util/nvmutil: split up nvmutil.c

i still use a global variable, but now only
one, which is a structure containing the
state of the entire program

now i can easily start modifying it to make
functions generic, and then i can start
making parts of it into easy libraries

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/nvmutil/todo.c

@@ -0,0 +1,134 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
+ *
+ * Five Year Plan
+ */
+
+/*
+ * Major TODO: split this into multiple files.
+ * This program has become quite large now, mostly
+ * due to all the extra sanity checks / portability.
+ * Make most of nvmutil a *library* for re-use
+ *
+ * TODO: gettimeofday not posible - use portable functions.
+ * TODO: ux fallback: modify the program instead
+ * to run on 16-bit systems: smaller buffers, and do
+ * operations byte-based instead of word-based.
+ *
+ * TODO: _XOPEN_SOURCE 500 probably not needed anymore.
+ * the portable fallbacks alone are likely enough.
+ * e.g. i don't need stdint, and i don't use pwrite/pread
+ * anymore.
+ *
+ * TODO: version detection of various BSDs to detect
+ * arc4random, use that if available. but also work on
+ * older versions of those BSDs (also MacOS) that lack it.
+ *
+ * TODO: portability/testing on non-Unix systems:
+ * old DOS. all windows versions (probably irrelevant
+ * because you can use cygwin/wsl, whatever), classic MacOS,
+ * also test really old unix e.g. sunos and irix. Be/Haiku too!
+ *
+ * TODO: reliance on global variables for status. make
+ * functions use structs passed as args instead, make
+ * functions re-useable (including libraries), etc.
+ *
+ * TODO: bound checks for files per-command, e.g. only
+ * first 6 bytes for CMD_SETMAC
+ *
+ * TODO: in command sanitizer: verify that each given
+ * entry corresponds to the correct function, in the
+ * pointer (this check is currently missing)
+ *
+ * TODO: general modularisierung of the entire codebase.
+ * TODO: better explain copy/swap read inversion trick
+ *       by improving existing comments
+ * TODO: lots of overwritten comments in code. tidy it up.
+ *
+ * TODO: use getopt for nvmutil args, so that multiple
+ *      operations can be performed, and also on many
+ *	files at once (noting limitations with cat)
+ *	BONUS: implement own getopt(), for portability
+ *
+ * TODO: document fuzzing / analysis methods
+ * 	for the code, and:
+ * TODO: implement rigorous unit tests (separate util)
+ *	NOTE: this would *include* known good test files
+ *	in various configurations, also invalid files.
+ *	the tests would likely be portable posix shell
+ *	scripts rather than a new C program, but a modularisiert
+ *	codebase would allow me to write a separate C
+ *	program to test some finer intricacies
+ * TODO: the unit tests would basically test regressions
+ * TODO: after writing back a gbe to file, x_i_close() and
+ *	open() it again, read it again, and check that
+ *	the contents were written correctly, providing
+ *	a warning if they were. do this in the main
+ *	program.
+ * TODO: the unit tests would include an aggressive set
+ *	of fuzz tests, under controlled conditions
+ *
+ * TODO: also document the layout of Intel GbE files, so
+ *       that wily individuals can easily expand the
+ *	featureset of nvmutil.
+ * TODO: write a manpage
+ * TODO: simplify the command sanitization, implement more
+ *	of it as build time checks, e.g. asserts.
+ *	generally remove cleverness from the code, instead
+ *	prefyerring readibility
+ * TODO: also document nvmutil's coding style, which is
+ *	its own style at this point!
+ * TODO: when all the above (and possibly more) is done,
+ *	submit this tool to coreboot with a further change
+ *	to their build system that lets users modify
+ *	GbE images, especially set MAC addresses, when
+ *	including GbE files in coreboot configs.
+ */
+/*
+ BONUS TODO:
+ CI/CD. woodpecker is good enough, sourcehut also has one.
+	tie this in with other things mentioned here, 
+	e.g. fuzzer / unit tests
+*/
+
+/* Major TODO: reproducible builds
+Test with and without these:
+
+CFLAGS += -fno-record-gcc-switches
+CFLAGS += -ffile-prefix-map=$(PWD)=.
+CFLAGS += -fdebug-prefix-map=$(PWD)=.
+
+I already avoid unique timestamps per-build,
+by not using them, e.g. not reporting build
+time in the program.
+
+When splitting the nvmutil.c file later, do e.g.:
+
+SRC = main.c io.c nvm.c cmd.c
+OBJ = $(SRC:.c=.o)
+
+^ explicitly declare the order in which to build
+*/
+
+/*
+TODO:
+further note when fuzzing is implemented:
+use deterministic randomisation, with a
+guaranteed seed - so e.g. don't use /dev/urandom
+in test builds. e.g. just use normal rand()
+but with a seed e.g. 1234
+*/
+/*
+TODO: stricter build flags, e.g.
+CFLAGS += -fstack-protector-strong
+CFLAGS += -fno-common
+CFLAGS += -D_FORTIFY_SOURCE=2
+CFLAGS += -fPIE
+
+also consider:
+-fstack-clash-protection
+-Wl,-z,relro
+-Wl,-z,now
+*/
+