Miscellaneous C99-compatible changes

[throwaway96]

This PR contains most of my minor commits, except for the ones that (more or less) require C11.

The fixes include not crashing on empty input files, eliminating a memory leak in EPKv1 extraction, and making the -n switch apply to filesystems other than Squashfs.

I've been personally using these for almost 2 years now. In that time, I've extracted a lot of EPKv3 files; the rest, not so much.

[smx-smx]

for the future: we could perhaps use something similar to the existing cursor_t type, so that we always do safe reads (similar to C# Span)

[Copilot]

Pull request overview

This PR bundles several small C99-oriented robustness and cleanup changes across the extractor, focused on preventing crashes on small/empty inputs, improving key/signature handling, and making the -n flag disable auto-extraction for more filesystem types (not just SquashFS).

Changes:

• Add size/bounds checks before probing file “magic” values (e.g., LZ4, Philips Fusion1, cramfs, symfile, MTK PKG cases).
• Refactor crypto/key handling and modernize signatures/compare helpers to use bool and const where appropriate.
• Replace noAutoUnsquashfs with a broader noAutoExtractFs option and gate additional filesystem auto-extraction paths.

Reviewed changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
src/util.c	Adds size checks and refactors helpers (datetime/part-type detection); updates kernel extraction I/O.
src/util_crypto.c	Refactors key-file handling and AES key scanning; updates types to bool/const.
src/symfile.c	Adds a minimum-size guard before mapping SYM files.
src/philips.c	Adds a minimum-size guard before checking the Philips Fusion1 magic.
src/mfile.c	Extends _mopen/mopen_private with a writable concept for private mappings.
src/mediatek_pkg.c	Tightens size checks and updates calls to the refactored crypto APIs.
src/main.c	Renames the -n behavior to apply to multiple filesystem extraction paths.
src/lzo-lg.c	Removes an unused variable read from the stream.
src/epk3.c	Updates compare callbacks and printf formats for portability; minor control-flow cleanup.
src/epk2.c	Updates compare callbacks and adapts to boolean crypto wrapper return values.
src/epk1.c	Improves const-correctness and uses snprintf; plugs a leak in one branch.
src/epk.c	Refactors header-type detection and switches crypto wrapper APIs to bool/const; adjusts OpenSSL usage.
src/cramfs/uncramfs.c	Adds a minimum-size guard before mapping cramfs images.
include/util.h	Updates is_datetime to return bool.
include/util_crypto.h	Updates CompareFunc and key-finder signature to use bool/const.
include/mfile.h	Adds bool and updates mopen_private signature.
include/main.h	Updates handle_file declaration (currently mismatched with implementation).
include/epk3.h	Updates compare function prototypes to bool/const.
include/epk2.h	Updates compare function prototypes to bool/const.
include/epk.h	Updates crypto wrapper prototypes to bool/const and adds an INVALID enum value.
include/config.h	Renames noAutoUnsquashfs to noAutoExtractFs.

Comments suppressed due to low confidence (2)

src/symfile.c:94

• mmap failure is checked incorrectly: mmap() returns MAP_FAILED (not NULL) on error, so the current if (header == NULL) check won’t catch failures and will later dereference an invalid pointer. Check p == MAP_FAILED (and close fd) before using the mapping.

	if (st_buf.st_size < sizeof(*header)) {
		close(fd);
		return -1;
	}

	p = mmap(NULL, st_buf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	header = p;
	p += sizeof(*header);
	if (header == NULL) {
		fprintf(stderr, "can't mmap `%s': %m\n", fname);

		return -1;
	}

src/util.c:281

• is_nfsb_mem performs memcmp at data + 0x1A for up to 6 bytes (and also reads the 4-byte magic), but it doesn’t validate that offset + 0x1A + 6 <= msize(file) before doing so. Since this helper is called with non-zero offsets (e.g., Sharp PKG handling), it can still read past the mapping and crash on small inputs. Add a bounds check up front and return false if the file is too small for the maximum probe offset.

bool is_nfsb_mem(MFILE *file, off_t offset){
	uint8_t *data = &(mdata(file, uint8_t))[offset];

	if(memcmp(data, "NFSB", 4) != 0){
		return false;
	}

	/* XXX: This needs to check the length of the file before reading anything.*/
	const char algo_md5[] = "md5";
	const char algo_sha256[] = "sha256";

	const int offsets[] = { 0x0E, 0x1A };
	const char *algos[] = { algo_md5, algo_sha256 };
	const int lengths[] = { sizeof(algo_md5) - 1, sizeof(algo_sha256) - 1 };

	const int num_offsets = countof(offsets);
	const int num_algos = countof(algos);

	for(int i=0; i<num_algos; i++){
		for(int j=0; j<num_offsets; j++){
			if(memcmp(data + offsets[j], algos[i], lengths[i]) == 0){
				return true;

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