0x%#08x will end up printing 0x0x12345678. Warn about the redundant
prefix (or flag).
Also warn about using 0x in front of a decimal or octal integer
specifer (e.g. 0x%d).
Signed-off-by: Rasmus Villemoes <rv@xxxxxxxxxxxxxxxxxx>
---
check_kernel_printf.c | 37 +++++++++++++++++++++++++++++++++++--
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/check_kernel_printf.c b/check_kernel_printf.c
index b6c387b..ac05c31 100644
--- a/check_kernel_printf.c
+++ b/check_kernel_printf.c
@@ -883,11 +883,38 @@ static int unknown_format(struct expression *expr)
return 0;
}
+static bool has_hex_prefix(const char *orig_fmt, const char *old_fmt)
+{
+ return old_fmt >= orig_fmt + 2 &&
+ old_fmt[-2] == '0' && _tolower(old_fmt[-1]) == 'x';
+}
+
+static bool is_integer_specifier(int type)
+{
+ switch (type) {
+ case FORMAT_TYPE_LONG_LONG:
+ case FORMAT_TYPE_ULONG:
+ case FORMAT_TYPE_LONG:
+ case FORMAT_TYPE_UBYTE:
+ case FORMAT_TYPE_BYTE:
+ case FORMAT_TYPE_USHORT:
+ case FORMAT_TYPE_SHORT:
+ case FORMAT_TYPE_UINT:
+ case FORMAT_TYPE_INT:
+ case FORMAT_TYPE_SIZE_T:
+ case FORMAT_TYPE_PTRDIFF:
+ return true;
+ default:
+ return false;
+ }
+}
+
+
static void
do_check_printf_call(const char *caller, const char *name, struct expression *callexpr, struct expression *fmtexpr, int vaidx)
{
struct printf_spec spec = {0};
- const char *fmt;
+ const char *fmt, *orig_fmt;
int caller_in_fmt;
fmtexpr = strip_parens(fmtexpr);
@@ -929,7 +956,7 @@ do_check_printf_call(const char *caller, const char *name, struct expression *ca
return;
}
- fmt = fmtexpr->string->data;
+ orig_fmt = fmt = fmtexpr->string->data;
caller_in_fmt = check_format_string(fmt, caller);
while (*fmt) {
@@ -952,6 +979,12 @@ do_check_printf_call(const char *caller, const char *name, struct expression *ca
*/
arg = get_argument_from_call_expr(callexpr->args, vaidx++);
+ if (spec.flags & SPECIAL && has_hex_prefix(orig_fmt, old_fmt))
+ sm_msg("warn: '%.2s' prefix is redundant when # flag is used", old_fmt-2);
+ if (is_integer_specifier(spec.type) && spec.base != 16 && has_hex_prefix(orig_fmt, old_fmt))
+ sm_msg("warn: '%.2s' prefix is confusing together with '%.*s' specifier",
+ old_fmt-2, (int)(fmt-old_fmt), old_fmt);
+
switch (spec.type) {
/* case FORMAT_TYPE_NONE: */
/* case FORMAT_TYPE_PERCENT_CHAR: */
--
2.6.1
--
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