std/sys/alloc/
mod.rs

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1#![forbid(unsafe_op_in_unsafe_fn)]
2
3use crate::alloc::{GlobalAlloc, Layout, System};
4use crate::ptr;
5
6// The minimum alignment guaranteed by the architecture. This value is used to
7// add fast paths for low alignment values.
8#[allow(dead_code)]
9const MIN_ALIGN: usize = if cfg!(any(
10    all(target_arch = "riscv32", any(target_os = "espidf", target_os = "zkvm")),
11    all(target_arch = "xtensa", target_os = "espidf"),
12)) {
13    // The allocator on the esp-idf and zkvm platforms guarantees 4 byte alignment.
14    4
15} else if cfg!(any(
16    target_arch = "x86",
17    target_arch = "arm",
18    target_arch = "m68k",
19    target_arch = "csky",
20    target_arch = "mips",
21    target_arch = "mips32r6",
22    target_arch = "powerpc",
23    target_arch = "powerpc64",
24    target_arch = "sparc",
25    target_arch = "wasm32",
26    target_arch = "hexagon",
27    target_arch = "riscv32",
28    target_arch = "xtensa",
29)) {
30    8
31} else if cfg!(any(
32    target_arch = "x86_64",
33    target_arch = "aarch64",
34    target_arch = "arm64ec",
35    target_arch = "loongarch64",
36    target_arch = "mips64",
37    target_arch = "mips64r6",
38    target_arch = "s390x",
39    target_arch = "sparc64",
40    target_arch = "riscv64",
41    target_arch = "wasm64",
42)) {
43    16
44} else {
45    panic!("add a value for MIN_ALIGN")
46};
47
48#[allow(dead_code)]
49unsafe fn realloc_fallback(
50    alloc: &System,
51    ptr: *mut u8,
52    old_layout: Layout,
53    new_size: usize,
54) -> *mut u8 {
55    // SAFETY: Docs for GlobalAlloc::realloc require this to be valid
56    unsafe {
57        let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());
58
59        let new_ptr = GlobalAlloc::alloc(alloc, new_layout);
60        if !new_ptr.is_null() {
61            let size = usize::min(old_layout.size(), new_size);
62            ptr::copy_nonoverlapping(ptr, new_ptr, size);
63            GlobalAlloc::dealloc(alloc, ptr, old_layout);
64        }
65
66        new_ptr
67    }
68}
69
70cfg_if::cfg_if! {
71    if #[cfg(any(
72        target_family = "unix",
73        target_os = "wasi",
74        target_os = "teeos",
75        target_os = "trusty",
76    ))] {
77        mod unix;
78    } else if #[cfg(target_os = "windows")] {
79        mod windows;
80    } else if #[cfg(target_os = "hermit")] {
81        mod hermit;
82    } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
83        mod sgx;
84    } else if #[cfg(target_os = "solid_asp3")] {
85        mod solid;
86    } else if #[cfg(target_os = "uefi")] {
87        mod uefi;
88    } else if #[cfg(target_family = "wasm")] {
89        mod wasm;
90    } else if #[cfg(target_os = "xous")] {
91        mod xous;
92    } else if #[cfg(target_os = "zkvm")] {
93        mod zkvm;
94    }
95}
std/sys/alloc/mod.rs

std/sys/alloc/
mod.rs
