Add -Wsign-compare to the project's CFLAGS#118
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The lttng-tools code base has many erroneous comparisons between
signed and unsigned values.
While some uses are benign, like using a signed integer to loop
between 0 and sizeof(struct some_structure), there are many
cases where the "signed integer" result of a syscall
(e.g. sendmsg, recvmsg, read, write) is compared to an expected
structure size using sizeof, which returns a result of type
size_t.
The following pattern:
ret = sendmsg(...);
if (ret < sizeof(struct some_structure)) {
/* Handle error. */
}
is common and _unsafe_ if the intention is to check for an error
(-1) and that the operation was completed (ret == sizeof(...)).
Follow-up patches address the various instances of the problem.
The "Clean-up:" prefix is used when the comparison was safe
and the change is mainly done to silence the warning.
The "Fix:" prefix is used when the commit fixes an unsafe
comparison and should be backported to previous versions.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
jgalar
added
bug
refactor
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The lttng-tools code base has many erroneous comparisons between
signed and unsigned values.
While some uses are benign, like using a signed integer to loop
between
0andsizeof(struct some_structure), there are manycases where the "signed integer" result of a syscall
(e.g.
sendmsg,recvmsg,read,write) is compared to an expectedstructure size using the
sizeofoperator, which returns a result of typesize_t.The following pattern:
is common and unsafe if the intention is to check for an error
(
-1) and that the operation was completed (ret == sizeof(...)).Follow-up patches address the various instances of the problem.
The
Clean-up:prefix is used when the comparison was safeand the change is mainly done to silence the warning.
The
Fix:prefix is used when the commit fixes an unsafecomparison and should be backported to previous versions.