os-release: add support for /usr/lib/extension-release.d/

Add helpers to look for extension-release.$NAME files in
/usr/lib/extension-release.d/ following the same pattern as os-release.

2 files changed, 59 insertions, 17 deletions

diff --git a/src/shared/os-util.c b/src/shared/os-util.c
index 3b7e495846..d1cf41283b 100644
--- a/src/shared/os-util.c
+++ b/src/shared/os-util.c
@@ -6,6 +6,7 @@
 #include "fileio.h"
 #include "fs-util.h"
 #include "macro.h"
+#include "machine-image.h"
 #include "os-util.h"
 #include "string-util.h"
 #include "strv.h"
@@ -31,17 +32,31 @@ int path_is_os_tree(const char *path) {
         return 1;
 }
 
-int open_os_release(const char *root, char **ret_path, int *ret_fd) {
+int open_extension_release(const char *root, const char *extension, char **ret_path, int *ret_fd) {
         _cleanup_free_ char *q = NULL;
-        const char *p;
         int r, fd;
 
-        FOREACH_STRING(p, "/etc/os-release", "/usr/lib/os-release") {
-                r = chase_symlinks(p, root, CHASE_PREFIX_ROOT,
-                                   ret_path ? &q : NULL,
-                                   ret_fd ? &fd : NULL);
-                if (r != -ENOENT)
-                        break;
+        if (extension) {
+                const char *extension_full_path;
+
+                if (!image_name_is_valid(extension))
+                        return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "The extension name %s is invalid.", extension);
+
+                extension_full_path = strjoina("/usr/lib/extension-release.d/extension-release.", extension);
+                r = chase_symlinks(extension_full_path, root, CHASE_PREFIX_ROOT,
+                                  ret_path ? &q : NULL,
+                                  ret_fd ? &fd : NULL);
+        } else {
+                const char *p;
+
+                FOREACH_STRING(p, "/etc/os-release", "/usr/lib/os-release") {
+                        r = chase_symlinks(p, root, CHASE_PREFIX_ROOT,
+                                        ret_path ? &q : NULL,
+                                        ret_fd ? &fd : NULL);
+                        if (r != -ENOENT)
+                                break;
+                }
         }
         if (r < 0)
                 return r;
@@ -64,16 +79,16 @@ int open_os_release(const char *root, char **ret_path, int *ret_fd) {
         return 0;
 }
 
-int fopen_os_release(const char *root, char **ret_path, FILE **ret_file) {
+int fopen_extension_release(const char *root, const char *extension, char **ret_path, FILE **ret_file) {
         _cleanup_free_ char *p = NULL;
         _cleanup_close_ int fd = -1;
         FILE *f;
         int r;
 
         if (!ret_file)
-                return open_os_release(root, ret_path, NULL);
+                return open_extension_release(root, extension, ret_path, NULL);
 
-        r = open_os_release(root, ret_path ? &p : NULL, &fd);
+        r = open_extension_release(root, extension, ret_path ? &p : NULL, &fd);
         if (r < 0)
                 return r;
 
@@ -89,18 +104,35 @@ int fopen_os_release(const char *root, char **ret_path, FILE **ret_file) {
         return 0;
 }
 
-int parse_os_release(const char *root, ...) {
+static int parse_release_internal(const char *root, const char *extension, va_list ap) {
         _cleanup_fclose_ FILE *f = NULL;
         _cleanup_free_ char *p = NULL;
-        va_list ap;
         int r;
 
-        r = fopen_os_release(root, &p, &f);
+        r = fopen_extension_release(root, extension, &p, &f);
         if (r < 0)
                 return r;
 
+        return parse_env_filev(f, p, ap);
+}
+
+int parse_extension_release(const char *root, const char *extension, ...) {
+        va_list ap;
+        int r;
+
+        va_start(ap, extension);
+        r = parse_release_internal(root, extension, ap);
+        va_end(ap);
+
+        return r;
+}
+
+int parse_os_release(const char *root, ...) {
+        va_list ap;
+        int r;
+
         va_start(ap, root);
-        r = parse_env_filev(f, p, ap);
+        r = parse_release_internal(root, NULL, ap);
         va_end(ap);
 
         return r;
diff --git a/src/shared/os-util.h b/src/shared/os-util.h
index 1d9b0b146b..5b724eb7ac 100644
--- a/src/shared/os-util.h
+++ b/src/shared/os-util.h
@@ -5,9 +5,19 @@
 
 int path_is_os_tree(const char *path);
 
-int open_os_release(const char *root, char **ret_path, int *ret_fd);
-int fopen_os_release(const char *root, char **ret_path, FILE **ret_file);
+/* The *_extension_release flavours will look for /usr/lib/extension-release/extension-release.NAME
+ * in accordance with the OS extension specification, rather than for /usr/lib/ or /etc/os-release. */
+int open_extension_release(const char *root, const char *extension, char **ret_path, int *ret_fd);
+static inline int open_os_release(const char *root, char **ret_path, int *ret_fd) {
+        return open_extension_release(root, NULL, ret_path, ret_fd);
+}
 
+int fopen_extension_release(const char *root, const char *extension, char **ret_path, FILE **ret_file);
+static inline int fopen_os_release(const char *root, char **ret_path, FILE **ret_file) {
+        return fopen_extension_release(root, NULL, ret_path, ret_file);
+}
+
+int parse_extension_release(const char *root, const char *extension, ...) _sentinel_;
 int parse_os_release(const char *root, ...) _sentinel_;
 int load_os_release_pairs(const char *root, char ***ret);
 int load_os_release_pairs_with_prefix(const char *root, const char *prefix, char ***ret);