{"record":{"id":"4ed55e00e9c75a3a","repo":"antonmedv/fx","slug":"non-patherror-from-os-open-filepath-panic-err","errorCode":null,"errorMessage":"<non-PathError from os.Open(filePath)> (panic(err))","messagePattern":"<non-PathError from os\\.Open\\(filePath\\)> \\(panic\\(err\\)\\)","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"utils.go","lineNumber":38,"sourceCode":"func lookup(names []string, defaultEditor string) string {\n\tfor _, name := range names {\n\t\tenv, ok := os.LookupEnv(name)\n\t\tif ok && env != \"\" {\n\t\t\treturn env\n\t\t}\n\t}\n\treturn defaultEditor\n}\n\nfunc open(filePath string, flagYaml, flagToml *bool) *os.File {\n\tf, err := os.Open(filePath)\n\tif err != nil {\n\t\tvar pathError *fs.PathError\n\t\tif errors.As(err, &pathError) {\n\t\t\tprintln(err.Error())\n\t\t\tos.Exit(1)\n\t\t} else {\n\t\t\tpanic(err)\n\t\t}\n\t}\n\tfileName := path.Base(filePath)\n\thasYamlExt, _ := regexp.MatchString(`(?i)\\.ya?ml$`, fileName)\n\thasTomlExt, _ := regexp.MatchString(`(?i)\\.toml$`, fileName)\n\tif !*flagYaml && hasYamlExt {\n\t\t*flagYaml = true\n\t}\n\tif !*flagToml && hasTomlExt {\n\t\t*flagToml = true\n\t}\n\treturn f\n}\n\nfunc regexCase(code string) (string, bool) {\n\tif strings.HasSuffix(code, \"/i\") {\n\t\treturn code[:len(code)-2], true\n\t} else if strings.HasSuffix(code, \"/\") {","sourceCodeStart":20,"sourceCodeEnd":56,"githubUrl":"https://github.com/antonmedv/fx/blob/4f31cd3a0c5d66f1b4290a2719bab14a5cee8ebe/utils.go#L20-L56","documentation":"The open() helper opens the input file with os.Open. Expected failures (os.PathError: file not found, permission denied) print the error and exit(1); any other error type panics. This panic means os.Open failed in a way that is not a path-related error — rare, e.g. too many open files or an OS-level fault.","triggerScenarios":"os.Open(filePath) returns a non-nil error that is not *fs.PathError — e.g. EMFILE (too many open files), ENOMEM, or errors from unusual file systems not wrapped in PathError.","commonSituations":"Hitting the file-descriptor limit when many files are open; running with a depleted ulimit; exotic FUSE/network filesystems returning non-standard errors.","solutions":["Check and raise the file-descriptor limit (ulimit -n) if EMFILE is the cause","Close other open files/handles in the process before calling open()","Retry the command — some failures are transient resource exhaustion","Convert the panic to a graceful exit for unexpected error types"],"exampleFix":"// before\n} else {\n\tpanic(err)\n}\n// after\n} else {\n\tprintln(err.Error())\n\tos.Exit(1)\n}","handlingStrategy":"validation","validationCode":"// pre-check file accessibility before invoking fx\nf, err := os.Open(filePath)\nif err != nil {\n\treturn fmt.Errorf(\"cannot open %s: %w\", filePath, err)\n}\nf.Close()","typeGuard":"func isOpenable(path string) bool {\n\tf, err := os.Open(path)\n\tif err != nil {\n\t\treturn false\n\t}\n\tf.Close()\n\treturn true\n}","tryCatchPattern":"// recover if calling open() indirectly through fx\nfunc safeRun(args []string) (err error) {\n\tdefer func() {\n\t\tif r := recover(); r != nil {\n\t\t\terr = fmt.Errorf(\"fx open failed: %v\", r)\n\t\t}\n\t}()\n\treturn callMain(args)\n}","preventionTips":["Verify the file exists and is readable (os.Stat / test -r) before running","Raise ulimit -n if processing many files concurrently","Close file handles promptly to avoid descriptor exhaustion","Check the file path is correct and on a reliable filesystem"],"tags":["go","panic","file-io","os","ulimit"],"backgroundTag":"too-many-open-files","analyzedSha":"4f31cd3a0c5d66f1b4290a2719bab14a5cee8ebe","analyzedAt":"2026-09-02T02:17:47.344Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-09T06:17:21.866Z"}