ftpd: reuse ls applet for LIST/NLST/STAT generation

function                                             old     new   delta
popen_ls                                               -     211    +211
ftpd_main                                           1760    1826     +66
handle_dir_common                                    199     228     +29
get_remote_transfer_fd                                89     104     +15
replace_char                                          30      34      +4
handle_upload_common                                 263     265      +2
bind_for_passive_mode                                129     121      -8
cmdio_write                                           84      62     -22
escape_text                                          166     136     -30
init_data_sock_params                                 81       -     -81
ftpdataio_dispose_transfer_fd                         87       -     -87
write_dirstats                                       149       -    -149
write_filestats                                      603       -    -603
------------------------------------------------------------------------------
(add/remove: 1/4 grow/shrink: 11/5 up/down: 384/-986)        Total: -602 bytes
   text    data     bss     dec     hex filename
 808804     476    7864  817144   c77f8 busybox_old
 808156     476    7864  816496   c7570 busybox_unstripped

1 files changed, 154 insertions, 246 deletions

diff --git a/networking/ftpd.c b/networking/ftpd.c
index e83066032..2a7d8006b 100644
--- a/networking/ftpd.c
+++ b/networking/ftpd.c
@@ -63,9 +63,24 @@
 #define STR1(s) #s
 #define STR(s) STR1(s)
 
+/* Convert a constant to 3-digit string, packed into uint32_t */
 enum {
-        OPT_v = (1 << 0),
-        OPT_w = (1 << 1),
+        /* Shift for Nth decimal digit */
+        SHIFT0 = 16 * BB_LITTLE_ENDIAN + 8 * BB_BIG_ENDIAN,
+        SHIFT1 =  8 * BB_LITTLE_ENDIAN + 16 * BB_BIG_ENDIAN,
+        SHIFT2 =  0 * BB_LITTLE_ENDIAN + 24 * BB_BIG_ENDIAN,
+};
+#define STRNUM32(s) (uint32_t)(0 \
+        | (('0' + ((s) / 1 % 10)) << SHIFT0) \
+        | (('0' + ((s) / 10 % 10)) << SHIFT1) \
+        | (('0' + ((s) / 100 % 10)) << SHIFT2) \
+)
+
+enum {
+        OPT_l = (1 << 0),
+        OPT_1 = (1 << 1),
+        OPT_v = (1 << 2),
+        OPT_w = (1 << 3),
 
 #define mk_const4(a,b,c,d) (((a * 0x100 + b) * 0x100 + c) * 0x100 + d)
 #define mk_const3(a,b,c)    ((a * 0x100 + b) * 0x100 + c)
@@ -106,78 +121,84 @@ struct globals {
         len_and_sockaddr *local_addr;
         len_and_sockaddr *port_addr;
         int pasv_listen_fd;
-        int data_fd;
+        int proc_self_fd;
         off_t restart_pos;
         char *ftp_cmd;
         char *ftp_arg;
 #if ENABLE_FEATURE_FTP_WRITE
         char *rnfr_filename;
 #endif
-        smallint opts;
 };
 #define G (*(struct globals*)&bb_common_bufsiz1)
 #define INIT_G() do { } while (0)
 
 
 static char *
-escape_text(const char *prepend, const char *str, char from, const char *to, char append)
+escape_text(const char *prepend, const char *str, unsigned escapee)
 {
-        size_t retlen, remainlen, chunklen, tolen;
-        const char *remain;
+        unsigned retlen, remainlen, chunklen;
         char *ret, *found;
+        char append;
 
-        remain = str;
-        remainlen = strlen(str);
-        tolen = strlen(to);
+        append = (char)escapee;
+        escapee >>= 8;
 
-        /* Simply alloc strlen(str)*strlen(to). "to" is max 2 so it's ok */
+        remainlen = strlen(str);
         retlen = strlen(prepend);
-        ret = xmalloc(retlen + remainlen * tolen + 1 + 1);
+        ret = xmalloc(retlen + remainlen * 2 + 1 + 1);
         strcpy(ret, prepend);
 
         for (;;) {
-                found = strchrnul(remain, from);
-                chunklen = found - remain;
+                found = strchrnul(str, escapee);
+                chunklen = found - str + 1;
 
-                /* Copy chunk which doesn't contain 'from' to ret */
-                memcpy(&ret[retlen], remain, chunklen);
+                /* Copy chunk up to and including escapee (or NUL) to ret */
+                memcpy(ret + retlen, str, chunklen);
                 retlen += chunklen;
 
-                if (*found != '\0') {
-                        /* Now copy 'to' instead of 'from' */
-                        memcpy(&ret[retlen], to, tolen);
-                        retlen += tolen;
-
-                        remain = found + 1;
-                } else {
-                        ret[retlen] = append;
-                        ret[retlen+1] = '\0';
+                if (*found == '\0') {
+                        /* It wasn't escapee, it was NUL! */
+                        ret[retlen - 1] = append; /* replace NUL */
+                        ret[retlen] = '\0'; /* add NUL */
                         break;
                 }
+                ret[retlen++] = escapee; /* duplicate escapee */
+                str = found + 1;
         }
         return ret;
 }
 
-static void
+/* Returns strlen as a bonus */
+static unsigned
 replace_char(char *str, char from, char to)
 {
-        while ((str = strchr(str, from)) != NULL)
-                *str++ = to;
+        char *p = str;
+        while (*p) {
+                if (*p == from)
+                        *p = to;
+                p++;
+        }
+        return p - str;
 }
 
 static void
-cmdio_write(unsigned status, const char *str)
+cmdio_write(uint32_t status_str, const char *str)
 {
+        union {
+                char buf[4];
+                uint32_t v32;
+        } u;
         char *response;
         int len;
 
+        u.v32 = status_str;
+
         /* FTP allegedly uses telnet protocol for command link.
          * In telnet, 0xff is an escape char, and needs to be escaped: */
-        response = escape_text(utoa(status), str, '\xff', "\xff\xff", '\r');
+        response = escape_text(u.buf, str, (0xff << 8) + '\r');
 
         /* ?! does FTP send embedded LFs as NULs? wow */
-        len = strlen(response);
-        replace_char(response, '\n', '\0');
+        len = replace_char(response, '\n', '\0');
 
         response[len++] = '\n'; /* tack on trailing '\n' */
         xwrite(STDOUT_FILENO, response, len);
@@ -215,9 +236,9 @@ handle_pwd(void)
                 cwd = xstrdup("");
 
         /* We have to promote each " to "" */
-        response = escape_text(" \"", cwd, '\"', "\"\"", '\"');
+        response = escape_text(" \"", cwd, ('"' << 8) + '"');
         free(cwd);
-        cmdio_write(FTP_PWDOK, response);
+        cmdio_write(STRNUM32(FTP_PWDOK), response);
         free(response);
 }
 
@@ -261,21 +282,6 @@ handle_help(void)
 
 /* Download commands */
 
-static void
-init_data_sock_params(int sock_fd)
-{
-        struct linger linger;
-
-        G.data_fd = sock_fd;
-
-        memset(&linger, 0, sizeof(linger));
-        linger.l_onoff = 1;
-        linger.l_linger = 32767;
-
-        setsockopt(sock_fd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
-        setsockopt(sock_fd, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
-}
-
 static int
 ftpdataio_get_pasv_fd(void)
 {
@@ -288,39 +294,10 @@ ftpdataio_get_pasv_fd(void)
                 return remote_fd;
         }
 
-        init_data_sock_params(remote_fd);
-        return remote_fd;
-}
-
-static int
-ftpdataio_get_port_fd(void)
-{
-        int remote_fd;
-
-        /* Do we want to die or print error to client? */
-        remote_fd = xconnect_stream(G.port_addr);
-
-        init_data_sock_params(remote_fd);
+        setsockopt(remote_fd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
         return remote_fd;
 }
 
-static void
-ftpdataio_dispose_transfer_fd(void)
-{
-        /* This close() blocks because we set SO_LINGER */
-        if (G.data_fd > STDOUT_FILENO) {
-                if (close(G.data_fd) < 0) {
-                        /* Do it again without blocking. */
-                        struct linger linger;
-
-                        memset(&linger, 0, sizeof(linger));
-                        setsockopt(G.data_fd, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
-                        close(G.data_fd);
-                }
-        }
-        G.data_fd = -1;
-}
-
 static inline int
 port_active(void)
 {
@@ -341,12 +318,12 @@ get_remote_transfer_fd(const char *p_status_msg)
         if (pasv_active())
                 remote_fd = ftpdataio_get_pasv_fd();
         else
-                remote_fd = ftpdataio_get_port_fd();
+                remote_fd = xconnect_stream(G.port_addr);
 
         if (remote_fd < 0)
                 return remote_fd;
 
-        cmdio_write(FTP_DATACONN, p_status_msg);
+        cmdio_write(STRNUM32(FTP_DATACONN), p_status_msg);
         return remote_fd;
 }
 
@@ -374,21 +351,21 @@ port_pasv_cleanup(void)
 static unsigned
 bind_for_passive_mode(void)
 {
+        int fd;
         unsigned port;
 
         port_pasv_cleanup();
 
-        G.pasv_listen_fd = xsocket(G.local_addr->u.sa.sa_family, SOCK_STREAM, 0);
-        setsockopt_reuseaddr(G.pasv_listen_fd);
+        G.pasv_listen_fd = fd = xsocket(G.local_addr->u.sa.sa_family, SOCK_STREAM, 0);
+        setsockopt_reuseaddr(fd);
 
         set_nport(G.local_addr, 0);
-        xbind(G.pasv_listen_fd, &G.local_addr->u.sa, G.local_addr->len);
-        xlisten(G.pasv_listen_fd, 1);
-        getsockname(G.pasv_listen_fd, &G.local_addr->u.sa, &G.local_addr->len);
+        xbind(fd, &G.local_addr->u.sa, G.local_addr->len);
+        xlisten(fd, 1);
+        getsockname(fd, &G.local_addr->u.sa, &G.local_addr->len);
 
         port = get_nport(&G.local_addr->u.sa);
         port = ntohs(port);
-
         return port;
 }
 
@@ -487,7 +464,7 @@ handle_retr(void)
         G.restart_pos = 0;
 
         if (!data_transfer_checks_ok())
-                return;
+                return; /* data_transfer_checks_ok emitted error response */
 
         /* O_NONBLOCK is useful if file happens to be a device node */
         opened_file = G.ftp_arg ? open(G.ftp_arg, O_RDONLY | O_NONBLOCK) : -1;
@@ -520,7 +497,7 @@ handle_retr(void)
                 goto port_pasv_cleanup_out;
 
         trans_ret = bb_copyfd_eof(opened_file, remote_fd);
-        ftpdataio_dispose_transfer_fd();
+        close(remote_fd);
         if (trans_ret < 0)
                 cmdio_write_error(FTP_BADSENDFILE);
         else
@@ -535,185 +512,105 @@ handle_retr(void)
 
 /* List commands */
 
-static char *
-statbuf_getperms(const struct stat *statbuf)
-{
-        char *perms;
-        enum { r = 'r', w = 'w', x = 'x', s = 's', S = 'S' };
-
-        perms = xmalloc(11);
-        memset(perms, '-', 10);
-
-        perms[0] = '?';
-        switch (statbuf->st_mode & S_IFMT) {
-        case S_IFREG: perms[0] = '-'; break;
-        case S_IFDIR: perms[0] = 'd'; break;
-        case S_IFLNK: perms[0] = 'l'; break;
-        case S_IFIFO: perms[0] = 'p'; break;
-        case S_IFSOCK: perms[0] = s; break;
-        case S_IFCHR: perms[0] = 'c'; break;
-        case S_IFBLK: perms[0] = 'b'; break;
-        }
-
-        if (statbuf->st_mode & S_IRUSR) perms[1] = r;
-        if (statbuf->st_mode & S_IWUSR) perms[2] = w;
-        if (statbuf->st_mode & S_IXUSR) perms[3] = x;
-        if (statbuf->st_mode & S_IRGRP) perms[4] = r;
-        if (statbuf->st_mode & S_IWGRP) perms[5] = w;
-        if (statbuf->st_mode & S_IXGRP) perms[6] = x;
-        if (statbuf->st_mode & S_IROTH) perms[7] = r;
-        if (statbuf->st_mode & S_IWOTH) perms[8] = w;
-        if (statbuf->st_mode & S_IXOTH) perms[9] = x;
-        if (statbuf->st_mode & S_ISUID) perms[3] = (perms[3] == x) ? s : S;
-        if (statbuf->st_mode & S_ISGID) perms[6] = (perms[6] == x) ? s : S;
-        if (statbuf->st_mode & S_ISVTX) perms[9] = (perms[9] == x) ? 't' : 'T';
-
-        perms[10] = '\0';
-
-        return perms;
-}
-
-static void
-write_filestats(int fd, const char *filename,
-                                const struct stat *statbuf)
-{
-        off_t size;
-        char *stats, *lnkname = NULL, *perms;
-        const char *name;
-        char timestr[32];
-        struct tm *tm;
-
-        name = bb_get_last_path_component_nostrip(filename);
-
-        if (statbuf != NULL) {
-                size = statbuf->st_size;
-
-                if (S_ISLNK(statbuf->st_mode))
-                        /* Damn symlink... */
-                        lnkname = xmalloc_readlink(filename);
-
-                tm = gmtime(&statbuf->st_mtime);
-                if (strftime(timestr, sizeof(timestr), "%b %d %H:%M", tm) == 0)
-                        bb_error_msg_and_die("strftime");
-
-                timestr[sizeof(timestr) - 1] = '\0';
-
-                perms = statbuf_getperms(statbuf);
-
-                stats = xasprintf("%s %u\tftp ftp %"OFF_FMT"u\t%s %s",
-                                perms, (int) statbuf->st_nlink,
-                                size, timestr, name);
-
-                free(perms);
-        } else
-                stats = xstrdup(name);
-
-        xwrite_str(fd, stats);
-        free(stats);
-        if (lnkname != NULL) {
-                xwrite_str(fd, " -> ");
-                xwrite_str(fd, lnkname);
-                free(lnkname);
-        }
-        xwrite_str(fd, "\r\n");
-}
-
-static void
-write_dirstats(int fd, const char *dname, int details)
+static int
+popen_ls(const char *opt)
 {
-        DIR *dir;
-        struct dirent *dirent;
-        struct stat statbuf;
-        char *filename;
-
-        dir = xopendir(dname);
+        char *cwd;
+        const char *argv[5] = { "ftpd", opt, NULL, G.ftp_arg, NULL };
+        struct fd_pair outfd;
+        pid_t pid;
 
-        for (;;) {
-                dirent = readdir(dir);
-                if (dirent == NULL)
-                        break;
+        cwd = xrealloc_getcwd_or_warn(NULL);
 
-                /* Ignore . and .. */
-                if (dirent->d_name[0] == '.') {
-                        if (dirent->d_name[1] == '\0'
-                         || (dirent->d_name[1] == '.' && dirent->d_name[2] == '\0')
-                        ) {
-                                continue;
-                        }
+        xpiped_pair(outfd);
+
+        fflush(NULL);
+        pid = vfork();
+
+        switch (pid) {
+        case -1:  /* failure */
+                bb_perror_msg_and_die("vfork");
+        case 0:  /* child */
+                /* NB: close _first_, then move fds! */
+                close(outfd.rd);
+                xmove_fd(outfd.wr, STDOUT_FILENO);
+                close(STDIN_FILENO);
+                /* xopen("/dev/null", O_RDONLY); - chroot may lack it! */
+                if (fchdir(G.proc_self_fd) == 0) {
+                        close(G.proc_self_fd);
+                        argv[2] = cwd;
+                        /* ftpd ls helper chdirs to argv[2],
+                         * preventing peer from seeing /proc/self
+                         */
+                        execv("exe", (char**) argv);
                 }
-
-                if (details) {
-                        filename = xasprintf("%s/%s", dname, dirent->d_name);
-                        if (lstat(filename, &statbuf) != 0) {
-                                free(filename);
-                                break;
-                        }
-                } else
-                        filename = xstrdup(dirent->d_name);
-
-                write_filestats(fd, filename, details ? &statbuf : NULL);
-                free(filename);
+                _exit(127);
         }
-
-        closedir(dir);
+        /* parent */
+        close(outfd.wr);
+        free(cwd);
+        return outfd.rd;
 }
 
 static void
-handle_dir_common(int full_details, int stat_cmd)
+handle_dir_common(int opts)
 {
-        int fd;
-        struct stat statbuf;
+        FILE *ls_fp;
+        char *line;
+        int ls_fd;
 
-        if (!stat_cmd && !data_transfer_checks_ok())
-                return;
+        if (!(opts & 1) && !data_transfer_checks_ok())
+                return; /* data_transfer_checks_ok emitted error response */
+
+        ls_fd = popen_ls((opts & 2) ? "-l" : "-1");
+        ls_fp = fdopen(ls_fd, "r");
+        if (!ls_fp) /* never happens. paranoia */
+                bb_perror_msg_and_die("fdopen");
 
-        if (stat_cmd) {
-                fd = STDIN_FILENO;
+        if (opts & 1) {
+                /* STAT <filename> */
                 cmdio_write_raw(STR(FTP_STATFILE_OK)"-Status follows:\r\n");
+                while (1) {
+                        line = xmalloc_fgetline(ls_fp);
+                        if (!line)
+                                break;
+                        cmdio_write(0, line); /* hack: 0 results in no status at all */
+                        free(line);
+                }
+                cmdio_write_ok(FTP_STATFILE_OK);
         } else {
-                fd = get_remote_transfer_fd(" Here comes the directory listing");
-                if (fd < 0)
-                        goto bail;
-        }
-
-        if (G.ftp_arg) {
-                if (lstat(G.ftp_arg, &statbuf) != 0) {
-                        /* Dir doesn't exist => return ok to client */
-                        goto bail;
+                /* LIST/NLST [<filename>] */
+                int remote_fd = get_remote_transfer_fd(" Here comes the directory listing");
+                if (remote_fd >= 0) {
+                        while (1) {
+                                line = xmalloc_fgetline(ls_fp);
+                                if (!line)
+                                        break;
+                                xwrite_str(remote_fd, line);
+                                xwrite(remote_fd, "\r\n", 2);
+                                free(line);
+                        }
                 }
-                if (S_ISREG(statbuf.st_mode) || S_ISLNK(statbuf.st_mode))
-                        write_filestats(fd, G.ftp_arg, &statbuf);
-                else if (S_ISDIR(statbuf.st_mode))
-                        write_dirstats(fd, G.ftp_arg, full_details);
-        } else
-                write_dirstats(fd, ".", full_details);
-
- bail:
-        /* Well, if we can't open directory/file it doesn't matter */
-        if (!stat_cmd) {
-                ftpdataio_dispose_transfer_fd();
+                close(remote_fd);
                 port_pasv_cleanup();
                 cmdio_write_ok(FTP_TRANSFEROK);
-        } else
-                cmdio_write_ok(FTP_STATFILE_OK);
+        }
+        fclose(ls_fp); /* closes ls_fd too */
 }
-
 static void
 handle_list(void)
 {
-        handle_dir_common(1, 0);
+        handle_dir_common(2);
 }
-
 static void
 handle_nlst(void)
 {
-        handle_dir_common(0, 0);
+        handle_dir_common(0);
 }
-
 static void
 handle_stat_file(void)
 {
-        handle_dir_common(1, 1);
+        handle_dir_common(3);
 }
 
 static void
@@ -840,7 +737,7 @@ handle_upload_common(int is_append, int is_unique)
                 goto bail;
 
         trans_ret = bb_copyfd_eof(remote_fd, local_file_fd);
-        ftpdataio_dispose_transfer_fd();
+        close(remote_fd);
 
         if (trans_ret < 0)
                 cmdio_write_error(FTP_BADSENDFILE);
@@ -905,8 +802,19 @@ cmdio_get_cmd_and_arg(void)
 }
 
 int ftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int ftpd_main(int argc UNUSED_PARAM, char **argv)
+int ftpd_main(int argc, char **argv)
 {
+        smallint opts;
+
+        opts = getopt32(argv, "l1v" USE_FEATURE_FTP_WRITE("w"));
+
+        if (opts & (OPT_l|OPT_1)) {
+                /* Our secret backdoor to ls */
+                xchdir(argv[2]);
+                argv[2] = (char*)"--";
+                return ls_main(argc, argv);
+        }
+
         INIT_G();
 
         G.local_addr = get_sock_lsa(STDIN_FILENO);
@@ -920,13 +828,13 @@ int ftpd_main(int argc UNUSED_PARAM, char **argv)
                  * failure */
         }
 
-        G.opts = getopt32(argv, "v" USE_FEATURE_FTP_WRITE("w"));
-
         openlog(applet_name, LOG_PID, LOG_DAEMON);
         logmode |= LOGMODE_SYSLOG;
-        if (!(G.opts & OPT_v))
+        if (!(opts & OPT_v))
                 logmode = LOGMODE_SYSLOG;
 
+        G.proc_self_fd = xopen("/proc/self", O_RDONLY | O_DIRECTORY);
+
         if (argv[optind]) {
                 xchdir(argv[optind]);
                 chroot(".");
@@ -1064,7 +972,7 @@ int ftpd_main(int argc UNUSED_PARAM, char **argv)
                 else if (cmdval == const_REST)
                         handle_rest();
 #if ENABLE_FEATURE_FTP_WRITE
-                else if (G.opts & OPT_w) {
+                else if (opts & OPT_w) {
                         if (cmdval == const_STOR)
                                 handle_stor();
                         else if (cmdval == const_MKD)