vsprintf: Recursive vsnprintf: Add "%pV", struct va_format
Add the ability to print a format and va_list from a structure pointer
Allows __dev_printk to be implemented as a single printk while
minimizing string space duplication.
%pV should not be used without some mechanism to verify the
format and argument use ala __attribute__(format (printf(...))).
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 8317ec4..01dfc05 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -171,6 +171,11 @@
}
#endif
+struct va_format {
+ const char *fmt;
+ va_list *va;
+};
+
extern struct atomic_notifier_head panic_notifier_list;
extern long (*panic_blink)(long time);
NORET_TYPE void panic(const char * fmt, ...)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index b8a2f54..4ee19d0 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -980,6 +980,11 @@
* [0][1][2][3]-[4][5]-[6][7]-[8][9]-[10][11][12][13][14][15]
* little endian output byte order is:
* [3][2][1][0]-[5][4]-[7][6]-[8][9]-[10][11][12][13][14][15]
+ * - 'V' For a struct va_format which contains a format string * and va_list *,
+ * call vsnprintf(->format, *->va_list).
+ * Implements a "recursive vsnprintf".
+ * Do not use this feature without some mechanism to verify the
+ * correctness of the format string and va_list arguments.
*
* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
* function pointers are really function descriptors, which contain a
@@ -1025,6 +1030,10 @@
break;
case 'U':
return uuid_string(buf, end, ptr, spec, fmt);
+ case 'V':
+ return buf + vsnprintf(buf, end - buf,
+ ((struct va_format *)ptr)->fmt,
+ *(((struct va_format *)ptr)->va));
}
spec.flags |= SMALL;
if (spec.field_width == -1) {
