Back

logappend

logappend -T <timestamp> -K <token> (-D <doctor-name> | -N <nurse-name>) (-A | -L) [-R <room-id>] -F <log>
logappend -B <file>

Appends data to the log at the specified timestamp using the authentication token. If the log does not exist, logappend will create it. Otherwise it will append to the existing log.

If the data to be appended to the log is not consistent with the current state of the log, logappend should exit with an error condition and leave the state of the log unchanged.

• -T timestamp Time the event is recorded.

• -K token Token used to authenticate the log. Once a log is created with a specific token, any subsequent appends or reads on that log must use the same token.

• -D name Name of doctor.

• -N name Name of nurse.

• -A Specify that the current event is an arrival; can be used with -D, -N, and -R. This option can be used to signify the arrival of an doctor or nurse to the hospital, or to a specific room with -R. If -R is not provided, -A indicates an arrival to the hospital as a whole.

• -L Specify that the current event is a departure, can be used with -D, -N, and -R.This option can be used to signify the departure of an doctor or nurse from the hospital, or from a specific room with -R. If -R is not provided, -L indicates a departure from the hospital as a whole.

• -R room-id Specifies the room ID for an event. Room IDs are positive integers with no spaces. Leading zeros in room IDs should be dropped, such that 003, 03, and 3 are all equivalent room IDs. The hospital is composed of multiple rooms. A complete list of the rooms of the hospital is not available and rooms will only be described when a doctor or nurse enters or leaves one. A room cannot be left by an doctor or nurse unless that doctor or nurse has previously entered that room. An doctor or nurse may only occupy one room at a time. If a room ID is not specified, the event is for the hospital as a whole.

• -F log The path to the file containing the event log. If the log does not exist, logappend should create it. logappend should add data to the log, preserving the history of the log such that queries from logread can be answered.

• -B file The path to a batch file of commands. The batch file's name may be specified with a string of alphanumeric characters (including underscores and periods), file contains one or more command lines, not including the logappend command itself (just its options), separated by \n (newlines). These commands should be processed by logappend individually, in order. This allows logappend to add data to the file without forking or re-invoking. Of course, option -B cannot itself appear in these command lines. Commands specified in a batch file include the log name. If a single line in a batch file results in an error condition, print the appropriate error message for that line and continue processing the rest of the batch file. Here is an example (the last one).

After logappend exits, the log specified by log argument should be updated. The added information should be accessible by the logread tool when the token provided to both programs is the same, and not available (e.g. by inspecting the file directly) otherwise.

Return values and error conditions

If logappend must exit with an error condition, or if the argument combination is incomplete or contradictory, the log should not be modified and logappend should print "invalid" to stdout and exit, returning 255.

• If the log file does not exist and cannot be created due to an invalid path, or any other I/O error, logappend should exit with an error condition.
• If logappend cannot authenticate the log with the token, then logappend should should exit with an integrity violation.
• Time should always increase, invoking logappend with an event at a time that is at or prior to the most recent event already recorded is an error.
• No doctor or nurse should enter a room without first entering the hospital. No doctor or nurse should enter a room without having left a previous room. Violation of either of these conditions implies inconsistency with the current log state and should result in logappend exiting with an error condition.
• No doctor or nurse should leave the hospital without first leaving the last room they entered. No doctor or nurse should leave a room without entering it. Violation of either of these conditions implies inconsistency with the current log state and should result in logappend exiting with an error condition.
• If -B is passed logappend should return 0 as long as the batch file exists and valid arguments are given to the batch command.
• If -B is passed and the batch file does not exist, logappend should exit with an error condition.

Some examples of conditions that would result in printing "invalid" and doing nothing to the log:

• The specified timestamp on the command line is smaller than the most recent timestamp in the existing log.
• -B is used in a batch file.
• The name for a doctor or nurse, or the room ID, does not correspond to the character constraints.
• Conflicting command line arguments are given, for example both -D and -N or -A and -L.