source: Evidence/Config/Config.cc @ 142

Last change on this file since 142 was 142, checked in by ogrimm, 11 years ago
Various updates
File size: 5.1 KB
Line 
1/********************************************************************\
2
3  Configuration server for the Evidence Control System
4
5  - The configuration file is opened without buffering to catch changes
6    without closing/opening.
7  - The name of a configuration file can be given as command line argument
8  - If a configuration file change is detected through inotify, the service
9    "Config/ModifyTime" is updated with the current UNIX time to inform applications.
10        The initial value of the server is the last file modification time.
11  - The employed line buffer has conservatively at least the size of the
12    configuration file. If needed, it will be enlarged.
13         
14  Oliver Grimm, November 2009
15
16\********************************************************************/
17
18#define DEFAULT_CONFIG "configuration.txt"
19#define SERVER_NAME "Config"
20
21#include "../Evidence.h"
22#include <ctype.h>
23#include <sys/stat.h>
24#include <sys/inotify.h>
25
26//
27// Class derived from DimRpc
28//
29class EvidenceConfig: public DimRpc, public EvidenceServer {
30
31  private:
32    FILE *File; 
33    char *Buffer;
34    unsigned int BufferLength;
35    DimService *ConfigModified;
36    int ModifyTime;
37       
38    void rpcHandler();
39 
40  public:
41    EvidenceConfig(const char *);
42    ~EvidenceConfig();
43       
44        void ConfigChanged(); 
45};
46
47// Constructor
48EvidenceConfig::EvidenceConfig(const char *Filename):
49        DimRpc("ConfigRequest", "C", "C"), EvidenceServer(SERVER_NAME) {
50
51  // Open configuration file
52  if ((File = fopen(Filename, "r")) == NULL) {
53    State(FATAL, "Could not open configuration file '%s' (%s)\n", Filename, strerror(errno));
54  }
55
56  // Create DIM service to indicate changes of configuration file
57  struct stat Stat;
58  if (stat(Filename, &Stat) == -1) {
59    State(WARN, "Could not read last modification time of configuration file '%s' (%s)", Filename, strerror(errno));
60        ModifyTime = 0;
61  }
62  else ModifyTime = Stat.st_mtime;   
63  ConfigModified = new DimService (SERVER_NAME"/ModifyTime", ModifyTime);
64
65  // Disable buffering, so file modifications are immediately seen
66  if (setvbuf(File, NULL, _IONBF, 0) != 0) {
67    State(WARN, "Error setting configuration file '%s' to unbuffered mode", Filename);
68  }
69   
70  Buffer = NULL;    // Will be allocated in rpcHandler()
71  BufferLength = 0;
72}
73
74// Destructor
75EvidenceConfig::~EvidenceConfig() {
76
77  if (File != NULL) fclose(File); 
78  delete[] Buffer;
79}
80
81// Implementation of response to configuration request
82void EvidenceConfig::rpcHandler() {
83
84  char *Token1,*Token2,*Token3, *Request = getString();
85  struct stat FileStatus;
86 
87  // Check if Buffer[] is large enough to hold full file, enlarge if necessary
88  if (fstat(fileno(File), &FileStatus) == -1) {
89     State(FATAL, "Could not determine size of configuration file to allocate buffer (%s)", strerror(errno));
90  }
91  else if(BufferLength < FileStatus.st_size) {
92    delete[] Buffer;
93    Buffer = new char [FileStatus.st_size];
94    BufferLength = FileStatus.st_size;   
95  }
96 
97  // Search for configuration item
98  rewind(File);
99  while (fgets(Buffer, BufferLength, File) != NULL) {
100   
101    // Combine lines that end with '+'
102    while (Buffer[strlen(Buffer)-2] == '+') {
103      if (fgets(Buffer+strlen(Buffer)-2, BufferLength-(strlen(Buffer)-2), File) == NULL) break;
104    }
105   
106    // Ignore comments
107    for (int i=0; i<strlen(Buffer); i++) if (Buffer[i] == '#') Buffer[i] = '\0';
108   
109    // Extract tokens
110    Token1 = strtok(Buffer, " \t:");
111    Token2 = strtok(NULL, " \t:");
112    Token3 = strtok(NULL, "\n");
113   
114    // Check if all tokens existing
115    if(Token1==NULL || Token2==NULL || Token3==NULL) continue;
116
117    // Check for match and then send data (removing trainlin whitespace)
118    if (strstr(Request, Token1)!=NULL && strstr(Request, Token2)!=NULL) {
119          while (isspace(*Token3) != 0) Token3++;
120      setData(Token3);
121      break;
122    }
123  }
124 
125  // If configuration data not found, send empty string
126  if (feof(File)!=0) setData((char *) "");
127 
128  State(INFO, "Client '%s' (ID %d) requested '%s'. Send '%s'.",
129                DimServer::getClientName(),
130                DimServer::getClientId(), 
131                Request, feof(File)!=0 ? "n/a" : Token3);
132}
133
134// Signalisation of configuration change
135void EvidenceConfig::ConfigChanged() {
136
137  ModifyTime = time(NULL);
138  ConfigModified->updateService();
139}
140
141//         
142// Declaring class static ensures destructor is called when exit() is invoked
143//
144int main(int argc, char *argv[]) {
145       
146  static EvidenceConfig Config(argc<2 ? DEFAULT_CONFIG : argv[1]);
147
148  int Notify;
149  struct inotify_event Event;
150 
151  if ((Notify = inotify_init()) == -1) {
152    Config.State(EvidenceConfig::WARN, "inotify_init() failed, cannot monitor changes of configuration file (%s)\n", strerror(errno));
153  }
154  else if (inotify_add_watch(Notify, argc<2 ? DEFAULT_CONFIG : argv[1], IN_MODIFY) == -1) { 
155      Config.State(EvidenceConfig::WARN, "Could not set inotify watch on configuration file (%s)\n", strerror(errno));
156          close(Notify);
157          Notify = -1;
158  }
159
160  // Sleep until file changes or signal caught
161  while (!EvidenceServer::ExitRequest) {
162    if (Notify != -1) {
163          read(Notify, &Event, sizeof(Event));
164          Config.ConfigChanged();
165        }
166    else pause();         
167  }
168 
169  if (Notify != -1) close(Notify);
170}
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