skaji/FB9859061.md

## FB9859061.md

      
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              FB9859061.md
            
          
    Summary

stat("../bin") on /Users directory sometimes fails with errno=2 (ENOENT)
Environment

I saw this failure on several Mac machines. Especially:

macOS Monterey 12.1, MacBook Pro 13-inch, 2020, M1
macOS Monterey 12.1, MacBook Pro 16-inch, 2019, Intel
macOS Catalina 10.15.7, MacBook Pro 15-inch, 2013, Intel

Steps to reproduce the problem

Step1: Create a simple C-program ~/a.c that calls stat forever

❯ cd ~
❯ cat a.c
#include <sys/stat.h>
#include <stdio.h>
#include <errno.h>

extern int errno;

int main() {
  struct stat buf;
  long i = 0;
  for (;;) {
    ++i;
    if (stat("../bin", &buf)) {
      printf("%ld: stat(\"../bin\"): errno=%d\n", i, errno);
    }
  }
}
❯ cc a.c
❯ ls a.out
a.out

Step2: Execute ~/a.out in /Users directory

❯ cd /Users
❯ ~/a.out

Step3: Then you'll see some failures of ~/a.out

❯ ~/a.out
2091386: stat("../bin"): errno=2
2092797: stat("../bin"): errno=2
2094995: stat("../bin"): errno=2
...

Please note that the failures may increase if we execute some programs in other terminal, especially:

cd /Users
/usr/local/bin/gls /Users (where gls comes from homebrew)
/opt/homebrew/bin/gls /Users (where gls comes from homebrew)

Note


The "dot-dot" notation (../bin) seems important; if we call stat("/bin"), then it doesn't fail very much.
Calling stat from /Users directory also seems important; if we call stat("../bin") from /Applications directory, then it doesn't fail very much.
I only mentioned stat function; but open("../bin/ls", O_RDONLY) also sometimes fails with errno=2 (ENOENT)