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unix: retry fetching of lists through sysctl if the size changes

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On macOS, the SysctlKinfoProcSlice() function may be used to fetch the
contents of the process table. As the process table may grow between the
first and second call to sysctl(), the second call may fail with ENOMEM.
In that case we simply need to retry.
This commit is contained in:
Ed Schouten
2023-07-25 08:52:39 +02:00
parent ad7130c58d
commit b63b6b8471
1 changed files with 28 additions and 22 deletions
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50
unix/syscall_darwin.go
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@@ -510,30 +510,36 @@ func SysctlKinfoProcSlice(name string, args ...int) ([]KinfoProc, error) {
return nil, err
}
// Find size.
n := uintptr(0)
if err := sysctl(mib, nil, &n, nil, 0); err != nil {
return nil, err
}
if n == 0 {
return nil, nil
}
if n%SizeofKinfoProc != 0 {
return nil, fmt.Errorf("sysctl() returned a size of %d, which is not a multiple of %d", n, SizeofKinfoProc)
}
for {
// Find size.
n := uintptr(0)
if err := sysctl(mib, nil, &n, nil, 0); err != nil {
return nil, err
}
if n == 0 {
return nil, nil
}
if n%SizeofKinfoProc != 0 {
return nil, fmt.Errorf("sysctl() returned a size of %d, which is not a multiple of %d", n, SizeofKinfoProc)
}
// Read into buffer of that size.
buf := make([]KinfoProc, n/SizeofKinfoProc)
if err := sysctl(mib, (*byte)(unsafe.Pointer(&buf[0])), &n, nil, 0); err != nil {
return nil, err
}
if n%SizeofKinfoProc != 0 {
return nil, fmt.Errorf("sysctl() returned a size of %d, which is not a multiple of %d", n, SizeofKinfoProc)
}
// Read into buffer of that size.
buf := make([]KinfoProc, n/SizeofKinfoProc)
if err := sysctl(mib, (*byte)(unsafe.Pointer(&buf[0])), &n, nil, 0); err != nil {
if err == ENOMEM {
// Process table grew. Try again.
continue
}
return nil, err
}
if n%SizeofKinfoProc != 0 {
return nil, fmt.Errorf("sysctl() returned a size of %d, which is not a multiple of %d", n, SizeofKinfoProc)
}
// The actual call may return less than the original reported required
// size so ensure we deal with that.
return buf[:n/SizeofKinfoProc], nil
// The actual call may return less than the original reported required
// size so ensure we deal with that.
return buf[:n/SizeofKinfoProc], nil
}
}
//sys sendfile(infd int, outfd int, offset int64, len *int64, hdtr unsafe.Pointer, flags int) (err error)