libc-top-half/musl/src/stdio/putc.h

   1 #include "stdio_impl.h"
   2 #if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
   3 #include "pthread_impl.h"
   4
   5 #ifdef __GNUC__
   6 __attribute__((__noinline__))
   7 #endif
   8 static int locking_putc(int c, FILE *f)
   9 {
  10         if (a_cas(&f->lock, 0, MAYBE_WAITERS-1)) __lockfile(f);
  11         c = putc_unlocked(c, f);
  12         if (a_swap(&f->lock, 0) & MAYBE_WAITERS)
  13                 __wake(&f->lock, 1, 1);
  14         return c;
  15 }
  16 #endif
  17
  18 static inline int do_putc(int c, FILE *f)
  19 {
  20 #if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
  21         int l = f->lock;
  22         if (l < 0 || l && (l & ~MAYBE_WAITERS) == __pthread_self()->tid)
  23                 return putc_unlocked(c, f);
  24         return locking_putc(c, f);
  25 #else
  26         // With no threads, locking is unnecessary.
  27         return putc_unlocked(c, f);
  28 #endif
  29 }