Add grub_dcprintf for continuations without file/line

The attached patch adds a new variant of grub_dprintf, grub_dcprintf, which avoids printing the __FILE__:__LINE__: prefix. This allows printing a single line with multiple print statements; for instance:

grub_dprintf("some_module", "Thingy: "); print_complicated_thingy(thingy); grub_dcprintf("some_module", ", more details here\n");

Without the dcprintf variant, this line will contain three different file/line prefixes.

I also added support for a "no-file-line" token in the debug environment variable, which turns off the file/line prefixes entirely.

- Josh Triplett

=== modified file 'include/grub/misc.h'

@@ -47,6 +47,8 @@
 #define COMPILE_TIME_ASSERT(cond) switch (0) { case 1: case !(cond): ; }
 
 #define grub_dprintf(condition, fmt, args...) grub_real_dprintf(GRUB_FILE, __LINE__, condition, fmt, ## args)
+/* A "continuation" variant of dprintf which doesn't print file and line. */
+#define grub_dcprintf(condition, fmt, args...) grub_real_dprintf(0, 0, condition, fmt, ## args)
 /* XXX: If grub_memmove is too slow, we must implement grub_memcpy.  */
 #define grub_memcpy(d,s,n)	grub_memmove ((d), (s), (n))
 

=== modified file 'kern/misc.c'

@@ -180,7 +180,8 @@
 
   if (grub_strword (debug, "all") || grub_strword (debug, condition))
     {
-      grub_printf ("%s:%d: ", file, line);
+      if (line != 0 && !grub_strword (debug, "no-file-line"))
+        grub_printf ("%s:%d: ", file, line);
       va_start (args, fmt);
       grub_vprintf (fmt, args);
       va_end (args);

core is very size sensitive. You need a valid usecase to justify such a feature in it. It feels like useful only for dumping a mass of info. In practice users can only report back around 4-5 lines, sometimes a compelete screen by taking its picture, so this info would be lost in bugreports anyway. If you're developping something you usually need a dump in that exact place only once and then using grub_printf is usually easier.

Regards
Vladimir 'φ-coder/phcoder' Serbinenko