diff options
| author | Heinrich Schuchardt | 2018-09-15 23:52:07 +0200 |
|---|---|---|
| committer | Alexander Graf | 2018-09-23 21:55:30 +0200 |
| commit | 6bb591f7041fdd201814b8866c1a55775662ab7f (patch) | |
| tree | 2eab2621cf5f58c5770bc7db4f77aad7abe1d7bd /lib | |
| parent | 7b05667ce23914f6989f8c2ade1ac96ce4ff4eb6 (diff) | |
efi_loader: query serial console size reliably
Not all terminals understand CSI [18t for querying the console size.
We should adhere to escape sequences documented in the console_codes
manpage and the ECMA-48 standard.
So here we follow a different approach. We position the cursor to the
bottom right and query its position. Before leaving the function we
restore the original cursor position.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/efi_loader/efi_console.c | 50 |
1 files changed, 37 insertions, 13 deletions
diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c index 41e0a493614..7ecdbb16669 100644 --- a/lib/efi_loader/efi_console.c +++ b/lib/efi_loader/efi_console.c @@ -185,32 +185,56 @@ static bool cout_mode_matches(struct cout_mode *mode, int rows, int cols) return (mode->rows == rows) && (mode->columns == cols); } +/** + * query_console_serial() - query console size + * + * @rows pointer to return number of rows + * @columns pointer to return number of columns + * Returns 0 on success + */ static int query_console_serial(int *rows, int *cols) { - /* Ask the terminal about its size */ - int n[3]; + int ret = 0; + int n[2]; u64 timeout; /* Empty input buffer */ while (tstc()) getc(); - printf(ESC"[18t"); + /* + * Not all terminals understand CSI [18t for querying the console size. + * We should adhere to escape sequences documented in the console_codes + * manpage and the ECMA-48 standard. + * + * So here we follow a different approach. We position the cursor to the + * bottom right and query its position. Before leaving the function we + * restore the original cursor position. + */ + printf(ESC "7" /* Save cursor position */ + ESC "[r" /* Set scrolling region to full window */ + ESC "[999;999H" /* Move to bottom right corner */ + ESC "[6n"); /* Query cursor position */ - /* Check if we have a terminal that understands */ + /* Allow up to one second for a response */ timeout = timer_get_us() + 1000000; while (!tstc()) - if (timer_get_us() > timeout) - return -1; - - /* Read {depth,rows,cols} */ - if (term_read_reply(n, 3, 't')) - return -1; + if (timer_get_us() > timeout) { + ret = -1; + goto out; + } - *cols = n[2]; - *rows = n[1]; + /* Read {rows,cols} */ + if (term_read_reply(n, 2, 'R')) { + ret = 1; + goto out; + } - return 0; + *cols = n[1]; + *rows = n[0]; +out: + printf(ESC "8"); /* Restore cursor position */ + return ret; } /* |