From: Karel Zak <kzak@redhat.com>
Date: Tue, 24 Jan 2023 16:05:25 +0000 (+0100)
Subject: include/c: add functions to print from signal handlers
X-Git-Tag: v2.39-rc1~122
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=32457b5efa5d4541a7d01bed9686a4f51952cd5b;p=thirdparty%2Futil-linux.git

include/c: add functions to print from signal handlers

Addresses: https://github.com/util-linux/util-linux/pull/2019
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/include/c.h b/include/c.h
index 4cb248f7f2..7e8177ac01 100644
--- a/include/c.h
+++ b/include/c.h
@@ -407,6 +407,29 @@ static inline int xusleep(useconds_t usec)
 #endif
 }
 
+
+#define ul_err_write(_m) ignore_result( write(STDERR_FILENO, _m, strlen(_m)) )
+
+/*
+ * warn() for signal handlers
+ */
+static inline void ul_sig_warn(const char *mesg)
+{
+	ul_err_write(program_invocation_short_name);
+	ul_err_write(": ");
+	ul_err_write(mesg);
+	ul_err_write("\n");
+}
+
+/*
+ * err() for signal handlers
+ */
+static inline void __attribute__((__noreturn__)) ul_sig_err(int excode, const char *mesg)
+{
+	ul_sig_warn(mesg);
+	_exit(excode);
+}
+
 /*
  * Constant strings for usage() functions. For more info see
  * Documentation/{howto-usage-function.txt,boilerplate.c}
diff --git a/lib/pager.c b/lib/pager.c
index 8f62310c07..2421703669 100644
--- a/lib/pager.c
+++ b/lib/pager.c
@@ -114,9 +114,7 @@ static int wait_or_whine(pid_t pid)
 		if (waiting < 0) {
 			if (errno == EINTR)
 				continue;
-			/* Can't err() on signal handler */
-			ignore_result(write(STDERR_FILENO, "waitpid failed", 14));
-			_exit(EXIT_FAILURE);
+			ul_sig_err(EXIT_FAILURE, "waitpid failed");
 		}
 		if (waiting != pid)
 			return -1;
diff --git a/login-utils/last.c b/login-utils/last.c
index 2b24f08a05..260a9f35e8 100644
--- a/login-utils/last.c
+++ b/login-utils/last.c
@@ -271,9 +271,7 @@ static int uread(FILE *fp, struct utmpx *u,  int *quit, const char *filename)
  */
 static void int_handler(int sig __attribute__((unused)))
 {
-	/* can't use err on signal handler */
-	write(STDERR_FILENO, "Interrupted\n", sizeof("Interrupted\n")-1);
-	_exit(EXIT_FAILURE);
+	ul_sig_err(EXIT_FAILURE, "Interrupted");
 }
 
 /*
@@ -281,7 +279,7 @@ static void int_handler(int sig __attribute__((unused)))
  */
 static void quit_handler(int sig __attribute__((unused)))
 {
-	write(STDERR_FILENO, "Interrupted\n", sizeof("Interrupted\n")-1);
+	ul_sig_warn("Interrupted");
 	signal(SIGQUIT, quit_handler);
 }
 #endif