libbb: rework NOMMU helper API so that it makes more sense
and easier to use. Doesn't compile - need two more commits.
This commit is contained in:
Denis Vlasenko
parent
f62c6fa1ca
commit
bb7fcb4229
@ -263,17 +263,9 @@ char *xrealloc_getcwd_or_warn(char *cwd);
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char *xmalloc_readlink_or_warn(const char *path);
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char *xmalloc_realpath(const char *path);
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extern void xstat(const char *filename, struct stat *buf);
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extern pid_t spawn(char **argv);
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extern pid_t xspawn(char **argv);
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extern int wait4pid(int pid);
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extern void xsetgid(gid_t gid);
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extern void xsetuid(uid_t uid);
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extern void xdaemon(int nochdir, int noclose);
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/* More clever/thorough xdaemon */
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extern void bb_sanitize_stdio_maybe_daemonize(int daemonize);
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extern void bb_sanitize_stdio(void);
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/* NB: be careful: dont open syslog/network sockets before bb_daemonize */
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extern void bb_daemonize(void);
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extern void xchdir(const char *path);
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extern void xsetenv(const char *key, const char *value);
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extern int xopen(const char *pathname, int flags);
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@ -460,6 +452,62 @@ void clear_username_cache(void);
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enum { USERNAME_MAX_SIZE = 16 - sizeof(int) };
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int execable_file(const char *name);
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char *find_execable(const char *filename);
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int exists_execable(const char *filename);
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#if ENABLE_FEATURE_EXEC_PREFER_APPLETS
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int bb_execvp(const char *file, char *const argv[]);
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#define BB_EXECVP(prog,cmd) bb_execvp(prog,cmd)
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#define BB_EXECLP(prog,cmd,...) \
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execlp((find_applet_by_name(prog)) ? CONFIG_BUSYBOX_EXEC_PATH : prog, \
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cmd, __VA_ARGS__)
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#else
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#define BB_EXECVP(prog,cmd) execvp(prog,cmd)
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#define BB_EXECLP(prog,cmd,...) execlp(prog,cmd, __VA_ARGS__)
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#endif
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/* NOMMU friendy fork+exec */
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pid_t spawn(char **argv);
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pid_t xspawn(char **argv);
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/* Helpers for daemonization.
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* bb_daemonize(flags) = daemonize, does not compile on NOMMU
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* bb_daemonize_or_rexec(flags, argv) = daemonizes on MMU (and ignores argv),
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* rexec's itself on NOMMU with argv passed as command line.
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* Thus bb_daemonize_or_rexec may cause your <applet>_main() to be re-executed
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* from the start. (It will detect it and not reexec again second time).
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* You have to audit carefully that you don't do something twice as a result
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* (opening files/sockets, parsing config files etc...)!
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*
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* Both of the above will redirect fd 0,1,2 to /dev/null and drop ctty
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* (will do setsid()).
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*
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* Helper for network daemons in foreground mode:
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* bb_sanitize_stdio() = make sure that fd 0,1,2 are opened by opening them
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* to /dev/null if they are not.
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*/
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enum {
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DAEMON_CHDIR_ROOT = 1,
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DAEMON_DEVNULL_STDIO = /* 2 */ 0, /* no users so far */
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DAEMON_CLOSE_EXTRA_FDS = 4,
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DAEMON_ONLY_SANITIZE = 8, /* internal use */
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};
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#ifndef BB_NOMMU
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#define bb_daemonize_or_rexec(flags, argv) bb_daemonize_or_rexec(flags)
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#define bb_daemonize(flags) bb_daemonize_or_rexec(flags, bogus)
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#else
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extern smallint re_execed;
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pid_t BUG_fork_is_unavailable_on_nommu(void);
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pid_t BUG_daemon_is_unavailable_on_nommu(void);
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pid_t BUG_bb_daemonize_is_unavailable_on_nommu(void);
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#define fork() BUG_fork_is_unavailable_on_nommu()
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#define daemon(a,b) BUG_daemon_is_unavailable_on_nommu()
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#define bb_daemonize(a) BUG_bb_daemonize_is_unavailable_on_nommu()
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#endif
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void bb_daemonize_or_rexec(int flags, char **argv);
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void bb_sanitize_stdio(void);
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enum { BB_GETOPT_ERROR = 0x80000000 };
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extern const char *opt_complementary;
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#if ENABLE_GETOPT_LONG
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@ -569,20 +617,6 @@ char *concat_path_file(const char *path, const char *filename);
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char *concat_subpath_file(const char *path, const char *filename);
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char *last_char_is(const char *s, int c);
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int execable_file(const char *name);
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char *find_execable(const char *filename);
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int exists_execable(const char *filename);
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#if ENABLE_FEATURE_EXEC_PREFER_APPLETS
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int bb_execvp(const char *file, char *const argv[]);
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#define BB_EXECVP(prog,cmd) bb_execvp(prog,cmd)
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#define BB_EXECLP(prog,cmd,...) \
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execlp((find_applet_by_name(prog)) ? CONFIG_BUSYBOX_EXEC_PATH : prog, \
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cmd, __VA_ARGS__)
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#else
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#define BB_EXECVP(prog,cmd) execvp(prog,cmd)
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#define BB_EXECLP(prog,cmd,...) execlp(prog,cmd, __VA_ARGS__)
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#endif
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USE_DESKTOP(long long) int uncompress(int fd_in, int fd_out);
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int inflate(int in, int out);
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@ -617,12 +651,8 @@ extern int index_in_str_array(const char * const string_array[], const char *key
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extern int index_in_substr_array(const char * const string_array[], const char *key);
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extern void print_login_issue(const char *issue_file, const char *tty);
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extern void print_login_prompt(void);
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#ifdef BB_NOMMU
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extern pid_t BUG_fork_is_unavailable_on_nommu(void);
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#define fork() BUG_fork_is_unavailable_on_nommu()
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extern void vfork_daemon_rexec(int nochdir, int noclose, char **argv);
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extern smallint re_execed;
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#endif
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extern int get_terminal_width_height(const int fd, int *width, int *height);
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char *is_in_ino_dev_hashtable(const struct stat *statbuf);
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@ -18,11 +18,68 @@
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#include <paths.h>
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#include "libbb.h"
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#ifdef BB_NOMMU
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/* This does a fork/exec in one call, using vfork(). Returns PID of new child,
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* -1 for failure. Runs argv[0], searching path if that has no / in it. */
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pid_t spawn(char **argv)
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{
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/* Compiler should not optimize stores here */
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volatile int failed;
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pid_t pid;
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// Be nice to nommu machines.
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failed = 0;
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pid = vfork();
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if (pid < 0) /* error */
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return pid;
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if (!pid) { /* child */
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/* Don't use BB_EXECVP tricks here! */
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execvp(argv[0], argv);
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/* We are (maybe) sharing a stack with blocked parent,
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* let parent know we failed and then exit to unblock parent
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* (but don't run atexit() stuff, which would screw up parent.)
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*/
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failed = errno;
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_exit(0);
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}
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/* parent */
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/* Unfortunately, this is not reliable: vfork()
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* can be equivalent to fork() according to standards */
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if (failed) {
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errno = failed;
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return -1;
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}
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return pid;
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}
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/* Die with an error message if we can't spawn a child process. */
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pid_t xspawn(char **argv)
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{
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pid_t pid = spawn(argv);
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if (pid < 0) bb_perror_msg_and_die("%s", *argv);
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return pid;
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}
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#if 0 //ndef BB_NOMMU
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// Die with an error message if we can't daemonize.
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void xdaemon(int nochdir, int noclose)
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{
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if (daemon(nochdir, noclose))
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bb_perror_msg_and_die("daemon");
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}
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#endif
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#if 0 // def BB_NOMMU
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void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
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{
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int fd;
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/* Maybe we are already re-execed and come here again? */
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if (re_execed)
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return;
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setsid();
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if (!nochdir)
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@ -56,3 +113,78 @@ void vfork_daemon_rexec(int nochdir, int noclose, char **argv)
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}
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}
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#endif /* BB_NOMMU */
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#ifdef BB_NOMMU
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static void daemon_or_rexec(char **argv)
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{
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pid_t pid;
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/* Maybe we are already re-execed and come here again? */
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if (re_execed)
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return;
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pid = vfork();
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if (pid < 0) /* wtf? */
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bb_perror_msg_and_die("vfork");
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if (pid) /* parent */
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exit(0);
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/* child - re-exec ourself */
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/* high-order bit of first char in argv[0] is a hidden
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* "we have (alrealy) re-execed, don't do it again" flag */
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argv[0][0] |= 0x80;
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execv(CONFIG_BUSYBOX_EXEC_PATH, argv);
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bb_perror_msg_and_die("exec %s", CONFIG_BUSYBOX_EXEC_PATH);
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}
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#else
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static void daemon_or_rexec(void)
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{
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pid_t pid;
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pid = fork();
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if (pid < 0) /* wtf? */
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bb_perror_msg_and_die("fork");
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if (pid) /* parent */
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exit(0);
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/* child */
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}
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#define daemon_or_rexec(argv) daemon_or_rexec()
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#endif
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/* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
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* char **argv "vanishes" */
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void bb_daemonize_or_rexec(int flags, char **argv)
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{
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int fd;
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fd = xopen(bb_dev_null, O_RDWR);
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if (flags & DAEMON_CHDIR_ROOT)
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xchdir("/");
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if (flags & DAEMON_DEVNULL_STDIO) {
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close(0);
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close(1);
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close(2);
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}
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while ((unsigned)fd < 2)
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fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
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if (!(flags & DAEMON_ONLY_SANITIZE)) {
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daemon_or_rexec(argv);
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/* if daemonizing, make sure we detach from stdio */
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setsid();
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dup2(fd, 0);
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dup2(fd, 1);
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dup2(fd, 2);
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}
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if (fd > 2)
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close(fd--);
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if (flags & DAEMON_CLOSE_EXTRA_FDS)
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while (fd > 2)
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close(fd--); /* close everything after fd#2 */
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}
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void bb_sanitize_stdio(void)
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{
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bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);
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}
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@ -187,43 +187,6 @@ void xfflush_stdout(void)
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}
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}
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// This does a fork/exec in one call, using vfork(). Return PID of new child,
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// -1 for failure. Runs argv[0], searching path if that has no / in it.
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pid_t spawn(char **argv)
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{
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/* Why static? */
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static int failed;
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pid_t pid;
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// Be nice to nommu machines.
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failed = 0;
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pid = vfork();
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if (pid < 0) return pid;
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if (!pid) {
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BB_EXECVP(argv[0], argv);
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// We're sharing a stack with blocked parent, let parent know we failed
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// and then exit to unblock parent (but don't run atexit() stuff, which
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// would screw up parent.)
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failed = errno;
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_exit(0);
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}
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if (failed) {
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errno = failed;
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return -1;
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}
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return pid;
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}
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// Die with an error message if we can't spawn a child process.
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pid_t xspawn(char **argv)
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{
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pid_t pid = spawn(argv);
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if (pid < 0) bb_perror_msg_and_die("%s", *argv);
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return pid;
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}
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// Wait for the specified child PID to exit, returning child's error return.
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int wait4pid(int pid)
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{
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@ -510,47 +473,6 @@ DIR *xopendir(const char *path)
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return dp;
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}
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#ifndef BB_NOMMU
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// Die with an error message if we can't daemonize.
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void xdaemon(int nochdir, int noclose)
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{
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if (daemon(nochdir, noclose))
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bb_perror_msg_and_die("daemon");
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}
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#endif
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void bb_sanitize_stdio_maybe_daemonize(int daemonize)
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{
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int fd;
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/* Mega-paranoid */
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fd = xopen(bb_dev_null, O_RDWR);
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while ((unsigned)fd < 2)
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fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
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if (daemonize) {
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pid_t pid = fork();
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if (pid < 0) /* wtf? */
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bb_perror_msg_and_die("fork");
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if (pid) /* parent */
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exit(0);
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/* child */
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/* if daemonizing, make sure we detach from stdio */
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setsid();
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dup2(fd, 0);
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dup2(fd, 1);
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dup2(fd, 2);
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}
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while (fd > 2)
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close(fd--); /* close everything after fd#2 */
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}
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void bb_sanitize_stdio(void)
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{
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bb_sanitize_stdio_maybe_daemonize(0);
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}
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void bb_daemonize(void)
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{
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bb_sanitize_stdio_maybe_daemonize(1);
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}
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// Die with an error message if we can't open a new socket.
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int xsocket(int domain, int type, int protocol)
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{
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