commit 22fb267ad6f95ab083abb56e914f8081552108a7
author Elliott Hughes <enh@google.com> Fri Nov 01 08:07:25 2019 -0700
committer Elliott Hughes <enh@google.com> Wed Jan 22 18:30:50 2020 -0800
tree 6c29afacad5803924a83a0430ea509eaa76a0564
parent 73e9f242ed07631798433df4e35f5f73443cb9f9

Reimplement realpath.

Use O_PATH like musl to let the kernel do the hard work, rather than the
traditional BSD manual scheme.

Also add the most obvious missing tests from reading the man page, plus
a non-obvious test for deleted files.

Bug: http://b/131435126
Test: treehugger
Change-Id: Ie8a8986fea55f045952a81afee377ce8288a49d5

tests/stdlib_test.cpp

diff --git a/tests/stdlib_test.cpp b/tests/stdlib_test.cpp
index ff4cb71..c522fff 100644
--- a/tests/stdlib_test.cpp
+++ b/tests/stdlib_test.cpp
@@ -29,6 +29,7 @@
 #include <limits>
 #include <string>
 
+#include <android-base/file.h>
 #include <android-base/macros.h>
 #include <gtest/gtest.h>
 
@@ -36,6 +37,8 @@
 #include "math_data_test.h"
 #include "utils.h"
 
+using namespace std::string_literals;
+
 template <typename T = int (*)(char*)>
 class GenericTemporaryFile {
  public:
@@ -322,6 +325,17 @@
   ASSERT_EQ(ENOENT, errno);
 }
 
+TEST(stdlib, realpath__ELOOP) {
+  TemporaryDir td;
+  std::string link = std::string(td.path) + "/loop";
+  ASSERT_EQ(0, symlink(link.c_str(), link.c_str()));
+
+  errno = 0;
+  char* p = realpath(link.c_str(), nullptr);
+  ASSERT_TRUE(p == nullptr);
+  ASSERT_EQ(ELOOP, errno);
+}
+
 TEST(stdlib, realpath__component_after_non_directory) {
   errno = 0;
   char* p = realpath("/dev/null/.", nullptr);
@@ -350,6 +364,47 @@
   free(p);
 }
 
+TEST(stdlib, realpath__dot) {
+  char* p = realpath("/proc/./version", nullptr);
+  ASSERT_STREQ("/proc/version", p);
+  free(p);
+}
+
+TEST(stdlib, realpath__dot_dot) {
+  char* p = realpath("/dev/../proc/version", nullptr);
+  ASSERT_STREQ("/proc/version", p);
+  free(p);
+}
+
+TEST(stdlib, realpath__deleted) {
+  TemporaryDir td;
+
+  // Create a file "A".
+  std::string A_path = td.path + "/A"s;
+  ASSERT_TRUE(android::base::WriteStringToFile("test\n", A_path));
+
+  // Get an O_PATH fd for it.
+  android::base::unique_fd fd(open(A_path.c_str(), O_PATH));
+  ASSERT_NE(fd, -1);
+
+  // Create a file "A (deleted)".
+  android::base::unique_fd fd2(open((td.path + "/A (deleted)"s).c_str(),
+                                    O_CREAT | O_TRUNC | O_WRONLY, 0644));
+  ASSERT_NE(fd2, -1);
+
+  // Delete "A".
+  ASSERT_EQ(0, unlink(A_path.c_str()));
+
+  // Now realpath() on the O_PATH fd, and check we *don't* get "A (deleted)".
+  std::string path = android::base::StringPrintf("/proc/%d/fd/%d", static_cast<int>(getpid()),
+                                                 fd.get());
+  errno = 0;
+  char* result = realpath(path.c_str(), nullptr);
+  ASSERT_EQ(nullptr, result) << result;
+  ASSERT_EQ(ENOENT, errno);
+  free(result);
+}
+
 TEST(stdlib, qsort) {
   struct s {
     char name[16];