Initial Query
I want to call some rust code from python on a linux machine. Specifically, I want to be able to run
python3 -c 'import magic; print(magic.do_add(3, 4))'
and have it give me the sum of these numbers. Here, do_add should be a rust function that adds two integers.
Please give me a complete set of instructions for how to make this run, so that when I run this code as-is it will work.
LLM Generation
Query
I want to call some rust code from python on a linux machine. Specifically, I want to be able to run
python3 -c 'import magic; print(magic.do_add(3, 4))'
and have it give me the sum of these numbers. Here, do_add should be a rust function that adds two integers.
Please give me a complete set of instructions for how to make this run, so that when I run this code as-is it will work.
Output
Okay, let's create a Rust library and call it from Python using `ctypes`.
Here are the complete steps:
**1. Prerequisites:**
* **Rust Toolchain:** Ensure you have Rust and Cargo installed. If not, install from [https://rustup.rs/](https://rustup.rs/).
* **Python 3:** Ensure you have Python 3 installed (`python3 --version`).
* **Linux Build Tools:** You'll likely need `gcc` or equivalent C compiler tools, which Rust uses for linking. On Debian/Ubuntu: `sudo apt update && sudo apt install build-essential`. On Fedora: `sudo dnf groupinstall "Development Tools"`.
**2. Create the Rust Project:**
Open your terminal and run these commands:
| # Create a new Rust library project
cargo new --lib magic_lib
cd magic_lib
|
This creates a directory `magic_lib` with a basic library structure.
**3. Write the Rust Code:**
Edit the `magic_lib/src/lib.rs` file and replace its contents with the following:
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21 | // magic_lib/src/lib.rs
// This function adds two 32-bit signed integers.
// #[no_mangle] ensures the function name isn't changed by the compiler.
// pub extern "C" makes it use the C calling convention, compatible with Python's ctypes.
#[no_mangle]
pub extern "C" fn do_add(a: i32, b: i32) -> i32 {
println!("Rust: Adding {} and {}", a, b); // Optional: for debugging
a + b
}
// Optional: Add a simple test within Rust (won't be called by Python)
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn it_adds() {
assert_eq!(do_add(2, 2), 4);
}
}
|
**Explanation:**
* `#[no_mangle]`: Prevents the Rust compiler from "mangling" the function name, ensuring Python can find it as `do_add`.
* `pub extern "C"`: Makes the function public (`pub`) and tells Rust to compile it using the standard C Application Binary Interface (ABI), which `ctypes` understands.
* `a: i32, b: i32`: Takes two 32-bit signed integers as input. This maps well to Python's standard integers via `ctypes.c_int`.
* `-> i32`: Returns a 32-bit signed integer.
**4. Configure Cargo for a C-compatible Dynamic Library:**
Edit the `magic_lib/Cargo.toml` file. Add a `[lib]` section to specify the crate type:
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15 | # magic_lib/Cargo.toml
[package]
name = "magic_lib"
version = "0.1.0"
edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
# Add this section:
[lib]
crate-type = ["cdylib"] # Compile to a C-compatible dynamic library (.so on Linux)
[dependencies]
# No dependencies needed for this simple example
|
**Explanation:**
* `crate-type = ["cdylib"]`: This tells Cargo to build a dynamic library suitable for linking into C programs (and thus callable via Python's `ctypes`). On Linux, this will produce a `.so` file (shared object).
**5. Build the Rust Library:**
Navigate back to the `magic_lib` directory in your terminal (if you aren't already there) and run the build command:
| # Inside the magic_lib directory
cargo build --release
|
* `--release`: Builds an optimized version of the library.
* This command will create the shared library file at `magic_lib/target/release/libmagic_lib.so`. (The name `libmagic_lib.so` comes from `lib` + your crate name `magic_lib` + `.so`).
**6. Create the Python Wrapper Module:**
Now, let's create the Python side. Go *outside* the `magic_lib` directory. Create a new file named `magic.py`:
| # Make sure you are OUTSIDE the magic_lib directory
# For example, if magic_lib is in /home/user/projects/, run 'cd /home/user/projects/'
touch magic.py
|
Edit `magic.py` with the following content:
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66 | # magic.py
import ctypes
import os
# --- Library Loading ---
# Construct the path to the compiled Rust library (.so file)
# It assumes the .so file is located relative to this Python script.
# Adjust this path if your structure is different.
_current_dir = os.path.dirname(os.path.abspath(__file__))
_lib_path = os.path.join(
_current_dir, # Directory containing magic.py
"magic_lib", # The Rust project directory relative to magic.py
"target",
"release",
"libmagic_lib.so" # The actual library file
)
# Check if the library file exists
if not os.path.exists(_lib_path):
raise ImportError(f"Shared library not found at expected path: {_lib_path}\n"
"Did you run 'cargo build --release' in the 'magic_lib' directory?")
# Load the shared library
try:
_lib = ctypes.CDLL(_lib_path)
except OSError as e:
raise ImportError(f"Could not load shared library '{_lib_path}': {e}")
# --- Function Signature Definition ---
# Define the argument types and return type for the Rust function
# This MUST match the Rust function signature.
try:
_do_add_rust = _lib.do_add
_do_add_rust.argtypes = [ctypes.c_int, ctypes.c_int] # Takes two C integers (i32)
_do_add_rust.restype = ctypes.c_int # Returns a C integer (i32)
except AttributeError:
raise ImportError("Function 'do_add' not found in the shared library. "
"Did you use #[no_mangle] and pub extern \"C\" in Rust?")
# --- Python Wrapper Function ---
# Create a user-friendly Python function that calls the Rust function
def do_add(a: int, b: int) -> int:
"""
Adds two integers using the Rust implementation.
"""
if not isinstance(a, int) or not isinstance(b, int):
raise TypeError("Arguments must be integers")
# Call the Rust function loaded via ctypes
result = _do_add_rust(a, b)
print(f"Python: Received {result} from Rust") # Optional: for debugging
return result
# --- Example Usage (optional, runs if script is executed directly) ---
if __name__ == '__main__':
num1 = 10
num2 = 5
sum_result = do_add(num1, num2)
print(f"Python: The sum of {num1} and {num2} is {sum_result}")
try:
print(f"Python: Testing do_add(3, 4) = {do_add(3, 4)}")
except Exception as e:
print(f"Error during test: {e}")
|
**Explanation:**
* `import ctypes, os`: Imports necessary modules.
* `_lib_path`: Constructs the path to the `.so` file. **Crucially**, this assumes `magic.py` is in the *parent* directory of `magic_lib`. Adjust this path if your layout is different.
* `ctypes.CDLL(_lib_path)`: Loads the shared library.
* `_lib.do_add`: Accesses the `do_add` function within the loaded library.
* `.argtypes = [...]`: Tells `ctypes` that the function expects two `c_int` arguments.
* `.restype = ctypes.c_int`: Tells `ctypes` that the function returns a `c_int`.
* `def do_add(...)`: Provides a clean Python interface that handles calling the underlying C-style function.
**7. Run the Python Code:**
Make sure you are in the directory containing `magic.py` (which should also contain the `magic_lib` subdirectory). Now, run the command you specified:
| # Make sure you are in the directory containing magic.py
# (e.g., /home/user/projects/ if magic_lib is /home/user/projects/magic_lib)
python3 -c 'import magic; print(magic.do_add(3, 4))'
|
**Expected Output:**
You should see output similar to this (the order of Rust/Python prints might vary slightly):
| Rust: Adding 3 and 4
Python: Received 7 from Rust
7
|
You have successfully called a Rust function from Python!
LLM Generation
Query
Now please conver this answer into a JSON array that packages it all up so I don't need to think and can just copy files to specific locations and then run things. Format your answer
{"path/to/file": "contents of rust file",
"path/to/python_file": "contents of any necessary python file that exposes do_add",
"build.sh": "contents of a bash file to build the project",
... # any other files necessary
}
The only thing I will do is put files in the right place and run `bash build.sh`. Do not give any explanation of the code. ONLY ANSWER WITH A SINGLE JSON OBJECT. Your answer should start
.
Output
| {
"magic_lib/Cargo.toml": "[package]\nname = \"magic_lib\"\nversion = \"0.1.0\"\nedition = \"2021\"\n\n# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html\n\n[lib]\ncrate-type = [\"cdylib\"] # Compile to a C-compatible dynamic library (.so on Linux)\n\n[dependencies]\n",
"magic_lib/src/lib.rs": "// magic_lib/src/lib.rs\n\n// This function adds two 32-bit signed integers.\n// #[no_mangle] ensures the function name isn't changed by the compiler.\n// pub extern \"C\" makes it use the C calling convention, compatible with Python's ctypes.\n#[no_mangle]\npub extern \"C\" fn do_add(a: i32, b: i32) -> i32 {\n a + b\n}\n",
"magic.py": "import ctypes\nimport os\n\n# --- Library Loading ---\n# Construct the path to the compiled Rust library (.so file)\n_current_dir = os.path.dirname(os.path.abspath(__file__))\n_lib_path = os.path.join(\n _current_dir, # Directory containing magic.py\n \"magic_lib\", # The Rust project directory relative to magic.py\n \"target\",\n \"release\",\n \"libmagic_lib.so\" # The actual library file\n)\n\n# Load the shared library - Assumes build.sh has been run\ntry:\n _lib = ctypes.CDLL(_lib_path)\nexcept OSError as e:\n raise ImportError(f\"Failed to load shared library at '{_lib_path}'. Did you run 'bash build.sh'? Error: {e}\")\n\n# --- Function Signature Definition ---\ntry:\n _do_add_rust = _lib.do_add\n _do_add_rust.argtypes = [ctypes.c_int, ctypes.c_int] # Takes two C integers (i32)\n _do_add_rust.restype = ctypes.c_int # Returns a C integer (i32)\nexcept AttributeError:\n raise ImportError(\"Function 'do_add' not found in the shared library. \"\n \"Did you use #[no_mangle] and pub extern \\\"C\\\" in Rust?\")\n\n# --- Python Wrapper Function ---\ndef do_add(a: int, b: int) -> int:\n \"\"\"\n Adds two integers using the Rust implementation.\n \"\"\"\n if not isinstance(a, int) or not isinstance(b, int):\n raise TypeError(\"Arguments must be integers\")\n # Call the Rust function loaded via ctypes\n result = _do_add_rust(a, b)\n return result\n",
"build.sh": "#!/bin/bash\nset -e # Exit immediately if a command exits with a non-zero status.\n\n# Ensure we are in the script's directory (where magic.py and magic_lib/ reside)\nSCRIPT_DIR=$(cd \"$(dirname \"${BASH_SOURCE[0]}\")\" &> /dev/null && pwd)\ncd \"$SCRIPT_DIR\"\n\n# Create the Rust project directory if it doesn't exist\nmkdir -p magic_lib/src\n\n# Check if Rust files exist before proceeding (basic check)\nif [ ! -f \"magic_lib/Cargo.toml\" ] || [ ! -f \"magic_lib/src/lib.rs\" ]; then\n echo \"Error: Rust source files (Cargo.toml, src/lib.rs) not found in magic_lib/ directory.\" >&2\n echo \"Please ensure you placed the files correctly according to the JSON structure.\" >&2\n exit 1\nfi\n\necho \"--- Building Rust Library --- (Requires Rust/Cargo to be installed)\"\n# Navigate into the Rust project directory\ncd magic_lib\n\n# Build the release version of the dynamic library\ncargo build --release\n\n# Get the absolute path for clarity\nLIB_PATH=$(pwd)/target/release/libmagic_lib.so\n\ncd .. # Go back to the parent directory (where build.sh is)\n\necho \"--- Build Complete ---\"\necho \"Library created at: $LIB_PATH\"\necho \"You should now be able to run:\"\necho \"python3 -c 'import magic; print(magic.do_add(3, 4))'\"\n"
}
|
Extract Json
I extracted the following JSON from that output:
| {
"magic_lib/Cargo.toml": "[package]\nname = \"magic_lib\"\nversion = \"0.1.0\"\nedition = \"2021\"\n\n# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html\n\n[lib]\ncrate-type = [\"cdylib\"] # Compile to a C-compatible dynamic library (.so on Linux)\n\n[dependencies]\n",
"magic_lib/src/lib.rs": "// magic_lib/src/lib.rs\n\n// This function adds two 32-bit signed integers.\n// #[no_mangle] ensures the function name isn't changed by the compiler.\n// pub extern \"C\" makes it use the C calling convention, compatible with Python's ctypes.\n#[no_mangle]\npub extern \"C\" fn do_add(a: i32, b: i32) -> i32 {\n a + b\n}\n",
"magic.py": "import ctypes\nimport os\n\n# --- Library Loading ---\n# Construct the path to the compiled Rust library (.so file)\n_current_dir = os.path.dirname(os.path.abspath(__file__))\n_lib_path = os.path.join(\n _current_dir, # Directory containing magic.py\n \"magic_lib\", # The Rust project directory relative to magic.py\n \"target\",\n \"release\",\n \"libmagic_lib.so\" # The actual library file\n)\n\n# Load the shared library - Assumes build.sh has been run\ntry:\n _lib = ctypes.CDLL(_lib_path)\nexcept OSError as e:\n raise ImportError(f\"Failed to load shared library at '{_lib_path}'. Did you run 'bash build.sh'? Error: {e}\")\n\n# --- Function Signature Definition ---\ntry:\n _do_add_rust = _lib.do_add\n _do_add_rust.argtypes = [ctypes.c_int, ctypes.c_int] # Takes two C integers (i32)\n _do_add_rust.restype = ctypes.c_int # Returns a C integer (i32)\nexcept AttributeError:\n raise ImportError(\"Function 'do_add' not found in the shared library. \"\n \"Did you use #[no_mangle] and pub extern \\\"C\\\" in Rust?\")\n\n# --- Python Wrapper Function ---\ndef do_add(a: int, b: int) -> int:\n \"\"\"\n Adds two integers using the Rust implementation.\n \"\"\"\n if not isinstance(a, int) or not isinstance(b, int):\n raise TypeError(\"Arguments must be integers\")\n # Call the Rust function loaded via ctypes\n result = _do_add_rust(a, b)\n return result\n",
"build.sh": "#!/bin/bash\nset -e # Exit immediately if a command exits with a non-zero status.\n\n# Ensure we are in the script's directory (where magic.py and magic_lib/ reside)\nSCRIPT_DIR=$(cd \"$(dirname \"${BASH_SOURCE[0]}\")\" &> /dev/null && pwd)\ncd \"$SCRIPT_DIR\"\n\n# Create the Rust project directory if it doesn't exist\nmkdir -p magic_lib/src\n\n# Check if Rust files exist before proceeding (basic check)\nif [ ! -f \"magic_lib/Cargo.toml\" ] || [ ! -f \"magic_lib/src/lib.rs\" ]; then\n echo \"Error: Rust source files (Cargo.toml, src/lib.rs) not found in magic_lib/ directory.\" >&2\n echo \"Please ensure you placed the files correctly according to the JSON structure.\" >&2\n exit 1\nfi\n\necho \"--- Building Rust Library --- (Requires Rust/Cargo to be installed)\"\n# Navigate into the Rust project directory\ncd magic_lib\n\n# Build the release version of the dynamic library\ncargo build --release\n\n# Get the absolute path for clarity\nLIB_PATH=$(pwd)/target/release/libmagic_lib.so\n\ncd .. # Go back to the parent directory (where build.sh is)\n\necho \"--- Build Complete ---\"\necho \"Library created at: $LIB_PATH\"\necho \"You should now be able to run:\"\necho \"python3 -c 'import magic; print(magic.do_add(3, 4))'\"\n"
}
|
UNKNOWN NODE TYPE:
PyFunc
final: True
Compiling magic_lib v0.1.0 (/usr/src/app/magic_lib)
Finished `release` profile [optimized] target(s) in 0.12s
Resulting in output:
True