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-rw-r--r--lib/getgroups.c125
1 files changed, 125 insertions, 0 deletions
diff --git a/lib/getgroups.c b/lib/getgroups.c
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+++ b/lib/getgroups.c
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+/* provide consistent interface to getgroups for systems that don't allow N==0
+
+ Copyright (C) 1996, 1999, 2003, 2006-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* written by Jim Meyering */
+
+#include <config.h>
+
+#include <unistd.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#if !HAVE_GETGROUPS
+
+/* Provide a stub that fails with ENOSYS, since there is no group
+ information available on mingw. */
+int
+getgroups (_GL_UNUSED int n, _GL_UNUSED GETGROUPS_T *groups)
+{
+ errno = ENOSYS;
+ return -1;
+}
+
+#else /* HAVE_GETGROUPS */
+
+# undef getgroups
+# ifndef GETGROUPS_ZERO_BUG
+# define GETGROUPS_ZERO_BUG 0
+# endif
+
+/* On OS X 10.6 and later, use the usual getgroups, not the one
+ supplied when _DARWIN_C_SOURCE is defined. _DARWIN_C_SOURCE is
+ normally defined, since it means "conform to POSIX, but add
+ non-POSIX extensions even if that violates the POSIX namespace
+ rules", which is what we normally want. But with getgroups there
+ is an inconsistency, and _DARWIN_C_SOURCE means "change getgroups()
+ so that it no longer works right". The BUGS section of compat(5)
+ says that the behavior is dubious if you compile different sections
+ of a program with different _DARWIN_C_SOURCE settings, so fix only
+ the offending symbol. */
+# ifdef __APPLE__
+int posix_getgroups (int, gid_t []) __asm ("_getgroups");
+# define getgroups posix_getgroups
+# endif
+
+/* On at least NeXTstep 3.2, getgroups (0, NULL) always fails.
+ On other systems, it returns the number of supplemental
+ groups for the process. This function handles that special case
+ and lets the system-provided function handle all others. However,
+ it can fail with ENOMEM if memory is tight. It is unspecified
+ whether the effective group id is included in the list. */
+
+int
+rpl_getgroups (int n, gid_t *group)
+{
+ int n_groups;
+ GETGROUPS_T *gbuf;
+
+ if (n < 0)
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
+ if (n != 0 || !GETGROUPS_ZERO_BUG)
+ {
+ int result;
+ if (sizeof *group == sizeof *gbuf)
+ return getgroups (n, (GETGROUPS_T *) group);
+
+ if (SIZE_MAX / sizeof *gbuf <= n)
+ {
+ errno = ENOMEM;
+ return -1;
+ }
+ gbuf = malloc (n * sizeof *gbuf);
+ if (!gbuf)
+ return -1;
+ result = getgroups (n, gbuf);
+ if (0 <= result)
+ {
+ n = result;
+ while (n--)
+ group[n] = gbuf[n];
+ }
+ free (gbuf);
+ return result;
+ }
+
+ n = 20;
+ while (1)
+ {
+ /* No need to worry about address arithmetic overflow here,
+ since the ancient systems that we're running on have low
+ limits on the number of secondary groups. */
+ gbuf = malloc (n * sizeof *gbuf);
+ if (!gbuf)
+ return -1;
+ n_groups = getgroups (n, gbuf);
+ if (n_groups == -1 ? errno != EINVAL : n_groups < n)
+ break;
+ free (gbuf);
+ n *= 2;
+ }
+
+ free (gbuf);
+ return n_groups;
+}
+
+#endif /* HAVE_GETGROUPS */