1 files changed, 66 insertions, 0 deletions
diff --git a/src/basic/dlfcn-util.c b/src/basic/dlfcn-util.c
new file mode 100644
index 0000000..8022f55
--- /dev/null
+++ b/src/basic/dlfcn-util.c
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "dlfcn-util.h"
+
+static int dlsym_many_or_warnv(void *dl, int log_level, va_list ap) {
+        void (**fn)(void);
+
+        /* Tries to resolve a bunch of function symbols, and logs an error about if it cannot resolve one of
+         * them. Note that this function possibly modifies the supplied function pointers if the whole
+         * operation fails. */
+
+        while ((fn = va_arg(ap, typeof(fn)))) {
+                void (*tfn)(void);
+                const char *symbol;
+
+                symbol = va_arg(ap, typeof(symbol));
+
+                tfn = (typeof(tfn)) dlsym(dl, symbol);
+                if (!tfn)
+                        return log_full_errno(log_level,
+                                              SYNTHETIC_ERRNO(ELIBBAD),
+                                              "Can't find symbol %s: %s", symbol, dlerror());
+                *fn = tfn;
+        }
+
+        return 0;
+}
+
+int dlsym_many_or_warn_sentinel(void *dl, int log_level, ...) {
+        va_list ap;
+        int r;
+
+        va_start(ap, log_level);
+        r = dlsym_many_or_warnv(dl, log_level, ap);
+        va_end(ap);
+
+        return r;
+}
+
+int dlopen_many_sym_or_warn_sentinel(void **dlp, const char *filename, int log_level, ...) {
+        _cleanup_(dlclosep) void *dl = NULL;
+        int r;
+
+        if (*dlp)
+                return 0; /* Already loaded */
+
+        dl = dlopen(filename, RTLD_LAZY);
+        if (!dl)
+                return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
+                                       "%s is not installed: %s", filename, dlerror());
+
+        log_debug("Loaded '%s' via dlopen()", filename);
+
+        va_list ap;
+        va_start(ap, log_level);
+        r = dlsym_many_or_warnv(dl, log_level, ap);
+        va_end(ap);
+
+        if (r < 0)
+                return r;
+
+        /* Note that we never release the reference here, because there's no real reason to. After all this
+         * was traditionally a regular shared library dependency which lives forever too. */
+        *dlp = TAKE_PTR(dl);
+        return 1;
+}