os-release: define /usr/lib/os-release as fallback for /etc/os-release

The file should have been in /usr/lib/ in the first place, since it
describes the OS container in /usr (and not the configuration in /etc),
hence, let's support os-release files in /usr/lib as fallback if no
version in /etc exists, following the usual override logic.

A prior commit already enabled tmpfiles to create /etc/os-release as a
symlink to /usr/lib/os-release should it be missing, thus providing nice
compatibility with applications only checking in /etc.

While it's probably a good idea if all apps check both locations via a
fallback logic, it is only necessary in the early boot process, as long
as the /etc/os-release symlink has not been restored, in case we boot
with an empty /etc.

8 files changed, 32 insertions, 10 deletions

diff --git a/src/bootchart/bootchart.c b/src/bootchart/bootchart.c
index 958a668aca..01a5bf18ef 100644
--- a/src/bootchart/bootchart.c
+++ b/src/bootchart/bootchart.c
@@ -386,10 +386,10 @@ int main(int argc, char *argv[]) {
                 if (sysfd < 0)
                         sysfd = open("/sys", O_RDONLY|O_CLOEXEC);
 
-                if (!build)
-                        parse_env_file("/etc/os-release", NEWLINE,
-                                       "PRETTY_NAME", &build,
-                                       NULL);
+                if (!build) {
+                        if (parse_env_file("/etc/os-release", NEWLINE, "PRETTY_NAME", &build, NULL) == -ENOENT)
+                                parse_env_file("/usr/lib/os-release", NEWLINE, "PRETTY_NAME", &build, NULL);
+                }
 
                 /* wait for /proc to become available, discarding samples */
                 if (graph_start <= 0.0)
diff --git a/src/core/dbus-manager.c b/src/core/dbus-manager.c
index 333c1d46e7..68a68a2d94 100644
--- a/src/core/dbus-manager.c
+++ b/src/core/dbus-manager.c
@@ -1191,7 +1191,7 @@ static int method_switch_root(sd_bus *bus, sd_bus_message *message, void *userda
         /* Safety check */
         if (isempty(init)) {
                 if (! path_is_os_tree(root))
-                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Specified switch root path %s does not seem to be an OS tree. /etc/os-release is missing.", root);
+                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Specified switch root path %s does not seem to be an OS tree. os-release file is missing.", root);
         } else {
                 _cleanup_free_ char *p = NULL;
 
diff --git a/src/core/main.c b/src/core/main.c
index d5d1ee2b0c..29f2d5a2a5 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -1251,9 +1251,15 @@ static int status_welcome(void) {
                            "PRETTY_NAME", &pretty_name,
                            "ANSI_COLOR", &ansi_color,
                            NULL);
+        if (r == -ENOENT) {
+                r = parse_env_file("/usr/lib/os-release", NEWLINE,
+                                   "PRETTY_NAME", &pretty_name,
+                                   "ANSI_COLOR", &ansi_color,
+                                   NULL);
+        }
 
         if (r < 0 && r != -ENOENT)
-                log_warning("Failed to read /etc/os-release: %s", strerror(-r));
+                log_warning("Failed to read os-release file: %s", strerror(-r));
 
         return status_printf(NULL, false, false,
                              "\nWelcome to \x1B[%sm%s\x1B[0m!\n",
diff --git a/src/hostname/hostnamed.c b/src/hostname/hostnamed.c
index a3504904a0..241d296916 100644
--- a/src/hostname/hostnamed.c
+++ b/src/hostname/hostnamed.c
@@ -108,6 +108,13 @@ static int context_read_data(Context *c) {
                            "PRETTY_NAME", &c->data[PROP_OS_PRETTY_NAME],
                            "CPE_NAME", &c->data[PROP_OS_CPE_NAME],
                            NULL);
+        if (r == -ENOENT) {
+                r = parse_env_file("/usr/lib/os-release", NEWLINE,
+                                   "PRETTY_NAME", &c->data[PROP_OS_PRETTY_NAME],
+                                   "CPE_NAME", &c->data[PROP_OS_CPE_NAME],
+                                   NULL);
+        }
+
         if (r < 0 && r != -ENOENT)
                 return r;
 
diff --git a/src/journal/journal-gatewayd.c b/src/journal/journal-gatewayd.c
index 9a88676242..c682666a22 100644
--- a/src/journal/journal-gatewayd.c
+++ b/src/journal/journal-gatewayd.c
@@ -767,7 +767,8 @@ static int request_handler_machine(
         if (r < 0)
                 return mhd_respondf(connection, MHD_HTTP_INTERNAL_SERVER_ERROR, "Failed to determine disk usage: %s\n", strerror(-r));
 
-        parse_env_file("/etc/os-release", NEWLINE, "PRETTY_NAME", &os_name, NULL);
+        if (parse_env_file("/etc/os-release", NEWLINE, "PRETTY_NAME", &os_name, NULL) == -ENOENT)
+                parse_env_file("/usr/lib/os-release", NEWLINE, "PRETTY_NAME", &os_name, NULL);
 
         get_virtualization(&v);
 
diff --git a/src/kernel-install/90-loaderentry.install b/src/kernel-install/90-loaderentry.install
index a6a8abc2bd..c17b8a98d5 100644
--- a/src/kernel-install/90-loaderentry.install
+++ b/src/kernel-install/90-loaderentry.install
@@ -32,6 +32,8 @@ fi
 
 if [[ -f /etc/os-release ]]; then
     . /etc/os-release
+elif [[ -f /usr/lib/os-release ]]; then
+    . /usr/lib/os-release
 fi
 
 if ! [[ $PRETTY_NAME ]]; then
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 29ddfbb1ff..8270348c17 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -2799,7 +2799,7 @@ int main(int argc, char *argv[]) {
 
                 if (arg_boot) {
                         if (path_is_os_tree(arg_directory) <= 0) {
-                                log_error("Directory %s doesn't look like an OS root directory (/etc/os-release is missing). Refusing.", arg_directory);
+                                log_error("Directory %s doesn't look like an OS root directory (os-release file is missing). Refusing.", arg_directory);
                                 goto finish;
                         }
                 } else {
diff --git a/src/shared/path-util.c b/src/shared/path-util.c
index 5863429c31..efe464d704 100644
--- a/src/shared/path-util.c
+++ b/src/shared/path-util.c
@@ -526,12 +526,18 @@ int path_is_os_tree(const char *path) {
         char *p;
         int r;
 
-        /* We use /etc/os-release as flag file if something is an OS */
+        /* We use /usr/lib/os-release as flag file if something is an OS */
+        p = strappenda(path, "/usr/lib/os-release");
+        r = access(p, F_OK);
+
+        if (r >= 0)
+                return 1;
 
+        /* Also check for the old location in /etc, just in case. */
         p = strappenda(path, "/etc/os-release");
         r = access(p, F_OK);
 
-        return r < 0 ? 0 : 1;
+        return r >= 0;
 }
 
 int find_binary(const char *name, char **filename) {