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systemd-nspawn: make SettingsMask 64 bit wide

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The use of UINT64_C() in the SettingsMask enum definition is misleading:
it does not mean that individual fields have this width. E.g., with
enum {
   FOO = UINT64_C(1)
}
sizeof(FOO) gives 4. It only means that the shift is done properly. So
1 << 35 is undefined, but UINT64_C(1) << 35 is the expected 64 bit
constant. Thus, the use UINT64_C() is useful, because we know that the shifts
are done properly, no matter what the value of _RLIMIT_MAX is, but when those
fields are used in expressions, we don't know what size they will be
(probably 4). Let's add a define which "hides" the enum definition behind a
define which gives the same value but is actually 64 bit. I think this is a
nicer solution than requiring all users to cast SETTING_RLIMIT_FIRST before
use.

Fixes #9035.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2018-05-22 09:13:31 +02:00
parent 9b505bc257
commit b49c6ca089
1 changed files with 11 additions and 1 deletions
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12
src/nspawn/nspawn-settings.h
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@ -56,9 +56,19 @@ typedef enum SettingsMask {
SETTING_CPU_AFFINITY = UINT64_C(1) << 20,
SETTING_RLIMIT_FIRST = UINT64_C(1) << 21, /* we define one bit per resource limit here */
SETTING_RLIMIT_LAST = UINT64_C(1) << (21 + _RLIMIT_MAX - 1),
_SETTINGS_MASK_ALL = (UINT64_C(1) << (21 + _RLIMIT_MAX)) - 1
_SETTINGS_MASK_ALL = (UINT64_C(1) << (21 + _RLIMIT_MAX)) - 1,
_FORCE_ENUM_WIDTH = UINT64_MAX
} SettingsMask;
/* We want to use SETTING_RLIMIT_FIRST in shifts, so make sure it is really 64 bits
* when used in expressions. */
#define SETTING_RLIMIT_FIRST ((uint64_t) SETTING_RLIMIT_FIRST)
#define SETTING_RLIMIT_LAST ((uint64_t) SETTING_RLIMIT_LAST)
assert_cc(sizeof(SettingsMask) == 8);
assert_cc(sizeof(SETTING_RLIMIT_FIRST) == 8);
assert_cc(sizeof(SETTING_RLIMIT_LAST) == 8);
typedef struct Settings {
/* [Run] */
StartMode start_mode;