glibc/grp/grp-merge.c

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NSS: Implement group merging support. https://sourceware.org/glibc/wiki/Proposals/GroupMerging == Justification == It is common today for users to rely on centrally-managed user stores for handling their user accounts. However, much software existing today does not have an innate understanding of such accounts. Instead, they commonly rely on membership in known groups for managing access-control (for example the "wheel" group on Fedora and RHEL systems or the "adm" group on Debian-derived systems). In the present incarnation of nsswitch, the only way to have such groups managed by a remote user store such as FreeIPA or Active Directory would be to manually remove the groups from /etc/group on the clients so that nsswitch would then move past nss_files and into the SSSD, nss-ldap or other remote user database. == Solution == With this patch, a new action is introduced for nsswitch: NSS_ACTION_MERGE. To take advantage of it, one will add [SUCCESS=merge] between two database entries in the nsswitch.conf file. When a group is located in the first of the two group entries, processing will continue on to the next one. If the group is also found in the next entry (and the group name and GID are an exact match), the member list of the second entry will be added to the group object to be returned. == Implementation == After each DL_LOOKUP_FN() returns, the next action is checked. If the function returned NSS_STATUS_SUCCESS and the next action is NSS_ACTION_MERGE, a copy of the result buffer is saved for the next pass through the loop. If on this next pass through the loop the database returns another instance of a group matching both the group name and GID, the member list is added to the previous list and it is returned as a single object. If the following database does not contain the same group, then the original is copied back into the destination buffer. This patch implements merge functionality only for the group database. For other databases, there is a default implementation that will return the EINVAL errno if a merge is requested. The merge functionality can be implemented for other databases at a later time if such is needed. Each database must provide a unique implementation of the deep-copy and merge functions. If [SUCCESS=merge] is present in nsswitch.conf for a glibc version that does not support it, glibc will process results up until that operation, at which time it will return results if it has found them or else will simply return an error. In practical terms, this ends up behaving like the remainder of the nsswitch.conf line does not exist. == Iterators == This feature does not modify the iterator functionality from its current behavior. If getgrnam() or getgrgid() is called, glibc will iterate through all entries in the `group` line in nsswitch.conf and display the list of members without attempting to merge them. This is consistent with the behavior of nss_files where if two separate lines are specified for the same group in /etc/groups, getgrnam()/getgrgid() will display both. Clients are already expected to handle this gracefully. == No Premature Optimizations == The following is a list of places that might be eligible for optimization, but were not overengineered for this initial contribution: * Any situation where a merge may occur will result in one malloc() of the same size as the input buffer. * Any situation where a merge does occur will result in a second malloc() to hold the list of pointers to member name strings. * The list of members is simply concatenated together and is not tested for uniqueness (which is identical to the behavior for nss_files, which will simply return identical values if they both exist on the line in the file. This could potentially be optimized to reduce space usage in the buffer, but it is both complex and computationally expensive to do so. == Testing == I performed testing by running the getent utility against my newly-built glibc and configuring /etc/nsswitch.conf with the following entry: group: group: files [SUCCESS=merge] sss In /etc/group I included the line: wheel:x:10:sgallagh I then configured my local SSSD using the id_provider=local to respond with: wheel:*:10:localuser,localuser2 I then ran `getent group wheel` against the newly-built glibc in multiple situations and received the expected output as described above: * When SSSD was running. * When SSSD was configured in nsswitch.conf but the daemon was not running. * When SSSD was configured in nsswitch.conf but nss_sss.so.2 was not installed on the system. * When the order of 'sss' and 'files' was reversed. * All of the above with the [SUCCESS=merge] removed (to ensure no regressions). * All of the above with `getent group 10`. * All of the above with `getent group` with and without `enumerate=true` set in SSSD. * All of the above with and without nscd enabled on the system.
2016-04-30 02:11:09 +00:00
/* Group merging implementation.
Copyright (C) 2016-2017 Free Software Foundation, Inc.
NSS: Implement group merging support. https://sourceware.org/glibc/wiki/Proposals/GroupMerging == Justification == It is common today for users to rely on centrally-managed user stores for handling their user accounts. However, much software existing today does not have an innate understanding of such accounts. Instead, they commonly rely on membership in known groups for managing access-control (for example the "wheel" group on Fedora and RHEL systems or the "adm" group on Debian-derived systems). In the present incarnation of nsswitch, the only way to have such groups managed by a remote user store such as FreeIPA or Active Directory would be to manually remove the groups from /etc/group on the clients so that nsswitch would then move past nss_files and into the SSSD, nss-ldap or other remote user database. == Solution == With this patch, a new action is introduced for nsswitch: NSS_ACTION_MERGE. To take advantage of it, one will add [SUCCESS=merge] between two database entries in the nsswitch.conf file. When a group is located in the first of the two group entries, processing will continue on to the next one. If the group is also found in the next entry (and the group name and GID are an exact match), the member list of the second entry will be added to the group object to be returned. == Implementation == After each DL_LOOKUP_FN() returns, the next action is checked. If the function returned NSS_STATUS_SUCCESS and the next action is NSS_ACTION_MERGE, a copy of the result buffer is saved for the next pass through the loop. If on this next pass through the loop the database returns another instance of a group matching both the group name and GID, the member list is added to the previous list and it is returned as a single object. If the following database does not contain the same group, then the original is copied back into the destination buffer. This patch implements merge functionality only for the group database. For other databases, there is a default implementation that will return the EINVAL errno if a merge is requested. The merge functionality can be implemented for other databases at a later time if such is needed. Each database must provide a unique implementation of the deep-copy and merge functions. If [SUCCESS=merge] is present in nsswitch.conf for a glibc version that does not support it, glibc will process results up until that operation, at which time it will return results if it has found them or else will simply return an error. In practical terms, this ends up behaving like the remainder of the nsswitch.conf line does not exist. == Iterators == This feature does not modify the iterator functionality from its current behavior. If getgrnam() or getgrgid() is called, glibc will iterate through all entries in the `group` line in nsswitch.conf and display the list of members without attempting to merge them. This is consistent with the behavior of nss_files where if two separate lines are specified for the same group in /etc/groups, getgrnam()/getgrgid() will display both. Clients are already expected to handle this gracefully. == No Premature Optimizations == The following is a list of places that might be eligible for optimization, but were not overengineered for this initial contribution: * Any situation where a merge may occur will result in one malloc() of the same size as the input buffer. * Any situation where a merge does occur will result in a second malloc() to hold the list of pointers to member name strings. * The list of members is simply concatenated together and is not tested for uniqueness (which is identical to the behavior for nss_files, which will simply return identical values if they both exist on the line in the file. This could potentially be optimized to reduce space usage in the buffer, but it is both complex and computationally expensive to do so. == Testing == I performed testing by running the getent utility against my newly-built glibc and configuring /etc/nsswitch.conf with the following entry: group: group: files [SUCCESS=merge] sss In /etc/group I included the line: wheel:x:10:sgallagh I then configured my local SSSD using the id_provider=local to respond with: wheel:*:10:localuser,localuser2 I then ran `getent group wheel` against the newly-built glibc in multiple situations and received the expected output as described above: * When SSSD was running. * When SSSD was configured in nsswitch.conf but the daemon was not running. * When SSSD was configured in nsswitch.conf but nss_sss.so.2 was not installed on the system. * When the order of 'sss' and 'files' was reversed. * All of the above with the [SUCCESS=merge] removed (to ensure no regressions). * All of the above with `getent group 10`. * All of the above with `getent group` with and without `enumerate=true` set in SSSD. * All of the above with and without nscd enabled on the system.
2016-04-30 02:11:09 +00:00
This file is part of the GNU C Library.
The GNU C Library 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.
The GNU C Library 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 the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <grp.h>
#include <grp-merge.h>
#define BUFCHECK(size) \
({ \
do \
{ \
if (c + (size) > buflen) \
{ \
free (members); \
return ERANGE; \
} \
} \
while (0); \
})
int
internal_function
__copy_grp (const struct group srcgrp, const size_t buflen,
struct group *destgrp, char *destbuf, char **endptr)
{
size_t i;
size_t c = 0;
size_t len;
size_t memcount;
char **members = NULL;
/* Copy the GID. */
destgrp->gr_gid = srcgrp.gr_gid;
/* Copy the name. */
len = strlen (srcgrp.gr_name) + 1;
BUFCHECK (len);
memcpy (&destbuf[c], srcgrp.gr_name, len);
destgrp->gr_name = &destbuf[c];
c += len;
/* Copy the password. */
len = strlen (srcgrp.gr_passwd) + 1;
BUFCHECK (len);
memcpy (&destbuf[c], srcgrp.gr_passwd, len);
destgrp->gr_passwd = &destbuf[c];
c += len;
/* Count all of the members. */
for (memcount = 0; srcgrp.gr_mem[memcount]; memcount++)
;
/* Allocate a temporary holding area for the pointers to the member
contents, including space for a NULL-terminator. */
members = malloc (sizeof (char *) * (memcount + 1));
if (members == NULL)
return ENOMEM;
/* Copy all of the group members to destbuf and add a pointer to each of
them into the 'members' array. */
for (i = 0; srcgrp.gr_mem[i]; i++)
{
len = strlen (srcgrp.gr_mem[i]) + 1;
BUFCHECK (len);
memcpy (&destbuf[c], srcgrp.gr_mem[i], len);
members[i] = &destbuf[c];
c += len;
}
members[i] = NULL;
/* Align for pointers. We can't simply align C because we need to
align destbuf[c]. */
if ((((uintptr_t)destbuf + c) & (__alignof__(char **) - 1)) != 0)
{
uintptr_t mis_align = ((uintptr_t)destbuf + c) & (__alignof__(char **) - 1);
c += __alignof__(char **) - mis_align;
}
NSS: Implement group merging support. https://sourceware.org/glibc/wiki/Proposals/GroupMerging == Justification == It is common today for users to rely on centrally-managed user stores for handling their user accounts. However, much software existing today does not have an innate understanding of such accounts. Instead, they commonly rely on membership in known groups for managing access-control (for example the "wheel" group on Fedora and RHEL systems or the "adm" group on Debian-derived systems). In the present incarnation of nsswitch, the only way to have such groups managed by a remote user store such as FreeIPA or Active Directory would be to manually remove the groups from /etc/group on the clients so that nsswitch would then move past nss_files and into the SSSD, nss-ldap or other remote user database. == Solution == With this patch, a new action is introduced for nsswitch: NSS_ACTION_MERGE. To take advantage of it, one will add [SUCCESS=merge] between two database entries in the nsswitch.conf file. When a group is located in the first of the two group entries, processing will continue on to the next one. If the group is also found in the next entry (and the group name and GID are an exact match), the member list of the second entry will be added to the group object to be returned. == Implementation == After each DL_LOOKUP_FN() returns, the next action is checked. If the function returned NSS_STATUS_SUCCESS and the next action is NSS_ACTION_MERGE, a copy of the result buffer is saved for the next pass through the loop. If on this next pass through the loop the database returns another instance of a group matching both the group name and GID, the member list is added to the previous list and it is returned as a single object. If the following database does not contain the same group, then the original is copied back into the destination buffer. This patch implements merge functionality only for the group database. For other databases, there is a default implementation that will return the EINVAL errno if a merge is requested. The merge functionality can be implemented for other databases at a later time if such is needed. Each database must provide a unique implementation of the deep-copy and merge functions. If [SUCCESS=merge] is present in nsswitch.conf for a glibc version that does not support it, glibc will process results up until that operation, at which time it will return results if it has found them or else will simply return an error. In practical terms, this ends up behaving like the remainder of the nsswitch.conf line does not exist. == Iterators == This feature does not modify the iterator functionality from its current behavior. If getgrnam() or getgrgid() is called, glibc will iterate through all entries in the `group` line in nsswitch.conf and display the list of members without attempting to merge them. This is consistent with the behavior of nss_files where if two separate lines are specified for the same group in /etc/groups, getgrnam()/getgrgid() will display both. Clients are already expected to handle this gracefully. == No Premature Optimizations == The following is a list of places that might be eligible for optimization, but were not overengineered for this initial contribution: * Any situation where a merge may occur will result in one malloc() of the same size as the input buffer. * Any situation where a merge does occur will result in a second malloc() to hold the list of pointers to member name strings. * The list of members is simply concatenated together and is not tested for uniqueness (which is identical to the behavior for nss_files, which will simply return identical values if they both exist on the line in the file. This could potentially be optimized to reduce space usage in the buffer, but it is both complex and computationally expensive to do so. == Testing == I performed testing by running the getent utility against my newly-built glibc and configuring /etc/nsswitch.conf with the following entry: group: group: files [SUCCESS=merge] sss In /etc/group I included the line: wheel:x:10:sgallagh I then configured my local SSSD using the id_provider=local to respond with: wheel:*:10:localuser,localuser2 I then ran `getent group wheel` against the newly-built glibc in multiple situations and received the expected output as described above: * When SSSD was running. * When SSSD was configured in nsswitch.conf but the daemon was not running. * When SSSD was configured in nsswitch.conf but nss_sss.so.2 was not installed on the system. * When the order of 'sss' and 'files' was reversed. * All of the above with the [SUCCESS=merge] removed (to ensure no regressions). * All of the above with `getent group 10`. * All of the above with `getent group` with and without `enumerate=true` set in SSSD. * All of the above with and without nscd enabled on the system.
2016-04-30 02:11:09 +00:00
/* Copy the pointers from the members array into the buffer and assign them
to the gr_mem member of destgrp. */
destgrp->gr_mem = (char **) &destbuf[c];
len = sizeof (char *) * (memcount + 1);
BUFCHECK (len);
memcpy (&destbuf[c], members, len);
c += len;
free (members);
members = NULL;
/* Save the count of members at the end. */
BUFCHECK (sizeof (size_t));
memcpy (&destbuf[c], &memcount, sizeof (size_t));
c += sizeof (size_t);
if (endptr)
*endptr = destbuf + c;
return 0;
}
libc_hidden_def (__copy_grp)
/* Check that the name, GID and passwd fields match, then
copy in the gr_mem array. */
int
internal_function
__merge_grp (struct group *savedgrp, char *savedbuf, char *savedend,
size_t buflen, struct group *mergegrp, char *mergebuf)
{
size_t c, i, len;
size_t savedmemcount;
size_t memcount;
size_t membersize;
char **members = NULL;
/* We only support merging members of groups with identical names and
GID values. If we hit this case, we need to overwrite the current
buffer with the saved one (which is functionally equivalent to
treating the new lookup as NSS_STATUS_NOTFOUND). */
if (mergegrp->gr_gid != savedgrp->gr_gid
|| strcmp (mergegrp->gr_name, savedgrp->gr_name))
return __copy_grp (*savedgrp, buflen, mergegrp, mergebuf, NULL);
/* Get the count of group members from the last sizeof (size_t) bytes in the
mergegrp buffer. */
savedmemcount = *(size_t *) (savedend - sizeof (size_t));
NSS: Implement group merging support. https://sourceware.org/glibc/wiki/Proposals/GroupMerging == Justification == It is common today for users to rely on centrally-managed user stores for handling their user accounts. However, much software existing today does not have an innate understanding of such accounts. Instead, they commonly rely on membership in known groups for managing access-control (for example the "wheel" group on Fedora and RHEL systems or the "adm" group on Debian-derived systems). In the present incarnation of nsswitch, the only way to have such groups managed by a remote user store such as FreeIPA or Active Directory would be to manually remove the groups from /etc/group on the clients so that nsswitch would then move past nss_files and into the SSSD, nss-ldap or other remote user database. == Solution == With this patch, a new action is introduced for nsswitch: NSS_ACTION_MERGE. To take advantage of it, one will add [SUCCESS=merge] between two database entries in the nsswitch.conf file. When a group is located in the first of the two group entries, processing will continue on to the next one. If the group is also found in the next entry (and the group name and GID are an exact match), the member list of the second entry will be added to the group object to be returned. == Implementation == After each DL_LOOKUP_FN() returns, the next action is checked. If the function returned NSS_STATUS_SUCCESS and the next action is NSS_ACTION_MERGE, a copy of the result buffer is saved for the next pass through the loop. If on this next pass through the loop the database returns another instance of a group matching both the group name and GID, the member list is added to the previous list and it is returned as a single object. If the following database does not contain the same group, then the original is copied back into the destination buffer. This patch implements merge functionality only for the group database. For other databases, there is a default implementation that will return the EINVAL errno if a merge is requested. The merge functionality can be implemented for other databases at a later time if such is needed. Each database must provide a unique implementation of the deep-copy and merge functions. If [SUCCESS=merge] is present in nsswitch.conf for a glibc version that does not support it, glibc will process results up until that operation, at which time it will return results if it has found them or else will simply return an error. In practical terms, this ends up behaving like the remainder of the nsswitch.conf line does not exist. == Iterators == This feature does not modify the iterator functionality from its current behavior. If getgrnam() or getgrgid() is called, glibc will iterate through all entries in the `group` line in nsswitch.conf and display the list of members without attempting to merge them. This is consistent with the behavior of nss_files where if two separate lines are specified for the same group in /etc/groups, getgrnam()/getgrgid() will display both. Clients are already expected to handle this gracefully. == No Premature Optimizations == The following is a list of places that might be eligible for optimization, but were not overengineered for this initial contribution: * Any situation where a merge may occur will result in one malloc() of the same size as the input buffer. * Any situation where a merge does occur will result in a second malloc() to hold the list of pointers to member name strings. * The list of members is simply concatenated together and is not tested for uniqueness (which is identical to the behavior for nss_files, which will simply return identical values if they both exist on the line in the file. This could potentially be optimized to reduce space usage in the buffer, but it is both complex and computationally expensive to do so. == Testing == I performed testing by running the getent utility against my newly-built glibc and configuring /etc/nsswitch.conf with the following entry: group: group: files [SUCCESS=merge] sss In /etc/group I included the line: wheel:x:10:sgallagh I then configured my local SSSD using the id_provider=local to respond with: wheel:*:10:localuser,localuser2 I then ran `getent group wheel` against the newly-built glibc in multiple situations and received the expected output as described above: * When SSSD was running. * When SSSD was configured in nsswitch.conf but the daemon was not running. * When SSSD was configured in nsswitch.conf but nss_sss.so.2 was not installed on the system. * When the order of 'sss' and 'files' was reversed. * All of the above with the [SUCCESS=merge] removed (to ensure no regressions). * All of the above with `getent group 10`. * All of the above with `getent group` with and without `enumerate=true` set in SSSD. * All of the above with and without nscd enabled on the system.
2016-04-30 02:11:09 +00:00
/* Get the count of new members to add. */
for (memcount = 0; mergegrp->gr_mem[memcount]; memcount++)
;
/* Create a temporary array to hold the pointers to the member values from
both the saved and merge groups. */
membersize = savedmemcount + memcount + 1;
members = malloc (sizeof (char *) * membersize);
if (members == NULL)
return ENOMEM;
/* Copy in the existing member pointers from the saved group
Note: this is not NULL-terminated yet. */
memcpy (members, savedgrp->gr_mem, sizeof (char *) * savedmemcount);
/* Back up into the savedbuf until we get back to the NULL-terminator of the
group member list. (This means walking back savedmemcount + 1 (char *) pointers
and the member count value.
The value of c is going to be the used length of the buffer backed up by
the member count and further backed up by the size of the pointers. */
c = savedend - savedbuf
- sizeof (size_t)
- sizeof (char *) * (savedmemcount + 1);
/* Add all the new group members, overwriting the old NULL-terminator while
adding the new pointers to the temporary array. */
for (i = 0; mergegrp->gr_mem[i]; i++)
{
len = strlen (mergegrp->gr_mem[i]) + 1;
BUFCHECK (len);
memcpy (&savedbuf[c], mergegrp->gr_mem[i], len);
members[savedmemcount + i] = &savedbuf[c];
c += len;
}
/* Add the NULL-terminator. */
members[savedmemcount + memcount] = NULL;
/* Align for pointers. We can't simply align C because we need to
align savedbuf[c]. */
if ((((uintptr_t)savedbuf + c) & (__alignof__(char **) - 1)) != 0)
{
uintptr_t mis_align = ((uintptr_t)savedbuf + c) & (__alignof__(char **) - 1);
c += __alignof__(char **) - mis_align;
}
NSS: Implement group merging support. https://sourceware.org/glibc/wiki/Proposals/GroupMerging == Justification == It is common today for users to rely on centrally-managed user stores for handling their user accounts. However, much software existing today does not have an innate understanding of such accounts. Instead, they commonly rely on membership in known groups for managing access-control (for example the "wheel" group on Fedora and RHEL systems or the "adm" group on Debian-derived systems). In the present incarnation of nsswitch, the only way to have such groups managed by a remote user store such as FreeIPA or Active Directory would be to manually remove the groups from /etc/group on the clients so that nsswitch would then move past nss_files and into the SSSD, nss-ldap or other remote user database. == Solution == With this patch, a new action is introduced for nsswitch: NSS_ACTION_MERGE. To take advantage of it, one will add [SUCCESS=merge] between two database entries in the nsswitch.conf file. When a group is located in the first of the two group entries, processing will continue on to the next one. If the group is also found in the next entry (and the group name and GID are an exact match), the member list of the second entry will be added to the group object to be returned. == Implementation == After each DL_LOOKUP_FN() returns, the next action is checked. If the function returned NSS_STATUS_SUCCESS and the next action is NSS_ACTION_MERGE, a copy of the result buffer is saved for the next pass through the loop. If on this next pass through the loop the database returns another instance of a group matching both the group name and GID, the member list is added to the previous list and it is returned as a single object. If the following database does not contain the same group, then the original is copied back into the destination buffer. This patch implements merge functionality only for the group database. For other databases, there is a default implementation that will return the EINVAL errno if a merge is requested. The merge functionality can be implemented for other databases at a later time if such is needed. Each database must provide a unique implementation of the deep-copy and merge functions. If [SUCCESS=merge] is present in nsswitch.conf for a glibc version that does not support it, glibc will process results up until that operation, at which time it will return results if it has found them or else will simply return an error. In practical terms, this ends up behaving like the remainder of the nsswitch.conf line does not exist. == Iterators == This feature does not modify the iterator functionality from its current behavior. If getgrnam() or getgrgid() is called, glibc will iterate through all entries in the `group` line in nsswitch.conf and display the list of members without attempting to merge them. This is consistent with the behavior of nss_files where if two separate lines are specified for the same group in /etc/groups, getgrnam()/getgrgid() will display both. Clients are already expected to handle this gracefully. == No Premature Optimizations == The following is a list of places that might be eligible for optimization, but were not overengineered for this initial contribution: * Any situation where a merge may occur will result in one malloc() of the same size as the input buffer. * Any situation where a merge does occur will result in a second malloc() to hold the list of pointers to member name strings. * The list of members is simply concatenated together and is not tested for uniqueness (which is identical to the behavior for nss_files, which will simply return identical values if they both exist on the line in the file. This could potentially be optimized to reduce space usage in the buffer, but it is both complex and computationally expensive to do so. == Testing == I performed testing by running the getent utility against my newly-built glibc and configuring /etc/nsswitch.conf with the following entry: group: group: files [SUCCESS=merge] sss In /etc/group I included the line: wheel:x:10:sgallagh I then configured my local SSSD using the id_provider=local to respond with: wheel:*:10:localuser,localuser2 I then ran `getent group wheel` against the newly-built glibc in multiple situations and received the expected output as described above: * When SSSD was running. * When SSSD was configured in nsswitch.conf but the daemon was not running. * When SSSD was configured in nsswitch.conf but nss_sss.so.2 was not installed on the system. * When the order of 'sss' and 'files' was reversed. * All of the above with the [SUCCESS=merge] removed (to ensure no regressions). * All of the above with `getent group 10`. * All of the above with `getent group` with and without `enumerate=true` set in SSSD. * All of the above with and without nscd enabled on the system.
2016-04-30 02:11:09 +00:00
/* Copy the member array back into the buffer after the member list and free
the member array. */
savedgrp->gr_mem = (char **) &savedbuf[c];
len = sizeof (char *) * membersize;
BUFCHECK (len);
memcpy (&savedbuf[c], members, len);
c += len;
free (members);
members = NULL;
/* Finally, copy the results back into mergebuf, since that's the buffer
that we were provided by the caller. */
return __copy_grp (*savedgrp, buflen, mergegrp, mergebuf, NULL);
}
libc_hidden_def (__merge_grp)