  • improve performance by using primitives instead of C stubs. the performance regression was introduced in #177 in 3.2.0 (#195 by @pqwy)

v3.2.0 2017-11-17

  • wrap hexdump_pp output in a box (#175 by @cfcs)

  • remove dependency on ocplib-endian (#177 by @hannesm)

  • add of_hex: string -> t (#179 by @hannesm and @pqwy)

  • add to_bytes: t -> Bytes.t (#183 by @hannesm)

  • add empty: t (#184 by @hannesm)

  • sub: check the bounds more carefully for overflow (#185 by @hannesm)

  • cstruct-unix: fix the build on OCaml 4.06.0 (#187 by @djs55)

  • travis: test OCaml 4.04.2 and 4.06.0 (#186 by @hannesm)

v3.1.1 2017-07-13

  • check_alignment now treats a large alignment as an unsigned value and so doesnt raise a signal (#171 by @yallop)

  • Improve Windows support by avoiding void * pointer arithmetic and have more portable headers in the C stubs (#170 by @fdopen)

v3.1.0 2017-07-12

  • Fix arithmetic overflow in Cstruct.lenv and copyv (#159 by @yallop)

  • Reject negative destination offsets in blit (#160 by @yallop)

  • Add AFL fuzz tests using Crowbar, which independently discovered #160 and also an overflow in of_bigarray and sub, now bith fixed (#164 by @talex5)

  • Improve performance of several allocation functions by eliminating an unnecessary buffer zero step (#158 by @hannesm)

  • Compile the source tree with stricter flags, including dead variable detection and deprecation warnings (#157 by @samoht)

  • Bump the required minimum OCaml version up to 4.03.0 (due to #157).

v3.0.2 2017-06-14

  • fix the cstruct-async package build, and depend on the latest Async packages (>="v0.9.0") as part of this. (#152 @jnfoster)

v3.0.1 2017-06-09

  • ppx: remove an errant standalone initialiser that was messing up the composition of cstruct with other ppx_driver based ppx converters (most notably ppx_sexp_conv. If you are having trouble with using ppx_cstruct with other drivers, put a constraint on ppx_cstruct>=3.0.1. (#151 #150 #149 #148 via @djs55 @g2p @avsm @diml).

  • ppx: also add a test case for cstruct and lwt working together, but this will not work until a lwt>3.0 release happens.

  • Update opam rules to use jbuilder subst for version information in the distribution.

  • Fix tests so that check_alignment expects a negative result.

  • Add opam test target for core library.

v3.0.0 2017-05-11

  • Split up OPAM packages into multiple independent ones. We now have a standalone cstruct, and then separate cstruct-lwt, cstruct-async, cstruct-unix packages, and a ppx_cstruct package for the syntax extension. Transitional findlib packages with the old scheme are available, but now packages should migrate to using cstruct-async instead of cstruct.async for example. This has the added benefit of the OPAM package names now matching the findlib names. (#138 by @avsm @rgrinberg).

  • Port build to jbuilder. See the README for local development instructions.

  • Ensure that check_alignment only takes a non-zero argument for alignment (#143 #145 by @cfcs @avsm).

v2.4.1 2017-05-03

  • fix missing ppx_tools_versioned dependency (#136, @let-def)

v2.4.0 2017-03-30

Distribute the PPX extension so that it is compatible with Jbuilder. ppx_cstruct is now distributed as both a library and a binary. Findlib predicates are used to distinguish usage:

  • the binary is used for toplevel and simple -ppx building

  • the library is used for linking custom rewriters

  • -package cstruct.ppx alone uses the binary for rewriting.

  • -package cstruct.ppx -predicates custom_ppx,ppx_driver" is used to link the rewriter.

To use the PPX extension in jbuilder, just add:

  (libraries (cstruct))
  (preprocess (pps (cstruct.ppx)))

to your jbuild file. This may be renamed to ppx_cstruct in a future release so that the PPX dependency is decoupled from the main library, so this cstruct.ppx is intended to be transitional as it is what was originally used.

v2.3.3 2017-03-28

  • Port ppx extension to use ocaml-migrate-parsetree so it should also compile on future revisions of OCaml (#127 via @let-def).

v2.3.2 2017-03-03

  • Add support for OCaml 4.05 for the PPX extension.

  • Docs: correct to description of shift function (#121 via @orbifx).

v2.3.1 2016-12-10

  • Fix a memory leak in the exception printing code (#130 via @djs55)

  • Appveyor CI fixes (#130 via @avsm)

  • Fix typo in docstring (#117 via @yomimono)

  • Fix opam base-unix dependency (#115 via @avsm)

v2.3.0 2016-08-16

  • Add Cstruct.of_bytes/to_bytes. In common with the existing implementation, this relies on the representation of bytes and string being the same, which is true as of OCaml 4.04 and lower (#105 via @yallop).

  • Support OCaml 4.04 (#111 via @gasche).

v2.2.0 2016-06-30

  • Make create zero out the new buffer. The new create_unsafe function can be used if you want to trade safety for speed.

v2.1.0 2016-05-04

  • Add hexdump_pp that uses the Format module. This works better with the Logs library than using hexdump_to_buffer, and also makes it easy to indent the hexdump (#100 via @talex5).

v2.0.0 2016-04-26

  • Remove camlp4 extension as it is no longer maintained (#95).

  • Add support for OCaml 4.03 in the PPX extension (#96).

  • Minimum supported OCaml version for the library is now 4.02.3.

  • Fix parsing of high int32 @@enum values.

  • Move Cstruct.check_alignment into the stubs. Before this patch we returned the buffer address from C and then calculated using OCaml's boxed Int64.t. This patch reduces minor allocations by performing the calculation in the C stubs. This makes the function suitable for use in an assert in a performance sensitive path.

v1.9.0 2016-02-19

  • Add support for a ppx-based extension that uses the extension point support in OCaml 4.02 and higher to generate Cstruct and Cenum function definitions. The new syntax is documented in the README file.

v1.8.0 2016-01-05

  • Add support for -safe-string in OCaml 4.02 upwards. The main change is to rename blit_to_string to blit_to_bytes and change its type so that it writes to bytes rather than string (#74 by @yallop).

  • Remove strong build-time dependency on camlp4 in the base library. The sexplib functions were only used in the interface, so replace them with manually written ones. This also enables compatibility with latest Core that has switched to ppx.

  • Add multi-distro testing via Travis/Docker containers.

v1.7.1 2015-12-15

  • Correct error output for LE.get_uint16 on invalid bounds (#75)

  • Fix fillv. If the source didn't fit in the buffer then we skipped the amount we wanted to copy, not the amount actually copied (#77).

v1.7.0 2015-07-11

  • Add Cstruct.concat and Cstruct.append (#57, @pqwy)

  • Add js_of_ocaml stubs (#63, #64, @djs55)

v1.6.0 2015-03-28

  • Add memset to set all the bytes of a cstruct value efficiently (#49)

  • More useful Invalid_argument parameters (#48).

  • Fix to_sexp to expose only the current view (#44 from David Kaloper).

  • Add compare and equal (#23, #24 and #45 from David Kaloper).

  • Add fillv to copy over a list of buffers (from Thomas Leonard).

  • Shift to centralised Travis scripts.

v1.5.0 2014-11-24

  • Make camlp4 an optional build-time dependency (#35).

  • Remove ounit as a dependency in the opam file.

  • Improve opam description file for OPAM 1.2 workflow (#36).

  • Refresh Merlin IDE description (#37).

v1.4.0 2014-08-10

Comprehensive addition of bounds checking to all cstruct operations (from @pqwy in #33). The major changes are:

  • Disallow negative indexing with all cstruct accessors.

  • Disallow negative sub and shift operations.

  • Make sure of_bigarray cannot create invalid cstruct values.

v1.3.1 2014-07-10

  • Also bounds test single-byte operations on views (#31 via @pqwy).

v1.3.0 2014-07-04

  • Add bounds checks for Cstruct.BE/LE functions that violate a view. Previously, only bounds errors on the underlying buffers would raise. Bug #25, reported by Mindy Preston in mirage/mirage-tcpip#56.

  • Add 'Lwt_cstruct.complete' to ensure that read/write operatiosn run to completion.

  • Add Sexplib conversion functions to Cstruct.t values (#27 #22).

v1.2.0 2014-06-06

Add a sexp optional decorator to cenum to output the values as s-expressions. This is compatible with the sexplib convention. The syntax is;

cenum foo64 {
} as uint64_t(sexp)

And sexp_of_foo64 and foo64_of_sexp functions will also be available. The representation of the Sexp is the string representation of the enum.

v1.1.0 2014-02-19

  • Improve bounds checks on sub, shift, set_len, add_len.

  • Add to_bigarray to convert back into a Bigarray slice.

v1.0.1 2013-12-09

  • Fix Cstruct.shift function

v1.0.0 2013-12-05

  • Remove IPv4/IPv6 types (now moved to ocaml-ipaddr).

  • Improved ocamldoc for the interface.

  • More conservative bounds checking in the length manipulation functions.

  • Build C stubs with -Wall.

v0.8.1 2013-11-06

  • Trailing semicolons are allowed in cstruct field definitions.

  • Buffer elements can be any primitive integer, not just uint8.

v0.8.0 2013-10-13

  • Improved ocamldoc for BE/LE modules.

  • Add Travis-CI test scripts and fix script compilation.

  • Support int32/int64 constant values in cenum like VAL = 0xffffffffl, useful for 32-bit hosts.

  • Check and raise error in case of negative offsets for blits (#4).

  • Correctly preserve the sequence after a constant constructor is set during a cenum definition.

  • Do not repeat the sizeof_<field> binding for every get/set field (should be no externally observable change).

  • Add Cstruct.hexdump_to_buffer to make spooling hexdump output easier.

  • Generate hexdump_foo and hexdump_foo_to_buffer prettyprinting functions for a cstruct foo.

v0.7.1 2013-03-06

  • Add Async_cstruct.Pipe to map pipes of Cstruct buffers to strings or Bigsubstring.

v0.7.0 2013-02-25

  • Add zero-copy conversion functions to/from the Core Bigsubstring.

  • Add an of_string function to simplify the construction from OCaml values.

  • Add Async interface to interoperate with Jane Street Core code.

v0.6.2 2013-02-08

  • Add experimental cstruct.obuild for the obuild build tool.

  • Use bounds checked version of all functions in the external interface.

  • Expose the Cstruct.debug to dump internal state of a buffer to a string.

  • Add set_len and add_len to manipulate the total-length field directly.

v0.6.1 2012-12-20

  • Add sendto, read and recvfrom functions to the Lwt subpackage.

v0.6.0 2012-12-20

  • Add fast bigarray<->string functions to replace byte-by-byte copies.

  • Add an Lwt sub-package to expose a write call.

  • Depend on ocplib-endian for fast low-level parsing of integers.

  • Make Cstruct.t a record type that doesn't use Bigarray slicing to provide views onto buffers. This lets views be allocated directly on the minor heap rather than forcing a major heap allocation. It does alter the external API, so previous users of cstruct wont work.

v0.5.3 2012-12-16

  • No functional changes, just OASIS packaging fix to right version.

v0.5.2 2012-12-11

  • Remove the separate xen and unix subdirectories, as the portable Bigarray is now provided by the xenbigarray package.

v0.5.1 2012-09-28

  • Add string_to_<cenum> function to match the <cenum>_to_string, primarily to help with command-line parsing of enum arguments.

v0.5.0 2012-09-20

  • Add a signature generator for cstruct and cenum to permit their use in .mli files.

  • Use the more reliable revised syntax camlp4 quotation expander, to avoid broken AST output from antiquotations.

  • Switch the xen/ version over to using OASIS also.

v0.4.0 2012-09-02

  • Fix META file for use with Xen

v0.3 2012-08-25

  • Initial public release


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