mirror of
https://github.com/google/sandboxed-api.git
synced 2024-03-22 13:11:30 +08:00
839914d6dd
`BUILD_TESTING` is a CMake provided option and we should use similar naming, just like how Abseil does it. - `SAPI_ENABLE_TESTS` -> `SAPI_BUILD_TESTING` - `SAPI_ENABLE_CONTRIB_TESTS` -> `SAPI_CONTRIB_BUILD_TESTING` - `SAPI_ENABLE_EXAMPLES` -> `SAPI_BUILD_EXAMPLES` Drive-by: - Fix option name in GitHub action PiperOrigin-RevId: 443305932 Change-Id: Ice2b42be1229a0f9ae7c2ceda9ce87187baf22c4
127 lines
4.6 KiB
Markdown
127 lines
4.6 KiB
Markdown
# LibCurl Sandbox
|
|
|
|
This library is a sandboxed version of curl's C API,
|
|
[libcurl](https://curl.haxx.se/libcurl/c/), implemented using Sandboxed API.
|
|
|
|
## Setup
|
|
|
|
The repository can be cloned using: `git clone --recursive <URL to this repo>`
|
|
The `--recursive` flag ensures that submodules are also cloned.
|
|
|
|
Alternatively, if the repository has already been cloned but the submodules have
|
|
not, these can be cloned using: `git submodule update --init --recursive`
|
|
|
|
The full list of Sandboxed API dependencies can be found on
|
|
[Sandboxed API Getting Started page](https://developers.google.com/code-sandboxing/sandboxed-api/getting-started).
|
|
|
|
The following commands, used from the current `curl/` directory, build the
|
|
library:
|
|
|
|
```bash
|
|
mkdir -p build && cd build
|
|
cmake .. -G Ninja -D SAPI_ROOT=<path to sandboxed-api>
|
|
cmake --build .
|
|
```
|
|
|
|
## Implementation details
|
|
|
|
All of libcurl's methods are supported by the library. However, a few of these
|
|
have different signatures defined in the sandboxed header `custom_curl.h`, which
|
|
wraps and extends libcurl.
|
|
|
|
This is necessary because Sandboxed API sandboxes most of libcurl correctly, but
|
|
encounters some issues when sandboxing a few methods. The simplest solution is
|
|
wrapping these methods into wrapper methods that accomplish the same tasks but
|
|
can also be sandboxed.
|
|
|
|
The next sections describe the issues encountered and contain some information
|
|
on the signatures of the wrapper methods solving these issues.
|
|
|
|
#### Variadic methods
|
|
|
|
Variadic methods are currently not supported by Sandboxed API. To solve this,
|
|
these methods are defined with an additional explicit parameter in
|
|
`custom_curl.h`.
|
|
|
|
The methods are:
|
|
|
|
- `curl_easy_setopt`. Use `curl_easy_setopt_ptr`, `curl_easy_setopt_long` or
|
|
`curl_easy_setopt_curl_off_t` instead.
|
|
- `curl_easy_getinfo`. Use `curl_easy_getinfo_ptr` instead.
|
|
- `curl_multi_setopt`. Use `curl_multi_setopt_ptr`, `curl_multi_setopt_long`
|
|
or `curl_multi_setopt_curl_off_t` instead.
|
|
- `curl_share_setopt`. Use `curl_share_setopt_ptr` or `curl_share_setopt_long`
|
|
instead
|
|
|
|
#### Methods with incomplete array arguments
|
|
|
|
Incomplete array arguments are currently not supported by Sandboxed API. To
|
|
solve this, methods taking an incomplete array argument have a wrapper in
|
|
`custom_curl.h`, and take a pointer as the argument.
|
|
|
|
The methods are:
|
|
|
|
- `curl_multi_poll`. Use `curl_multi_poll_sapi` instead.
|
|
- `curl_multi_wait`. Use `curl_multi_wait_sapi` instead.
|
|
|
|
#### Methods with conflicts on the generated header
|
|
|
|
Some methods create conflicts on the generated header because of redefined
|
|
`#define` directives from files included by the header. To solve this, the
|
|
conflicting types and methods are redefined in `custom_curl.h`.
|
|
|
|
The types are:
|
|
|
|
- `time_t`. Use `time_t_sapi` instead.
|
|
- `fd_set`. Use `fd_set_sapi` instead.
|
|
|
|
The methods are:
|
|
|
|
- `curl_getdate`. Use `curl_getdate_sapi` instead.
|
|
- `curl_multi_fdset`. Use `curl_multi_fdset_sapi` instead.
|
|
|
|
#### Function pointers
|
|
|
|
The functions whose pointers will be passed to the library's methods
|
|
(*callbacks*) can't be implemented in the files making use of the library, but
|
|
must be in other files. These files must be compiled together with the library,
|
|
and this is done by adding their absolute path to the cmake variable
|
|
`CURL_SAPI_CALLBACKS`.
|
|
|
|
The pointers can then be obtained using an `RPCChannel` object, as shown in
|
|
`example2.cc`.
|
|
|
|
## Examples
|
|
|
|
The `examples` directory contains the sandboxed versions of example source codes
|
|
taken from [this page](https://curl.haxx.se/libcurl/c/example.html) on curl's
|
|
website. More information about each example can be found in the examples'
|
|
[README](examples/README.md).
|
|
|
|
To build these examples when building the library, the cmake variable
|
|
`CURL_SAPI_BUILD_EXAMPLES` must be set to `ON`. This enables Sandboxed API
|
|
examples as well.
|
|
|
|
## Policy
|
|
|
|
The `sandbox.h` file contains a policy allowing all is necessary for libcurl to
|
|
perform simple requests. It is used by all the examples, except by example3.
|
|
This example needs some additional policies and files in its namespace (since it
|
|
uses HTTPS), and the file `example3.cc` shows how to easily extend an existing
|
|
policy.
|
|
|
|
## Testing
|
|
|
|
The `tests` folder contains some test cases created using Google Test. The class
|
|
`CurlTestUtils` is used to facilitate some tasks that all test cases need,
|
|
including the setup of a mock local server on which test requests are performed.
|
|
|
|
To build these tests when building the library, the cmake variable
|
|
`CURL_SAPI_BUILD_TESTING` must be set to `ON`. This enables Sandboxed API tests
|
|
as well.
|
|
|
|
## Callbacks
|
|
|
|
The `callbacks.h` and `callbacks.cc` files implement all the callbacks used by
|
|
examples and tests.
|