From: Mike Yuan <me@yhndnzj.com>
Date: Fri, 22 Dec 2023 09:59:39 +0000 (+0800)
Subject: terminal-util: introduce isatty_safe that rejects EBADF
X-Git-Tag: v256-rc1~1417^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=76270f5c090ef103e2f75a73fa9fba8b213828ea;p=thirdparty%2Fsystemd.git

terminal-util: introduce isatty_safe that rejects EBADF
---

diff --git a/src/basic/terminal-util.c b/src/basic/terminal-util.c
index 89823ab7953..c6ced3f7c10 100644
--- a/src/basic/terminal-util.c
+++ b/src/basic/terminal-util.c
@@ -54,6 +54,18 @@ static volatile int cached_on_dev_null = -1;
 static volatile int cached_color_mode = _COLOR_INVALID;
 static volatile int cached_underline_enabled = -1;
 
+bool isatty_safe(int fd) {
+        assert(fd >= 0);
+
+        if (isatty(fd))
+                return true;
+
+        /* Be resilient if we're working on stdio, since they're set up by parent process. */
+        assert(errno != EBADF || IN_SET(fd, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO));
+
+        return false;
+}
+
 int chvt(int vt) {
         _cleanup_close_ int fd = -EBADF;
 
diff --git a/src/basic/terminal-util.h b/src/basic/terminal-util.h
index 1ec057c2dd5..ee60ff4840c 100644
--- a/src/basic/terminal-util.h
+++ b/src/basic/terminal-util.h
@@ -86,6 +86,8 @@
 /* Set cursor to top left corner and clear screen */
 #define ANSI_HOME_CLEAR "\x1B[H\x1B[2J"
 
+bool isatty_safe(int fd);
+
 int reset_terminal_fd(int fd, bool switch_to_text);
 int reset_terminal(const char *name);
 int set_terminal_cursor_position(int fd, unsigned int row, unsigned int column);