libmainloop/select.c

   1 /*
   2  * libmainloop/select.c
   3  *
   4  * Partly based on a contributed code.
   5  *
   6  * See the included file LICENSE for details.
   7  */
   8
   9 #include <signal.h>
  10 #include <sys/select.h>
  11 #include <errno.h>
  12 #include <string.h>
  13
  14 #include <libtu/types.h>
  15 #include <libtu/misc.h>
  16 #include <libtu/dlist.h>
  17
  18 #include "select.h"
  19 #include "signal.h"
  20
  21
  22 /*{{{ File descriptor management */
  23
  24
  25 static WInputFd *input_fds=NULL;
  26
  27 static WInputFd *find_input_fd(int fd)
  28 {
  29     WInputFd *tmp=input_fds;
  30
  31     while(tmp){
  32         if(tmp->fd==fd)
  33             break;
  34         tmp=tmp->next;
  35     }
  36     return tmp;
  37 }
  38
  39 bool mainloop_register_input_fd(int fd, void *data,
  40                                 void (*callback)(int fd, void *d))
  41 {
  42     WInputFd *tmp;
  43
  44     if(find_input_fd(fd)!=NULL)
  45         return FALSE;
  46
  47     tmp=ALLOC(WInputFd);
  48     if(tmp==NULL)
  49         return FALSE;
  50
  51     tmp->fd=fd;
  52     tmp->data=data;
  53     tmp->process_input_fn=callback;
  54
  55     LINK_ITEM(input_fds, tmp, next, prev);
  56
  57     return TRUE;
  58 }
  59
  60 void mainloop_unregister_input_fd(int fd)
  61 {
  62     WInputFd *tmp=find_input_fd(fd);
  63
  64     if(tmp!=NULL){
  65         UNLINK_ITEM(input_fds, tmp, next, prev);
  66         free(tmp);
  67     }
  68 }
  69
  70 static void set_input_fds(fd_set *rfds, int *nfds)
  71 {
  72     WInputFd *tmp=input_fds;
  73
  74     while(tmp){
  75         FD_SET(tmp->fd, rfds);
  76         if(tmp->fd>*nfds)
  77             *nfds=tmp->fd;
  78         tmp=tmp->next;
  79     }
  80 }
  81
  82 static void check_input_fds(fd_set *rfds)
  83 {
  84     WInputFd *tmp=input_fds, *next=NULL;
  85
  86     while(tmp){
  87         next=tmp->next;
  88         if(FD_ISSET(tmp->fd, rfds))
  89             tmp->process_input_fn(tmp->fd, tmp->data);
  90         tmp=next;
  91     }
  92 }
  93
  94 /*}}}*/
  95
  96
  97 /*{{{ Select */
  98
  99 void mainloop_select()
 100 {
 101     fd_set rfds;
 102     int nfds=0;
 103     int ret=0;
 104
 105
 106 #if _POSIX_SELECT || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600
 107     {
 108         sigset_t oldmask;
 109
 110         FD_ZERO(&rfds);
 111         set_input_fds(&rfds, &nfds);
 112
 113         mainloop_block_signals(&oldmask);
 114
 115         if(!mainloop_unhandled_signals())
 116             ret=pselect(nfds+1, &rfds, NULL, NULL, NULL, &oldmask);
 117
 118         sigprocmask(SIG_SETMASK, &oldmask, NULL);
 119     }
 120 #else
 121     #warning "pselect() unavailable -- using dirty hacks"
 122     {
 123         struct timeval tv={0, 0};
 124         bool to;
 125
 126         /* If there are timers, make sure we return from select with
 127          * some delay, if the timer signal happens right before
 128          * entering select(). Race conditions with other signals
 129          * we'll just have to ignore without pselect().
 130          */
 131         do{
 132             bool to;
 133             FD_ZERO(&rfds);
 134             set_input_fds(&rfds, &nfds);
 135
 136             to=libmainloop_get_timeout(&tv);
 137
 138             if(mainloop_unhandled_signals()){
 139                 ret=0;
 140                 break;
 141             }
 142
 143             ret=select(nfds+1, &rfds, NULL, NULL, to ? &tv : NULL);
 144         }while(ret<0 && errno==EINTR && !mainloop_unhandled_signals());
 145     }
 146 #endif
 147     if(ret>0)
 148         check_input_fds(&rfds);
 149 }
 150
 151
 152 /*}}}*/