sd_bus_creds_new_from_pid() creates a new credentials object and
fills it with information about the process pid. The pointer to this
object will be stored in the ret pointer. Note that credential
objects may also be created and retrieved via
sd_bus_get_name_creds(3), sd_bus_get_owner_creds(3) and
The information that will be stored is determined by creds_mask. It
may contain a subset of ORed constants SD_BUS_CREDS_PID,
SD_BUS_CREDS_PPID, SD_BUS_CREDS_TID, SD_BUS_CREDS_UID,
SD_BUS_CREDS_EUID, SD_BUS_CREDS_SUID, SD_BUS_CREDS_FSUID,
SD_BUS_CREDS_GID, SD_BUS_CREDS_EGID, SD_BUS_CREDS_SGID,
SD_BUS_CREDS_COMM, SD_BUS_CREDS_TID_COMM, SD_BUS_CREDS_EXE,
SD_BUS_CREDS_CMDLINE, SD_BUS_CREDS_CGROUP, SD_BUS_CREDS_UNIT,
SD_BUS_CREDS_SLICE, SD_BUS_CREDS_USER_UNIT, SD_BUS_CREDS_USER_SLICE,
SD_BUS_CREDS_UNIQUE_NAME, SD_BUS_CREDS_WELL_KNOWN_NAMES, and
SD_BUS_CREDS_DESCRIPTION. Use the special value _SD_BUS_CREDS_ALL to
request all supported fields. The SD_BUS_CREDS_AUGMENT constant may
not be ORed into the mask for invocations of
Fields can be retrieved from the credentials object using
sd_bus_creds_get_pid(3) and other functions which correspond directly
to the constants listed above.
A mask of fields which were actually successfully retrieved can be
retrieved with sd_bus_creds_get_mask(). If the credentials object was
created with sd_bus_creds_new_from_pid(), this will be a subset of
fields requested in creds_mask.
Similar to sd_bus_creds_get_mask(), the function
sd_bus_creds_get_augmented_mask() returns a bitmask of field
constants. The mask indicates which credential fields have been
retrieved in a non-atomic fashion. For credential objects created via
sd_bus_creds_new_from_pid(), this mask will be identical to the mask
returned by sd_bus_creds_get_mask(). However, for credential objects
retrieved via sd_bus_get_name_creds(), this mask will be set for the
credential fields that could not be determined atomically at peer
connection time, and which were later added by reading augmenting
credential data from /proc. Similarly, for credential objects
retrieved via sd_bus_get_owner_creds(), the mask is set for the
fields that could not be determined atomically at bus creation time,
but have been augmented. Similarly, for credential objects retrieved
via sd_bus_message_get_creds(), the mask is set for the fields that
could not be determined atomically at message sending time, but have
been augmented. The mask returned by
sd_bus_creds_get_augmented_mask() is always a subset of (or identical
to) the mask returned by sd_bus_creds_get_mask() for the same object.
The latter call hence returns all credential fields available in the
credential object, the former then marks the subset of those that
have been augmented. Note that augmented fields are unsuitable for
authorization decisions, as they may be retrieved at different times,
thus being subject to races. Hence, augmented fields should be used
exclusively for informational purposes.
sd_bus_creds_ref() creates a new reference to the credentials object
c. This object will not be destroyed until sd_bus_creds_unref() has
been called as many times plus once more. Once the reference count
has dropped to zero, c cannot be used anymore, so further calls to
sd_bus_creds_ref(c) or sd_bus_creds_unref(c) are illegal.
sd_bus_creds_unref() destroys a reference to c.
sd_bus_creds_unrefp() is similar to sd_bus_creds_unref() but takes a
pointer to a pointer to an sd_bus_creds object. This call is useful
in conjunction with GCC's and LLVM's Clean-up Variable Attribute.
Note that this function is defined as inline function.
sd_bus_creds_ref(), sd_bus_creds_unref() and sd_bus_creds_unrefp()
execute no operation if the passed in bus credentials object is NULL.
On success, sd_bus_creds_new_from_pid() returns 0 or a positive
integer. On failure, it returns a negative errno-style error code.
sd_bus_creds_get_mask() returns the mask of successfully acquired
sd_bus_creds_get_augmented_mask() returns the mask of fields that
have been augmented from data in /proc, and are thus not suitable for
sd_bus_creds_ref() always returns the argument.
sd_bus_creds_unref() always returns NULL.
Returned errors may indicate the following problems:
Specified pid could not be found.
Specified parameter is invalid (NULL in case of output
Memory allocation failed.
One of the requested fields is unknown to the local system.
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systemd 233 SD_BUS_CREDS_NEW_FROM_PID(3)