Skip to content

Commit

Permalink
lib: test_scanf: Remove pointless use of type_min() with unsigned types
Browse files Browse the repository at this point in the history
sparse was producing warnings of the form:

 sparse: cast truncates bits from constant value (ffff0001 becomes 1)

There is no actual problem here. Using type_min() on an unsigned type
results in an (expected) truncation.

However, there is no need to test an unsigned value against type_min().
The minimum value of an unsigned is obviously 0, and any value cast to
an unsigned type is >= 0, so for unsigneds only type_max() need be tested.

This patch also takes the opportunity to clean up the implementation of
simple_numbers_loop() to use a common pattern for the positive and
negative test.

Reported-by: kernel test robot <[email protected]>
Signed-off-by: Richard Fitzgerald <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
  • Loading branch information
rfvirgil authored and pmladek committed May 27, 2021
1 parent ef04d4f commit 1b93268
Showing 1 changed file with 6 additions and 7 deletions.
13 changes: 6 additions & 7 deletions lib/test_scanf.c
Original file line number Diff line number Diff line change
Expand Up @@ -187,8 +187,8 @@ static const unsigned long long numbers[] __initconst = {
#define value_representable_in_type(T, val) \
(is_signed_type(T) \
? ((long long)(val) >= type_min(T)) && ((long long)(val) <= type_max(T)) \
: ((unsigned long long)(val) >= type_min(T)) && \
((unsigned long long)(val) <= type_max(T)))
: ((unsigned long long)(val) <= type_max(T)))


#define test_one_number(T, gen_fmt, scan_fmt, val, fn) \
do { \
Expand All @@ -204,12 +204,11 @@ do { \
int i; \
\
for (i = 0; i < ARRAY_SIZE(numbers); i++) { \
if (!value_representable_in_type(T, numbers[i])) \
continue; \
\
test_one_number(T, gen_fmt, scan_fmt, numbers[i], fn); \
if (value_representable_in_type(T, numbers[i])) \
test_one_number(T, gen_fmt, scan_fmt, \
numbers[i], fn); \
\
if (is_signed_type(T)) \
if (value_representable_in_type(T, -numbers[i])) \
test_one_number(T, gen_fmt, scan_fmt, \
-numbers[i], fn); \
} \
Expand Down

0 comments on commit 1b93268

Please sign in to comment.