+/* Wrapper around exec:
+ * Takes string (max COMMAND_SIZE chars).
+ * If chars like '>' detected, execs '[-]/bin/sh -c "exec ......."'.
+ * Otherwise splits words on whitespace, deals with leading dash,
+ * and uses plain exec().
+ * NB: careful, we can be called after vfork!
+ */
+static void init_exec(const char *command)
+{
+ char *cmd[COMMAND_SIZE / 2];
+ char buf[COMMAND_SIZE + 6]; /* COMMAND_SIZE+strlen("exec ")+1 */
+ int dash = (command[0] == '-' /* maybe? && command[1] == '/' */);
+
+ /* See if any special /bin/sh requiring characters are present */
+ if (strpbrk(command, "~`!$^&*()=|\\{}[];\"'<>?") != NULL) {
+ strcpy(buf, "exec ");
+ strcpy(buf + 5, command + dash); /* excluding "-" */
+ /* NB: LIBBB_DEFAULT_LOGIN_SHELL define has leading dash */
+ cmd[0] = (char*)(LIBBB_DEFAULT_LOGIN_SHELL + !dash);
+ cmd[1] = (char*)"-c";
+ cmd[2] = buf;
+ cmd[3] = NULL;
+ } else {
+ /* Convert command (char*) into cmd (char**, one word per string) */
+ char *word, *next;
+ int i = 0;
+ next = strcpy(buf, command); /* including "-" */
+ while ((word = strsep(&next, " \t")) != NULL) {
+ if (*word != '\0') { /* not two spaces/tabs together? */
+ cmd[i] = word;
+ i++;
+ }
+ }
+ cmd[i] = NULL;
+ }
+ /* If we saw leading "-", it is interactive shell.
+ * Try harder to give it a controlling tty.
+ * And skip "-" in actual exec call. */
+ if (dash) {
+ /* _Attempt_ to make stdin a controlling tty. */
+ if (ENABLE_FEATURE_INIT_SCTTY)
+ ioctl(STDIN_FILENO, TIOCSCTTY, 0 /*only try, don't steal*/);
+ }
+ BB_EXECVP(cmd[0] + dash, cmd);
+ message(L_LOG | L_CONSOLE, "cannot run '%s': %s", cmd[0], strerror(errno));
+ /* returns if execvp fails */
+}
+