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Possibly incorrect fd assertion in pal_utilities.h #131506
Description
Description
This assertion:
Is incorrect because the value of _SC_OPEN_MAX can change during execution via setrlimit, and other processes can set your rlimit so it can change even if the application code never changes it. I think it should be simplified to
assert(0 <= fd). As a bonus, that would probably make it possible to enable the assertion on WASI.
Reproduction Steps
The equivalent of this in C#:
struct rlimit rl = { 4096, 4096 };
setrlimit(RLIMIT_NOFILE, &rl);
int fd = dup2(0, 3000);
rl.rlim_cur = 1024;
setrlimit(RLIMIT_NOFILE, &rl);
assert(fd < sysconf(_SC_OPEN_MAX));Would make this assertion fail.
Expected behavior
The assertion should only reject definitely-invalid fds like -1. The linux kernel's maximum valid FD is currently 1024*1024 but I wouldn't personally hard-code that into a runtime assertion.
Actual behavior
Any valid FD over the current rlimit will cause this assertion to fail.
Regression?
Not a regression.
Known Workarounds
No response
Configuration
No response
Other information
No response
Activity
dotnet-policy-service commentedon Jul 29, 2026
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Fix Unix file descriptor assertion (#132136)