feat(c-api) Add the `WASMER_VERSION` constants, and the `wasmer_version` functions #1916

Hywan · 2020-12-10T16:05:24Z

Description

~~This PR adds the wasmer_version. It compute a string based on the CARGO_PKG_VERSION environment variable value at compile-time. I know an enum could be better, but it's a start.~~

This PR adds 4 C constants:

#define WASMER_VERSION "1.0.0-beta1"
#define WASMER_VERSION_MAJOR 1
#define WASMER_VERSION_MINOR 0
#define WASMER_VERSION_PATCH 0
#define WASMER_VERSION_PRE "beta1"

Thay way, the user can query the version of Wasmer more easily.

In addition, it adds 4 functions (when the header files aren't accessible):

const char* wasmer_version(void);
uint8_t wasmer_version_major(void);
uint8_t wasmer_version_minor(void);
uint8_t wasmer_version_patch(void);
const char* wasmer_version_pre(void);

Review

Add a short description of the the change to the CHANGELOG.md file

Hywan · 2020-12-10T16:09:09Z

bors try

bors · 2020-12-10T16:50:13Z

try

Build succeeded:

syrusakbary · 2020-12-10T18:31:35Z

lib/c-api/src/lib.rs

+/// # }
+/// ```
+#[no_mangle]
+pub extern "C" fn wasmer_version() -> *mut c_char {


Should it be *const c_char ?

same as @syrusakbary, why a *mut?

So that the user doesn't need to cast it when freeing it. That's stupid, but I think it's a better ergonomic.

tl;dr: It avoids writing this:

const char* version = wasmer_version(); free((char*) version); // this cast

MarkMcCaskey

We'll need to fix the free bug before we can ship this but otherwise looks good

MarkMcCaskey · 2020-12-10T18:48:14Z

lib/c-api/src/lib.rs

+///     printf("%s", version);
+///
+///     // Free it, as we own it.
+///     free(version);


From the docs:

The pointer which this function returns must be returned to Rust and reconstituted using CString::from_raw to be properly deallocated. Specifically, one should not use the standard C free() function to deallocate this string.

I don't think we can ever mix C and Rust ownership: CString is an owned type on the Rust side, we can't pass it back to C without providing our own destructor. Probably simpler to have the user pass us a buffer or to return a pointer to a static string which does not need to be freed

lib/c-api/wasmer.h

syrusakbary

Note: I did the comments as an approval by mistake.

Actually, I think there might be a better solution than a function that returns a string.

Since we are generating the headers at build time, we can check what the version is for the crate, and add that as a constant string variable in the generated header file.

Thoughts @Hywan @MarkMcCaskey @jubianchi ?

syrusakbary · 2020-12-11T00:42:08Z

Let's use:

static const char * WASMER_VERSION = "1.0.0";

MarkMcCaskey · 2020-12-11T00:45:26Z

Note: I did the comments as an approval by mistake.

Actually, I think there might be a better solution than a function that returns a string.

Since we are generating the headers at build time, we can check what the version is for the crate, and add that as a constant string variable in the generated header file.

Thoughts @Hywan @MarkMcCaskey @jubianchi ?

Yeah, that makes sense, though we should probably use a C macro:

#define WASMER_VERSION "version-number"

because static variables take up space and can collide with each other when linking and stuff

MarkMcCaskey · 2020-12-11T00:46:37Z

Actually, this has one major draw back... perhaps we want to do both, but it's nice to have a standard API for querying which version of Wasmer you're running against. This will be important with 1.0.0 when we have more claims to stability and users may ship code that dynamically links against the Wasmer C API and may want to query what version it's running against

syrusakbary · 2020-12-11T00:47:15Z

Actually, this has one major draw back... perhaps we want to do both, but it's nice to have a standard API for querying which version of Wasmer you're running against. This will be important with 1.0.0 when we have more claims to stability and users may ship code that dynamically links against the Wasmer C API and may want to query what version it's running against

Yup, that's the same I was thinking. Let's do it via macro and static string then?

MarkMcCaskey · 2020-12-11T00:50:23Z

Actually, this has one major draw back... perhaps we want to do both, but it's nice to have a standard API for querying which version of Wasmer you're running against. This will be important with 1.0.0 when we have more claims to stability and users may ship code that dynamically links against the Wasmer C API and may want to query what version it's running against

Yup, that's the same I was thinking. Let's do it via macro and static string then?

Yeah, a static string works but the static has to be defined on the Rust side, not the C side, or it has the same problem as the macro

Hywan · 2020-12-11T09:33:38Z

Actually, I think there might be a better solution than a function that returns a string.

Of course there is! This PR was a kickstart for the discussion :-).

Hywan · 2020-12-11T10:00:06Z

I wonder whether it's required to add a C function for that. I've added the following C constants, and I believe the user can query everything that is common with those:

#define WASMER_VERSION "1.0.0-beta1"
#define WASMER_VERSION_MAJOR 1
#define WASMER_VERSION_MINOR 0
#define WASMER_VERSION_PATCH 0
#define WASMER_VERSION_PRE "beta1"

Note that _MAJOR, _MINOR and _PATCH are integers, not strings.

Thoughts?

…s in C.

Hywan · 2020-12-11T13:01:29Z

bors try

bors · 2020-12-11T13:29:44Z

try

Build succeeded:

syrusakbary · 2020-12-11T16:17:50Z

Yeah, a static string works but the static has to be defined on the Rust side, not the C side, or it has the same problem as the macro

This was not addressed @Hywan

When the `.h` files aren't accessible, it is useful to get a function to retrieve the version of the Wasmer C API.

jubianchi

Seems good but:

What about having wasmer_version_major(), wasmer_version_minor(), wasmer_version_patch()?
We also have to expose the pre-release part if we want a "full" API;

Hywan · 2020-12-14T12:46:14Z

bors r+

bors · 2020-12-14T13:33:05Z

Build succeeded:

feat(c-api) Add the wasmer_version function.

b5fb4d0

Hywan added 🎉 enhancement New feature! 📦 lib-c-api About wasmer-c-api 🧪 tests I love tests 📚 documentation Do you like to read? labels Dec 10, 2020

Hywan self-assigned this Dec 10, 2020

Hywan requested review from jubianchi and MarkMcCaskey as code owners December 10, 2020 16:05

Hywan added the 1.0 Wasmer at 1.0 label Dec 10, 2020

Hywan added 2 commits December 10, 2020 17:08

doc(changelog) Add wasmerio#1916.

417fc26

chore(c-api) Update the header files.

685ef32

bors bot added a commit that referenced this pull request Dec 10, 2020

Try #1916:

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syrusakbary approved these changes Dec 10, 2020

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syrusakbary reviewed Dec 10, 2020

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MarkMcCaskey reviewed Dec 10, 2020

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syrusakbary approved these changes Dec 10, 2020

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Hywan added 2 commits December 11, 2020 10:35

Merge branch 'master' into feat-c-api-version

18f388d

feat(c-api) Add the WASMER_VERSION constant in C.

fdeb4a6

feat(c-api) Add the WASMER_VERSION_{MAJOR|MINOR|PATCH|PRE} constant…

2ce2c9c

…s in C.

Hywan force-pushed the feat-c-api-version branch from 13d38f3 to 2ce2c9c Compare December 11, 2020 10:03

doc(changelog) Update wasmerio#1916.

a0abe41

Hywan changed the title ~~feat(c-api) Add the wasmer_version function~~ feat(c-api) Add the WASMER_VERSION* C constants Dec 11, 2020

bors bot added a commit that referenced this pull request Dec 11, 2020

Try #1916:

e881a8f

Hywan added 4 commits December 14, 2020 10:31

Merge branch 'master' into feat-c-api-version

7f085e3

feat(c-api) Implement the wasmer_version function.

3a8a0d3

When the `.h` files aren't accessible, it is useful to get a function to retrieve the version of the Wasmer C API.

chore(c-api) Update the header files.

f75eb29

doc(changelog) Update wasmerio#1916.

43caa8a

jubianchi reviewed Dec 14, 2020

View reviewed changes

Hywan added 3 commits December 14, 2020 13:42

feat(c-api) Add wasmer_version_(major,minor,patch,pre) functions.

f4e3f2a

chore(c-api) Update the header files.

b045b41

doc(changelog) Update wasmerio#1916.

110c6aa

Hywan changed the title ~~feat(c-api) Add the WASMER_VERSION* C constants~~ feat(c-api) Add the WASMER_VERSION* constants, and the wasmer_version* functions Dec 14, 2020

bors bot merged commit 35e0021 into wasmerio:master Dec 14, 2020

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feat(c-api) Add the `WASMER_VERSION` constants, and the `wasmer_version` functions #1916

feat(c-api) Add the `WASMER_VERSION` constants, and the `wasmer_version` functions #1916

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feat(c-api) Add the WASMER_VERSION* constants, and the wasmer_version* functions #1916

feat(c-api) Add the WASMER_VERSION* constants, and the wasmer_version* functions #1916

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feat(c-api) Add the `WASMER_VERSION` constants, and the `wasmer_version` functions #1916

feat(c-api) Add the `WASMER_VERSION` constants, and the `wasmer_version` functions #1916

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