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

[Anatol Pomozov]

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 | 13 +++++++++++++
 src/common/util-common.h |  3 +++
 src/pacman/pacman.c      |  2 ++
 src/pacman/sighandler.c  |  5 +++++
 src/pacman/util.c        | 19 ++++++++++++++-----
 src/pacman/util.h        |  1 +
 6 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/src/common/util-common.c b/src/common/util-common.c
index 7d43ac0d..3850cffb 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))) {
+		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
diff --git a/src/common/util-common.h b/src/common/util-common.h
index 483d5da4..8eacde7e 100644
--- a/src/common/util-common.h
+++ b/src/common/util-common.h
@@ -28,6 +28,9 @@ char *mdirname(const char *path);
 
 int llstat(char *path, struct stat *buf);
 
+void console_hide_cursor(void);
+void console_show_cursor(void);
+
 char *safe_fgets(char *s, int size, FILE *stream);
 
 void wordsplit_free(char **ws);
diff --git a/src/pacman/pacman.c b/src/pacman/pacman.c
index d58c428a..aafd9e63 100644
--- a/src/pacman/pacman.c
+++ b/src/pacman/pacman.c
@@ -300,6 +300,7 @@ static void cleanup(int ret)
 
 	/* free memory */
 	FREELIST(pm_targets);
+	console_show_cursor();
 	exit(ret);
 }
 
@@ -1084,6 +1085,7 @@ int main(int argc, char *argv[])
 	int ret = 0;
 	uid_t myuid = getuid();
 
+	console_hide_cursor();
 	install_segv_handler();
 
 	/* i18n init */
diff --git a/src/pacman/sighandler.c b/src/pacman/sighandler.c
index 46e6481f..59aaa61f 100644
--- a/src/pacman/sighandler.c
+++ b/src/pacman/sighandler.c
@@ -27,6 +27,9 @@
 #include "sighandler.h"
 #include "util.h"
 
+/* the same ANSI sequence as used in console_show_cursor */
+#define SHOW_CURSOR_ANSI "\x1B[?25h"
+
 /** Write function that correctly handles EINTR.
  */
 static ssize_t xwrite(int fd, const void *buf, size_t count)
@@ -60,6 +63,7 @@ static void soft_interrupt_handler(int signum)
 		const char msg[] = "\nHangup signal received\n";
 		xwrite(STDERR_FILENO, msg, ARRAYSIZE(msg) - 1);
 	}
+	xwrite(STDOUT_FILENO, SHOW_CURSOR_ANSI, sizeof(SHOW_CURSOR_ANSI) - 1);
 	if(alpm_trans_interrupt(config->handle) == 0) {
 		/* a transaction is being interrupted, don't exit pacman yet. */
 		return;
@@ -95,6 +99,7 @@ static void segv_handler(int signum)
 	const char msg[] = "\nerror: segmentation fault\n"
 		"Please submit a full bug report with --debug if appropriate.\n";
 	xwrite(STDERR_FILENO, msg, sizeof(msg) - 1);
+	xwrite(STDOUT_FILENO, SHOW_CURSOR_ANSI, sizeof(SHOW_CURSOR_ANSI) - 1);
 
 	/* restore the default handler */
 	_reset_handler(signum);
diff --git a/src/pacman/util.c b/src/pacman/util.c
index a640ffb4..7dfbdbca 100644
--- a/src/pacman/util.c
+++ b/src/pacman/util.c
@@ -1391,6 +1391,15 @@ static int multiselect_parse(char *array, int count, char *response)
 	return 0;
 }
 
+char *safe_fgets_stdin(char *s, int size)
+{
+	char *result;
+	console_show_cursor();
+	result = safe_fgets(s, size, stdin);
+	console_hide_cursor();
+	return result;
+}
+
 int multiselect_question(char *array, int count)
 {
 	char *response, *lastchar;
@@ -1427,7 +1436,7 @@ int multiselect_question(char *array, int count)
 
 		flush_term_input(fileno(stdin));
 
-		if(safe_fgets(response, response_len, stdin)) {
+		if(safe_fgets_stdin(response, response_len)) {
 			const size_t response_incr = 64;
 			size_t len;
 			/* handle buffer not being large enough to read full line case */
@@ -1443,8 +1452,8 @@ int multiselect_question(char *array, int count)
 				lastchar = response + response_len - 1;
 				/* sentinel byte */
 				*lastchar = 1;
-				if(safe_fgets(response + response_len - response_incr - 1,
-							response_incr + 1, stdin) == 0) {
+				if(safe_fgets_stdin(response + response_len - response_incr - 1,
+							response_incr + 1) == 0) {
 					free(response);
 					return -1;
 				}
@@ -1494,7 +1503,7 @@ int select_question(int count)
 
 		flush_term_input(fileno(stdin));
 
-		if(safe_fgets(response, sizeof(response), stdin)) {
+		if(safe_fgets_stdin(response, sizeof(response))) {
 			size_t len = strtrim(response);
 			if(len > 0) {
 				int n;
@@ -1582,7 +1591,7 @@ static int question(short preset, const char *format, va_list args)
 
 	flush_term_input(fd_in);
 
-	if(safe_fgets(response, sizeof(response), stdin)) {
+	if(safe_fgets_stdin(response, sizeof(response))) {
 		size_t len = strtrim(response);
 		if(len == 0) {
 			return preset;
diff --git a/src/pacman/util.h b/src/pacman/util.h
index 2cee479f..fbc5f33c 100644
--- a/src/pacman/util.h
+++ b/src/pacman/util.h
@@ -77,6 +77,7 @@ int colon_printf(const char *format, ...) __attribute__((format(printf, 1, 2)));
 int yesno(const char *format, ...) __attribute__((format(printf, 1, 2)));
 int noyes(const char *format, ...) __attribute__((format(printf, 1, 2)));
 char *arg_to_string(int argc, char *argv[]);
+char *safe_fgets_stdin(char *s, int size);
 
 int pm_printf(alpm_loglevel_t level, const char *format, ...) __attribute__((format(printf,2,3)));
 int pm_asprintf(char **string, const char *format, ...) __attribute__((format(printf,2,3)));
-- 
2.25.1