lib/pwdutils: add xgetlogin()

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/include/pwdutils.h b/include/pwdutils.h
index c2967d31576919e4d6fd742a5e1976244e3a2d48..a69dd6b454273e1f0685afd44a83b2671e35ab02 100644 (file)
--- a/include/pwdutils.h
+++ b/include/pwdutils.h
@@ -5,6 +5,7 @@
 #include <pwd.h>
 
 extern struct passwd *xgetpwnam(const char *username, char **pwdbuf);
+extern char *xgetlogin(void);
 
 #endif /* UTIL_LINUX_PWDUTILS_H */
 

diff --git a/lib/pwdutils.c b/lib/pwdutils.c
index 58e75a45b94ce2f31391e9a686feb00f088b7904..25b4daed0e859ba695fd112fb47b9758e3f5ccdf 100644 (file)
--- a/lib/pwdutils.c
+++ b/lib/pwdutils.c
@@ -36,11 +36,39 @@ failed:
        return NULL;
 }
 
+char *xgetlogin(void)
+{
+       struct passwd *pw = NULL;
+       uid_t ruid;
+       char *user;
+
+       user = getlogin();
+       if (user)
+               return xstrdup(user);
+
+       /* GNU Hurd implementation has an extension where a process can exist in a
+        * non-conforming environment, and thus be outside the realms of POSIX
+        * process identifiers; on this platform, getuid() fails with a status of
+        * (uid_t)(-1) and sets errno if a program is run from a non-conforming
+        * environment.
+        *
+        * http://austingroupbugs.net/view.php?id=511
+        */
+       errno = 0;
+       ruid = getuid();
+
+       if (errno == 0)
+               pw = getpwuid(ruid);
+       if (pw && pw->pw_name && *pw->pw_name)
+               return xstrdup(pw->pw_name);
+
+       return NULL;
+}
 
 #ifdef TEST_PROGRAM
 int main(int argc, char *argv[])
 {
-       char *pwdbuf = NULL;
+       char *buf = NULL;
        struct passwd *pwd = NULL;
 
        if (argc != 2) {
@@ -48,7 +76,7 @@ int main(int argc, char *argv[])
                return EXIT_FAILURE;
        }
 
-       pwd = xgetpwnam(argv[1], &pwdbuf);
+       pwd = xgetpwnam(argv[1], &buf);
        if (!pwd)
                err(EXIT_FAILURE, "failed to get %s pwd entry", argv[1]);
 
@@ -58,7 +86,11 @@ int main(int argc, char *argv[])
        printf("GECO:     %s\n", pwd->pw_gecos);
 
        free(pwd);
-       free(pwdbuf);
+       free(buf);
+
+       printf("Current:  %s\n", (buf = xgetlogin()));
+       free(buf);
+
        return EXIT_SUCCESS;
 }
 #endif /* TEST_PROGRAM */