From 42b6b927c9b899b9cb82f7b576776b34c1a1bb03 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Sat, 15 Oct 2022 17:24:22 +0200
Subject: [PATCH] libc: Implement strlcpy(), and make strncpy()
 standard-compliant

---
 libs/libc/include/string.h | 17 ++++++++++-------
 libs/libc/src/string.cpp   | 27 ++++++++++++++++++++++-----
 2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/libs/libc/include/string.h b/libs/libc/include/string.h
index 64d0eaf2..6dddf2f3 100644
--- a/libs/libc/include/string.h
+++ b/libs/libc/include/string.h
@@ -33,9 +33,8 @@ extern "C"
     /* Returns the length of the string str, while examining at most max bytes of str. */
     size_t strnlen(const char* str, size_t max);
 
-    /* Copies the string src into dest. This function is unsafe, use strncpy instead. */
-    __lc_deprecated("strcpy is unsafe and should not be used; use strncpy instead") char* strcpy(char* dest,
-                                                                                                 const char* src);
+    /* Copies at most size-1 bytes from the string src into dest, null-terminating the result. */
+    size_t strlcpy(char* dst, const char* src, size_t size);
 
     /* Copies at most max bytes from the string src into dest. */
     char* strncpy(char* dest, const char* src, size_t max);
@@ -46,10 +45,6 @@ extern "C"
     /* Returns a pointer to the last occurrence of the character c in str, or NULL if it is not found. */
     char* strrchr(const char* str, int c);
 
-    /* Concatenates the string src into dest. This function is unsafe, use strncat instead. */
-    __lc_deprecated("strcat is unsafe and should not be used; use strncat instead") char* strcat(char* dest,
-                                                                                                 const char* src);
-
     /* Concatenates at most max bytes of the string src into dest. */
     char* strncat(char* dest, const char* src, size_t max);
 
@@ -68,6 +63,14 @@ extern "C"
     /* Clears n bytes of buf. */
     void* bzero(void* buf, size_t n);
 
+    /* Copies the string src into dest. This function is unsafe, use strlcpy instead. */
+    __lc_deprecated("strcpy is unsafe and should not be used; use strlcpy instead") char* strcpy(char* dest,
+                                                                                                 const char* src);
+
+    /* Concatenates the string src into dest. This function is unsafe, use strncat instead. */
+    __lc_deprecated("strcat is unsafe and should not be used; use strncat instead") char* strcat(char* dest,
+                                                                                                 const char* src);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/libs/libc/src/string.cpp b/libs/libc/src/string.cpp
index 958182d7..683168ff 100644
--- a/libs/libc/src/string.cpp
+++ b/libs/libc/src/string.cpp
@@ -70,15 +70,32 @@ extern "C"
 
     char* strcpy(char* dest, const char* src)
     {
-        memcpy(dest, src, strlen(src) + 1);
+        return (char*)memcpy(dest, src, strlen(src) + 1);
+    }
+
+    char* strncpy(char* dest, const char* src, size_t max)
+    {
+        size_t i;
+        for (i = 0; i < max && src[i] != 0; i++) dest[i] = src[i];
+        for (; i < max; i++) dest[i] = 0;
         return dest;
     }
 
-    char* strncpy(char* dest, const char* src, size_t max) // FIXME: Implement strncpy according to the specification.
+    size_t strlcpy(char* dest, const char* src, size_t size)
     {
-        size_t src_len = strlen(src) + 1; // NULL byte
-        memcpy(dest, src, src_len > max ? max : src_len);
-        return dest;
+        size_t len = strlen(src);
+        if (size == 0) return len;
+        if (len < (size - 1))
+        {
+            memcpy(dest, src, len);
+            dest[len] = 0;
+        }
+        else
+        {
+            memcpy(dest, src, size - 1);
+            dest[size - 1] = 0;
+        }
+        return len;
     }
 
     int strcmp(const char* a, const char* b)