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Diffstat (limited to 'man2/getgroups.2')
| -rw-r--r-- | man2/getgroups.2 | 66 |
1 files changed, 37 insertions, 29 deletions
diff --git a/man2/getgroups.2 b/man2/getgroups.2 index 36300bf61b..83a1508efb 100644 --- a/man2/getgroups.2 +++ b/man2/getgroups.2 @@ -138,15 +138,48 @@ See the description of .IR /proc/ pid /setgroups in .BR user_namespaces (7). +.SH VERSIONS +.SS C library/kernel differences +At the kernel level, user IDs and group IDs are a per-thread attribute. +However, POSIX requires that all threads in a process +share the same credentials. +The NPTL threading implementation handles the POSIX requirements by +providing wrapper functions for +the various system calls that change process UIDs and GIDs. +These wrapper functions (including the one for +.BR setgroups ()) +employ a signal-based technique to ensure +that when one thread changes credentials, +all of the other threads in the process also change their credentials. +For details, see +.BR nptl (7). .SH STANDARDS -.BR getgroups (): -SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008. -.PP -.BR setgroups (): +.TP +.BR getgroups () +POSIX.1-2008. +.TP +.BR setgroups () +None. +.SH HISTORY +.TP +.BR getgroups () +SVr4, 4.3BSD, POSIX.1-2001. +.TP +.BR setgroups () SVr4, 4.3BSD. Since .BR setgroups () requires privilege, it is not covered by POSIX.1. +.PP +The original Linux +.BR getgroups () +system call supported only 16-bit group IDs. +Subsequently, Linux 2.4 added +.BR getgroups32 (), +supporting 32-bit IDs. +The glibc +.BR getgroups () +wrapper function transparently deals with the variation across kernel versions. .SH NOTES A process can have up to .B NGROUPS_MAX @@ -176,31 +209,6 @@ cannot be larger than one more than this value. Since Linux 2.6.4, the maximum number of supplementary group IDs is also exposed via the Linux-specific read-only file, .IR /proc/sys/kernel/ngroups_max . -.PP -The original Linux -.BR getgroups () -system call supported only 16-bit group IDs. -Subsequently, Linux 2.4 added -.BR getgroups32 (), -supporting 32-bit IDs. -The glibc -.BR getgroups () -wrapper function transparently deals with the variation across kernel versions. -.\" -.SS C library/kernel differences -At the kernel level, user IDs and group IDs are a per-thread attribute. -However, POSIX requires that all threads in a process -share the same credentials. -The NPTL threading implementation handles the POSIX requirements by -providing wrapper functions for -the various system calls that change process UIDs and GIDs. -These wrapper functions (including the one for -.BR setgroups ()) -employ a signal-based technique to ensure -that when one thread changes credentials, -all of the other threads in the process also change their credentials. -For details, see -.BR nptl (7). .SH SEE ALSO .BR getgid (2), .BR setgid (2), |