Add pvalloc()

src/header/malloc/cbindgen.toml

@@ -0,0 +1,10 @@
+sys_includes = ["features.h", "stddef.h"]
+include_guard = "_RELIBC_MALLOC_H"
+trailer = "#include <bits/malloc.h>"
+language = "C"
+style = "Type"
+no_includes = true
+cpp_compat = true
+
+[enum]
+prefix_with_name = true

src/header/malloc/mod.rs

@@ -0,0 +1,39 @@
+//! `malloc.h` implementation.
+//!
+//! Non-POSIX, see <https://man7.org/linux/man-pages/man3/posix_memalign.3.html>.
+
+use crate::{
+    header::errno::*,
+    platform::{self, types::*, Pal, Sys, ERRNO},
+};
+use core::ptr;
+
+/// See <https://man7.org/linux/man-pages/man3/posix_memalign.3.html>.
+#[deprecated]
+#[no_mangle]
+pub unsafe extern "C" fn pvalloc(size: size_t) -> *mut c_void {
+    let page_size = Sys::getpagesize();
+    // Find the smallest multiple of the page size in which the requested size
+    // will fit. The result of the division will always be less than or equal
+    // to size_t::MAX - 1, and the num_pages calculation will therefore never
+    // overflow.
+    let num_pages = if size != 0 {
+        (size - 1) / page_size + 1
+    } else {
+        0
+    };
+
+    match num_pages.checked_mul(page_size) {
+        Some(alloc_size) => {
+            let ptr = platform::alloc_align(alloc_size, page_size);
+            if ptr.is_null() {
+                platform::ERRNO.set(ENOMEM);
+            }
+            ptr
+        }
+        None => {
+            platform::ERRNO.set(ENOMEM);
+            ptr::null_mut()
+        }
+    }
+}