src/stdio/ftrylockfile.c

   1 #include "stdio_impl.h"
   2 #include "pthread_impl.h"
   3 #include <limits.h>
   4
   5 void __do_orphaned_stdio_locks()
   6 {
   7         FILE *f;
   8         for (f=__pthread_self()->stdio_locks; f; f=f->next_locked)
   9                 a_store(&f->lock, 0x40000000);
  10 }
  11
  12 void __unlist_locked_file(FILE *f)
  13 {
  14         if (f->lockcount) {
  15                 if (f->next_locked) f->next_locked->prev_locked = f->prev_locked;
  16                 if (f->prev_locked) f->prev_locked->next_locked = f->next_locked;
  17                 else __pthread_self()->stdio_locks = f->next_locked;
  18         }
  19 }
  20
  21 int ftrylockfile(FILE *f)
  22 {
  23         pthread_t self = __pthread_self();
  24         int tid = self->tid;
  25         if (f->lock == tid) {
  26                 if (f->lockcount == LONG_MAX)
  27                         return -1;
  28                 f->lockcount++;
  29                 return 0;
  30         }
  31         if (f->lock < 0) f->lock = 0;
  32         if (f->lock || a_cas(&f->lock, 0, tid))
  33                 return -1;
  34         f->lockcount = 1;
  35         f->prev_locked = 0;
  36         f->next_locked = self->stdio_locks;
  37         if (f->next_locked) f->next_locked->prev_locked = f;
  38         self->stdio_locks = f;
  39         return 0;
  40 }