From: Karel Zak <kzak@redhat.com>
Date: Tue, 12 May 2020 13:21:21 +0000 (+0200)
Subject: login: add MOTD_FIRSTONLY=
X-Git-Tag: v2.36-rc1~104
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9789d21a96be47fdd9b2c330b640e23254a22194;p=thirdparty%2Futil-linux.git

login: add MOTD_FIRSTONLY=

This login.defs option allow to configure login to be more compatible
with pam_motd.

Addresses: https://github.com/karelzak/util-linux/issues/1034
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/login-utils/login.1 b/login-utils/login.1
index 1e2d3cb289..24cd7d2bc1 100644
--- a/login-utils/login.1
+++ b/login-utils/login.1
@@ -168,6 +168,25 @@ PAM module.
 The directories in the
 .B MOTD_FILE
 are supported since version 2.36.
+.PP
+Note that
+.B login
+does not implement any filenames overriding behavior like pam_motd
+(see also MOTD_FIRSTONLY), but all content from all files is displayed.  It is
+recommended to keep extra logic in content generators and use /run/motd.d rather
+than rely on overriding behavior hardcoded in system tools.
+.RE
+.PP
+.B MOTD_FIRSTONLY (boolean)
+.RS 4
+Forces
+.B login
+to stop display content specified by
+.B MOTD_FILE
+after first accessible item in the list.  Note that a directory is one item in this case.
+This option allows to configure
+.B login
+semantic to be more compatible with pam_motd.
 .RE
 .PP
 .B LOGIN_PLAIN_PROMPT
diff --git a/login-utils/login.c b/login-utils/login.c
index 0ea2fbb3fa..4be8bcfaf3 100644
--- a/login-utils/login.c
+++ b/login-utils/login.c
@@ -267,14 +267,14 @@ static int motddir_filter(const struct dirent *d)
 	return 1; /* accept */
 }
 
-static void motddir(const char *dirname)
+static int motddir(const char *dirname)
 {
-        int dd, nfiles, i;
+        int dd, nfiles, i, done = 0;
         struct dirent **namelist = NULL;
 
 	dd = open(dirname, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
 	if (dd < 0)
-		return;
+		return 0;
 
 	nfiles = scandirat(dd, ".", &namelist, motddir_filter, versionsort);
 	if (nfiles <= 0)
@@ -290,6 +290,7 @@ static void motddir(const char *dirname)
 			if (fstat(fd, &st) == 0 && st.st_size > 0)
 				sendfile(fileno(stdout), fd, NULL, st.st_size);
 			close(fd);
+			done++;
 		}
 	}
 
@@ -298,6 +299,7 @@ static void motddir(const char *dirname)
 	free(namelist);
 done:
 	close(dd);
+	return done;
 }
 #endif /* MOTDDIR_SUPPORT */
 
@@ -313,6 +315,9 @@ static void motd(void)
 {
 	const char *mb;
 	char *file, *list;
+	int firstonly, done = 0;
+
+	firstonly = getlogindefs_bool("MOTD_FIRSTONLY", 0);
 
 	mb = getlogindefs_str("MOTD_FILE", _PATH_MOTDFILE);
 	if (!mb || !*mb)
@@ -327,15 +332,17 @@ static void motd(void)
 			continue;
 #ifdef MOTDDIR_SUPPORT
 		if (S_ISDIR(st.st_mode))
-			motddir(file);
-		else
+			done += motddir(file);
 #endif
 		if (S_ISREG(st.st_mode) && st.st_size > 0) {
 			int fd = open(file, O_RDONLY, 0);
 			if (fd >= 0)
 				sendfile(fileno(stdout), fd, NULL, st.st_size);
 			close(fd);
+			done++;
 		}
+		if (firstonly && done)
+			break;
 	}
 	free(list);
 }