{"record":{"id":"dc65625b9f4a736e","repo":"kovidgoyal/kitty","slug":"failed-to-write-to-shm-file-with-error-w","errorCode":null,"errorMessage":"Failed to write to SHM file with error: %w","messagePattern":"Failed to write to SHM file with error: %w","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"kittens/ssh/askpass.go","lineNumber":139,"sourceCode":"\tq := map[string]any{\n\t\t\"message\":     msg,\n\t\t\"type\":        q_type,\n\t\t\"is_password\": !is_fingerprint_check,\n\t}\n\tdata, err := json.Marshal(q)\n\tif err != nil {\n\t\treturn fatal(err)\n\t}\n\tdata_shm, err := shm.CreateTemp(\"askpass-*\", uint64(len(data)+32))\n\tif err != nil {\n\t\treturn fatal(fmt.Errorf(\"Failed to create SHM file with error: %w\", err))\n\t}\n\tdefer data_shm.Close()\n\tdefer func() { _ = data_shm.Unlink() }()\n\n\tdata_shm.Slice()[0] = 0\n\tif err = shm.WriteWithSize(data_shm, data, 1); err != nil {\n\t\treturn fatal(fmt.Errorf(\"Failed to write to SHM file with error: %w\", err))\n\t}\n\tif err = data_shm.Flush(); err != nil {\n\t\treturn fatal(fmt.Errorf(\"Failed to flush SHM file with error: %w\", err))\n\t}\n\ttrigger_ask(data_shm.Name())\n\tfor {\n\t\ttime.Sleep(50 * time.Millisecond)\n\t\tif data_shm.Slice()[0] == 1 {\n\t\t\tbreak\n\t\t}\n\t}\n\tdata, err = shm.ReadWithSize(data_shm, 1)\n\tif err != nil {\n\t\treturn fatal(fmt.Errorf(\"Failed to read from SHM file with error: %w\", err))\n\t}\n\tresponse := \"\"\n\tif is_confirm {\n\t\tvar ok bool","sourceCodeStart":121,"sourceCodeEnd":157,"githubUrl":"https://github.com/kovidgoyal/kitty/blob/6d5d0c440603ad9bdf6dcd599f73f6dde21acb44/kittens/ssh/askpass.go#L121-L157","documentation":"After creating the SHM file, RunSSHAskpass writes the JSON request with shm.WriteWithSize at offset 1 (offset 0 is the ready flag). If that write fails (mapping too small, mmap error, I/O error), this fatal error is returned.","triggerScenarios":"SHM file created with insufficient size for the payload, or mmap write failure on the shared memory region.","commonSituations":"Odd filesystem backing for /dev/shm that does not support the mmap semantics, or a truncated CreateTemp size due to integer issues.","solutions":["Verify /dev/shm is a real tmpfs","Check dmesg for mmap/SHM errors","Retry; if persistent, report with the wrapped error details"],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"if err := shm.WriteWithSize(f, data, 1); err != nil { /* log, close, unlink, abort askpass */ }","preventionTips":["Size SHM allocations generously (payload + header)","Verify tmpfs backing before use"],"tags":["shared-memory","shm","io","ssh","askpass"],"backgroundTag":"shared-memory-write-failed","analyzedSha":"6d5d0c440603ad9bdf6dcd599f73f6dde21acb44","analyzedAt":"2026-08-27T14:20:20.142Z","schemaVersion":2},"datasetVersion":"2026-08-27T19:17:21.184Z"}