1// SPDX-License-Identifier: GPL-2.0-only
  2/// do_div() does a 64-by-32 division.
  3/// When the divisor is long, unsigned long, u64, or s64,
  4/// do_div() truncates it to 32 bits, this means it can test
  5/// non-zero and be truncated to 0 for division on 64bit platforms.
  6///
  7//# This makes an effort to find those inappropriate do_div() calls.
  8//
  9// Confidence: Moderate
 10// Copyright: (C) 2020 Wen Yang, Alibaba.
 11// Comments:
 12// Options: --no-includes --include-headers
 13
 14virtual context
 15virtual org
 16virtual report
 17
 18@initialize:python@
 19@@
 20
 21def get_digit_type_and_value(str):
 22    is_digit = False
 23    value = 0
 24
 25    try:
 26        if (str.isdigit()):
 27           is_digit = True
 28           value =  int(str, 0)
 29        elif (str.upper().endswith('ULL')):
 30           is_digit = True
 31           value = int(str[:-3], 0)
 32        elif (str.upper().endswith('LL')):
 33           is_digit = True
 34           value = int(str[:-2], 0)
 35        elif (str.upper().endswith('UL')):
 36           is_digit = True
 37           value = int(str[:-2], 0)
 38        elif (str.upper().endswith('L')):
 39           is_digit = True
 40           value = int(str[:-1], 0)
 41        elif (str.upper().endswith('U')):
 42           is_digit = True
 43           value = int(str[:-1], 0)
 44    except Exception as e:
 45          print('Error:',e)
 46          is_digit = False
 47          value = 0
 48    finally:
 49        return is_digit, value
 50
 51def filter_out_safe_constants(str):
 52    is_digit, value = get_digit_type_and_value(str)
 53    if (is_digit):
 54        if (value >= 0x100000000):
 55            return True
 56        else:
 57            return False
 58    else:
 59        return True
 60
 61def construct_warnings(suggested_fun):
 62    msg="WARNING: do_div() does a 64-by-32 division, please consider using %s instead."
 63    return  msg % suggested_fun
 64
 65@depends on context@
 66expression f;
 67long l: script:python() { filter_out_safe_constants(l) };
 68unsigned long ul : script:python() { filter_out_safe_constants(ul) };
 69u64 ul64 : script:python() { filter_out_safe_constants(ul64) };
 70s64 sl64 : script:python() { filter_out_safe_constants(sl64) };
 71
 72@@
 73(
 74* do_div(f, l);
 75|
 76* do_div(f, ul);
 77|
 78* do_div(f, ul64);
 79|
 80* do_div(f, sl64);
 81)
 82
 83@r depends on (org || report)@
 84expression f;
 85position p;
 86long l: script:python() { filter_out_safe_constants(l) };
 87unsigned long ul : script:python() { filter_out_safe_constants(ul) };
 88u64 ul64 : script:python() { filter_out_safe_constants(ul64) };
 89s64 sl64 : script:python() { filter_out_safe_constants(sl64) };
 90@@
 91(
 92do_div@p(f, l);
 93|
 94do_div@p(f, ul);
 95|
 96do_div@p(f, ul64);
 97|
 98do_div@p(f, sl64);
 99)
100
101@script:python depends on org@
102p << r.p;
103ul << r.ul;
104@@
105
106coccilib.org.print_todo(p[0], construct_warnings("div64_ul"))
107
108@script:python depends on org@
109p << r.p;
110l << r.l;
111@@
112
113coccilib.org.print_todo(p[0], construct_warnings("div64_long"))
114
115@script:python depends on org@
116p << r.p;
117ul64 << r.ul64;
118@@
119
120coccilib.org.print_todo(p[0], construct_warnings("div64_u64"))
121
122@script:python depends on org@
123p << r.p;
124sl64 << r.sl64;
125@@
126
127coccilib.org.print_todo(p[0], construct_warnings("div64_s64"))
128
129@script:python depends on report@
130p << r.p;
131ul << r.ul;
132@@
133
134coccilib.report.print_report(p[0], construct_warnings("div64_ul"))
135
136@script:python depends on report@
137p << r.p;
138l << r.l;
139@@
140
141coccilib.report.print_report(p[0], construct_warnings("div64_long"))
142
143@script:python depends on report@
144p << r.p;
145sl64 << r.sl64;
146@@
147
148coccilib.report.print_report(p[0], construct_warnings("div64_s64"))
149
150@script:python depends on report@
151p << r.p;
152ul64 << r.ul64;
153@@
154
155coccilib.report.print_report(p[0], construct_warnings("div64_u64"))