hexedit: restore screen on exit

function                                             old     new   delta
hexedit_main                                         998    1082     +84
restore_term                                           -      29     +29
remap                                                168     173      +5
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 118/0)             Total: 118 bytes

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

2 files changed, 53 insertions, 28 deletions

diff --git a/miscutils/hexedit.c b/miscutils/hexedit.c
index e8bc73b7e..b8627e826 100644
--- a/miscutils/hexedit.c
+++ b/miscutils/hexedit.c
@@ -15,19 +15,28 @@
 
 #include "libbb.h"
 
-#define ESC     "\033"
-#define HOME    ESC"[H"
-#define CLEAR   ESC"[H"ESC"[J"
+#define ESC             "\033"
+#define HOME            ESC"[H"
+#define CLEAR           ESC"[H"ESC"[J"
+#define SET_ALT_SCR     ESC"[?1049h"
+#define POP_ALT_SCR     ESC"[?1049l"
+
+#undef CTRL
+#define CTRL(c)  ((c) & (uint8_t)~0x60)
 
 struct globals {
         smallint half;
+        smallint in_read_key;
         int fd;
         unsigned height;
+        unsigned row;
         uint8_t *addr;
         uint8_t *current_byte;
         uint8_t *eof_byte;
         off_t size;
         off_t offset;
+        /* needs to be zero-inited, thus keeping it in G: */
+        char read_key_buffer[KEYCODE_BUFFER_SIZE];
         struct termios orig_termios;
 };
 #define G (*ptr_to_globals)
@@ -41,6 +50,24 @@ struct globals {
 /* "12ef5670 (xx )*16 _1_3_5_7_9abcdef\n"NUL */
 #define LINEBUF_SIZE (8 + 1 + 3*16 + 16 + 1 + 1 /*paranoia:*/ + 13)
 
+static void restore_term(void)
+{
+        tcsetattr_stdin_TCSANOW(&G.orig_termios);
+        printf(POP_ALT_SCR);
+        fflush_all();
+}
+
+static void sig_catcher(int sig)
+{
+        if (!G.in_read_key) {
+                /* now it's not safe to do I/O, just inform the main loop */
+                bb_got_signal = sig;
+                return;
+        }
+        restore_term();
+        kill_myself_with_sig(sig);
+}
+
 static int format_line(char *hex, uint8_t *data, off_t offset)
 {
         int ofs_pos;
@@ -141,9 +168,10 @@ static void remap(unsigned cur_pos)
                 G.fd,
                 G.offset
         );
-        if (G.addr == MAP_FAILED)
-//TODO: restore termios?
+        if (G.addr == MAP_FAILED) {
+                restore_term();
                 bb_perror_msg_and_die("mmap");
+        }
 
         G.current_byte = G.addr + cur_pos;
 
@@ -201,12 +229,6 @@ static void move_mapping_lower(void)
         remap(pos);
 }
 
-static void sig_catcher(int sig)
-{
-        tcsetattr_stdin_TCSANOW(&G.orig_termios);
-        kill_myself_with_sig(sig);
-}
-
 //usage:#define hexedit_trivial_usage
 //usage:        "FILE"
 //usage:#define hexedit_full_usage "\n\n"
@@ -214,8 +236,6 @@ static void sig_catcher(int sig)
 int hexedit_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int hexedit_main(int argc UNUSED_PARAM, char **argv)
 {
-        unsigned row = 0;
-
         INIT_G();
 
         get_terminal_width_height(-1, NULL, &G.height);
@@ -237,7 +257,7 @@ int hexedit_main(int argc UNUSED_PARAM, char **argv)
 
         remap(0);
 
-        printf(CLEAR);
+        printf(SET_ALT_SCR);
         redraw();
         printf(ESC"[1;10H"); /* position on 1st hex byte in first line */
 
@@ -245,21 +265,22 @@ int hexedit_main(int argc UNUSED_PARAM, char **argv)
         //Backspace: undo
         //Enter: goto specified position
         //Ctrl-L: redraw
-        //Ctrl-X: save and exit (maybe also Q?)
         //Ctrl-Z: suspend
         //'/', Ctrl-S: search
-//TODO: go to end-of-screen on exit (for this, sighandler should interrupt read_key())
 //TODO: detect window resize
-//TODO: read-only mode if open(O_RDWR) fails? hide cursor in this case?
 
         for (;;) {
-                char read_key_buffer[KEYCODE_BUFFER_SIZE];
                 unsigned cnt;
-                int32_t key;
+                int32_t key = key; // for compiler
                 uint8_t byte;
 
                 fflush_all();
-                key = read_key(STDIN_FILENO, read_key_buffer, -1);
+                G.in_read_key = 1;
+                if (!bb_got_signal)
+                        key = read_key(STDIN_FILENO, G.read_key_buffer, -1);
+                G.in_read_key = 0;
+                if (bb_got_signal)
+                        key = CTRL('X');
 
                 cnt = 1;
                 switch (key) {
@@ -329,9 +350,9 @@ int hexedit_main(int argc UNUSED_PARAM, char **argv)
                         }
  down:
                         putchar('\n'); /* down one line, possibly scroll screen */
-                        row++;
-                        if (row >= G.height) {
-                                row--;
+                        G.row++;
+                        if (G.row >= G.height) {
+                                G.row--;
                                 redraw_cur_line();
                         }
                         if (--cnt)
@@ -371,8 +392,8 @@ int hexedit_main(int argc UNUSED_PARAM, char **argv)
                         }
                         G.current_byte -= 16;
  up:
-                        if (row != 0) {
-                                row--;
+                        if (G.row != 0) {
+                                G.row--;
                                 printf(ESC"[A"); /* up (won't scroll) */
                         } else {
                                 //printf(ESC"[T"); /* scroll up */ - not implemented on Linux VT!
@@ -382,8 +403,12 @@ int hexedit_main(int argc UNUSED_PARAM, char **argv)
                         if (--cnt)
                                 goto k_up;
                         break;
-                }
-        }
+                case CTRL('X'):
+                        restore_term();
+                        return EXIT_SUCCESS;
+                } /* switch */
+        } /* for (;;) */
 
+        /* not reached */
         return EXIT_SUCCESS;
 }
diff --git a/miscutils/less.c b/miscutils/less.c
index 241f7f8ba..f869a9e82 100644
--- a/miscutils/less.c
+++ b/miscutils/less.c
@@ -1103,7 +1103,7 @@ static int64_t getch_nowait(void)
                         goto again;
                 }
                 /* EOF/error (ssh session got killed etc) */
-                less_exit(0);
+                less_exit(EXIT_SUCCESS);
         }
         set_tty_cooked();
         return key64;