From e8b9376573a1defbdc5ba496523c9e94031818a5 Mon Sep 17 00:00:00 2001
From: Danny Holman <dholman@gymli.org>
Date: Fri, 16 Feb 2024 12:39:37 -0600
Subject: kernel: string: add more functions to string library

Add more functions to the string library to process buffers and strings.

Signed-off-by: Danny Holman <dholman@gymli.org>
---
 include/kernel/string.h |  5 ++++
 kernel/string.c         | 64 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/include/kernel/string.h b/include/kernel/string.h
index 8761211..f9a8eed 100644
--- a/include/kernel/string.h
+++ b/include/kernel/string.h
@@ -7,6 +7,11 @@ int memcmp(const void *str1, const void *str2, size_t n);
 void* memcpy(void* __restrict dest, const void* __restrict src, size_t n);
 void* memmove(void* __restrict dest, const void* __restrict src, size_t n);
 void* memset(void *str, int c, size_t n);
+int strncmp(const char *str1, const char *str2, size_t n);
+int strcmp(const char *str1, const char *str2);
 size_t strlen(const char *str);
+char* strcpy(char* __restrict dest, const char* __restrict src);
+char* strcat(char* __restrict dest, const char* __restrict src);
+char* strtok(char* __restrict str, const char* __restrict delim);
 
 #endif
diff --git a/kernel/string.c b/kernel/string.c
index 30fe40d..35dc16e 100644
--- a/kernel/string.c
+++ b/kernel/string.c
@@ -31,6 +31,16 @@ void* memcpy(void* __restrict dest, const void* __restrict src, size_t n) {
         return dest;
 }
 
+char* strcpy(char* __restrict dest, const char* __restrict src) {
+        if (strlen(src) > strlen(dest))
+                return NULL;
+        return (char*)memcpy(dest, src, strlen(src));
+}
+
+char* strcat(char* __restrict dest, const char* __restrict src) {
+        return (char*)memcpy(&dest[strlen(dest)], src, strlen(src));
+}
+
 void* memmove(void* __restrict dest, const void* __restrict src, size_t n) {
         if (dest == src)
                 return dest;
@@ -50,9 +60,63 @@ void* memset(void *str, int c, size_t n) {
         return str;
 }
 
+int strncmp(const char *str1, const char *str2, size_t n) {
+        return memcmp(str1, str2, n);
+}
+
+int strcmp(const char *str1, const char *str2) {
+        size_t str1_sz = strlen(str1);
+        size_t str2_sz = strlen(str2);
+        if (str1_sz > str2_sz)
+                return memcmp(str1, str2, str2_sz);
+        return memcmp(str1, str2, str1_sz);
+}
+
 size_t strlen(const char *str) {
         size_t i = 0;
         while (str[i] != '\0')
                 i++;
         return i;
 }
+
+int _is_delim(char c, const char *delim) {
+        while (*delim != '\0') {
+                if (c == *delim)
+                        return 1;
+                delim++;
+        }
+        return 0;
+}
+
+char* strtok(char* __restrict str, const char* __restrict delim) {
+        static char *old_str;
+
+        if (str == NULL)
+                str = old_str;
+
+        while (1) {
+                if (_is_delim(*str, delim)) {
+                        str++;
+                        continue;
+                }
+
+                if (*str == '\0')
+                        return NULL;
+                break;
+        }
+
+        char *ret = str;
+        while (1) {
+                if (*str == '\0') {
+                        old_str = str;
+                        return ret;
+                }
+
+                if (_is_delim(*str, delim)) {
+                        *str = '\0';
+                        old_str = str + 1;
+                        return ret;
+                }
+                str++;
+        }
+}
-- 
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