Improve execsh() and don't allow anonymous shells

This patch improves the shell selection on execsh and forbid
shell with users don't registered in the passwd file.

diff --git a/st.c b/st.c
index 1c998ec65f37f948475a39022c39f0899eff8452..009388c01d7ed9c453e672494eca90be2d3938f7 100644 (file)
--- a/st.c
+++ b/st.c
@@ -1139,23 +1139,29 @@ die(const char *errstr, ...) {
 
 void
 execsh(void) {
-       char **args;
-       char *envshell = getenv("SHELL");
-       const struct passwd *pass = getpwuid(getuid());
+       char **args, *sh;
+       const struct passwd *pw;
        char buf[sizeof(long) * 8 + 1];
 
+       errno = 0;
+       if((pw = getpwuid(getuid())) == NULL) {
+               if(errno)
+                       die("getpwuid:%s\n", strerror(errno));
+               else
+                       die("who are you?\n");
+       }
        unsetenv("COLUMNS");
        unsetenv("LINES");
        unsetenv("TERMCAP");
 
-       if(pass) {
-               setenv("LOGNAME", pass->pw_name, 1);
-               setenv("USER", pass->pw_name, 1);
-               setenv("SHELL", pass->pw_shell, 0);
-               setenv("HOME", pass->pw_dir, 0);
-       }
-
+       sh = (pw->pw_shell[0]) ? pw->pw_shell : shell;
        snprintf(buf, sizeof(buf), "%lu", xw.win);
+
+       setenv("LOGNAME", pw->pw_name, 1);
+       setenv("USER", pw->pw_name, 1);
+       setenv("SHELL", sh, 1);
+       setenv("HOME", pw->pw_dir, 1);
+       setenv("TERM", termname, 1);
        setenv("WINDOWID", buf, 1);
 
        signal(SIGCHLD, SIG_DFL);
@@ -1165,9 +1171,7 @@ execsh(void) {
        signal(SIGTERM, SIG_DFL);
        signal(SIGALRM, SIG_DFL);
 
-       DEFAULT(envshell, shell);
-       setenv("TERM", termname, 1);
-       args = opt_cmd ? opt_cmd : (char *[]){envshell, "-i", NULL};
+       args = opt_cmd ? opt_cmd : (char *[]){sh, "-i", NULL};
        execvp(args[0], args);
        exit(EXIT_FAILURE);
 }