setreuid(2) - osol9

1setreuid(2)                      System Calls                      setreuid(2)
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NAME

6       setreuid - set real and effective user IDs
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SYNOPSIS

9       #include <unistd.h>
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11       int setreuid(uid_t ruid, uid_t euid);
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DESCRIPTION

15       The  setreuid() function is used to set the real and effective user IDs
16       of the calling process. If ruid is −1, the real user ID is not changed;
17       if  euid  is  −1,  the  effective  user ID is not changed. The real and
18       effective user IDs may be set to different values in the same call.
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21       If the {PRIV_PROC_SETID} privilege is asserted in the effective set  of
22       the  calling process, the real user ID and the effective user ID can be
23       set to any legal value.
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26       If the {PRIV_PROC_SETID} privilege is not asserted in the effective set
27       of  the  calling  process,  either  the  real user ID can be set to the
28       effective user ID, or the effective user ID can either be  set  to  the
29       saved set-user ID from execve() (seeexec(2)) or the real user ID.
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32       In  either case, if the real user ID is being changed (that is, if ruid
33       is not  −1), or the effective user ID is being changed to a  value  not
34       equal  to  the  real user ID, the saved set-user ID is set equal to the
35       new effective user ID.
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38       All privileges are required to change to uid 0.
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RETURN VALUES

41       Upon successful completion, 0 is returned. Otherwise, −1  is  returned,
42       errno is set to indicate the error, and neither of the user IDs will be
43       changed.
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ERRORS

46       The setreuid() function will fail if:
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48       EINVAL    The value of ruid or euid is less than   0  or  greater  than
49                 UID_MAX (defined in <limits.h>).
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52       EPERM     The {PRIV_PROC_SETID} privilege is not asserted in the effec‐
53                 tive set of the calling processes and a change was  specified
54                 other  than  changing  the real user ID to the effective user
55                 ID, or changing the effective user ID to the real user ID  or
56                 the  saved  set-user  ID.  See  privileges(5)  for additional
57                 restrictions which apply when changing to UID 0.
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USAGE

61       If a set-user-ID process sets its effective user ID to  its  real  user
62       ID,  it  can still set its effective user ID back to the saved set-user
63       ID.
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ATTRIBUTES

66       See attributes(5) for descriptions of the following attributes:
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71       ┌─────────────────────────────┬─────────────────────────────┐
72       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
73       ├─────────────────────────────┼─────────────────────────────┤
74       │Interface Stability          │Standard                     │
75       └─────────────────────────────┴─────────────────────────────┘
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