[pacman-dev] [PATCH v2] Hide cursor while pacman is running

[Allan McRae]

On 6/3/20 10:39 am, Anatol Pomozov wrote:
> Use ASCII control codes to hide cursor at the pacman start and then
> show the cursor when pacman finishes.
> 
> It helps to avoid annoying blinking when progress bars are re-drawn.
> 
> Cursor is reenabled if pacman expects user's input.
> 
> Signed-off-by: Anatol Pomozov <anatol.pomozov at gmail.com>
> ---
>  src/common/util-common.c | 22 ++++++++++++++++++++++
>  src/common/util-common.h |  3 +++
>  src/pacman/pacman.c      |  2 ++
>  src/pacman/sighandler.c  |  5 +++++
>  4 files changed, 32 insertions(+)
> 
> diff --git a/src/common/util-common.c b/src/common/util-common.c
> index 7d43ac0d..09a41ea6 100644
> --- a/src/common/util-common.c
> +++ b/src/common/util-common.c
> @@ -21,6 +21,7 @@
>  #include <errno.h>
>  #include <stdlib.h>
>  #include <string.h>
> +#include <unistd.h>
>  
>  #include "util-common.h"
>  
> @@ -104,6 +105,18 @@ int llstat(char *path, struct stat *buf)
>  	return ret;
>  }
>  
> +void console_hide_cursor(void) {
> +	if(isatty(fileno(stdout))) {

I don't think we should run this every line we read.

In fact, I doubt that is needed anywhere in libalpm currently.
safe_fgets is used to read the localdb and when grepping install files
for functions.  And libalpm should really not output anything...

> +		printf("\x1B[?25l");
> +	}
> +}
> +
> +void console_show_cursor(void) {
> +	if(isatty(fileno(stdout))) {
> +		printf("\x1B[?25h");
> +	}
> +}
> +
>  /** Wrapper around fgets() which properly handles EINTR
>   * @param s string to read into
>   * @param size maximum length to read
> @@ -114,6 +127,12 @@ char *safe_fgets(char *s, int size, FILE *stream)
>  {
>  	char *ret;
>  	int errno_save = errno, ferror_save = ferror(stream);
> +	int is_tty = isatty(fileno(stream));
> +
> +	if(is_tty) > +		/* Show cursor if read from STDIN */
> +		console_show_cursor();
> +	}

I don't like having to do this every time we read something.  And now we
are checking that "stream" is a tty and then "stdout" is a tty in the
console_*_cursor() functions.

It would be better to add a "safe_fgets_stdin()" in src/pacman/util.c
that wraps safe_fgets() and does the cursor on/off when pacman is asking
for input.  That is where we need it.

A