Move LD_LIBRARY_PATH handling to native code. NFC (#19321)

Split out from #19310

Author: sbc100

src/library_dylink.js

@@ -1071,25 +1071,6 @@ var LibraryDylink = {
     filename = PATH.normalize(filename);
     var searchpaths = [];
 
-    var isValidFile = (filename) => {
-      var target = FS.findObject(filename);
-      return target && !target.isFolder && !target.isDevice;
-    };
-
-    if (!isValidFile(filename)) {
-      if (ENV['LD_LIBRARY_PATH']) {
-        searchpaths = ENV['LD_LIBRARY_PATH'].split(':');
-      }
-
-      for (var ident in searchpaths) {
-        var searchfile = PATH.join2(searchpaths[ident], filename);
-        if (isValidFile(searchfile)) {
-          filename = searchfile;
-          break;
-        }
-      }
-    }
-
     var global = Boolean(flags & {{{ cDefs.RTLD_GLOBAL }}});
     var localScope = global ? null : {};
 

system/lib/libc/dynlink.c

@@ -18,6 +18,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
 
 #include <emscripten/console.h>
 #include <emscripten/threading.h>
@@ -441,6 +442,37 @@ static void dlopen_onerror(struct dso* dso, void* user_data) {
   free(data);
 }
 
+// Modified version of path_open from musl/ldso/dynlink.c
+static int path_find(const char *name, const char *s, char *buf, size_t buf_size) {
+  size_t l;
+  int fd;
+  for (;;) {
+    s += strspn(s, ":\n");
+    l = strcspn(s, ":\n");
+    if (l-1 >= INT_MAX) return -1;
+    if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
+      dbg("dlopen: path_find: %s", buf);
+      struct stat statbuf;
+      if (stat(buf, &statbuf) == 0 && S_ISREG(statbuf.st_mode)) {
+        return 0;
+      }
+      switch (errno) {
+      case ENOENT:
+      case ENOTDIR:
+      case EACCES:
+      case ENAMETOOLONG:
+        break;
+      default:
+        dbg("dlopen: path_find failed: %s", strerror(errno));
+        /* Any negative value but -1 will inhibit
+         * futher path search. */
+        return -2;
+      }
+    }
+    s += l;
+  }
+}
+
 // Internal version of dlopen with typed return value.
 // Without this, the compiler won't tell us if we have the wrong return type.
 static struct dso* _dlopen(const char* file, int flags) {
@@ -462,6 +494,16 @@ static struct dso* _dlopen(const char* file, int flags) {
 
   struct dso* p;
 
+  /* Resolve filename using LD_LIBRARY_PATH */
+  char buf[2*NAME_MAX+2];
+  if (!strchr(file, '/')) {
+    const char* env_path = getenv("LD_LIBRARY_PATH");
+    if (env_path && path_find(file, env_path, buf, sizeof buf) == 0) {
+      dbg("dlopen: found in LD_LIBRARY_PATH: %s", buf);
+      file = buf;
+    }
+  }
+
   /* Search for the name to see if it's already loaded */
   for (struct dlevent* e = head; e; e = e->next) {
     if (e->sym_index == -1 && !strcmp(e->dso->name, file)) {

test/test_other.py

@@ -6407,10 +6407,11 @@ def test_ld_library_path(self):
 ''')
     create_file('pre.js', r'''
 Module['preRun'] = function () {
-  ENV['LD_LIBRARY_PATH']='/lib:/usr/lib';
+  ENV['LD_LIBRARY_PATH']='/lib:/usr/lib:/usr/local/lib';
 };
 ''')
     create_file('main.c', r'''
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -6422,22 +6423,30 @@ def test_ld_library_path(self):
   double (*f2)(double);
 
   h = dlopen("libhello1.wasm", RTLD_NOW);
+  assert(h);
   f = dlsym(h, "hello1");
+  assert(f);
   f();
   dlclose(h);
 
   h = dlopen("libhello2.wasm", RTLD_NOW);
+  assert(h);
   f = dlsym(h, "hello2");
+  assert(f);
   f();
   dlclose(h);
 
   h = dlopen("libhello3.wasm", RTLD_NOW);
+  assert(h);
   f = dlsym(h, "hello3");
+  assert(f);
   f();
   dlclose(h);
 
   h = dlopen("/usr/local/lib/libhello4.wasm", RTLD_NOW);
+  assert(h);
   f2 = dlsym(h, "hello4");
+  assert(f2);
   double result = f2(5.5);
   dlclose(h);
 
@@ -6447,16 +6456,16 @@ def test_ld_library_path(self):
   return 0;
 }
 ''')
-    self.run_process([EMCC, '-o', 'libhello1.wasm', 'hello1.c', '-sSIDE_MODULE'])
-    self.run_process([EMCC, '-o', 'libhello2.wasm', 'hello2.c', '-sSIDE_MODULE'])
-    self.run_process([EMCC, '-o', 'libhello3.wasm', 'hello3.c', '-sSIDE_MODULE'])
-    self.run_process([EMCC, '-o', 'libhello4.wasm', 'hello4.c', '-sSIDE_MODULE'])
+    self.run_process([EMCC, '-o', 'hello1.wasm', 'hello1.c', '-sSIDE_MODULE'])
+    self.run_process([EMCC, '-o', 'hello2.wasm', 'hello2.c', '-sSIDE_MODULE'])
+    self.run_process([EMCC, '-o', 'hello3.wasm', 'hello3.c', '-sSIDE_MODULE'])
+    self.run_process([EMCC, '-o', 'hello4.wasm', 'hello4.c', '-sSIDE_MODULE'])
     self.run_process([EMCC, '--profiling-funcs', '-o', 'main.js', 'main.c', '-sMAIN_MODULE=2', '-sINITIAL_MEMORY=32Mb',
-                      '--embed-file', 'libhello1.wasm@/lib/libhello1.wasm',
-                      '--embed-file', 'libhello2.wasm@/usr/lib/libhello2.wasm',
-                      '--embed-file', 'libhello3.wasm@/libhello3.wasm',
-                      '--embed-file', 'libhello4.wasm@/usr/local/lib/libhello4.wasm',
-                      'libhello1.wasm', 'libhello2.wasm', 'libhello3.wasm', 'libhello4.wasm', '-sNO_AUTOLOAD_DYLIBS',
+                      '--embed-file', 'hello1.wasm@/lib/libhello1.wasm',
+                      '--embed-file', 'hello2.wasm@/usr/lib/libhello2.wasm',
+                      '--embed-file', 'hello3.wasm@/libhello3.wasm',
+                      '--embed-file', 'hello4.wasm@/usr/local/lib/libhello4.wasm',
+                      'hello1.wasm', 'hello2.wasm', 'hello3.wasm', 'hello4.wasm', '-sNO_AUTOLOAD_DYLIBS',
                       '--pre-js', 'pre.js'])
     out = self.run_js('main.js')
     self.assertContained('Hello1', out)