libbb: add sketch of tentative 'better' passwd/group API

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/libbb/bb_pwd.c b/libbb/bb_pwd.c
index 4829b72..8250cd4 100644 (file)
--- a/libbb/bb_pwd.c
+++ b/libbb/bb_pwd.c
@@ -110,3 +110,51 @@ unsigned long FAST_FUNC get_ug_id(const char *s,
                return xname2id(s);
        return r;
 }
+
+/* Experimental "mallocing" API.
+ * The goal is nice: "we want to support a case when "guests" group is very large"
+ * but the code is butt-ugly.
+ */
+#if 0
+static char *find_latest(char last, char *cp)
+{
+       if (!cp)
+               return last;
+       cp += strlen(cp) + 1;
+       if (last < cp)
+               last = cp;
+       return last;
+}
+
+struct group* FAST_FUNC xmalloc_getgrnam(const char *name)
+{
+       struct {
+               struct group gr;
+               // May still be not enough!
+               char buf[64*1024 - sizeof(struct group) - 16];
+       } *s;
+       struct group *grp;
+       int r;
+       char *last;
+       char **gr_mem;
+
+       s = xmalloc(sizeof(*s));
+       r = getgrnam_r(name, &s->gr, s->buf, sizeof(s->buf), &grp);
+       if (!grp) {
+               free(s);
+               return grp;
+       }
+       last = find_latest(s->buf, grp->gr_name);
+       last = find_latest(last, grp->gr_passwd);
+       gr_mem = grp->gr_mem;
+       while (*gr_mem)
+               last = find_latest(last, *gr_mem++);
+       gr_mem++; /* points past NULL */
+       if (last < (char*)gr_mem)
+               last = (char*)gr_mem;
+//FIXME: what if we get not only truncated, but also moved here?
+// grp->gr_name pointer and friends are invalid now!!!
+       s = xrealloc(s, last - (char*)s);
+       return grp;
+}
+#endif