telnet: code shrink

function                                             old     new   delta
write_to_stdout                                      105     113      +8
put_iac                                               28      35      +7
write_to_net                                         596     598      +2
read_from_stdin                                      227     229      +2
read_from_net                                        543     534      -9
telnet_main                                          476     455     -21
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/2 up/down: 19/-30)            Total: -11 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 25 insertions, 21 deletions

diff --git a/networking/telnet.c b/networking/telnet.c
index 18a13860a..8a7803637 100644
--- a/networking/telnet.c
+++ b/networking/telnet.c
@@ -103,9 +103,6 @@ static char *bin_to_hex(const void *hash_value, unsigned hash_length)
 #endif
 
 enum {
-        BUFSIZE = 1024,
-        BUFMASK = BUFSIZE - 1,
-
         TS_NORMAL = 0,
         TS_IAC  = 1,
         TS_OPT  = 2,
@@ -114,31 +111,24 @@ enum {
         TS_CR   = 5,
 
         MAX_NAWS_SIZE = 13, /* pathological 65535x65535 case needs full escaping */
+
+        netfd   = 3,
 };
 
 typedef unsigned char byte;
 
-enum { netfd = 3 };
-
 typedef struct stdin_to_net {
         STRUCT_CONNECTION
         int rdidx, wridx, size;
-        byte buf[BUFSIZE];
+        //byte buf[BUFSIZE];
 } stdin_to_net_t;
-
 typedef struct net_to_stdout {
         STRUCT_CONNECTION
         int rdidx, wridx, size;
         byte input_state;
         byte negotiation_verb;
-        byte buf[BUFSIZE];
+        //byte buf[BUFSIZE];
 } net_to_stdout_t;
-
-static int remaining_free_bytes(int n)
-{
-        return BUFSIZE - n;
-}
-
 #if DEBUG
 static void set_input_state(net_to_stdout_t *conn, int new_state, int c)
 {
@@ -155,7 +145,9 @@ static void set_input_state(net_to_stdout_t *conn, int new_state, int c)
 
 struct globals {
         unsigned flags;
+/* Set when server agreed to use NAWS: */
 #define FLAGS_NAWS_ON  (1 << 0)
+/* SGA option seen and responded to, no longer look for it: */
 #define FLAGS_SGA_SEEN (1 << 1)
 /* Seen telnet protocol from server and sent our wishes: */
 #define INITIAL_SENT   (1 << 2)
@@ -183,12 +175,24 @@ struct globals {
         net_to_stdout_t conn_net2stdout;
         struct termios termios_def;
         struct termios termios_raw;
+// buf[] arrays in conn structs are conceptually cleaner, but they
+// make G.member offsets larger -> larger code
+#define BUF_TTY2NET ((byte*)bb_common_bufsiz1)
+#define BUF_NET2TTY G.buf2
+#define BUFSIZE     1024
+/* Note: can't just increase BUFSIZE arbitrarily: common bufsiz1 is not guaranteed to be >1k! */
+#define BUFMASK     (BUFSIZE - 1)
+        byte        buf2[BUFSIZE];
 } FIX_ALIASING;
 #define G (*ptr_to_globals)
 #define INIT_G() do { \
         SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
 } while (0)
 
+static int remaining_free_bytes(int n)
+{
+        return BUFSIZE - n;
+}
 
 #if ENABLE_FEATURE_TELNET_WIDTH
 static void handle_SIGWINCH(int sig UNUSED_PARAM)
@@ -221,7 +225,7 @@ static void put_iac(int c)
 {
         stdin_to_net_t *conn = &G.conn_stdin2net;
         /* Write directly to stdin2net buffer */
-        conn->buf[conn->rdidx] = c; /* "... & 0xff" is implicit */
+        BUF_TTY2NET[conn->rdidx] = c; /* "... & 0xff" is implicit */
         conn->rdidx = (conn->rdidx + 1) & BUFMASK;
         conn->size++;
 }
@@ -528,7 +532,7 @@ static int read_from_stdin(void *this)
         if (count == 0)
                 return 0;
 
-        start = conn->buf + conn->rdidx;
+        start = BUF_TTY2NET + conn->rdidx;
         count = safe_read(conn->read_fd, start, count);
         if (count <= 0) {
                 conn->read_fd = -1;
@@ -606,7 +610,7 @@ static int write_to_net(void *this)
                 handle_changes_in_options(conn); /* yes */
 
         count = MIN(BUFSIZE - conn->wridx, conn->size);
-        count = safe_write(conn->write_fd, conn->buf + conn->wridx, count);
+        count = safe_write(conn->write_fd, BUF_TTY2NET + conn->wridx, count);
         if (count <= 0) {
                 if (count < 0 && errno == EAGAIN)
                         return 0;
@@ -647,7 +651,7 @@ static int read_from_net(void *this)
         count = MIN(BUFSIZE - conn->rdidx, count); /* can't be zero */
 
         /* Read directly into circular buffer's linear fragment */
-        dst = conn->buf + conn->rdidx;
+        dst = BUF_NET2TTY + conn->rdidx;
         count = safe_read(conn->read_fd, dst, count);
         dbg("read_from_net bytes:%d input_state:%d %s",
                 count, conn->input_state, bin_to_hex(dst, count > 0 ? count : 0));
@@ -804,7 +808,7 @@ static int read_from_net(void *this)
         }
 
         /* Update circular buffer: only the compacted data */
-        count = dst - (conn->buf + conn->rdidx);
+        count = dst - (BUF_NET2TTY + conn->rdidx);
         conn->size += count;
         conn->rdidx = (conn->rdidx + count) & BUFMASK;
 
@@ -831,8 +835,8 @@ static int write_to_stdout(void *this)
         int wr = MIN(BUFSIZE - conn->wridx, conn->size);
         ssize_t count;
 
-        dbg("write_to_stdout: wr:%d %s", wr, bin_to_hex(conn->buf + conn->wridx, wr));
-        count = safe_write(conn->write_fd, conn->buf + conn->wridx, wr);
+        dbg("write_to_stdout: wr:%d %s", wr, bin_to_hex(BUF_NET2TTY + conn->wridx, wr));
+        count = safe_write(conn->write_fd, BUF_NET2TTY + conn->wridx, wr);
         if (count <= 0) {
                 if (count < 0 && errno == EAGAIN)
                         return 0;