How many bugs can you spot?

lol.c

// By [Colin Finck] and used by the [Comprehensive Rust] course, 
// developed by the Android team at Google.
//
// This code compiles warning-free at the default warning level, 
// even in the latest GCC version (13.2 as of writing).
//
// [Colin Finck]: https://colinfinck.de/Master_Thesis_Slides.pdf
// [Comprehensive Rust]: https://github.com/google/comprehensive-rust

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

int main(int argc, char* argv[]) {
	char *buf, *filename;
	FILE *fp;
	size_t bytes, len;
	struct stat st;

	switch (argc) {
		case 1:
			printf("Too few arguments!\n");
			return 1;

		case 2:
			filename = argv[argc];
			stat(filename, &st);
			len = st.st_size;
			
			buf = (char*)malloc(len);
			if (!buf)
				printf("malloc failed!\n", len);
				return 1;

			fp = fopen(filename, "rb");
			bytes = fread(buf, 1, len, fp);
			if (bytes = st.st_size)
				printf("%s", buf);
			else
				printf("fread failed!\n");

		case 3:
			printf("Too many arguments!\n");
			return 1;
	}

	return 0;
}