Merge pull request #30183 from poettering/nlcr

NL → CRNL conversion fixes when logging at the same time as ptyfwd runs

src/basic/log.c

@@ -53,6 +53,7 @@ static int log_facility = LOG_DAEMON;
 static bool ratelimit_kmsg = true;
 
 static int console_fd = STDERR_FILENO;
+static int console_fd_is_tty = -1; /* tri-state: -1 means don't know */
 static int syslog_fd = -EBADF;
 static int kmsg_fd = -EBADF;
 static int journal_fd = -EBADF;
@@ -108,12 +109,14 @@ bool _log_message_dummy = false; /* Always false */
 static void log_close_console(void) {
         /* See comment in log_close_journal() */
         (void) safe_close_above_stdio(TAKE_FD(console_fd));
+        console_fd_is_tty = -1;
 }
 
 static int log_open_console(void) {
 
         if (!always_reopen_console) {
                 console_fd = STDERR_FILENO;
+                console_fd_is_tty = -1;
                 return 0;
         }
 
@@ -125,6 +128,7 @@ static int log_open_console(void) {
                         return fd;
 
                 console_fd = fd_move_above_stdio(fd);
+                console_fd_is_tty = true;
         }
 
         return 0;
@@ -381,6 +385,7 @@ void log_forget_fds(void) {
         /* Do not call from library code. */
 
         console_fd = kmsg_fd = syslog_fd = journal_fd = -EBADF;
+        console_fd_is_tty = -1;
 }
 
 void log_set_max_level(int level) {
@@ -404,6 +409,16 @@ void log_set_facility(int facility) {
         log_facility = facility;
 }
 
+static bool check_console_fd_is_tty(void) {
+        if (console_fd < 0)
+                return false;
+
+        if (console_fd_is_tty < 0)
+                console_fd_is_tty = isatty(console_fd) > 0;
+
+        return console_fd_is_tty;
+}
+
 static int write_to_console(
                 int level,
                 int error,
@@ -462,7 +477,12 @@ static int write_to_console(
         iovec[n++] = IOVEC_MAKE_STRING(buffer);
         if (off)
                 iovec[n++] = IOVEC_MAKE_STRING(off);
-        iovec[n++] = IOVEC_MAKE_STRING("\n");
+
+        /* When writing to a TTY we output an extra '\r' (i.e. CR) first, to generate CRNL rather than just
+         * NL. This is a robustness thing in case the TTY is currently in raw mode (specifically: has the
+         * ONLCR flag off). We want that subsequent output definitely starts at the beginning of the line
+         * again, after all. If the TTY is not in raw mode the extra CR should not hurt. */
+        iovec[n++] = IOVEC_MAKE_STRING(check_console_fd_is_tty() ? "\r\n" : "\n");
 
         if (writev(console_fd, iovec, n) < 0) {
 

src/basic/stat-util.c

@@ -187,14 +187,12 @@ int inode_same_at(int fda, const char *filea, int fdb, const char *fileb, int fl
         struct stat a, b;
 
         assert(fda >= 0 || fda == AT_FDCWD);
-        assert(filea);
         assert(fdb >= 0 || fdb == AT_FDCWD);
-        assert(fileb);
 
-        if (fstatat(fda, filea, &a, flags) < 0)
+        if (fstatat(fda, strempty(filea), &a, flags) < 0)
                 return log_debug_errno(errno, "Cannot stat %s: %m", filea);
 
-        if (fstatat(fdb, fileb, &b, flags) < 0)
+        if (fstatat(fdb, strempty(fileb), &b, flags) < 0)
                 return log_debug_errno(errno, "Cannot stat %s: %m", fileb);
 
         return stat_inode_same(&a, &b);

src/shared/ptyfwd.c

@@ -22,6 +22,7 @@
 #include "log.h"
 #include "macro.h"
 #include "ptyfwd.h"
+#include "stat-util.h"
 #include "terminal-util.h"
 #include "time-util.h"
 
@@ -142,7 +143,7 @@ static bool look_for_escape(PTYForward *f, const char *buffer, size_t n) {
                 if (*p == 0x1D) {
                         usec_t nw = now(CLOCK_MONOTONIC);
 
-                        if (f->escape_counter == 0 || nw > f->escape_timestamp + ESCAPE_USEC)  {
+                        if (f->escape_counter == 0 || nw > f->escape_timestamp + ESCAPE_USEC) {
                                 f->escape_timestamp = nw;
                                 f->escape_counter = 1;
                         } else {
@@ -228,7 +229,7 @@ static int shovel(PTYForward *f) {
                                 f->stdin_hangup = true;
 
                                 f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
-                        } else  {
+                        } else {
                                 /* Check if ^] has been pressed three times within one second. If we get this we quite
                                  * immediately. */
                                 if (look_for_escape(f, f->in_buffer + f->in_buffer_full, k))
@@ -266,12 +267,9 @@ static int shovel(PTYForward *f) {
                         k = read(f->master, f->out_buffer + f->out_buffer_full, LINE_MAX - f->out_buffer_full);
                         if (k < 0) {
 
-                                /* Note that EIO on the master device
-                                 * might be caused by vhangup() or
-                                 * temporary closing of everything on
-                                 * the other side, we treat it like
-                                 * EAGAIN here and try again, unless
-                                 * ignore_vhangup is off. */
+                                /* Note that EIO on the master device might be caused by vhangup() or
+                                 * temporary closing of everything on the other side, we treat it like EAGAIN
+                                 * here and try again, unless ignore_vhangup is off. */
 
                                 if (errno == EAGAIN || (errno == EIO && ignore_vhangup(f)))
                                         f->master_readable = false;
@@ -284,7 +282,7 @@ static int shovel(PTYForward *f) {
                                         log_error_errno(errno, "read(): %m");
                                         return pty_forward_done(f, -errno);
                                 }
-                        }  else {
+                        } else {
                                 f->read_from_master = true;
                                 f->out_buffer_full += (size_t) k;
                         }
@@ -480,8 +478,14 @@ int pty_forward_new(
         (void) ioctl(master, TIOCSWINSZ, &ws);
 
         if (!(flags & PTY_FORWARD_READ_ONLY)) {
+                int same;
+
                 assert(f->input_fd >= 0);
 
+                same = inode_same_at(f->input_fd, NULL, f->output_fd, NULL, AT_EMPTY_PATH);
+                if (same < 0)
+                        return same;
+
                 if (tcgetattr(f->input_fd, &f->saved_stdin_attr) >= 0) {
                         struct termios raw_stdin_attr;
 
@@ -489,11 +493,14 @@ int pty_forward_new(
 
                         raw_stdin_attr = f->saved_stdin_attr;
                         cfmakeraw(&raw_stdin_attr);
-                        raw_stdin_attr.c_oflag = f->saved_stdin_attr.c_oflag;
-                        tcsetattr(f->input_fd, TCSANOW, &raw_stdin_attr);
+
+                        if (!same)
+                                raw_stdin_attr.c_oflag = f->saved_stdin_attr.c_oflag;
+
+                        (void) tcsetattr(f->input_fd, TCSANOW, &raw_stdin_attr);
                 }
 
-                if (tcgetattr(f->output_fd, &f->saved_stdout_attr) >= 0) {
+                if (!same && tcgetattr(f->output_fd, &f->saved_stdout_attr) >= 0) {
                         struct termios raw_stdout_attr;
 
                         f->saved_stdout = true;
@@ -502,7 +509,7 @@ int pty_forward_new(
                         cfmakeraw(&raw_stdout_attr);
                         raw_stdout_attr.c_iflag = f->saved_stdout_attr.c_iflag;
                         raw_stdout_attr.c_lflag = f->saved_stdout_attr.c_lflag;
-                        tcsetattr(f->output_fd, TCSANOW, &raw_stdout_attr);
+                        (void) tcsetattr(f->output_fd, TCSANOW, &raw_stdout_attr);
                 }
 
                 r = sd_event_add_io(f->event, &f->stdin_event_source, f->input_fd, EPOLLIN|EPOLLET, on_stdin_event, f);