X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/e04c2d50fd96f3f31bc96851c55c6efecc10469c..844abf94571ffdd3e113c518947073ff5375d748:/common/util.c

diff --git a/common/util.c b/common/util.c
index c6c2b22c..78358b31 100644
--- a/common/util.c
+++ b/common/util.c
@@ -1,6 +1,4 @@
 /* -*-c-*-
- *
- * $Id: util.c,v 1.3 2004/04/08 01:36:17 mdw Exp $
  *
  * Utilities for the client and the server
  *
@@ -33,7 +31,14 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <pwd.h>
+#include <grp.h>
+
 #include <mLib/dstr.h>
+#include <mLib/report.h>
 
 #include "util.h"
 
@@ -67,4 +72,85 @@ void u_quotify(dstr *d, const char *p)
   }
 }
 
+/* --- @u_getuser@ --- *
+ *
+ * Arguments:	@const char *name@ = user name or id requested
+ *		@gid_t *gg@ = where to store corresponding gid
+ *
+ * Returns:	Corresponding uid.
+ *
+ * Use:		Resolves a user name into a uid.  Dies on failure; suitable
+ *		for use in argument parsing.
+ */
+
+uid_t u_getuser(const char *name, gid_t *gg)
+{
+  struct passwd *pw;
+  char *p;
+  unsigned long i = strtoul(name, &p, 0);
+
+  if (!*p)
+    pw = getpwuid(i);
+  else
+    pw = getpwnam(name);
+  if (!pw)
+    die(EXIT_FAILURE, "user `%s' not found", name);
+  if (gg && *gg == -1)
+    *gg = pw->pw_gid;
+  return (pw->pw_uid);
+}
+
+/* --- @u_getgroup@ --- *
+ *
+ * Arguments:	@const char *name@ = user name or id requested
+ *
+ * Returns:	Corresponding gid.
+ *
+ * Use:		Resolves a group name into a gid.  Dies on failure; suitable
+ *		for use in argument parsing.
+ */
+
+gid_t u_getgroup(const char *name)
+{
+  struct group *gr;
+  char *p;
+  unsigned long i = strtoul(name, &p, 0);
+
+  if (!*p)
+    gr = getgrgid(i);
+  else
+    gr = getgrnam(name);
+  if (!gr)
+    die(EXIT_FAILURE, "group `%s' not found", name);
+  return (gr->gr_gid);
+}
+
+/* --- @u_setugid@ --- *
+ *
+ * Arguments:	@uid_t u@ = user to set
+ *		@gid_t g@ = group to set
+ *
+ * Returns:	---
+ *
+ * Use:		Sets user and group to the given values; aborts on failure.
+ */
+
+void u_setugid(uid_t u, gid_t g)
+{
+  uid_t cu = geteuid();
+
+  if (cu == 0 && g != (gid_t)-1) {
+    if (setgid(g) || (getuid() == 0 && setgroups(1, &g))) {
+      die(EXIT_FAILURE, "couldn't setgid to %u: %s",
+	  (unsigned)g, strerror(errno));
+    }
+  }
+  if (u != (uid_t)-1) {
+    if (setuid(u)) {
+      die(EXIT_FAILURE, "couldn't setuid to %u: %s",
+	  (unsigned)u, strerror(errno));
+    }
+  }
+}
+
 /*----- That's all, folks -------------------------------------------------*/