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I feel like I have been writing and then losing this program once every couple years for at least a decade so I'm putting it on github this time: mmgrep, search for a binary string in some files using mmap+memmem

github.com

GitHub - moyix/mmgrep: Fast search for binary strings

Fast search for binary strings. Contribute to moyix/mmgrep development by creating an account on GitHub.

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I remember

teaching his students to check the results of functions and then being dismayed when they checked the result of printf; I see that you put malloc and sscanf on that side of the divide.

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Yup! I have pretty low standards for filing off sharp edges on tools that I'm ony using myself

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But if it will make you happy,

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it also makes me happy, Brendan! but I am also crying:

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I am told this is a perfectly acceptable use of goto

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Definitely. If aeronautics software relied on dynamic allocation, this is how it would be structured.

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oh I like the gotos, I had only meant that Brendan was not checking the return values from these two fine system calls

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one can almost never do anything about these errors at the moment, but knowing that they happened usually points to logic errors elsewhere in the program

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ENOMEM can unfortunately happen for no fault of your own though. It's why this wrapper exists:

github.com

hardened_malloc/memory.c at main · GrapheneOS/hardened_malloc

Hardened allocator designed for modern systems. It has integration into Android's Bionic libc and can be used externally with musl and glibc as a dynamic library for use on other Linux-base...

3:58 PM · Feb 27, 2021Twitter Web App

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yep, it's really only EBADF that I want to know about for bug-fixing purposes

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Yeah, it makes sense to wrap close, check for that and abort the program. Not much point in checking for other close errors though. You generally have to design around using fsync if you need things to be reliable and the fsync is where you actually need to handle the errors.

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