1 files changed, 77 insertions, 0 deletions
diff --git a/toys/pending/chsh.c b/toys/pending/chsh.c
new file mode 100644
index 00000000..bf409783
--- /dev/null
+++ b/toys/pending/chsh.c
@@ -0,0 +1,77 @@
+/* chsh.c - Change login shell.
+ *
+ * Copyright 2021 Michael Christensen
+ *
+ * See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/chsh.html
+
+USE_CHSH(NEWTOY(chsh, "s:", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_STAYROOT))
+
+config CHSH
+  bool "chsh"
+  default y
+  help
+    usage: chsh [-s SHELL] [USER]
+
+    Change user's login shell.
+
+    -s	Use SHELL instead of prompting
+
+    Non-root users can only change their own shell to one listed in /etc/shells.
+*/
+
+#define FOR_chsh
+#include "toys.h"
+
+GLOBALS(
+  char *s;
+)
+
+void chsh_main()
+{
+  FILE *file;
+  char *user, *line, *shell, *encrypted;
+  struct passwd *passwd_info;
+  struct spwd *shadow_info;
+
+  // Get uid user information, may be discarded later
+
+  if ((user = *toys.optargs)) {
+    passwd_info = xgetpwnam(user);
+    if (geteuid() && strcmp(passwd_info->pw_name, user))
+      error_exit("Permission denied\n");
+  } else {
+    passwd_info = xgetpwuid(getuid());
+    user = passwd_info->pw_name;
+  }
+
+  // Get a password, encrypt it, wipe it, and check it
+  if (mlock(toybuf, sizeof(toybuf))) perror_exit("mlock");
+  if (!(shadow_info = getspnam(passwd_info->pw_name))) perror_exit("getspnam");
+  if (read_password(toybuf, sizeof(toybuf), "Password: ")) perror_exit("woaj"); //xexit();
+  if (!(encrypted = crypt(toybuf, shadow_info->sp_pwdp))) perror_exit("crypt");
+  memset(toybuf, 0, sizeof(toybuf));
+  munlock(toybuf, sizeof(toybuf)); // prevents memset from "optimizing" away.
+  if (strcmp(encrypted, shadow_info->sp_pwdp)) perror_exit("Bad password");
+
+  // Get new shell (either -s or interactive)
+  file = xfopen("/etc/shells", "r");
+  if (toys.optflags) shell = TT.s;
+  else {
+    xprintf("Changing the login shell for %s\n"
+            "Enter the new value, or press ENTER for default\n"
+            "    Login shell [%s]: ", user, passwd_info->pw_shell);
+    if (!(shell = xgetline(stdin))) xexit();
+  }
+
+  // Verify supplied shell in /etc/shells, or get default shell
+  if (strlen(shell))
+    while ((line = xgetline(file)) && strcmp(shell, line)) free(line);
+  else do line = xgetline(file); while (line && *line != '/');
+  if (!line) error_exit("Shell not found in '/etc/shells'");
+
+  // Update /etc/passwd
+  passwd_info->pw_shell = line;
+  if (-1 == update_password("/etc/passwd", user, NULL)) perror_exit("Failed to remove passwd entry");
+  file = xfopen("/etc/passwd", "a");
+  if (putpwent(passwd_info, file)) perror_exit("putwent");
+}