alt Hacker Newsmalloc() and friends may always return NULL. From the man page:
If successful, calloc(), malloc(), realloc(), reallocf(), valloc(), and aligned_alloc() functions return a pointer to allocated memory. If there is an error, they return a NULL pointer and set errno to ENOMEM.
In practice, I find a lot of code that does not check for NULL, which is rather distressing.
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sidewndr46 • last Friday at 9:33 PM
It's been a while but while I agree the man page says that, my limited understanding was the typical libc on linux won't really return NULL under any sane scenario. Even when the memory can't be backed
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No non-embedded libc will actually return NULL. Very, very little practical C code actually relies only on specified behavior of the spec and will work with literally any compliant C compiler on any architecture, so I don’t find this particularly concerning.
Usefully handling allocation errors is very hard to do well, since it infects literally every error handling path in your codebase. Any error handling that calls a function that might return an indirect allocation error needs to not allocate itself. Even if you have a codepath that speculatively allocates and can fallback, the process is likely so close to ruin that some other function that allocates will fail soon.
It’s almost universally more effective (not to mention easier) to keep track of your large/variable allocations proactively, and then maintain a buffer for little “normal” allocations that should have an approximate constant bound.