kern/misc: Allow selective disabling of debug facility names

Sometimes you only know which debug logging facility names you want to
turn off, not necessarily all the ones you want enabled. This patch allows
the debug string to contain facility names in the $debug variable which are
prefixed with a "-" to disable debug log messages for that conditional. Say
you want all debug logging on except for btrfs and scripting, then do:
"set debug=all,-btrfs,-scripting"

Note, that only the last occurrence of the facility name with or without a
leading "-" is considered. So simply appending ",-facilityname" to the
$debug variable will disable that conditional. To illustrate, the command
"set debug=all,-btrfs,-scripting,btrfs" will enable btrfs.

Also, add documentation explaining this new behavior.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/docs/grub.texi b/docs/grub.texi
index a72d73ce3c08ffca0c4972b879eb66e4071cf86a..851b7b09364460a1bd08062186185dc5aa41301a 100644 (file)
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -3388,9 +3388,16 @@ processed by commands @command{configfile} (@pxref{configfile}) or @command{norm
 @subsection debug
 
 This variable may be set to enable debugging output from various components
-of GRUB.  The value is a list of debug facility names separated by
-whitespace or @samp{,}, or @samp{all} to enable all available debugging
-output. The facility names are the first argument to grub_dprintf. Consult
+of GRUB. The value is an ordered list of debug facility names separated by
+whitespace or @samp{,}. If the special facility named @samp{all} is present
+then debugging output of all facility names is enabled at the start of
+processing the value of this variable. A facility's debug output can then be
+disabled by prefixing its name with a @samp{-}. The last occurence facility
+name with or without a leading @samp{-} takes precendent over any previous
+occurence. This allows the easy enabling or disabling of facilities by
+appending a @samp{,} and then the facility name with or without the leading
+@samp{-}, which will preserve the state of the rest of the facilities.
+The facility names are the first argument to grub_dprintf. Consult the
 source for more details.
 
 

diff --git a/grub-core/kern/misc.c b/grub-core/kern/misc.c
index 11b8592c8010bd2aa88b1c58dcfd3e3dd756a9bd..de40f566d6f696b35ee9940583275ae7d01d283e 100644 (file)
--- a/grub-core/kern/misc.c
+++ b/grub-core/kern/misc.c
@@ -162,16 +162,49 @@ __attribute__ ((alias("grub_printf")));
 int
 grub_debug_enabled (const char * condition)
 {
-  const char *debug;
+  const char *debug, *found;
+  grub_size_t clen;
+  int ret = 0;
 
   debug = grub_env_get ("debug");
   if (!debug)
     return 0;
 
-  if (grub_strword (debug, "all") || grub_strword (debug, condition))
-    return 1;
+  if (grub_strword (debug, "all"))
+    {
+      if (debug[3] == '\0')
+       return 1;
+      ret = 1;
+    }
 
-  return 0;
+  clen = grub_strlen (condition);
+  found = debug-1;
+  while(1)
+    {
+      found = grub_strstr (found+1, condition);
+
+      if (found == NULL)
+       break;
+
+      /* Found condition is not a whole word, so ignore it. */
+      if (*(found + clen) != '\0' && *(found + clen) != ','
+        && !grub_isspace (*(found + clen)))
+       continue;
+
+      /*
+       * If found condition is at the start of debug or the start is on a word
+       * boundary, then enable debug. Else if found condition is prefixed with
+       * '-' and the start is on a word boundary, then disable debug. If none
+       * of these cases, ignore.
+       */
+      if (found == debug || *(found - 1) == ',' || grub_isspace (*(found - 1)))
+       ret = 1;
+      else if (*(found - 1) == '-' && ((found == debug + 1) || (*(found - 2) == ','
+                              || grub_isspace (*(found - 2)))))
+       ret = 0;
+    }
+
+  return ret;
 }
 
 void