ftp: reduce amount of realloc's done in cmdio_write

   text    data     bss     dec     hex filename
 808562     476    7864  816902   c7706 busybox_old
 808568     476    7864  816908   c770c busybox_unstripped

1 files changed, 20 insertions, 26 deletions

diff --git a/networking/ftpd.c b/networking/ftpd.c
index 4988ce02e..b2d6ef2d2 100644
--- a/networking/ftpd.c
+++ b/networking/ftpd.c
@@ -102,7 +102,7 @@ struct globals {
         int pasv_listen_fd;
         int data_fd;
         off_t restart_pos;
-        char *ftp_cmp;
+        char *ftp_cmd;
         char *ftp_arg;
 #if ENABLE_FEATURE_FTP_WRITE
         char *rnfr_filename;
@@ -112,8 +112,9 @@ struct globals {
 #define G (*(struct globals*)&bb_common_bufsiz1)
 #define INIT_G() do { } while (0)
 
+
 static char *
-replace_text(const char *str, const char from, const char *to)
+escape_text(const char *prepend, const char *str, char from, const char *to, char append)
 {
         size_t retlen, remainlen, chunklen, tolen;
         const char *remain;
@@ -124,29 +125,27 @@ replace_text(const char *str, const char from, const char *to)
         tolen = strlen(to);
 
         /* Simply alloc strlen(str)*strlen(to). "to" is max 2 so it's ok */
-        ret = xmalloc(remainlen * tolen + 1);
-        retlen = 0;
+        retlen = strlen(prepend);
+        ret = xmalloc(retlen + remainlen * tolen + 1 + 1);
+        strcpy(ret, prepend);
 
         for (;;) {
-                found = strchr(remain, from);
-                if (found != NULL) {
-                        chunklen = found - remain;
+                found = strchrnul(remain, from);
+                chunklen = found - remain;
 
-                        /* Copy chunk which doesn't contain 'from' to ret */
-                        memcpy(&ret[retlen], remain, chunklen);
-                        retlen += chunklen;
+                /* Copy chunk which doesn't contain 'from' to ret */
+                memcpy(&ret[retlen], remain, chunklen);
+                retlen += chunklen;
 
+                if (*found != '\0') {
                         /* Now copy 'to' instead of 'from' */
                         memcpy(&ret[retlen], to, tolen);
                         retlen += tolen;
 
                         remain = found + 1;
                 } else {
-                        /*
-                         * The last chunk. We are already sure that we have enough space
-                         * so we can use strcpy.
-                         */
-                        strcpy(&ret[retlen], remain);
+                        ret[retlen] = append;
+                        ret[retlen+1] = '\0';
                         break;
                 }
         }
@@ -163,15 +162,12 @@ replace_char(char *str, char from, char to)
 static void
 cmdio_write(unsigned status, const char *str)
 {
-        char *escaped_str, *response;
+        char *response;
         int len;
 
         /* FTP allegedly uses telnet protocol for command link.
          * In telnet, 0xff is an escape char, and needs to be escaped: */
-        escaped_str = replace_text(str, '\xff', "\xff\xff");
-
-        response = xasprintf("%u%s\r", status, escaped_str);
-        free(escaped_str);
+        response = escape_text(utoa(status), str, '\xff', "\xff\xff", '\r');
 
         /* ?! does FTP send embedded LFs as NULs? wow */
         len = strlen(response);
@@ -206,17 +202,15 @@ cmdio_write_raw(const char *p_text)
 static void
 handle_pwd(void)
 {
-        char *cwd, *promoted_cwd, *response;
+        char *cwd, *response;
 
         cwd = xrealloc_getcwd_or_warn(NULL);
         if (cwd == NULL)
                 cwd = xstrdup("");
 
         /* We have to promote each " to "" */
-        promoted_cwd = replace_text(cwd, '\"', "\"\"");
+        response = escape_text(" \"", cwd, '\"', "\"\"", '\"');
         free(cwd);
-        response = xasprintf(" \"%s\"", promoted_cwd);
-        free(promoted_cwd);
         cmdio_write(FTP_PWDOK, response);
         free(response);
 }
@@ -872,9 +866,9 @@ cmdio_get_cmd_and_arg(void)
         uint32_t cmdval;
         char *cmd;
 
-        free(G.ftp_cmp);
+        free(G.ftp_cmd);
         len = 8 * 1024; /* Paranoia. Peer may send 1 gigabyte long cmd... */
-        G.ftp_cmp = cmd = xmalloc_reads(STDIN_FILENO, NULL, &len);
+        G.ftp_cmd = cmd = xmalloc_reads(STDIN_FILENO, NULL, &len);
         if (!cmd)
                 exit(0);