am dd9fbc86: am 8e630dac: Merge "Simple tests for dladdr(3)."

* commit 'dd9fbc8646178dc34a92c5fbc0adc8b503cc3cd9':
  Simple tests for dladdr(3).

tests/dlopen_test.cpp

@@ -17,6 +17,12 @@
 #include <gtest/gtest.h>
 
 #include <dlfcn.h>
+#include <libgen.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdint.h>
+
+#include <string>
 
 static bool gCalled = false;
 extern "C" void DlSymTestFunction() {
@@ -36,3 +42,69 @@ TEST(dlopen, dlsym_in_self) {
   function();
   ASSERT_TRUE(gCalled);
 }
+
+TEST(dlopen, dladdr) {
+  void* self = dlopen(NULL, RTLD_NOW);
+  ASSERT_TRUE(self != NULL);
+
+  void* sym = dlsym(self, "DlSymTestFunction");
+  ASSERT_TRUE(sym != NULL);
+
+  // Deliberately ask dladdr for an address inside a symbol, rather than the symbol base address.
+  void* addr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(sym) + 2);
+
+  Dl_info info;
+  int rc = dladdr(addr, &info);
+  ASSERT_NE(rc, 0); // Zero on error, non-zero on success.
+
+  // Get the name of this executable.
+  char executable_path[PATH_MAX];
+  rc = readlink("/proc/self/exe", executable_path, sizeof(executable_path));
+  ASSERT_NE(rc, -1);
+  executable_path[rc] = '\0';
+  std::string executable_name(basename(executable_path));
+
+  // The filename should be that of this executable.
+  // Note that we don't know whether or not we have the full path, so we want an "ends_with" test.
+  std::string dli_fname(info.dli_fname);
+  dli_fname = basename(&dli_fname[0]);
+  ASSERT_EQ(dli_fname, executable_name);
+
+  // The symbol name should be the symbol we looked up.
+  ASSERT_STREQ(info.dli_sname, "DlSymTestFunction");
+
+  // The address should be the exact address of the symbol.
+  ASSERT_EQ(info.dli_saddr, sym);
+
+  // Look in /proc/pid/maps to find out what address we were loaded at.
+  // TODO: factor /proc/pid/maps parsing out into a class and reuse all over bionic.
+  void* base_address = NULL;
+  char path[PATH_MAX];
+  snprintf(path, sizeof(path), "/proc/%d/maps", getpid());
+  char line[BUFSIZ];
+  FILE* fp = fopen(path, "r");
+  ASSERT_TRUE(fp != NULL);
+  while (fgets(line, sizeof(line), fp) != NULL) {
+    uintptr_t start = strtoul(line, 0, 16);
+    line[strlen(line) - 1] = '\0'; // Chomp the '\n'.
+    char* path = strchr(line, '/');
+    if (strcmp(executable_path, path) == 0) {
+      base_address = reinterpret_cast<void*>(start);
+      break;
+    }
+  }
+  fclose(fp);
+
+  // The base address should be the address we were loaded at.
+  ASSERT_EQ(info.dli_fbase, base_address);
+}
+
+TEST(dlopen, dladdr_invalid) {
+  Dl_info info;
+
+  // No symbol corresponding to NULL.
+  ASSERT_EQ(dladdr(NULL, &info), 0); // Zero on error, non-zero on success.
+
+  // No symbol corresponding to a stack address.
+  ASSERT_EQ(dladdr(&info, &info), 0); // Zero on error, non-zero on success.
+}