From 7155005be22c403e216f10cbd3f1bf84ee76782e Mon Sep 17 00:00:00 2001
From: Darley Barreto <darleybarreto@gmail.com>
Date: Mon, 8 May 2023 12:39:53 +0000
Subject: [PATCH] Adding `wcsrtombs`.

---
 src/header/stdlib/mod.rs |  2 +-
 src/header/wchar/mod.rs  | 89 +++++++++++++++++++++++++++++++++++-----
 tests/Makefile           |  1 +
 tests/wchar/wcsrtombs.c  | 21 ++++++++++
 4 files changed, 102 insertions(+), 11 deletions(-)
 create mode 100644 tests/wchar/wcsrtombs.c

diff --git a/src/header/stdlib/mod.rs b/src/header/stdlib/mod.rs
index ad54751c3f..4803852219 100644
--- a/src/header/stdlib/mod.rs
+++ b/src/header/stdlib/mod.rs
@@ -1266,7 +1266,7 @@ pub unsafe extern "C" fn valloc(size: size_t) -> *mut c_void {
 }
 
 #[no_mangle]
-pub extern "C" fn wcstombs(s: *mut c_char, mut pwcs: *const wchar_t, n: size_t) -> size_t {
+pub unsafe extern "C" fn wcstombs(s: *mut c_char, mut pwcs: *const wchar_t, n: size_t) -> size_t {
     let mut state: mbstate_t = mbstate_t {};
     wcsrtombs(s, &mut pwcs, n, &mut state)
 }
diff --git a/src/header/wchar/mod.rs b/src/header/wchar/mod.rs
index fd8e32d7e4..c947a4e4c2 100644
--- a/src/header/wchar/mod.rs
+++ b/src/header/wchar/mod.rs
@@ -275,6 +275,85 @@ pub unsafe extern "C" fn wcrtomb(s: *mut c_char, wc: wchar_t, ps: *mut mbstate_t
     utf8::wcrtomb(s_cpy, wc_cpy, ps)
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn wcsrtombs(
+    mut s: *mut c_char,
+    ws: *mut *const wchar_t,
+    mut n: size_t,
+    st: *mut mbstate_t,
+) -> size_t {
+    let mut ws2 = 0 as *const wchar_t;
+    let mut buf = [0i8; 4];
+    let N = n;
+    let mut l = 0usize;
+
+    if s.is_null() {
+        n = 0;
+        ws2 = *ws;
+        while *ws2 != 0 {
+            if *ws2 >= 0x80 {
+                l = wcrtomb(buf.as_mut_ptr(), *ws2, ptr::null_mut());
+                if l.wrapping_add(1) == 0 {
+                    return usize::MAX;
+                }
+                n = n.wrapping_add(l);
+            } else {
+                n = n.wrapping_add(1);
+            }
+            ws2 = ws2.offset(1);
+        }
+        return n;
+    }
+
+    while n >= 4 {
+        if **ws.wrapping_sub(1) >= 0x7f {
+            if **ws == 0 {
+                *s = 0;
+                *ws = 0 as *const wchar_t;
+                return N.wrapping_sub(n);
+            }
+            l = wcrtomb(s, **ws, ptr::null_mut());
+            if l.wrapping_add(1) == 0 {
+                return usize::MAX;
+            }
+            s = s.offset(l as isize);
+            n = n.wrapping_sub(l);
+        } else {
+            let new_s = s;
+            s = s.offset(1);
+            *new_s = **ws as c_char;
+            n = n.wrapping_sub(1);
+        }
+        *ws = (*ws).offset(1);
+    }
+    while n != 0 {
+        if **ws.wrapping_sub(1) >= 0x7f {
+            if **ws == 0 {
+                *s = 0;
+                *ws = 0 as *const wchar_t;
+                return N.wrapping_sub(n);
+            }
+            l = wcrtomb(buf.as_mut_ptr(), **ws, ptr::null_mut());
+            if l.wrapping_add(1) == 0 {
+                return usize::MAX;
+            }
+            if l > n {
+                return N.wrapping_sub(n);
+            }
+            wcrtomb(s, **ws, ptr::null_mut());
+            s = s.offset(l as isize);
+            n = n.wrapping_sub(l) as size_t;
+        } else {
+            let new_s = s;
+            s = s.offset(1);
+            *new_s = **ws as c_char;
+            n = n.wrapping_sub(1);
+        }
+        *ws = (*ws).offset(1);
+    }
+    return N;
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn wcscat(ws1: *mut wchar_t, ws2: *const wchar_t) -> *mut wchar_t {
     wcsncat(ws1, ws2, usize::MAX)
@@ -436,16 +515,6 @@ pub unsafe extern "C" fn wcsrchr(ws1: *const wchar_t, wc: wchar_t) -> *mut wchar
     last_matching_wc as *mut wchar_t
 }
 
-// #[no_mangle]
-pub extern "C" fn wcsrtombs(
-    dst: *mut c_char,
-    src: *mut *const wchar_t,
-    len: size_t,
-    ps: *mut mbstate_t,
-) -> size_t {
-    unimplemented!();
-}
-
 #[no_mangle]
 pub unsafe extern "C" fn wcsspn(wcs: *const wchar_t, set: *const wchar_t) -> size_t {
     inner_wcsspn(wcs, set, false)
diff --git a/tests/Makefile b/tests/Makefile
index d28dc313b9..84d51f740c 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -110,6 +110,7 @@ EXPECT_NAMES=\
 	wchar/wcrtomb \
 	wchar/wcscspn \
 	wchar/wcsrchr \
+	wchar/wcsrtombs \
 	wchar/wcsstr \
 	wchar/wcstod \
 	wchar/wcstok \
diff --git a/tests/wchar/wcsrtombs.c b/tests/wchar/wcsrtombs.c
new file mode 100644
index 0000000000..0a070ca696
--- /dev/null
+++ b/tests/wchar/wcsrtombs.c
@@ -0,0 +1,21 @@
+#include <assert.h>
+#include <wchar.h>
+#include <string.h>
+#include <stdlib.h>
+
+int main() {
+    const wchar_t *wcs1 = L"";
+    size_t mb_len1 = wcsrtombs(NULL, &wcs1, 0, NULL);
+    assert(mb_len1 == 0);
+    
+    const wchar_t *wcs2 = L"Hello, world!";
+    size_t mb_len2 = wcsrtombs(NULL, &wcs2, 0, NULL);
+    assert(mb_len2 == strlen("Hello, world!"));
+    
+    char *mbs2 = malloc(mb_len2 + 1);
+    wcsrtombs(mbs2, &wcs2, mb_len2 + 1, NULL);
+    assert(strcmp(mbs2, "Hello, world!") == 0);
+    free(mbs2);
+
+    return 0;
+}
\ No newline at end of file