go system_error ai_generated true

error: cgo: C function returned error: errno 2

ID: go/cgo-errno-handling

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80%Fix Rate
85%Confidence
0Evidence
2025-01-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.18 active — — —
1.19 active — — —

Root Cause

C function sets `errno` on failure, but Go code does not check it, leading to silent failures.

generic

中文

C函数在失败时设置`errno`，但Go代码未检查，导致静默失败。

Workarounds

  1. 90% success Check return value and use `C.CString` to get error message 
    ret := C.someCFunction()
if ret != 0 {
    errno := C.errno
    errStr := C.GoString(C.strerror(errno))
    return fmt.Errorf("C error: %s", errStr)
}
  2. 80% success Use `cgo.Handle` to capture error in a thread-safe way 
    // Not directly applicable; use mutex to protect errno reading

Dead Ends

Common approaches that don't work:

  1. Ignoring the return value of C function 90% fail

    No error handling at all.

  2. Using `C.errno` directly without thread safety 60% fail

    errno is thread-local in C, but Go may not preserve it.