Refactor, wrap write() syscall in new dprint() function

Fixes the GCC warning for unchecked return value from write():

  ... ignoring return value of ‘write’, declared with attribute warn_unused_result

The new dprint() function wraps write() in a bounded retry-loop that
catches EINTR.  The length argument is optional computed with strlen()
if omitted (zero).

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/exec.c

@@ -316,7 +316,7 @@ static int activate_console(int noclear, int nowait)
 		return 1;
 
 	if (!noclear)
-		(void)write(STDERR_FILENO, "\e[r\e[H\e[J", 9);
+		dprint(STDERR_FILENO, "\e[r\e[H\e[J", 9);
 
 	/* Disable ECHO, XON/OFF while waiting for <CR> */
 	if (!tcgetattr(STDIN_FILENO, &orig)) {
@@ -340,16 +340,16 @@ static int activate_console(int noclear, int nowait)
 			continue;
 		}
 
-		(void)write(STDERR_FILENO, clr, strlen(clr));
-		(void)write(STDERR_FILENO, msg, strlen(msg));
+		dprint(STDERR_FILENO, clr, strlen(clr));
+		dprint(STDERR_FILENO, msg, strlen(msg));
 		while (read(STDIN_FILENO, &c, 1) == 1 && c != '\r')
 			continue;
 
 		if (fexist(SYNC_STOPPED))
 			continue;
 
-		(void)write(STDERR_FILENO, clr, strlen(clr));
-		(void)write(STDERR_FILENO, cup, strlen(cup));
+		dprint(STDERR_FILENO, clr, strlen(clr));
+		dprint(STDERR_FILENO, cup, strlen(cup));
 		ret = 1;
 		break;
 	}

src/getty.c

@@ -41,9 +41,6 @@
 #define _PATH_LOGIN  "/bin/login"
 #endif
 
-#define print(s) (void)write(STDOUT_FILENO, s, strlen(s))
-
-
 /*
  * Read one character from stdin.
  */
@@ -54,7 +51,7 @@ static int readch(char *tty)
 
 	st = read(STDIN_FILENO, &ch1, 1);
 	if (st == 0) {
-		print("\n");
+		dprint(STDOUT_FILENO, "\n", 0);
 		_exit(0);
 	}
 
@@ -74,31 +71,31 @@ static void do_parse(char *line, struct utsname *uts, char *tty)
 	s0 = line;
 	for (s = line; *s != 0; s++) {
 		if (*s == '\\') {
-			(void)write(1, s0, s - s0);
+			dprint(STDOUT_FILENO, s0, s - s0);
 			s0 = s + 2;
 			switch (*++s) {
 			case 'l':
-				print(tty);
+				dprint(STDOUT_FILENO, tty, 0);
 				break;
 			case 'm':
-				print(uts->machine);
+				dprint(STDOUT_FILENO, uts->machine, 0);
 				break;
 			case 'n':
-				print(uts->nodename);
+				dprint(STDOUT_FILENO, uts->nodename, 0);
 				break;
 #ifdef _GNU_SOURCE
 			case 'o':
-				print(uts->domainname);
+				dprint(STDOUT_FILENO, uts->domainname, 0);
 				break;
 #endif
 			case 'r':
-				print(uts->release);
+				dprint(STDOUT_FILENO, uts->release, 0);
 				break;
 			case 's':
-				print(uts->sysname);
+				dprint(STDOUT_FILENO, uts->sysname, 0);
 				break;
 			case 'v':
-				print(uts->version);
+				dprint(STDOUT_FILENO, uts->version, 0);
 				break;
 			case 0:
 				goto leave;
@@ -109,7 +106,7 @@ static void do_parse(char *line, struct utsname *uts, char *tty)
 	}
 
 leave:
-	(void)write(1, s0, s - s0);
+	dprint(STDOUT_FILENO, s0, s - s0);
 }
 
 /*
@@ -159,7 +156,7 @@ static void do_getty(char *tty, char *name, size_t len)
 		while ((ch = readch(tty)) != '\n') {
 			if (ch == CTRL('U')) {
 				while (np > name) {
-					(void)write(1, "\b \b", 3);
+					dprint(STDOUT_FILENO, "\b \b", 3);
 					np--;
 				}
 				continue;
@@ -215,7 +212,7 @@ int getty(char *tty, speed_t speed, char *term, char *user)
 
 	/* Set up TTY, re-enabling ISIG et al. */
 	stty(STDIN_FILENO, speed);
-	(void)write(STDERR_FILENO, cln, strlen(cln));
+	dprint(STDERR_FILENO, cln, strlen(cln));
 
 	/* The getty process is responsible for the UTMP login record */
 	utmp_set_login(tty, NULL);

src/helpers.c

@@ -170,7 +170,7 @@ ssize_t cprintf(const char *fmt, ...)
 	va_end(ap);
 
 	for (i = 0; i < num_cons; i++)
-		(void)write(fds[i], buf, size);
+		dprint(fds[i], buf, size);
 
 	return size;
 }

src/helpers.h

@@ -70,7 +70,7 @@ void    show_progress   (pstyle_t style);
 int     getty           (char *tty, speed_t speed, char *term, char *user);
 int     sh              (char *tty);
 
-int     stty            (int fd, speed_t speed);
+void    stty            (int fd, speed_t speed);
 speed_t stty_parse_speed(char *baud);
 
 void    print_banner    (const char *heading);
@@ -109,6 +109,24 @@ static inline int create(char *path, mode_t mode, uid_t uid, gid_t gid)
 	return 0;
 }
 
+static inline int dprint(int fd, const char *s, size_t len)
+{
+	size_t loop = 3;
+	int rc = -1;
+
+	if (!len)
+		len = strlen(s);
+
+	while (loop--) {
+		rc = write(fd, s, len);
+		if (rc == -1 && errno == EINTR)
+			continue;
+		break;
+	}
+
+	return rc;
+}
+
 int	ismnt		(char *file, char *dir, char *mode);
 int	fismnt		(char *dir);
 

src/stty.c

@@ -27,6 +27,8 @@
 #include <sys/ttydefaults.h>  /* Not included by default in musl libc */
 #include <termios.h>
 
+#include <helpers.h>
+
 /* B0 means; keep kernel default */
 speed_t stty_parse_speed(char *baud)
 {
@@ -123,10 +125,10 @@ void stty(int fd, speed_t speed)
 	tcsetattr(fd, TCSAFLUSH, &term);
 
 	/* Show cursor again, if it was hidden previously */
-	write(fd, "\033[?25h", 6);
+	dprint(fd, "\033[?25h", 6);
 
 	/* Enable line wrap, if disabled previously */
-	write(fd, "\033[7h", 4);
+	dprint(fd, "\033[7h", 4);
 }
 
 /**