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-rw-r--r--src/shared/dropin.c255
1 files changed, 255 insertions, 0 deletions
diff --git a/src/shared/dropin.c b/src/shared/dropin.c
new file mode 100644
index 0000000..409eef2
--- /dev/null
+++ b/src/shared/dropin.c
@@ -0,0 +1,255 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "alloc-util.h"
+#include "conf-files.h"
+#include "dirent-util.h"
+#include "dropin.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fileio-label.h"
+#include "fs-util.h"
+#include "hashmap.h"
+#include "log.h"
+#include "macro.h"
+#include "mkdir.h"
+#include "path-util.h"
+#include "set.h"
+#include "string-util.h"
+#include "strv.h"
+#include "unit-name.h"
+
+int drop_in_file(const char *dir, const char *unit, unsigned level,
+ const char *name, char **_p, char **_q) {
+
+ char prefix[DECIMAL_STR_MAX(unsigned)];
+ _cleanup_free_ char *b = NULL;
+ char *p, *q;
+
+ assert(unit);
+ assert(name);
+ assert(_p);
+ assert(_q);
+
+ sprintf(prefix, "%u", level);
+
+ b = xescape(name, "/.");
+ if (!b)
+ return -ENOMEM;
+
+ if (!filename_is_valid(b))
+ return -EINVAL;
+
+ p = strjoin(dir, "/", unit, ".d");
+ if (!p)
+ return -ENOMEM;
+
+ q = strjoin(p, "/", prefix, "-", b, ".conf");
+ if (!q) {
+ free(p);
+ return -ENOMEM;
+ }
+
+ *_p = p;
+ *_q = q;
+ return 0;
+}
+
+int write_drop_in(const char *dir, const char *unit, unsigned level,
+ const char *name, const char *data) {
+
+ _cleanup_free_ char *p = NULL, *q = NULL;
+ int r;
+
+ assert(dir);
+ assert(unit);
+ assert(name);
+ assert(data);
+
+ r = drop_in_file(dir, unit, level, name, &p, &q);
+ if (r < 0)
+ return r;
+
+ (void) mkdir_p(p, 0755);
+ return write_string_file_atomic_label(q, data);
+}
+
+int write_drop_in_format(const char *dir, const char *unit, unsigned level,
+ const char *name, const char *format, ...) {
+ _cleanup_free_ char *p = NULL;
+ va_list ap;
+ int r;
+
+ assert(dir);
+ assert(unit);
+ assert(name);
+ assert(format);
+
+ va_start(ap, format);
+ r = vasprintf(&p, format, ap);
+ va_end(ap);
+
+ if (r < 0)
+ return -ENOMEM;
+
+ return write_drop_in(dir, unit, level, name, p);
+}
+
+static int unit_file_find_dir(
+ const char *original_root,
+ const char *path,
+ char ***dirs) {
+
+ _cleanup_free_ char *chased = NULL;
+ int r;
+
+ assert(path);
+
+ r = chase_symlinks(path, original_root, 0, &chased);
+ if (r == -ENOENT) /* Ignore -ENOENT, after all most units won't have a drop-in dir. */
+ return 0;
+ if (r == -ENAMETOOLONG) {
+ /* Also, ignore -ENAMETOOLONG but log about it. After all, users are not even able to create the
+ * drop-in dir in such case. This mostly happens for device units with an overly long /sys path. */
+ log_debug_errno(r, "Path '%s' too long, couldn't canonicalize, ignoring.", path);
+ return 0;
+ }
+ if (r < 0)
+ return log_warning_errno(r, "Failed to canonicalize path '%s': %m", path);
+
+ r = strv_push(dirs, chased);
+ if (r < 0)
+ return log_oom();
+
+ chased = NULL;
+ return 0;
+}
+
+static int unit_file_find_dirs(
+ const char *original_root,
+ Set *unit_path_cache,
+ const char *unit_path,
+ const char *name,
+ const char *suffix,
+ char ***dirs) {
+
+ _cleanup_free_ char *prefix = NULL, *instance = NULL, *built = NULL;
+ bool is_instance, chopped;
+ const char *dash;
+ UnitType type;
+ char *path;
+ size_t n;
+ int r;
+
+ assert(unit_path);
+ assert(name);
+ assert(suffix);
+
+ path = strjoina(unit_path, "/", name, suffix);
+ if (!unit_path_cache || set_get(unit_path_cache, path)) {
+ r = unit_file_find_dir(original_root, path, dirs);
+ if (r < 0)
+ return r;
+ }
+
+ is_instance = unit_name_is_valid(name, UNIT_NAME_INSTANCE);
+ if (is_instance) { /* Also try the template dir */
+ _cleanup_free_ char *template = NULL;
+
+ r = unit_name_template(name, &template);
+ if (r < 0)
+ return log_error_errno(r, "Failed to generate template from unit name: %m");
+
+ r = unit_file_find_dirs(original_root, unit_path_cache, unit_path, template, suffix, dirs);
+ if (r < 0)
+ return r;
+ }
+
+ /* Let's see if there's a "-" prefix for this unit name. If so, let's invoke ourselves for it. This will then
+ * recursively do the same for all our prefixes. i.e. this means given "foo-bar-waldo.service" we'll also
+ * search "foo-bar-.service" and "foo-.service".
+ *
+ * Note the order in which we do it: we traverse up adding drop-ins on each step. This means the more specific
+ * drop-ins may override the more generic drop-ins, which is the intended behaviour. */
+
+ r = unit_name_to_prefix(name, &prefix);
+ if (r < 0)
+ return log_error_errno(r, "Failed to derive unit name prefix from unit name: %m");
+
+ chopped = false;
+ for (;;) {
+ dash = strrchr(prefix, '-');
+ if (!dash) /* No dash? if so we are done */
+ return 0;
+
+ n = (size_t) (dash - prefix);
+ if (n == 0) /* Leading dash? If so, we are done */
+ return 0;
+
+ if (prefix[n+1] != 0 || chopped) {
+ prefix[n+1] = 0;
+ break;
+ }
+
+ /* Trailing dash? If so, chop it off and try again, but not more than once. */
+ prefix[n] = 0;
+ chopped = true;
+ }
+
+ if (!unit_prefix_is_valid(prefix))
+ return 0;
+
+ type = unit_name_to_type(name);
+ if (type < 0)
+ return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+ "Failed to to derive unit type from unit name: %s",
+ name);
+
+ if (is_instance) {
+ r = unit_name_to_instance(name, &instance);
+ if (r < 0)
+ return log_error_errno(r, "Failed to derive unit name instance from unit name: %m");
+ }
+
+ r = unit_name_build_from_type(prefix, instance, type, &built);
+ if (r < 0)
+ return log_error_errno(r, "Failed to build prefix unit name: %m");
+
+ return unit_file_find_dirs(original_root, unit_path_cache, unit_path, built, suffix, dirs);
+}
+
+int unit_file_find_dropin_paths(
+ const char *original_root,
+ char **lookup_path,
+ Set *unit_path_cache,
+ const char *dir_suffix,
+ const char *file_suffix,
+ Set *names,
+ char ***ret) {
+
+ _cleanup_strv_free_ char **dirs = NULL;
+ char *t, **p;
+ Iterator i;
+ int r;
+
+ assert(ret);
+
+ SET_FOREACH(t, names, i)
+ STRV_FOREACH(p, lookup_path)
+ (void) unit_file_find_dirs(original_root, unit_path_cache, *p, t, dir_suffix, &dirs);
+
+ if (strv_isempty(dirs)) {
+ *ret = NULL;
+ return 0;
+ }
+
+ r = conf_files_list_strv(ret, file_suffix, NULL, 0, (const char**) dirs);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to create the list of configuration files: %m");
+
+ return 1;
+}
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