Fake setgroups() and initgroups() implementation.

include/unistd.h

@@ -185,6 +185,7 @@ _PROTOTYPE( int devctl, (int ctl_req, int driver, int device, int style));
 /* For compatibility with other Unix systems */
 _PROTOTYPE( int getpagesize, (void)					);
 _PROTOTYPE( int setgroups, (int ngroups, const gid_t *gidset)		);
+_PROTOTYPE( int initgroups, (const char *name, gid_t basegid)		);
 
 #endif
 

lib/other/setgroups.c

@@ -4,12 +4,48 @@ setgroups.c
 
 #include <errno.h>
 #include <unistd.h>
+#include <string.h>
+#include <grp.h>
 
 int setgroups(int ngroups, const gid_t *gidset)
 {
-	/* Not implemented */
+	if(!gidset || ngroups > 1) {
+		/* Supplementary groups not implemented */
+		errno= EINVAL;
+		return -1;
+	}
 
-	errno= ENOSYS;
-	return -1;
+	if(ngroups == 1)
+		return setgid(gidset[0]);
+
+	return 0;
+}
+
+int initgroups(const char *name, gid_t basegid)
+{
+	struct group *gr;
+	int r, found = 0;
+	if((r = setgid(basegid)) < 0)
+		return r;
+
+	setgrent();
+	while (!found && (gr = getgrent()) != NULL) {
+		char **mem;
+		for(mem = gr->gr_mem; mem && *mem; mem++) {
+			if(!strcmp(name, *mem)) {
+				found = 1;
+				break;
+			}
+		}
+	}
+	endgrent();
+
+	/* Because supplemental groups aren't implemented, this call
+	 * should fail if the user is in any supplemental groups.
+	 */
+	if(found)
+		return EINVAL;
+
+	return 0;
 }