// Don't bail on the first error, but remember the worst one. let mut worst = 0; for file in files { if let Err(e) = chmod_one(file) { worst = worst.max(e.exit_code()); } } process::exit(worst);This is not rustic, I feel.
files.iter() .map(chmod_one) .filter_map(Result::err)is more like it.
From there, you can
next()for first error,last()for last error, orfold()for max error, orcollect()if you need to save all errors.
And no, static compilation doesn’t help here, because
get_user_by_namegoes through NSS, which dlopenslibnss_*modules at runtime regardless of whether your binary is statically linked.This is not true in musl systems. I just quickly checked in a Chimera rootfs (which has a system dynamic musl libc btw).
I believe the described
dlopening is one of the well known reasons why GNU libc is not suitable for static linking, unlike musl!In Arch, this indeed loads
/usr/lib/libnss_systemd.so.2.Everyone can test this with
strace id 2>&1 | egrep 'open.*\.so'.Rust or any other compiler can’t catch those type of bugs because they are not bugs at compiler level 🤷
We said the same about memory safety: That’s something a compiler can not solve. Now it does.
It is nice to see that sometines things do improve.
I thought one of the goals of Java and similar was partial memory safety? If it didn’t have null it seems it would be most of the way there.
And don’t forget Basic. Yeah most variants had pointers and equivalents to null, but they are ‘advanced’ and not meant for general code. (Although that’s interpreted and you said compiled, often it could be ‘complied’ similarly to Java bytecode)
Java and similar (i.e. c#) are memory safe and run on garbage collected runtime.
@davidgro @hunger Last basic variant I worked with was the basic of the commodore machines. It had no NULL. I have also seen vbscript a little, afaik also it had not.
In Java, null does not mean a real 0 value, I think it is more like a static const, more similar to the None type of the Python. Its name is only a helper for the C/C++ guys to better understand a stack trace.
Ah, yeah looks like address 0 is nothing special on C64. I was thinking more about things like Qbasic and especially Visual Basic where dereferencing address 0 expecting a string or object is easy enough to do.
@davidgro That was a different thing. You can write or read from the physical memory address 0 even on the systems of the today - except that practically all the OS-es are using their paging or memory management to make that address unreeachable. Actually, as far I can remember, on Linux, the addresses between 0 - 65535 are mapped unreachable. If try to write them, you will get SIGSEGV. This is because a memory page is 4K, that is the granularity of the memory permissions. Beside that, we also need SIGSEGV (which would map to a “null pointer dereference” or analog) if it actually tried to access the part of a larger struct (what would be visible as an access to a non-zero, but very small memory address).
C64 had no memory protection, you could read or write anywhere where you wanted. Although it had memory-mapped I/O, meaning that instead of bus-level port communication, all the IO, i.e. communication of the CPU with the chips of the mainboard, happened as if they would be memory. Some chip happily crashed the system on such writes, particularly the CIA did it (general purpose I/O chip and hw clock) for not enough well thought memory operations in the $DC00 - $DFFF range.
You could happily write into 0 on C64. Actually, on the address 1, you could access the chip select pin of some RAM chips, meaning that you could with that switch from the basic ROM into an additional RAM area. Writing to the 0 byte did not had any on the spot visible effect on my experiments, but today I read in the docs, it had actually effect to the GPIO ports related to the memory chips managed at the address 1.
Actually, c64 went even more: the first page, i.e. the addresses between 0-255, very accessible a bit faster, because they required a lesser amount of CPU and data bus cycles. Very important registers, used for important operations, were there.
However, this all is about the C64 hardware. The C64 basic v2.0, which was written by the microsoft, quickly evaporating all my youth nostalgy, had nothing similar to the NULL (of C) or null (of Java). It not even had an “unset”, “undefined” or similar type. The 3 types it had, were: 32-bit floating point, 16-bit integer and 0-254 byte long string.
I can’t claim to have learned them well, but I have used Java and various Basics over the last 30+ years.
Which parts of my comment do you disagree with?
@davidgro The way that #Rust guards memory is completely different to the way Java or Basic does. Rust is a fully compiled language suitable for systems programming, and the memory protection all happens at compile time; the runtime actually gains speed through the compilation process, rather than having the memory protection slow it down.
The real difference is that the Rust compiler actually reads into the code it is compiling, rather than just making a mechanical translation.
That’s true, it is a very different paradigm.
I wouldn’t go so far as to say that nobody thought it possible before Rust, but I agree it’s much more effective and performant.
Memory safety is something compiler understands and has under control, this stuff it does not. Nor it should.
Many of their TOCTOU issues are something a type system can help with. Require operations to execute on a fd handle directly rather than using convenience functions.
let fd = FileDescriptor::new(path); fd.delete()?; fd.create(mode)?; let is_root = fd == FileDescriptor::new("/"); // does (dev, inode) comparison internally // etcThe uutils devs would need to create that themselves, but
OpenOptionsseems to get them part of the way there at least.That’s a question of API, not type system. And FD types (e.g.
OwnedFd,BorrowedFd) are already in std.That’s a question of API, not type system.
It’s only enforced because of Rust’s strict type system. Python, on the other hand, lets you do whatever you want by comparison, and complains only at runtime. I’ve seen far too many
**kwargsfor my liking.And FD types (e.g.
OwnedFd,BorrowedFd) are already in std.My example would be a thin wrapper around these, most likely. It’s only an example of what I’m trying to convey, though.
Author couldn’t help himself but do some “wisdomry” at the end!
Time for Haskell?
How many more bugs would Haskell catch?
“Entire classes of bugs”?
More than C would.
