string.h

Memory operations:

• void* memset(void *b, int c, size_t len);
• void* memccpy(void *dest, const void *src, int c, size_t n);
• void* memcpy(void *dest, const void *src, size_t n);
• void* memmove(void *dest, const void *src, size_t len);
• void* memchr(const void *s, int c, size_t n);
• int memcmp(const void *s1, const void *s2, size_t n);

String operations:

• char* strchr(const char *s, int c)
• char* strrchr(const char *s, int c);
• int strncmp(const char *s1, const char *s2, size_t n);

Wrappers:

size_t strnlen(const char* s, size_t maxlen) {
    return memchr(s, 0, maxlen) - s;
}
size_t strlen(const char* s) {
    return strnlen(s, SIZE_MAX);
}
int strcmp(const char* s1, const char* s2) {
    return strncmp(s1, s2, SIZE_MAX);
}
char* stpncpy(char* dest, const char* src, size_t n) {
    char* e = memccpy(dest, src, 0, n);
    if (!e)  return dest + n;
    memset(e, 0, n - (e - dest));
    return e - 1;
}
char* stpcpy(char* dest, const char* src) {
    return stpncpy(dest, src, strlen(src) + 1);
}
char* strncpy(char* dest, const char* src, size_t n) {
    char* e = memccpy(dest, src, 0, n);
    if (e)  memset(e, 0, n - (e - dest));;
    return dest;
}
char* strcpy(char* dest, const char* src) {
    return strncpy(dest, src, strlen(src) + 1);
}
char *strncat(char* dest, const char* src, size_t n) {
    *(stpncpy(memchr(dest, 0, SIZE_MAX), src, n)) = 0;
    return dest;
}
char *strcat(char* dest, const char* src) {
    return strncat(dest, src, strlen(src) + 1);
}
char *strdup(const char* s) {
    size_t len = strlen(s) + 1;
    char* buf = malloc(len);
    return memcpy(buf, s, len);
}