getgrouplist(3) for those without it

diff --git a/compat/getgrouplist.c b/compat/getgrouplist.c
new file mode 100644 (file)
index 0000000..c054fbd
--- /dev/null
+++ b/compat/getgrouplist.c
@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2010 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+#ifdef HAVE_STRING_H
+# include <string.h>
+#else
+# ifdef HAVE_STRINGS_H
+#  include <strings.h>
+# endif
+#endif /* HAVE_STRING_H */
+#include <grp.h>
+
+#include <compat.h>
+
+/*
+ * BSD-compatible getgrouplist(3) using getgrent(3)
+ */
+int
+getgrouplist(const char *name, gid_t basegid, gid_t *groups, int *ngroupsp)
+{
+    int i, ngroups = 1;
+    int grpsize = *ngroupsp;
+    int rval = -1;
+    struct group *grp;
+
+    /* We support BSD semantics where the first element is the base gid */
+    if (grpsize <= 0)
+       return -1;
+    groups[0] = basegid;
+
+    setgrent();
+    while ((grp = getgrent()) != NULL) {
+       if (grp->gr_gid == basegid)
+           continue;
+
+       for (i = 0; grp->gr_mem[i] != NULL; i++) {
+           if (strcmp(name, grp->gr_mem[i]) == 0)
+               break;
+       }
+       if (grp->gr_mem[i] == NULL)
+           continue; /* user not found */
+
+       /* Only add if it is not the same as an existing gid */
+       for (i = 0; i < ngroups; i++) {
+           if (grp->gr_gid == groups[i])
+               break;
+       }
+       if (i == ngroups) {
+           if (ngroups == grpsize)
+               goto done;
+           groups[ngroups++] = grp->gr_gid;
+       }
+    }
+    rval = 0;
+
+done:
+    endgrent();
+    *ngroupsp = ngroups;
+
+    return rval;
+}