LibC, LibM: Add functions needed to compile python3

Author: https://github.com/lnzero1dev
Commit: https://github.com/SerenityOS/serenity/commit/e7affa24dca
Pull-request: https://github.com/SerenityOS/serenity/pull/763
Reviewed-by: https://github.com/awesomekling ✅
Reviewed-by: https://github.com/bugaevc

Libraries/LibC/stdlib.cpp

@@ -3,6 +3,7 @@
 #include <AK/StdLibExtras.h>
 #include <AK/String.h>
 #include <AK/Types.h>
+#include <AK/Utf8View.h>
 #include <Kernel/Syscall.h>
 #include <alloca.h>
 #include <assert.h>
@@ -469,6 +470,28 @@ int wctomb(char*, wchar_t)
     ASSERT_NOT_REACHED();
 }
 
+size_t wcstombs(char* dest, const wchar_t* src, size_t max)
+{
+    char* originalDest = dest;
+    while ((size_t)(dest - originalDest) < max) {
+        StringView v { (const char*)src, sizeof(wchar_t) };
+
+        // FIXME: dependent on locale, for now utf-8 is supported.
+        Utf8View utf8 { v };
+        if (*utf8.begin() == '\0') {
+            *dest = '\0';
+            return (size_t)(dest - originalDest); // Exclude null character in returned size
+        }
+
+        for (auto byte : utf8) {
+            if (byte != '\0')
+                *dest++ = byte;
+        }
+        ++src;
+    }
+    return max;
+}
+
 template<typename T, T min_value, T max_value>
 static T strtol_impl(const char* nptr, char** endptr, int base)
 {

Libraries/LibC/stdlib.h

@@ -46,6 +46,7 @@ void* bsearch(const void* key, const void* base, size_t nmemb, size_t size, int
 size_t mbstowcs(wchar_t*, const char*, size_t);
 size_t mbtowc(wchar_t*, const char*, size_t);
 int wctomb(char*, wchar_t);
+size_t wcstombs(char*, const wchar_t*, size_t);
 
 #define RAND_MAX 32767
 int rand();

Libraries/LibC/time.cpp

@@ -134,4 +134,18 @@ int clock_nanosleep(clockid_t clock_id, int flags, const struct timespec* reques
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+int clock_getres(clockid_t, struct timespec*)
+{
+    ASSERT_NOT_REACHED();
+}
+
+struct tm* gmtime_r(const time_t*, struct tm*)
+{
+    ASSERT_NOT_REACHED();
+}
+
+struct tm* localtime_r(const time_t*, struct tm*)
+{
+    ASSERT_NOT_REACHED();
+}
 }

Libraries/LibC/time.h

@@ -48,11 +48,13 @@ typedef int clockid_t;
 
 int clock_gettime(clockid_t, struct timespec*);
 int clock_nanosleep(clockid_t, int flags, const struct timespec* requested_sleep, struct timespec* remaining_sleep);
+int clock_getres(clockid_t, struct timespec* result);
+struct tm* gmtime_r(const time_t* timep, struct tm* result);
+struct tm* localtime_r(const time_t* timep, struct tm* result);
 
 double difftime(time_t, time_t);
 size_t strftime(char* s, size_t max, const char* format, const struct tm*);
 
 #define difftime(t1, t0) (double)(t1 - t0)
 
-
 __END_DECLS

Libraries/LibC/wchar.cpp

@@ -1,3 +1,4 @@
+#include <AK/Assertions.h>
 #include <wchar.h>
 
 extern "C" {
@@ -18,6 +19,14 @@ wchar_t* wcscpy(wchar_t* dest, const wchar_t* src)
     return originalDest;
 }
 
+wchar_t* wcsncpy(wchar_t* dest, const wchar_t* src, size_t num)
+{
+    wchar_t* originalDest = dest;
+    while (((*dest++ = *src++) != '\0') && ((size_t)(dest - originalDest) < num))
+        ;
+    return originalDest;
+}
+
 int wcscmp(const wchar_t* s1, const wchar_t* s2)
 {
     while (*s1 == *s2++)
@@ -37,4 +46,79 @@ wchar_t* wcschr(const wchar_t* str, int c)
     }
 }
 
+const wchar_t* wcsrchr(const wchar_t* str, wchar_t wc)
+{
+    wchar_t* last = nullptr;
+    wchar_t c;
+    for (; (c = *str); ++str) {
+        if (c == wc)
+            last = const_cast<wchar_t*>(str);
+    }
+    return last;
+}
+
+wchar_t* wcscat(wchar_t* dest, const wchar_t* src)
+{
+    size_t dest_length = wcslen(dest);
+    size_t i;
+    for (i = 0; src[i] != '\0'; i++)
+        dest[dest_length + i] = src[i];
+    dest[dest_length + i] = '\0';
+    return dest;
+}
+
+wchar_t* wcstok(wchar_t* str, const wchar_t* delim, wchar_t** ptr)
+{
+    wchar_t* used_str = str;
+    if (!used_str) {
+        used_str = *ptr;
+    }
+
+    size_t token_start = 0;
+    size_t token_end = 0;
+    size_t str_len = wcslen(used_str);
+    size_t delim_len = wcslen(delim);
+
+    for (size_t i = 0; i < str_len; ++i) {
+        bool is_proper_delim = false;
+
+        for (size_t j = 0; j < delim_len; ++j) {
+            if (used_str[i] == delim[j]) {
+                // Skip beginning delimiters
+                if (token_end - token_start == 0) {
+                    ++token_start;
+                    break;
+                }
+
+                is_proper_delim = true;
+            }
+        }
+
+        ++token_end;
+        if (is_proper_delim && token_end > 0) {
+            --token_end;
+            break;
+        }
+    }
+
+    if (used_str[token_start] == '\0')
+        return nullptr;
+
+    if (token_end == 0) {
+        return &used_str[token_start];
+    }
+
+    used_str[token_end] = '\0';
+    return &used_str[token_start];
+}
+
+wchar_t* wcsncat(wchar_t* dest, const wchar_t* src, size_t n)
+{
+    size_t dest_length = wcslen(dest);
+    size_t i;
+    for (i = 0; i < n && src[i] != '\0'; i++)
+        dest[dest_length + i] = src[i];
+    dest[dest_length + i] = '\0';
+    return dest;
+}
 }

Libraries/LibC/wchar.h

@@ -11,7 +11,12 @@ __BEGIN_DECLS
 
 size_t wcslen(const wchar_t*);
 wchar_t* wcscpy(wchar_t*, const wchar_t*);
+wchar_t* wcsncpy(wchar_t*, const wchar_t*, size_t);
 int wcscmp(const wchar_t*, const wchar_t*);
 wchar_t* wcschr(const wchar_t*, int);
+const wchar_t* wcsrchr(const wchar_t*, wchar_t);
+wchar_t* wcscat(wchar_t*, const wchar_t*);
+wchar_t* wcstok(wchar_t*, const wchar_t*, wchar_t**);
+wchar_t* wcsncat(wchar_t*, const wchar_t*, size_t);
 
 __END_DECLS

Libraries/LibM/math.cpp

@@ -301,4 +301,10 @@ float ceilf(float value)
     }
     return as_int + 1;
 }
+
+double modf(double x, double* intpart)
+{
+    *intpart = (double)((int)(x));
+    return x - (int)x;
+}
 }