1 files changed, 86 insertions, 0 deletions
diff --git a/src/nvim/os/dl.c b/src/nvim/os/dl.c
new file mode 100644
index 0000000000..980998eb40
--- /dev/null
+++ b/src/nvim/os/dl.c
@@ -0,0 +1,86 @@
+/// Functions for using external native libraries
+
+#include <stdint.h>
+#include <uv.h>
+
+#include "nvim/os/os.h"
+#include "nvim/memory.h"
+#include "nvim/message.h"
+
+/// possible function prototypes that can be called by os_libcall()
+/// int -> int
+/// int -> string
+/// string -> string
+/// string -> int
+typedef void (*gen_fn)();
+typedef const char *(*str_str_fn)(const char *str);
+typedef int64_t (*str_int_fn)(const char *str);
+typedef const char *(*int_str_fn)(int64_t i);
+typedef int64_t (*int_int_fn)(int64_t i);
+
+/// os_libcall - call a function in a dynamic loadable library
+///
+/// an example of calling a function that takes a string and returns an int:
+///
+///   int64_t int_out = 0;
+///   os_libcall("mylib.so", "somefn", "string-argument", 0, NULL, &int_out);
+///
+/// @param libname the name of the library to load (e.g.: libsomething.so)
+/// @param funcname the name of the library function (e.g.: myfunc)
+/// @param argv the input string, NULL when using `argi`
+/// @param argi the input integer, not used when using `argv` != NULL
+/// @param[out] str_out an allocated output string, caller must free if
+///             not NULL. NULL when using `int_out`.
+/// @param[out] int_out the output integer param
+/// @return true on success, false on failure
+bool os_libcall(const char *libname,
+                const char *funcname,
+                const char *argv,
+                int64_t argi,
+                char **str_out,
+                int64_t *int_out)
+{
+  if (!libname || !funcname) {
+    return false;
+  }
+
+  uv_lib_t lib;
+
+  // open the dynamic loadable library
+  if (uv_dlopen(libname, &lib)) {
+      EMSG2(_("dlerror = \"%s\""), uv_dlerror(&lib));
+      return false;
+  }
+
+  // find and load the requested function in the library
+  gen_fn fn;
+  if (uv_dlsym(&lib, funcname, (void **) &fn)) {
+      EMSG2(_("dlerror = \"%s\""), uv_dlerror(&lib));
+      uv_dlclose(&lib);
+      return false;
+  }
+
+  // call the library and save the result
+  // TODO(aktau): catch signals and use jmp (if available) to handle
+  // exceptions. jmp's on UNIX seem to interact trickily with signals as
+  // well. So for now we only support those libraries that are well-behaved.
+  if (str_out) {
+    str_str_fn sfn = (str_str_fn) fn;
+    int_str_fn ifn = (int_str_fn) fn;
+
+    const char *res = argv ? sfn(argv) : ifn(argi);
+
+    // assume that ptr values of NULL, 1 or -1 are illegal
+    *str_out = (res && (intptr_t) res != 1 && (intptr_t) res != -1)
+        ? xstrdup(res) : NULL;
+  } else {
+    str_int_fn sfn = (str_int_fn) fn;
+    int_int_fn ifn = (int_int_fn) fn;
+    *int_out = argv ? sfn(argv) : ifn(argi);
+  }
+
+  // free the library
+  uv_dlclose(&lib);
+
+  return true;
+}