libcsupport: Implement getgroups()

1 files changed, 54 insertions, 3 deletions

diff --git a/cpukit/libcsupport/src/getgroups.c b/cpukit/libcsupport/src/getgroups.c
index 6bf58a70fe..73a42cee1f 100644
--- a/cpukit/libcsupport/src/getgroups.c
+++ b/cpukit/libcsupport/src/getgroups.c
@@ -10,15 +10,66 @@
 #endif
 
 #include <sys/types.h>
+#include <grp.h>
+#include <pwd.h>
+#include <string.h>
 #include <unistd.h>
 
+#include <rtems/seterr.h>
+
 /**
  *  4.2.3 Get Supplementary IDs, P1003.1b-1993, p. 86
  */
 int getgroups(
-  int    gidsetsize __attribute__((unused)),
-  gid_t  grouplist[] __attribute__((unused))
+  int    gidsetsize,
+  gid_t  grouplist[]
 )
 {
-  return 0;  /* no supplemental group ids */
+  int rv;
+  struct passwd pwd;
+  struct passwd *pwd_res;
+  char buf[256];
+  gid_t gid;
+  const char *user;
+  struct group *grp;
+
+  rv = getpwuid_r(getuid(), &pwd, &buf[0], sizeof(buf), &pwd_res);
+  if (rv != 0) {
+    return rv;
+  }
+
+  gid = pwd.pw_gid;
+  user = pwd.pw_name;
+
+  setgrent();
+
+  while ((grp = getgrent()) != NULL) {
+    char **mem = &grp->gr_mem[0];
+
+    if (grp->gr_gid == gid) {
+      continue;
+    }
+
+    while (*mem != NULL) {
+      if (strcmp(*mem, user) == 0) {
+        if (rv < gidsetsize) {
+          grouplist[rv] = grp->gr_gid;
+        }
+
+        ++rv;
+
+        break;
+      }
+
+      ++mem;
+    }
+  }
+
+  endgrent();
+
+  if (gidsetsize == 0 || rv <= gidsetsize) {
+    return rv;
+  } else {
+    rtems_set_errno_and_return_minus_one(EINVAL);
+  }
 }