citadel/dynloader.c

   1 /*******************************************************
   2  *
   3  * Citadel Dynamic Loading Module
   4  * Written by Brian Costello
   5  * btx@calyx.net
   6  *
   7  ******************************************************/
   8
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <dlfcn.h>
  13 #include <sys/types.h>
  14 #include <dirent.h>
  15 #include <strings.h>
  16 #include <syslog.h>
  17 #include <pthread.h>
  18 #include "dynloader.h"
  19 #include "citadel.h"
  20 #include "server.h"
  21
  22 symtab *global_symtab;
  23
  24 struct FunctionHook *HookTable = NULL;
  25
  26 int DLoader_Exec_Cmd(char *cmdbuf)
  27 {
  28    symtab *t_sym;
  29    void *fcn_handle;
  30    char *dl_error;
  31    void (*cmd_ptr)(void *);
  32
  33    for (t_sym = global_symtab; ((t_sym) && (strncmp(t_sym->server_cmd, cmdbuf, strlen(t_sym->server_cmd))) ); t_sym=t_sym->next)
  34       ;
  35
  36    if (t_sym)
  37    {
  38       if (!(fcn_handle = dlopen(t_sym->module_path, RTLD_LAZY)))
  39       {
  40          dl_error = dlerror();
  41          syslog(LOG_NOTICE, "WARNING: module %s failed to load", t_sym->module_path);
  42          return(0);
  43       }
  44
  45       cmd_ptr = dlsym(fcn_handle, t_sym->fcn_name);
  46       if ((dl_error = dlerror()) != NULL)
  47       {
  48          syslog(LOG_NOTICE, "dlsym error: %s - %s", dl_error, t_sym->module_path);
  49          return(0);
  50       }
  51       (*cmd_ptr)(&cmdbuf[5]);
  52       dlclose(fcn_handle);
  53       if ((dl_error = dlerror()) != NULL)
  54       {
  55          syslog(LOG_NOTICE, "dlclose error: %s", dl_error);
  56          return(0);
  57       }
  58       return(1);
  59    }  /* If symbol found */
  60
  61    return(0);
  62 }
  63
  64 void add_symbol(char *fcn_name, char *server_cmd, char *info_msg, symtab **first_symtab)
  65 {
  66    symtab *new_symtab, *t_sym, *last_sym;
  67
  68    if (!(new_symtab = malloc(sizeof(symtab))))
  69    {
  70       perror("Malloc new symtab");
  71       exit(1);
  72    }
  73
  74    new_symtab->fcn_name = strdup(fcn_name);
  75    new_symtab->server_cmd = strdup(server_cmd);
  76    new_symtab->info_msg = strdup(info_msg);
  77    new_symtab->next = NULL;
  78
  79    if (!(*first_symtab))
  80       (*first_symtab) = new_symtab;
  81    else
  82    {
  83       last_sym = NULL;
  84       for (t_sym = (*first_symtab); (t_sym); t_sym = t_sym->next)
  85          last_sym = t_sym;
  86       last_sym->next = new_symtab;
  87    }
  88 }
  89
  90 void DLoader_Init(char *pathname, symtab **my_symtab)
  91 {
  92    void *fcn_handle;
  93    void (*h_init_fcn)(struct DLModule_Info *);
  94    void (*h_get_symtab)(symtab **);
  95    char *dl_error;
  96    char *filename;
  97    DIR *dir;
  98    struct dirent *dptr;
  99
 100    char pathbuf[512];
 101    struct DLModule_Info dl_info;
 102    symtab *stab = NULL;
 103    symtab *t_sym;
 104
 105    global_symtab = NULL;                        /* Global symbol table */
 106
 107    if ((dir = opendir(pathname))==NULL)
 108    {
 109       perror("opendir");
 110       exit(1);
 111    }
 112
 113    while ((dptr=readdir(dir))!= NULL)
 114    {
 115       if (dptr->d_name[0] == '.')
 116          continue;
 117
 118       filename = strdup(dptr->d_name);
 119       snprintf(pathbuf, 512, "%s/%s", pathname, filename);
 120       if (!(fcn_handle = dlopen(pathbuf, RTLD_LAZY)))
 121       {
 122          dl_error = dlerror();
 123          fprintf(stderr, "DLoader_Init dlopen failed (%s)", dl_error);
 124          continue;
 125       }
 126
 127       h_init_fcn = dlsym(fcn_handle, "Dynamic_Module_Init");
 128       if ((dl_error = dlerror()) != NULL)
 129       {
 130          fprintf(stderr,"DLoader_Init dlsym failed (%s)", dl_error);
 131          continue;
 132       }
 133
 134       (*h_init_fcn)(&dl_info);
 135
 136       printf("Loaded module %s v%d.%d\nBy %s (%s)\n", dl_info.module_name,
 137                                                      dl_info.major_version,
 138                                                      dl_info.minor_version,
 139                                                      dl_info.module_author,
 140                                                      dl_info.module_author_email);
 141
 142       h_get_symtab = dlsym(fcn_handle, "Get_Symtab");
 143       if ((dl_error = dlerror()) != NULL)
 144       {
 145          fprintf(stderr,"DLoader_Init dlsym failed for Get_Symtab (%s) on module %s", dl_error, dl_info.module_name);
 146          continue;
 147       }
 148
 149 /* Get the symbol table for the current module and link it on */
 150
 151       (*h_get_symtab)(&stab);
 152       if (!(*my_symtab))
 153       {
 154          (*my_symtab) = global_symtab = stab;
 155       }
 156       else
 157       {
 158          for (t_sym = (*my_symtab) ; t_sym->next; t_sym=t_sym->next);
 159             ;
 160          t_sym->next = stab;
 161       }
 162       for (t_sym = stab; t_sym; t_sym=t_sym->next)
 163          t_sym->module_path = (char *)strdup(pathbuf);
 164       dlclose(fcn_handle);
 165       if ((dl_error = dlerror()) != NULL)
 166       {
 167          fprintf(stderr,"DLoader_Init dlclose failed (%s)", dl_error);
 168          continue;
 169       }
 170
 171    }    /* While */
 172
 173 }
 174
 175
 176
 177 void CtdlRegisterHook(void *fcn_ptr, int fcn_type) {
 178
 179         struct FunctionHook *newfcn;
 180
 181         newfcn = (struct FunctionHook *) malloc(sizeof(struct FunctionHook));
 182         newfcn->next = HookTable;
 183         newfcn->h_function_pointer = fcn_ptr;
 184         newfcn->h_type = fcn_type;
 185
 186         HookTable = newfcn;
 187
 188         lprintf(5, "Registered a new function (type %d)\n", fcn_type);
 189         }