%pV allows to pass in a struct va_format as a pointer. UBIFS uses this
for its logging functions, but it may be useful in other places aswell.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
include/printk.h | 5 +++++
lib/vsprintf.c | 15 +++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/include/printk.h b/include/printk.h
index b4ae0b3217..4384fb85ea 100644
--- a/include/printk.h
+++ b/include/printk.h
@@ -120,4 +120,9 @@ extern void log_clean(unsigned int limit);
void log_print(unsigned flags);
+struct va_format {
+ const char *fmt;
+ va_list *va;
+};
+
#endif
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index fa9fb75800..6fe0283e84 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -302,6 +302,11 @@ char *address_val(char *buf, char *end, const void *addr,
* [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.
* - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and derivatives
* (default assumed to be phys_addr_t, passed by reference)
*
@@ -318,6 +323,16 @@ static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field
if (IS_ENABLED(CONFIG_PRINTF_UUID))
return uuid_string(buf, end, ptr, field_width, precision, flags, fmt);
break;
+ case 'V':
+ {
+ va_list va;
+
+ va_copy(va, *((struct va_format *)ptr)->va);
+ buf += vsnprintf(buf, end > buf ? end - buf : 0,
+ ((struct va_format *)ptr)->fmt, va);
+ va_end(va);
+ return buf;
+ }
case 'a':
return address_val(buf, end, ptr, field_width, precision, flags, fmt);
case 'I':
--
2.19.0
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