Jeremy Soller
416 lines
10 KiB
Rust
416 lines
10 KiB
Rust
//! string implementation for Redox, following http://pubs.opengroup.org/onlinepubs/7908799/xsh/string.h.html
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use core::mem;
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use core::ptr;
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use core::usize;
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use cbitset::BitSet256;
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use header::errno::*;
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use header::signal;
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use platform;
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use platform::types::*;
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#[no_mangle]
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pub unsafe extern "C" fn memccpy(
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dest: *mut c_void,
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src: *const c_void,
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c: c_int,
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n: usize,
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) -> *mut c_void {
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let to = memchr(src, c, n);
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if to.is_null() {
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return to;
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}
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let dist = (to as usize) - (src as usize);
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if memcpy(dest, src, dist).is_null() {
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return ptr::null_mut();
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}
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(dest as *mut u8).offset(dist as isize + 1) as *mut c_void
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}
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#[no_mangle]
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pub unsafe extern "C" fn memchr(s: *const c_void, c: c_int, n: usize) -> *mut c_void {
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let mut s = s as *const u8;
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let c = c as u8;
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let mut n = n;
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// read one byte at a time until s is aligned
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while s as usize % mem::size_of::<usize>() != 0 {
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if n == 0 {
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return ptr::null_mut();
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}
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if *s == c {
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return s as *mut c_void;
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}
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n -= 1;
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s = s.offset(1);
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}
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let mut s = s as *const usize;
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let lowbits = !0 as usize / 255;
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let highbits = lowbits * 0x80;
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let repeated_c = lowbits * c as usize;
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while n >= mem::size_of::<usize>() {
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// read multiple bytes at a time
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// turn the requested byte into 8 zero bits
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let m = *s ^ repeated_c;
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// subtracting one from zero flips high bit from 0 to 1
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if (m.wrapping_sub(lowbits) & !m & highbits) != 0 {
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break;
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}
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n -= mem::size_of::<usize>();
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s = s.offset(1);
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}
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let mut s = s as *const u8;
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while n > 0 {
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if *s == c {
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return s as *mut c_void;
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}
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n -= 1;
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s = s.offset(1);
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}
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ptr::null_mut()
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}
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#[no_mangle]
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pub unsafe extern "C" fn memcmp(s1: *const c_void, s2: *const c_void, n: usize) -> c_int {
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let mut i = 0;
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while i < n {
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let a = *(s1 as *const u8).offset(i as isize);
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let b = *(s2 as *const u8).offset(i as isize);
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if a != b {
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return a as i32 - b as i32;
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}
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i += 1;
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}
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0
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}
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#[no_mangle]
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pub unsafe extern "C" fn memcpy(s1: *mut c_void, s2: *const c_void, n: usize) -> *mut c_void {
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platform::memcpy(s1, s2, n)
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}
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#[no_mangle]
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pub unsafe extern "C" fn memmove(s1: *mut c_void, s2: *const c_void, n: usize) -> *mut c_void {
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if s2 < s1 as *const c_void {
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// copy from end
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let mut i = n;
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while i != 0 {
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i -= 1;
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*(s1 as *mut u8).offset(i as isize) = *(s2 as *const u8).offset(i as isize);
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}
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} else {
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// copy from beginning
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let mut i = 0;
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while i < n {
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*(s1 as *mut u8).offset(i as isize) = *(s2 as *const u8).offset(i as isize);
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i += 1;
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}
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}
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s1
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}
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#[no_mangle]
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pub unsafe extern "C" fn memset(s: *mut c_void, c: c_int, n: usize) -> *mut c_void {
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let mut i = 0;
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while i < n {
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*(s as *mut u8).offset(i as isize) = c as u8;
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i += 1;
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}
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s
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}
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#[no_mangle]
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pub unsafe extern "C" fn strcat(s1: *mut c_char, s2: *const c_char) -> *mut c_char {
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strncat(s1, s2, usize::MAX)
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}
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#[no_mangle]
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pub unsafe extern "C" fn strchr(mut s: *const c_char, c: c_int) -> *mut c_char {
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let c = c as c_char;
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while *s != 0 {
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if *s == c {
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return s as *mut c_char;
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}
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s = s.offset(1);
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}
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ptr::null_mut()
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}
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#[no_mangle]
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pub unsafe extern "C" fn strcmp(s1: *const c_char, s2: *const c_char) -> c_int {
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strncmp(s1, s2, usize::MAX)
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}
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#[no_mangle]
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pub unsafe extern "C" fn strcoll(s1: *const c_char, s2: *const c_char) -> c_int {
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// relibc has no locale stuff (yet)
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strcmp(s1, s2)
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}
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#[no_mangle]
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pub unsafe extern "C" fn strcpy(dst: *mut c_char, src: *const c_char) -> *mut c_char {
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let mut i = 0;
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loop {
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let byte = *src.offset(i);
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*dst.offset(i) = byte;
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if byte == 0 {
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break;
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}
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i += 1;
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}
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dst
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}
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pub unsafe fn inner_strspn(s1: *const c_char, s2: *const c_char, cmp: bool) -> size_t {
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let mut s1 = s1 as *const u8;
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let mut s2 = s2 as *const u8;
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// The below logic is effectively ripped from the musl implementation. It
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// works by placing each byte as it's own bit in an array of numbers. Each
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// number can hold up to 8 * mem::size_of::<usize>() bits. We need 256 bits
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// in total, to fit one byte.
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let mut set = BitSet256::new();
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while *s2 != 0 {
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set.insert(*s2 as usize);
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s2 = s2.offset(1);
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}
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let mut i = 0;
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while *s1 != 0 {
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if set.contains(*s1 as usize) != cmp {
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break;
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}
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i += 1;
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s1 = s1.offset(1);
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}
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i
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}
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#[no_mangle]
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pub unsafe extern "C" fn strcspn(s1: *const c_char, s2: *const c_char) -> size_t {
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inner_strspn(s1, s2, false)
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}
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#[no_mangle]
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pub unsafe extern "C" fn strdup(s1: *const c_char) -> *mut c_char {
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strndup(s1, usize::MAX)
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}
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#[no_mangle]
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pub unsafe extern "C" fn strndup(s1: *const c_char, size: usize) -> *mut c_char {
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let len = strnlen(s1, size);
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// the "+ 1" is to account for the NUL byte
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let buffer = platform::alloc(len + 1) as *mut c_char;
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if buffer.is_null() {
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platform::errno = ENOMEM as c_int;
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} else {
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//memcpy(buffer, s1, len)
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for i in 0..len as isize {
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*buffer.offset(i) = *s1.offset(i);
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}
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*buffer.offset(len as isize) = 0;
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}
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buffer
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}
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#[no_mangle]
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pub unsafe extern "C" fn strerror(errnum: c_int) -> *mut c_char {
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use core::fmt::Write;
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static mut strerror_buf: [u8; 256] = [0; 256];
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let mut w = platform::StringWriter(strerror_buf.as_mut_ptr(), strerror_buf.len());
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if errnum >= 0 && errnum < STR_ERROR.len() as c_int {
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w.write_str(STR_ERROR[errnum as usize]);
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} else {
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w.write_fmt(format_args!("Unknown error {}", errnum));
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}
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strerror_buf.as_mut_ptr() as *mut c_char
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}
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#[no_mangle]
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pub unsafe extern "C" fn strlen(s: *const c_char) -> size_t {
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strnlen(s, usize::MAX)
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}
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#[no_mangle]
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pub unsafe extern "C" fn strnlen(s: *const c_char, size: usize) -> size_t {
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let mut i = 0;
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while i < size {
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if *s.offset(i as isize) == 0 {
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break;
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}
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i += 1;
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}
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i as size_t
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}
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#[no_mangle]
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pub unsafe extern "C" fn strncat(s1: *mut c_char, s2: *const c_char, n: usize) -> *mut c_char {
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let mut idx = strlen(s1 as *const _) as isize;
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for i in 0..n as isize {
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if *s2.offset(i) == 0 {
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break;
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}
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*s1.offset(idx) = *s2.offset(i);
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idx += 1;
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}
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*s1.offset(idx) = 0;
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s1
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}
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#[no_mangle]
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pub unsafe extern "C" fn strncmp(s1: *const c_char, s2: *const c_char, n: usize) -> c_int {
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let s1 = core::slice::from_raw_parts(s1 as *const c_uchar, n);
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let s2 = core::slice::from_raw_parts(s2 as *const c_uchar, n);
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for (&a, &b) in s1.iter().zip(s2.iter()) {
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let val = (a as c_int) - (b as c_int);
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if a != b || a == 0 {
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return val;
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}
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}
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0
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}
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#[no_mangle]
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pub unsafe extern "C" fn strncpy(dst: *mut c_char, src: *const c_char, n: usize) -> *mut c_char {
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let mut i = 0;
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while *src.offset(i) != 0 && (i as usize) < n {
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*dst.offset(i) = *src.offset(i);
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i += 1;
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}
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for i in i..n as isize {
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*dst.offset(i) = 0;
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}
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dst
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}
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#[no_mangle]
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pub unsafe extern "C" fn strpbrk(s1: *const c_char, s2: *const c_char) -> *mut c_char {
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let p = s1.offset(strcspn(s1, s2) as isize);
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if *p != 0 {
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p as *mut c_char
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} else {
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ptr::null_mut()
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}
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}
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#[no_mangle]
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pub unsafe extern "C" fn strrchr(s: *const c_char, c: c_int) -> *mut c_char {
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let len = strlen(s) as isize;
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let c = c as i8;
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let mut i = len - 1;
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while i >= 0 {
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if *s.offset(i) == c {
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return s.offset(i) as *mut c_char;
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}
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i -= 1;
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}
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ptr::null_mut()
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}
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#[no_mangle]
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pub unsafe extern "C" fn strsignal(sig: c_int) -> *mut c_char {
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// Mutating this is undefined behavior I believe. But I just can't create a
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// &'static mut str. Alternative is allocating everything on the heap...
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signal::_signal_strings[sig as usize].as_ptr() as *const c_char as *mut c_char
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}
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#[no_mangle]
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pub unsafe extern "C" fn strspn(s1: *const c_char, s2: *const c_char) -> size_t {
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inner_strspn(s1, s2, true)
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}
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#[no_mangle]
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pub unsafe extern "C" fn strstr(s1: *const c_char, s2: *const c_char) -> *mut c_char {
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let mut i = 0;
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while *s1.offset(i) != 0 {
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let mut j = 0;
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while *s2.offset(j) != 0 && *s1.offset(j + i) != 0 {
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if *s2.offset(j) != *s1.offset(j + i) {
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break;
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}
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j += 1;
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if *s2.offset(j) == 0 {
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return s1.offset(i) as *mut c_char;
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}
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}
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i += 1;
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}
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ptr::null_mut()
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}
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#[no_mangle]
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pub extern "C" fn strtok(s1: *mut c_char, delimiter: *const c_char) -> *mut c_char {
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static mut HAYSTACK: *mut c_char = ptr::null_mut();
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unsafe {
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return strtok_r(s1, delimiter, &mut HAYSTACK);
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}
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}
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#[no_mangle]
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pub extern "C" fn strtok_r(
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s: *mut c_char,
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delimiter: *const c_char,
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lasts: *mut *mut c_char,
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) -> *mut c_char {
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// Loosely based on GLIBC implementation
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unsafe {
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let mut haystack = s;
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if haystack.is_null() {
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if (*lasts).is_null() {
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return ptr::null_mut();
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}
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haystack = *lasts;
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}
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// Skip past any extra delimiter left over from previous call
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haystack = haystack.add(strspn(haystack, delimiter));
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if *haystack == 0 {
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*lasts = ptr::null_mut();
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return ptr::null_mut();
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}
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// Build token by injecting null byte into delimiter
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let token = haystack;
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haystack = strpbrk(token, delimiter);
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if !haystack.is_null() {
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haystack.write(0);
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haystack = haystack.add(1);
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*lasts = haystack;
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} else {
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*lasts = ptr::null_mut();
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}
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return token;
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}
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}
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#[no_mangle]
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pub unsafe extern "C" fn strxfrm(s1: *mut c_char, s2: *const c_char, n: usize) -> size_t {
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// relibc has no locale stuff (yet)
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let len = strlen(s2);
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if len < n {
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strcpy(s1, s2);
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}
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len
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}
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