fix descriptor leak in iob_addfile_close if the range was 0 (oops)

CHANGES

@@ -8,6 +8,7 @@
   document that the iob_write callback should limit itself
   fix mmap_shared
   add iob_free, add man pages for iob_free and iob_reset
+  fix descriptor leak in iob_addfile_close if the range was 0 (oops)
 
 0.21:
   errno cleanup and man page updates (Rolf Eike Beer)

io/iob_addbuf_internal.c

@@ -1,8 +1,12 @@
 #include "iob_internal.h"
 
 int iob_addbuf_internal(io_batch* b,const void* buf,uint64 n,int _free) {
-  iob_entry* e=array_allocate(&b->b,sizeof(iob_entry),
-			     array_length(&b->b,sizeof(iob_entry)));
+  iob_entry* e;
+  if (!n) {
+    if (_free) free(buf);
+    return 1;
+  }
+  e=array_allocate(&b->b,sizeof(iob_entry),array_length(&b->b,sizeof(iob_entry)));
   if (!e) return 0;
   e->type=_free?FROMBUF_FREE:FROMBUF;
   e->fd=-1;

io/iob_addfile_close.c

@@ -2,7 +2,10 @@
 
 int iob_addfile_close(io_batch* b,int64 fd,uint64 off,uint64 n) {
   iob_entry* e;
-  if (n==0) return 1;
+  if (n==0) {
+    io_close(fd);
+    return 1;
+  }
   io_fd(fd);
   e=array_allocate(&b->b,sizeof(iob_entry),
 		   array_length(&b->b,sizeof(iob_entry)));