[hackers] [st] Add support for DSR response "OK" escape sequence || Adam Price

[git]

commit f17abd25b376c292f783062ecf821453eaa9cc4c
Author:     Adam Price <komidor...@gmail.com>
AuthorDate: Tue Feb 7 19:54:29 2023 +0100
Commit:     Hiltjo Posthuma <hil...@codemadness.org>
CommitDate: Tue Feb 7 19:57:34 2023 +0100

    Add support for DSR response "OK" escape sequence
    
    "VT100 defines an escape sequence [1] called Device Status Report (DSR). 
When
    the DSR sequence received is `csi 5n`, an "OK" response `csi 0n` is 
returned.
    This patch adds that "OK" response.
    
    I encountered this missing sequence when I noticed that fzf [2] would 
clobber
    my prompt whenever completing a find.
    
    To test that ST doesn't currently respond to `csi 5n`, use fzf's shell
    extension in ST's repo to complete the path for a file.
    
        my-fancy-prompt $ vim **<tab>
        <select a file>
        st.c
    
    Select a file with <enter>, and notice that fzf clobbers some or all of your
    prompt.
    
    After applying this patch, do the same test as above and notice that fzf 
has no
    longer clobbered your prompt by placing the file name in the correct 
position
    in your command.
    
        my-fancy-prompt $ vim **<tab>
        <select a file>
        my-fancy prompt $ vim st.c
    
    Thank you for considering my first patch submission.
    
    [1] https://www.xfree86.org/current/ctlseqs.html#VT100%20Mode
    [2] https://github.com/junegunn/fzf
    "
    
    Patch slightly adapted with input from the mailinglist,

diff --git a/st.c b/st.c
index 34c27ad..49357cc 100644
--- a/st.c
+++ b/st.c
@@ -1769,11 +1769,18 @@ csihandle(void)
        case 'm': /* SGR -- Terminal attribute (color) */
                tsetattr(csiescseq.arg, csiescseq.narg);
                break;
-       case 'n': /* DSR – Device Status Report (cursor position) */
-               if (csiescseq.arg[0] == 6) {
+       case 'n': /* DSR -- Device Status Report */
+               switch (csiescseq.arg[0]) {
+               case 5: /* Status Report "OK" `0n` */
+                       ttywrite("\033[0n", sizeof("\033[0n") - 1, 0);
+                       break;
+               case 6: /* Report Cursor Position (CPR) "<row>;<column>R" */
                        len = snprintf(buf, sizeof(buf), "\033[%i;%iR",
-                                       term.c.y+1, term.c.x+1);
+                                      term.c.y+1, term.c.x+1);
                        ttywrite(buf, len, 0);
+                       break;
+               default:
+                       goto unknown;
                }
                break;
        case 'r': /* DECSTBM -- Set Scrolling Region */