1/// Unsigned expressions cannot be lesser than zero. Presence of
2/// comparisons 'unsigned (<|<=|>|>=) 0' often indicates a bug,
3/// usually wrong type of variable.
4///
5/// To reduce number of false positives following tests have been added:
6/// - parts of range checks are skipped, eg. "if (u < 0 || u > 15) ...",
7///   developers prefer to keep such code,
8/// - comparisons "<= 0" and "> 0" are performed only on results of
9///   signed functions/macros,
10/// - hardcoded list of signed functions/macros with always non-negative
11///   result is used to avoid false positives difficult to detect by other ways
12///
13// Confidence: Average
14// Copyright: (C) 2015 Andrzej Hajda, Samsung Electronics Co., Ltd. GPLv2.
15// URL: http://coccinelle.lip6.fr/
16// Options: --all-includes
17
18virtual context
19virtual org
20virtual report
21
22@r_cmp@
23position p;
24typedef bool, u8, u16, u32, u64;
25{unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long,
26	size_t, bool, u8, u16, u32, u64} v;
27expression e;
28@@
29
30	\( v = e \| &v \)
31	...
32	(\( v@p < 0 \| v@p <= 0 \| v@p >= 0 \| v@p > 0 \))
33
34@r@
35position r_cmp.p;
36typedef s8, s16, s32, s64;
37{char, short, int, long, long long, ssize_t, s8, s16, s32, s64} vs;
38expression c, e, v;
39identifier 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_]+)$";
40@@
41
42(
43	v = f(...)@vs;
44	... when != v = e;
45*	(\( v@p <=@e 0 \| v@p >@e 0 \))
46	... when any
47|
48(
49	(\( v@p < 0 \| v@p <= 0 \)) || ... || (\( v >= c \| v > c \))
50|
51	(\( v >= c \| v > c \)) || ... || (\( v@p < 0 \| v@p <= 0 \))
52|
53	(\( v@p >= 0 \| v@p > 0 \)) && ... && (\( v < c \| v <= c \))
54|
55	((\( v < c \| v <= c \) && ... && \( v@p >= 0 \| v@p > 0 \)))
56|
57*	(\( v@p <@e 0 \| v@p >=@e 0 \))
58)
59)
60
61@script:python depends on org@
62p << r_cmp.p;
63e << r.e;
64@@
65
66msg = "WARNING: Unsigned expression compared with zero: %s" % (e)
67coccilib.org.print_todo(p[0], msg)
68
69@script:python depends on report@
70p << r_cmp.p;
71e << r.e;
72@@
73
74msg = "WARNING: Unsigned expression compared with zero: %s" % (e)
75coccilib.report.print_report(p[0], msg)
76