* src/output.h (output_write): Remove unused function declaration

* src/makeint.h (dbg): Add formatting attribute
* src/misc.c (dbg): Keep the file open, once opened

src/makeint.h

diff --git a/src/makeint.h b/src/makeint.h
index 8a8eab3..f88e3fd 100644
--- a/src/makeint.h
+++ b/src/makeint.h
@@ -668,7 +668,7 @@
 # define SPIN(_s) spin (_s)
 void spin (const char* suffix);
 # define DBG(_f) dbg _f
-void dbg (const char *fmt, ...);
+void dbg (const char *fmt, ...) ATTRIBUTE ((__format__ (__printf__, 1, 2)));
 #else
 # define SPIN(_s)
 /* Never put this code into Git or a release.  */

src/misc.c

diff --git a/src/misc.c b/src/misc.c
index a6633fa..2352d6d 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -613,7 +613,6 @@
 void
 dbg (const char *fmt, ...)
 {
-  FILE *fp = fopen ("/tmp/gmkdebug.log", "a+");
   va_list args;
   char buf[4096];
 
@@ -621,9 +620,13 @@
   vsprintf (buf, fmt, args);
   va_end (args);
 
-  fprintf(fp, "%u: %s\n", (unsigned) make_pid (), buf);
-  fflush (fp);
-  fclose (fp);
+  {
+    static FILE *fp = NULL;
+    if (!fp)
+      fp = fopen ("/tmp/gmkdebug.log", "a+");
+    fprintf (fp, "%u: %s\n", (unsigned) make_pid (), buf);
+    fflush (fp);
+  }
 }
 
 #endif

src/output.h

diff --git a/src/output.h b/src/output.h
index a6c714b..f643113 100644
--- a/src/output.h
+++ b/src/output.h
@@ -34,10 +34,6 @@
 #define OUTPUT_TRACED()     do{ stdio_traced = 1; }while(0)
 #define OUTPUT_IS_TRACED()  (!!stdio_traced)
 
-/* Write a buffer directly to the given file descriptor.
-   This handles errors etc.  */
-int output_write (int fd, const void *buffer, size_t len);
-
 /* Initialize and close a child output structure: if NULL do this program's
    output (this should only be done once).  */
 void output_init (struct output *out);