chore: switch to picolibc fork

Author: andreiltd

.gitmodules

@@ -1,4 +1,4 @@
 [submodule "src/hyperlight_guest_bin/third_party/picolibc"]
 	path = src/hyperlight_guest_bin/third_party/picolibc
-	url = https://github.com/picolibc/picolibc.git
+	url = https://github.com/andreiltd/picolibc-bsd.git
 	shallow = true

NOTICE.txt

@@ -55,7 +55,8 @@ permissive licenses. The full license details for all files are
 documented in the COPYING.picolibc and COPYING.NEWLIB files in the
 picolibc submodule at src/hyperlight_guest_bin/third_party/picolibc/.
 
-Note: The picolibc submodule uses sparse checkout to exclude
-GPL/AGPL-licensed test and script files that are not needed for
-building. Only BSD/MIT/permissive-licensed source files are included.
+Note: The picolibc submodule uses the picolibc-bsd fork
+(https://github.com/hyperlight-dev/picolibc-bsd), which is a redistribution
+with all copyleft-licensed files removed from the tree and history.
+Only BSD/MIT/permissive-licensed source files are present.
 

docs/picolibc.md

@@ -12,9 +12,10 @@ The picolibc integration is controlled by the `libc` feature flag on the
 script compiles picolibc from source using the vendored submodule at
 `src/hyperlight_guest_bin/third_party/picolibc`.
 
-The build uses a sparse checkout to exclude GPL/AGPL-licensed test and script
-files and only BSD/MIT/permissive-licensed source files are included. See
-`NOTICE.txt` for full licensing details.
+The submodule points to [picolibc-bsd](https://github.com/hyperlight-dev/picolibc-bsd),
+a redistribution of picolibc with all copyleft-licensed files (GPL/AGPL)
+removed from the tree and history. Only BSD/MIT/permissive-licensed source
+files are present. See `NOTICE.txt` for full licensing details.
 
 ## Host Function Stubs
 
@@ -63,33 +64,34 @@ The file list of picolibc sources to compile is maintained in `build_files.rs`.
 
 To update picolibc to a new version:
 
-1. Update the submodule:
+1. Import new upstream commits into the [picolibc-bsd](https://github.com/hyperlight-dev/picolibc-bsd) fork.
+   See `picolibc-bsd` README.md for instructions how to do that. 
+
+2. Update the submodule in hyperlight:
    ```bash
    cd src/hyperlight_guest_bin/third_party/picolibc
    git fetch origin
-   git checkout <new-version-tag>
+   git checkout <new-fork-tag>
    cd ../../../..
    git add src/hyperlight_guest_bin/third_party/picolibc
    ```
 
-2. Verify licensing: Check that no new GPL/AGPL-licensed source files
-   have been added to the directories we compile. The sparse checkout
-   (configured in `build.rs` `sparse_checkout()`) excludes `test/`,
-   `scripts/`, and `COPYING.GPL2`, but review any new files.
+3. Verify licensing: The fork's CI runs scancode-toolkit to ensure no
+   copyleft files are present. Review the CI results on the fork.
 
-3. Update `build_files.rs`: Compare the file list against the new
+4. Update `build_files.rs`: Compare the file list against the new
    version's meson build files. Files may have been added, removed, or
    renamed. The meson build definitions in `libc/meson.build` and
    `libm/meson.build` (and their subdirectory `meson.build` files)
    are the source of truth for which files to compile.
 
-4. Update version strings in `build.rs`: Update the `__PICOLIBC_VERSION__`,
+5. Update version strings in `build.rs`: Update the `__PICOLIBC_VERSION__`,
    `__PICOLIBC__`, `__PICOLIBC_MINOR__`, `__PICOLIBC_PATCHLEVEL__`,
    `_NEWLIB_VERSION`, and related defines in `gen_config_file()`.
 
-5. Update `NOTICE.txt`: Bump the version number in the picolibc entry.
+6. Update `NOTICE.txt`: Bump the version number in the picolibc entry.
 
-6. Build and test:
+7. Build and test:
    ```bash
    just guests
    just test

src/hyperlight_guest_bin/build.rs

@@ -309,7 +309,7 @@ fn add_libm(build: &mut cc::Build, picolibc_dir: &Path, target: &str) -> Result<
     Ok(())
 }
 
-fn sparse_checkout() -> Result<()> {
+fn init_submodule() -> Result<()> {
     let status = Command::new("git")
         .args(["submodule", "update", "--init"])
         .status()?;
@@ -318,30 +318,6 @@ fn sparse_checkout() -> Result<()> {
         bail!("git submodule update --init failed");
     }
 
-    // Exclude GPL/AGPL-licensed files from the picolibc submodule
-    Command::new("git")
-        .args([
-            "-C",
-            "third_party/picolibc",
-            "sparse-checkout",
-            "init",
-            "--no-cone",
-        ])
-        .status()?;
-
-    Command::new("git")
-        .args([
-            "-C",
-            "third_party/picolibc",
-            "sparse-checkout",
-            "set",
-            "**",
-            "!test/**",
-            "!scripts/**",
-            "!COPYING.GPL2",
-        ])
-        .status()?;
-
     Ok(())
 }
 
@@ -360,7 +336,7 @@ fn cargo_main() -> Result<()> {
     if cfg!(feature = "libc") {
         if !Path::new("third_party/picolibc/COPYING.picolibc").exists() {
             eprintln!("Setting up submodules");
-            sparse_checkout().with_context(|| "failed to init picolibc submodule")?;
+            init_submodule().with_context(|| "failed to init picolibc submodule")?;
         }
 
         let picolibc_dir = PathBuf::from("third_party/picolibc");

src/hyperlight_guest_bin/src/libc.rs

@@ -111,6 +111,11 @@ pub extern "C" fn write(fd: c_int, buf: *const c_void, count: usize) -> isize {
 
 #[unsafe(no_mangle)]
 pub extern "C" fn _current_time(ts: *mut u64) -> c_int {
+    if ts.is_null() {
+        set_errno(EINVAL);
+        return -1;
+    }
+
     let (secs, nanos) = current_time();
     let ts = unsafe { core::slice::from_raw_parts_mut(ts, 2) };
     ts[0] = secs;

src/hyperlight_guest_bin/third_party/README.md

@@ -1,15 +1,21 @@
 # Third Party Library Use
 
-This project makes use of the following third party libraries, each of which is contained in a subdirectory of `third_party` with a COPYRIGHT/LICENSE file in the root of the subdirectory. These libraries are used under the terms of their respective licenses. They are also listed in the NOTICE file in the root of the repository.
+This project makes use of the following third party libraries, each of which is contained in a
+subdirectory of `third_party` with a COPYRIGHT/LICENSE file in the root of the subdirectory. These
+libraries are used under the terms of their respective licenses. They are also listed in the NOTICE
+file in the root of the repository.
 
 ## picolibc
 
-[picolibc](https://github.com/picolibc/picolibc) is a C library designed for embedded systems, derived from newlib. It is included as a git submodule.
+[picolibc](https://github.com/picolibc/picolibc) is a C library designed for embedded systems,
+derived from newlib. It is included as a git submodule pointing to the
+[picolibc-bsd](https://github.com/hyperlight-dev/picolibc-bsd) fork.
 
 - **Version**: 1.8.11
-- **License**: BSD-3-Clause (picolibc), with BSD/MIT-compatible licenses for newlib portions (see `COPYING.picolibc` and `COPYING.NEWLIB`)
+- **License**: BSD-3-Clause (picolibc), with BSD/MIT-compatible licenses for newlib portions (see
+  `COPYING.picolibc` and `COPYING.NEWLIB`)
 - **Submodule path**: `third_party/picolibc`
 
-The submodule uses sparse checkout to exclude GPL/AGPL-licensed files (`test/`, `scripts/`, `COPYING.GPL2`) that are not needed for building and are not compatible with the project's license.
-
-Only the `newlib/` subtree is used by the build (libc and libm sources). Complex math (`complex/`) files from libm are intentionally excluded to reduce binary size.
+The submodule uses the picolibc-bsd fork, which is a redistribution of picolibc with all
+copyleft-licensed files (GPL/AGPL) removed from the tree and history. Only permissively-licensed
+source files are present.