Separate art::Exec from utils

The rest of utils.cc does not depend on art::Runtime. This separates
the part dependent on that class, so that including utils.cc in the
build does not require the entire Runtime. Another preparatory cleanup
to getting tools to build on Windows.

Bug: 22322814
Test: test-art
Change-Id: I194ff363fc2ab87e5311ecea6973a2d0fad2621d

1 files changed, 102 insertions, 0 deletions

diff --git a/runtime/exec_utils.cc b/runtime/exec_utils.cc
new file mode 100644
index 0000000000..9efb1a353c
--- /dev/null
+++ b/runtime/exec_utils.cc
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "exec_utils.h"
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <string>
+#include <vector>
+
+#include "android-base/stringprintf.h"
+#include "android-base/strings.h"
+
+#include "runtime.h"
+
+namespace art {
+
+using android::base::StringAppendF;
+using android::base::StringPrintf;
+
+int ExecAndReturnCode(std::vector<std::string>& arg_vector, std::string* error_msg) {
+  const std::string command_line(android::base::Join(arg_vector, ' '));
+  CHECK_GE(arg_vector.size(), 1U) << command_line;
+
+  // Convert the args to char pointers.
+  const char* program = arg_vector[0].c_str();
+  std::vector<char*> args;
+  for (size_t i = 0; i < arg_vector.size(); ++i) {
+    const std::string& arg = arg_vector[i];
+    char* arg_str = const_cast<char*>(arg.c_str());
+    CHECK(arg_str != nullptr) << i;
+    args.push_back(arg_str);
+  }
+  args.push_back(nullptr);
+
+  // fork and exec
+  pid_t pid = fork();
+  if (pid == 0) {
+    // no allocation allowed between fork and exec
+
+    // change process groups, so we don't get reaped by ProcessManager
+    setpgid(0, 0);
+
+    // (b/30160149): protect subprocesses from modifications to LD_LIBRARY_PATH, etc.
+    // Use the snapshot of the environment from the time the runtime was created.
+    char** envp = (Runtime::Current() == nullptr) ? nullptr : Runtime::Current()->GetEnvSnapshot();
+    if (envp == nullptr) {
+      execv(program, &args[0]);
+    } else {
+      execve(program, &args[0], envp);
+    }
+    PLOG(ERROR) << "Failed to execve(" << command_line << ")";
+    // _exit to avoid atexit handlers in child.
+    _exit(1);
+  } else {
+    if (pid == -1) {
+      *error_msg = StringPrintf("Failed to execv(%s) because fork failed: %s",
+                                command_line.c_str(), strerror(errno));
+      return -1;
+    }
+
+    // wait for subprocess to finish
+    int status = -1;
+    pid_t got_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
+    if (got_pid != pid) {
+      *error_msg = StringPrintf("Failed after fork for execv(%s) because waitpid failed: "
+                                "wanted %d, got %d: %s",
+                                command_line.c_str(), pid, got_pid, strerror(errno));
+      return -1;
+    }
+    if (WIFEXITED(status)) {
+      return WEXITSTATUS(status);
+    }
+    return -1;
+  }
+}
+
+bool Exec(std::vector<std::string>& arg_vector, std::string* error_msg) {
+  int status = ExecAndReturnCode(arg_vector, error_msg);
+  if (status != 0) {
+    const std::string command_line(android::base::Join(arg_vector, ' '));
+    *error_msg = StringPrintf("Failed execv(%s) because non-0 exit status",
+                              command_line.c_str());
+    return false;
+  }
+  return true;
+}
+
+}  // namespace art