1 files changed, 43 insertions, 0 deletions
diff --git a/open_inout.h b/open_inout.h
new file mode 100644
index 0000000..1a8a61b
--- /dev/null
+++ b/open_inout.h
@@ -0,0 +1,43 @@
+#include <sys/file.h>
+#define NANO_wait \
+	if (nsec < 500000000) nsec *= 2;\
+	else carp("could not acquire lock on: ",home,"/in");\
+	nano_sleep(0,nsec)
+
+static void open_inout(char *home) {
+  char *x,*y;
+  uint32t nsec = 3906249;
+  int len=str_len(home);
+
+  x=alloca(len+6);	  if (x==0) _exit(1);
+  y=x+len;
+  while (len--) x[len] = home[len];
+
+  y[0]='/'; y[1]='i'; y[2]='n'; y[3]=0;
+  infd = open(x, O_WRONLY);
+
+  y[1]='o'; y[2]='u'; y[3]='t'; y[4]=0;
+  outfd = open(x, O_RDONLY);
+
+  if (infd<0 || outfd<0) die(1, "could not open ",home,"/[in|out]");
+
+#ifdef HAVE__NR_flock
+  while (flock(infd, LOCK_EX | LOCK_NB)) { NANO_wait; }
+#else
+
+#ifndef INIT_SYSTEM
+  while (lockf(infd, F_LOCKW, 1)) { NANO_wait; }
+#else
+  { 
+    struct flock fl;
+    byte_zero(&fl, sizeof(fl));
+    fl.l_whence=SEEK_CUR;
+    fl.l_len = 1;
+    fl.l_type = F_WRLCK;
+    while (fcntl(infd, F_SETLKW, &fl)) { NANO_wait; }
+  }
+#endif
+#endif
+}
+
+#undef NANO_wait