{"record":{"id":"da0d6216bc59d748","repo":"kovidgoyal/kitty","slug":"failed-to-read-from-shm-file-with-error-w","errorCode":null,"errorMessage":"Failed to read from SHM file with error: %w","messagePattern":"Failed to read from SHM file with error: %w","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"kittens/ssh/askpass.go","lineNumber":153,"sourceCode":"\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\n\t\terr = json.Unmarshal(data, &ok)\n\t\tif err != nil {\n\t\t\treturn fatal(fmt.Errorf(\"Failed to parse response data: %#v with error: %w\", string(data), err))\n\t\t}\n\t\tresponse = \"no\"\n\t\tif ok {\n\t\t\tresponse = \"yes\"\n\t\t}\n\t} else {\n\t\terr = json.Unmarshal(data, &response)\n\t\tif err != nil {\n\t\t\treturn fatal(fmt.Errorf(\"Failed to parse response data: %#v with error: %w\", string(data), err))\n\t\t}\n\t\tif is_fingerprint_check {","sourceCodeStart":135,"sourceCodeEnd":171,"githubUrl":"https://github.com/kovidgoyal/kitty/blob/6d5d0c440603ad9bdf6dcd599f73f6dde21acb44/kittens/ssh/askpass.go#L135-L171","documentation":"After the parent sets the ready flag, RunSSHAskpass reads the response back with shm.ReadWithSize. If the size header or payload read fails, this fatal error is returned, meaning the IPC round-trip was corrupted.","triggerScenarios":"Parent process wrote a malformed size prefix, SHM region was resized/truncated, or the parent crashed mid-write leaving inconsistent data.","commonSituations":"kitty or the askpass UI process being killed while answering, version mismatch between the askpass helper and kitty changing the SHM protocol.","solutions":["Ensure kitty and the ssh kitten askpass helper are the same version","Avoid killing the UI while an askpass prompt is open","Retry the ssh operation; persistent failures suggest protocol mismatch — upgrade kitty"],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":null,"typeGuard":null,"tryCatchPattern":"data, err := shm.ReadWithSize(f, 1)\nif err != nil { /* treat askpass session as failed, unlink and exit */ }","preventionTips":["Keep helper and kitty versions in sync","Do not kill the UI process mid-prompt"],"tags":["shared-memory","shm","ipc","ssh","askpass"],"backgroundTag":"ipc-shared-memory-read-failed","analyzedSha":"6d5d0c440603ad9bdf6dcd599f73f6dde21acb44","analyzedAt":"2026-08-27T14:20:20.142Z","schemaVersion":2},"datasetVersion":"2026-08-27T19:17:21.184Z"}