libmuslim Rust binding
libmuslim-rs is the official Rust binding for libmuslim. It wraps the C headers in a safe, idiomatic API: invalid input is rejected by the type system or returned as a Result, and no unsafe is required of the caller.
The C sources are vendored into the crate and compiled by a build script, so there is no system libmuslim to install and nothing to link by hand. Adding the crate is the whole installation.
Package name and import name
The crates.io package is libmuslim-rs, but the Rust library it produces is named libmuslim. Your Cargo.toml names the first and your use statements name the second.
cargo add libmuslim-rs
use libmuslim::prayertimes::calculate;
The minimum supported Rust version is 1.85. A C compiler is required at build time, since the vendored C sources are compiled as part of the crate.
Modules
| Module | Wraps | Purpose |
|---|---|---|
libmuslim::prayertimes | prayertimes.h | Pure astronomy. Turns a date, location and explicit UTC offset into prayer times. |
libmuslim::timezone | timezone.h | Optional. Resolves the UTC offset for an IANA time zone at an instant, with daylight saving applied. |
prayertimes never consults a time zone database. It takes the offset you give it and does arithmetic. timezone exists only so you do not have to work that offset out yourself, and you can ignore the module entirely if you already know it.
What the binding adds over the C API
The binding is deliberately thin. It exposes what the headers expose and nothing more, so there are no calculation features here that the C library does not have. What it does add is enforcement of the contracts the C API documents but cannot check.
Values are validated on construction rather than on use. Date, Coordinates and UtcOffset are constructed through fallible constructors, so an out-of-range latitude or a 31 February is rejected at the point you create it, not silently folded into a wrong answer several calls later.
Failures are values, not sentinels. Where the C API returns a sentinel that overlaps a legitimate result, the Rust API returns a Result. CalculationMethod::from_str distinguishes a genuine Custom from an unrecognized name, and timezone::offset_at distinguishes real UTC from a zone the host cannot resolve.
Results are checked before they reach you. A non-finite time coming back from C is reported as Error::NonFiniteResult rather than propagating a NaN into your formatting code.
Thread safety
Both modules are safe to call concurrently from any number of threads. Neither takes a lock nor mutates process-global state.
This was not always true. Earlier versions resolved offsets through the C parse_timezone_offset(), which set the process TZ environment variable and so raced with any other thread in the program calling getenv, localtime or tzset. The C library now reads the zone's TZif file directly instead, and the binding no longer serializes calls.
License
libmuslim-rs is released under the MIT License, the same as libmuslim itself.
Continue to the Quick start for a complete working program, or jump to the API reference for every type and function.