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5 * A.R. Gordon (andrew.gordon@net-tel.co.uk). All rights reserved.
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41 /* ------------------------------------------------------------------------- */
43 Data structures for recording monitored hosts
45 The information held by the status monitor comprises a list of hosts
46 that we have been asked to monitor, and, associated with each monitored
47 host, one or more clients to be called back if the monitored host crashes.
49 The list of monitored hosts must be retained over a crash, so that upon
50 re-boot we can call the SM_NOTIFY procedure in all those hosts so as to
51 cause them to start recovery processing. On the other hand, the client
52 call-backs are not required to be preserved: they are assumed (in the
53 protocol design) to be local processes which will have crashed when
54 we did, and so are discarded on restart.
56 We handle this by keeping the list of monitored hosts in a file
57 (/var/statd.state) which is mmap()ed and whose format is described
58 by the typedef FileLayout. The lists of client callbacks are chained
59 off this structure, but are held in normal memory and so will be
60 lost after a re-boot. Hence the actual values of MonList * pointers
61 in the copy on disc have no significance, but their NULL/non-NULL
62 status indicates whether this host is actually being monitored or if it
63 is an empty slot in the file.
66 typedef struct MonList_s
68 struct MonList_s *next; /* Next in list or NULL */
69 char notifyHost[SM_MAXSTRLEN + 1]; /* Host to notify */
70 int notifyProg; /* RPC program number to call */
71 int notifyVers; /* version number */
72 int notifyProc; /* procedure number */
73 unsigned char notifyData[16]; /* Opaque data from caller */
78 char hostname[SM_MAXSTRLEN + 1]; /* Name of monitored host */
79 int notifyReqd; /* TRUE if we've crashed and not yet */
80 /* informed the monitored host */
81 MonList *monList; /* List of clients to inform if we */
82 /* hear that the monitored host has */
83 /* crashed, NULL if no longer monitored */
87 /* Overall file layout. */
91 int ourState; /* State number as defined in statd protocol */
92 int noOfHosts; /* Number of elements in hosts[] */
93 char reserved[248]; /* Reserved for future use */
94 HostInfo hosts[1]; /* vector of monitored hosts */
97 #define HEADER_LEN (sizeof(FileLayout) - sizeof(HostInfo))
99 /* ------------------------------------------------------------------------- */
101 /* Global variables */
103 extern FileLayout *status_info; /* The mmap()ed status file */
105 extern int debug; /* =1 to enable diagnostics to syslog */
107 /* Function prototypes */
109 extern HostInfo *find_host(char * /*hostname*/, int /*create*/);
110 extern void init_file(const char * /*filename*/);
111 extern void notify_hosts(void);
112 extern void sync_file(void);
113 extern int sm_check_hostname(struct svc_req *req, char *arg);