[PATCH] Introduce xasprintf

[Colin Watson]

Ubuntu builds with -D_FORTIFY_SOURCE=2 by default, and thus produces a
bunch of warnings like this:

  util/grub-mkfont.c: In function ‘write_font’:
  util/grub-mkfont.c:366: warning: ignoring return value of ‘asprintf’, 
declared with attribute warn_unused_result

I came across the idea of an xasprintf function in Gnulib a while back.
Using this both fixes the above class of warnings by always checking the
return value of asprintf, and also provides an IMO more intuitive
interface to formatting an allocated string. Do people like the
following patch? The warnings are minor so there's no problem with this
being post-1.97.

Index: configure.ac
===================================================================
--- configure.ac        (revision 2557)
+++ configure.ac        (working copy)
@@ -172,7 +172,7 @@
 fi
 
 # Check for functions.
-AC_CHECK_FUNCS(posix_memalign memalign asprintf)
+AC_CHECK_FUNCS(posix_memalign memalign asprintf vasprintf)
 
 #
 # Check for target programs.
Index: include/grub/util/misc.h
===================================================================
--- include/grub/util/misc.h    (revision 2557)
+++ include/grub/util/misc.h    (working copy)
@@ -21,6 +21,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <stdarg.h>
 #include <setjmp.h>
 #include <unistd.h>
 
@@ -57,12 +58,20 @@
 void grub_util_write_image_at (const void *img, size_t size, off_t offset,
                               FILE *out);
 
+#ifndef HAVE_VASPRINTF
+
+int vasprintf (char **buf, const char *fmt, va_list ap);
+
+#endif
+
 #ifndef  HAVE_ASPRINTF
 
 int asprintf (char **buf, const char *fmt, ...);
 
 #endif
 
+char *xasprintf (const char *fmt, ...);
+
 #ifdef __MINGW32__
 
 #define fseeko fseeko64
Index: util/grub-probe.c
===================================================================
--- util/grub-probe.c   (revision 2558)
+++ util/grub-probe.c   (working copy)
@@ -248,7 +248,7 @@
          filebuf_via_sys = grub_util_read_image (path);
 
          grub_util_info ("reading %s via GRUB facilities", path);
-         asprintf (&grub_path, "(%s)%s", drive_name, path);
+         grub_path = xasprintf ("(%s)%s", drive_name, path);
          file = grub_file_open (grub_path);
          filebuf_via_grub = xmalloc (file->size);
          grub_file_read (file, filebuf_via_grub, file->size);
Index: util/getroot.c
===================================================================
--- util/getroot.c      (revision 2557)
+++ util/getroot.c      (working copy)
@@ -454,7 +454,7 @@
          if (q)
            *q = ',';
 
-         asprintf (&grub_dev, "md%s", p);
+         grub_dev = xasprintf ("md%s", p);
          free (p);
        }
       else if (os_dev[7] == '/' && os_dev[8] == 'd')
@@ -469,7 +469,7 @@
          if (q)
            *q = ',';
 
-         asprintf (&grub_dev, "md%s", p);
+         grub_dev = xasprintf ("md%s", p);
          free (p);
        }
       else if (os_dev[7] >= '0' && os_dev[7] <= '9')
@@ -482,7 +482,7 @@
          if (q)
            *q = ',';
 
-         asprintf (&grub_dev, "md%s", p);
+         grub_dev = xasprintf ("md%s", p);
          free (p);
        }
       else if (os_dev[7] == '/' && os_dev[8] >= '0' && os_dev[8] <= '9')
@@ -495,7 +495,7 @@
          if (q)
            *q = ',';
 
-         asprintf (&grub_dev, "md%s", p);
+         grub_dev = xasprintf ("md%s", p);
          free (p);
        }
       else
Index: util/grub-mkfont.c
===================================================================
--- util/grub-mkfont.c  (revision 2557)
+++ util/grub-mkfont.c  (working copy)
@@ -363,8 +363,8 @@
   if (! style_name[0])
     strcpy (style_name, " Regular");
 
-  asprintf (&font_name, "%s %s %d", font_info->name, &style_name[1],
-           font_info->size);
+  font_name = xasprintf ("%s %s %d", font_info->name, &style_name[1],
+                        font_info->size);
 
   write_string_section ("NAME", font_name, &offset, file);
   write_string_section ("FAMI", font_info->name, &offset, file);
Index: util/misc.c
===================================================================
--- util/misc.c (revision 2557)
+++ util/misc.c (working copy)
@@ -28,6 +28,7 @@
 #include <sys/time.h>
 #include <unistd.h>
 #include <time.h>
+#include <errno.h>
 
 #include <grub/kernel.h>
 #include <grub/misc.h>
@@ -369,6 +370,19 @@
 {
 }
 
+#ifndef HAVE_VASPRINTF
+
+int
+vasprintf (char **buf, const char *fmt, va_list ap)
+{
+  /* Should be large enough.  */
+  *buf = xmalloc (512);
+
+  return vsprintf (*buf, fmt, ap);
+}
+
+#endif
+
 #ifndef  HAVE_ASPRINTF
 
 int
@@ -377,11 +391,8 @@
   int status;
   va_list ap;
 
-  /* Should be large enough.  */
-  *buf = xmalloc (512);
-
   va_start (ap, fmt);
-  status = vsprintf (*buf, fmt, ap);
+  status = vasprintf (*buf, fmt, ap);
   va_end (ap);
 
   return status;
@@ -389,6 +400,23 @@
 
 #endif
 
+char *
+xasprintf (const char *fmt, ...)
+{
+  va_list ap;
+  char *result;
+
+  va_start (ap, fmt);
+  if (vasprintf (&result, fmt, ap) < 0)
+    {
+      if (errno == ENOMEM)
+       grub_util_error ("out of memory");
+      return NULL;
+    }
+
+  return result;
+}
+
 #ifdef __MINGW32__
 
 void sync (void)

Thanks,

-- 
Colin Watson                                       address@hidden