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-rw-r--r--src/shared/os-util.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/src/shared/os-util.c b/src/shared/os-util.c
new file mode 100644
index 0000000..b2d5ce3
--- /dev/null
+++ b/src/shared/os-util.c
@@ -0,0 +1,117 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "alloc-util.h"
+#include "env-file.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "macro.h"
+#include "os-util.h"
+#include "string-util.h"
+#include "strv.h"
+
+int path_is_os_tree(const char *path) {
+ int r;
+
+ assert(path);
+
+ /* Does the path exist at all? If not, generate an error immediately. This is useful so that a missing root dir
+ * always results in -ENOENT, and we can properly distuingish the case where the whole root doesn't exist from
+ * the case where just the os-release file is missing. */
+ if (laccess(path, F_OK) < 0)
+ return -errno;
+
+ /* We use {/etc|/usr/lib}/os-release as flag file if something is an OS */
+ r = open_os_release(path, NULL, NULL);
+ if (r == -ENOENT) /* We got nothing */
+ return 0;
+ if (r < 0)
+ return r;
+
+ return 1;
+}
+
+int open_os_release(const char *root, char **ret_path, int *ret_fd) {
+ _cleanup_free_ char *q = NULL;
+ const char *p;
+ int k;
+
+ FOREACH_STRING(p, "/etc/os-release", "/usr/lib/os-release") {
+ k = chase_symlinks(p, root, CHASE_PREFIX_ROOT|(ret_fd ? CHASE_OPEN : 0), (ret_path ? &q : NULL));
+ if (k != -ENOENT)
+ break;
+ }
+ if (k < 0)
+ return k;
+
+ if (ret_fd) {
+ int real_fd;
+
+ /* Convert the O_PATH fd into a proper, readable one */
+ real_fd = fd_reopen(k, O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ safe_close(k);
+ if (real_fd < 0)
+ return real_fd;
+
+ *ret_fd = real_fd;
+ }
+
+ if (ret_path)
+ *ret_path = TAKE_PTR(q);
+
+ return 0;
+}
+
+int fopen_os_release(const char *root, 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);
+
+ r = open_os_release(root, ret_path ? &p : NULL, &fd);
+ if (r < 0)
+ return r;
+
+ f = fdopen(fd, "r");
+ if (!f)
+ return -errno;
+ fd = -1;
+
+ *ret_file = f;
+
+ if (ret_path)
+ *ret_path = TAKE_PTR(p);
+
+ return 0;
+}
+
+int parse_os_release(const char *root, ...) {
+ _cleanup_fclose_ FILE *f = NULL;
+ _cleanup_free_ char *p = NULL;
+ va_list ap;
+ int r;
+
+ r = fopen_os_release(root, &p, &f);
+ if (r < 0)
+ return r;
+
+ va_start(ap, root);
+ r = parse_env_filev(f, p, ap);
+ va_end(ap);
+
+ return r;
+}
+
+int load_os_release_pairs(const char *root, char ***ret) {
+ _cleanup_fclose_ FILE *f = NULL;
+ _cleanup_free_ char *p = NULL;
+ int r;
+
+ r = fopen_os_release(root, &p, &f);
+ if (r < 0)
+ return r;
+
+ return load_env_file_pairs(f, p, ret);
+}