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Commit 3f984cb3 authored by Andrzej Hajda's avatar Andrzej Hajda Committed by Michal Marek
Browse files

coccinelle: tests: unsigned value cannot be lesser than zero 



Unsigned expressions cannot be lesser than zero. Presence of comparisons
'unsigned (<|<=|>|>=) 0' often indicates a bug, usually wrong type of variable.
The patch beside finding such comparisons tries to eliminate false positives,
mainly by bypassing range checks.

gcc can detect such comparisons also using -Wtype-limits switch, but it warns
also in correct cases, making too much noise.

Signed-off-by: default avatarAndrzej Hajda <a.hajda@samsung.com>
Acked-by: default avatarJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
parent 93209d65

scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci

0 → 100644
+75 −0
Original line number Diff line number Diff line 
/// Unsigned expressions cannot be lesser than zero. Presence of

/// comparisons 'unsigned (<|<=|>|>=) 0' often indicates a bug,

/// usually wrong type of variable.

///

/// To reduce number of false positives following tests have been added:

/// - parts of range checks are skipped, eg. "if (u < 0 || u > 15) ...",

///   developers prefer to keep such code,

/// - comparisons "<= 0" and "> 0" are performed only on results of

///   signed functions/macros,

/// - hardcoded list of signed functions/macros with always non-negative

///   result is used to avoid false positives difficult to detect by other ways

///

// Confidence: Average

// Copyright: (C) 2015 Andrzej Hajda, Samsung Electronics Co., Ltd. GPLv2.

// URL: http://coccinelle.lip6.fr/

// Options: --all-includes



virtual context

virtual org

virtual report



@r_cmp@

position p;

typedef bool, u8, u16, u32, u64;

{unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long,

	size_t, bool, u8, u16, u32, u64} v;

expression e;

@@



	\( v = e \| &v \)

	...

	(\( v@p < 0 \| v@p <= 0 \| v@p >= 0 \| v@p > 0 \))



@r@

position r_cmp.p;

typedef s8, s16, s32, s64;

{char, short, int, long, long long, ssize_t, s8, s16, s32, s64} vs;

expression c, e, v;

identifier f !~ "^(ata_id_queue_depth|btrfs_copy_from_user|dma_map_sg|dma_map_sg_attrs|fls|fls64|gameport_time|get_write_extents|nla_len|ntoh24|of_flat_dt_match|of_get_child_count|uart_circ_chars_pending|[A-Z0-9_]+)$";

@@



(

	v = f(...)@vs;

	... when != v = e;

*	(\( v@p <=@e 0 \| v@p >@e 0 \))

	... when any

|

(

	(\( v@p < 0 \| v@p <= 0 \)) || ... || (\( v >= c \| v > c \))

|

	(\( v >= c \| v > c \)) || ... || (\( v@p < 0 \| v@p <= 0 \))

|

	(\( v@p >= 0 \| v@p > 0 \)) && ... && (\( v < c \| v <= c \))

|

	((\( v < c \| v <= c \) && ... && \( v@p >= 0 \| v@p > 0 \)))

|

*	(\( v@p <@e 0 \| v@p >=@e 0 \))

)

)



@script:python depends on org@

p << r_cmp.p;

e << r.e;

@@



msg = "WARNING: Unsigned expression compared with zero: %s" % (e)

coccilib.org.print_todo(p[0], msg)



@script:python depends on report@

p << r_cmp.p;

e << r.e;

@@



msg = "WARNING: Unsigned expression compared with zero: %s" % (e)

coccilib.report.print_report(p[0], msg)