pico8-musl/fillin.c

// pico8-fill-in.c // 16.11.2020 04:02

#include <stddef.h>
#include <stdio.h>
#include <setjmp.h>
#include <string.h>
#include <stdarg.h>

// prefix for debug prints
#define SSS "-fillin-\t"

// TODO: use this to enable / disable debug prints
#if 1
# define DBP printf
#else
# define DBP(...)
#endif

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---strcpy-chk-1.html
// TODO: actually check for overflows
char * __strcpy_chk(char * dest, const char * src, size_t destlen) {
	char *d = dest;

	//printf(SSS "STRCPY %s :::: %s\n", src, dest);

	while (*src != '\0') {
		*d++ = *src++;
	}
	*d++ = *src++;
	//printf("STRCPY FINAL %s\n", dest);

	return dest;
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---stpcpy-chk-1.html
char * __stpcpy_chk(char * dest, const char * src, size_t destlen) {

	// printf(SSS "STPCPY %s :::: %s\n", src, dest);

	return stpcpy(dest, src);
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---strncpy-chk-1.html
char * __strncpy_chk(char * dest, const char * src, size_t n, size_t dest_1len) {

	// printf(SSS "STRNCPY %s :::: %s\n", src, dest);

	return strncpy(dest, src, n);
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---strcat-chk-1.html
// TODO: There's some good info being dumped here
char * __strcat_chk(char * dest, const char * src, size_t destlen) {
	// printf("!!! strcat %s :::: %s\n", src, dest);

	char *res = strncat(dest, src, destlen);
	
	return res;
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---memcpy-chk-1.html
void * __memcpy_chk(void * dest, const void * src, size_t len, size_t destlen) {

	//puts(SSS "MEMCPY \n");

	return memcpy(dest, src, len);
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---memset-chk-1.html
void * __memset_chk(void * dest, int c, size_t len, size_t destlen) {

	// puts(SSS "MEMSET\n");

	return memset(dest, c, len);
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---printf-chk-1.html
int __printf_chk(int flag, const char * format, ...) {
	va_list args;

	//printf("\nPRINTF\n");

	va_start(args, format);
	int ret = vprintf(format, args);
	va_end(args);

	return ret;
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---fprintf-chk-1.htm
int __fprintf_chk(FILE * stream, int flag, const char * format, ...) {
	va_list args;

	//printf("\nFPRINTF\n");

	va_start(args, format);
	int ret = vfprintf(stream, format, args);
	va_end(args);

	return ret;
}

// https://refspecs.linuxbase.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/libc---sprintf-chk-1.html
// TODO: some intresting info
int __sprintf_chk(char * str, int flag, size_t strlen, const char * format, ...) {
	va_list args;

	//printf("!!!ORIGINAL %s\n", str);

	va_start(args, format);
	// int ret = vsnprintf(str, strlen, format, args);
	// TOOD: Look more into the nature of this function getting passed a -1
	// strlen and how else it might be mitigated ?
	int ret = vsprintf(str, format, args);
	va_end(args);

	//printf("!!! sprintf !!!ADR:%p !!!STRLEN:%i !!!RET::%i !!!FORMAT::%s\n!!!OUTPUT::%s\n", str, strlen, ret, format, str);

	return ret;
}

void __longjmp_chk () {
	// puts(SSS "LONG JMP\n");
	asm("pop %rbp");
	// I think this is a GNU extention, but it's an easy way to do it
	goto *(&longjmp);
}

void __fread_chk () {
	// asm ("pop %rbp");
	puts(SSS "FREAD\n");
	// stub
}