{"record":{"id":"ed055f53168dc3e2","repo":"lionsoul2014/ip2region","slug":"read-segment-index-at-d-w","errorCode":null,"errorMessage":"read segment index at %d: %w","messagePattern":"read segment index at (.+?): %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"binding/golang/xdb/searcher.go","lineNumber":174,"sourceCode":"\t// fmt.Printf(\"sPtr=%d, ePtr=%d\\n\", sPtr, ePtr)\n\t// @Note: ptr validate, zero ptr means source data missing\n\t// so we could just stop here and return an empty string.\n\tif sPtr == 0 || ePtr == 0 {\n\t\treturn \"\", nil\n\t}\n\n\t// binary search the segment index to get the region\n\tvar bytes, dBytes = len(ipBytes), len(ipBytes) << 1\n\tvar segIndexSize = uint32(s.version.SegmentIndexSize)\n\tvar dataLen, dataPtr = 0, uint32(0)\n\tvar buff = make([]byte, segIndexSize)\n\tvar l, h = 0, int((ePtr - sPtr) / segIndexSize)\n\tfor l <= h {\n\t\tm := (l + h) >> 1\n\t\tp := sPtr + uint32(m)*segIndexSize\n\t\terr := s.read(int64(p), buff)\n\t\tif err != nil {\n\t\t\treturn \"\", fmt.Errorf(\"read segment index at %d: %w\", p, err)\n\t\t}\n\n\t\t// decode the data step by step to reduce the unnecessary operations\n\t\tif s.version.IPCompare(ipBytes, buff[0:bytes]) < 0 {\n\t\t\th = m - 1\n\t\t} else if s.version.IPCompare(ipBytes, buff[bytes:dBytes]) > 0 {\n\t\t\tl = m + 1\n\t\t} else {\n\t\t\tdataLen = int(binary.LittleEndian.Uint16(buff[dBytes:]))\n\t\t\tdataPtr = binary.LittleEndian.Uint32(buff[dBytes+2:])\n\t\t\tbreak\n\t\t}\n\t}\n\n\t// fmt.Printf(\"dataLen: %d, dataPtr: %d\\n\", dataLen, dataPtr)\n\tif dataLen == 0 {\n\t\treturn \"\", nil\n\t}","sourceCodeStart":156,"sourceCodeEnd":192,"githubUrl":"https://github.com/lionsoul2014/ip2region/blob/c1a1fc7d5941760db3f8431dc05c48cf7f0e30a1/binding/golang/xdb/searcher.go#L156-L192","documentation":"Go xdb searcher: reading one fixed-size segment-index row (during the binary search over the index block) failed via the internal read(); the wrapped error is a seek/read/short-read failure against the file or content buffer, indicating a truncated or corrupt xdb.","triggerScenarios":"File-based read failure (bad seek/short read) at segment index offset p; a corrupted or truncated xdb whose index area is shorter than the header's start/end pointers claim; content buffer missing the index tail.","commonSituations":"Truncated download cutting off the index section; corrupted xdb produced by a failed maker run; searching an xdb loaded from a partially cached buffer.","solutions":["Verify file integrity (size vs header end-pointer; compare checksum if available) and re-download the xdb.","Ensure content-buffer searchers get the entire file, matching header.StartIndexPtr/HeaderInfoLength+IndexSize expectations.","Check disk space / permissions for file-based searchers.","Inspect the wrapped OS error to distinguish seek failure from short read."],"exampleFix":"// before\nst, _ := os.Stat(path)\n// no size check, searcher reads garbage index\n// after\nst, err := os.Stat(path)\nif err != nil { return err }\nhdr, err := xdb.LoadHeaderFromFile(path)\nif err != nil { return err }\nif int64(hdr.Length) > st.Size() {\n    return fmt.Errorf(\"xdb truncated: have %d, need %d\", st.Size(), hdr.Length)\n}","handlingStrategy":"validation","validationCode":"fi, _ := os.Stat(xdbPath)\nhdr, err := xdb.LoadHeaderFromFile(xdbPath)\nif err != nil { return err }\nif fi.Size() < int64(hdr.Length) {\n    return fmt.Errorf(\"xdb truncated: %d < %d\", fi.Size(), hdr.Length)\n}","typeGuard":null,"tryCatchPattern":"region, err := searcher.Search(ctx, ip)\nif err != nil {\n    if strings.Contains(err.Error(), \"read segment index\") {\n        return nil, fmt.Errorf(\"xdb index corrupt — regenerate the xdb file\")\n    }\n    return err\n}","preventionTips":["Compare file size against header.Length after download.","Prefer LoadContentFromFile-based searchers to avoid mid-search I/O failures.","Keep a checksum of the xdb build and verify on deploy.","Never mix buffers/header from different xdb builds."],"tags":["golang","xdb","io-error","binary-search","corrupt-file"],"backgroundTag":"xdb-read-failed","analyzedSha":"c1a1fc7d5941760db3f8431dc05c48cf7f0e30a1","analyzedAt":"2026-09-02T16:58:39.988Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-09T21:17:11.164Z"}