From: Lennart Poettering <lennart@poettering.net>
Date: Sat, 30 Dec 2017 13:02:36 +0000 (+0100)
Subject: socket-util: add new getpeergroups() call
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=dfecc42944e40ab1763b16ed5ef54e8a88fb3590;p=elogind.git

socket-util: add new getpeergroups() call

It's a wrapper around the new SO_PEERGROUPS sockopt, similar in style as
getpeersec() and getpeercred().
---

diff --git a/src/basic/missing.h b/src/basic/missing.h
index 5aafa390f..536fd1114 100644
--- a/src/basic/missing.h
+++ b/src/basic/missing.h
@@ -626,6 +626,10 @@ struct btrfs_ioctl_quota_ctl_args {
 #  define SO_REUSEPORT 15
 #endif
 
+#ifndef SO_PEERGROUPS
+#  define SO_PEERGROUPS 59
+#endif
+
 #ifndef EVIOCREVOKE
 #  define EVIOCREVOKE _IOW('E', 0x91, int)
 #endif
diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
index 5969aa761..ea4647776 100644
--- a/src/basic/socket-util.c
+++ b/src/basic/socket-util.c
@@ -1027,6 +1027,39 @@ int getpeersec(int fd, char **ret) {
         return 0;
 }
 
+int getpeergroups(int fd, gid_t **ret) {
+        socklen_t n = sizeof(gid_t) * 64;
+        _cleanup_free_ gid_t *d = NULL;
+
+        assert(fd);
+        assert(ret);
+
+        for (;;) {
+                d = malloc(n);
+                if (!d)
+                        return -ENOMEM;
+
+                if (getsockopt(fd, SOL_SOCKET, SO_PEERGROUPS, d, &n) >= 0)
+                        break;
+
+                if (errno != ERANGE)
+                        return -errno;
+
+                d = mfree(d);
+        }
+
+        assert_se(n % sizeof(gid_t) == 0);
+        n /= sizeof(gid_t);
+
+        if ((socklen_t) (int) n != n)
+                return -E2BIG;
+
+        *ret = d;
+        d = NULL;
+
+        return (int) n;
+}
+
 int send_one_fd_sa(
                 int transport_fd,
                 int fd,
diff --git a/src/basic/socket-util.h b/src/basic/socket-util.h
index 368e6a6dd..c9c3e1f6e 100644
--- a/src/basic/socket-util.h
+++ b/src/basic/socket-util.h
@@ -144,6 +144,7 @@ bool address_label_valid(const char *p);
 
 int getpeercred(int fd, struct ucred *ucred);
 int getpeersec(int fd, char **ret);
+int getpeergroups(int fd, gid_t **ret);
 
 int send_one_fd_sa(int transport_fd,
                    int fd,