OutputFile.cpp revision eee91d73534835e42c4011c5e8bb051be86c6694 
1/*
2 * Copyright 2012, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "bcc/Support/OutputFile.h"
18
19#include <cstdlib>
20
21#include <llvm/Support/raw_ostream.h>
22
23#include "bcc/Support/Log.h"
24
25using namespace bcc;
26
27OutputFile *OutputFile::CreateTemporary(const std::string &pFileTemplate,
28                                        unsigned pFlags) {
29  char *tmp_filename = NULL;
30  int tmp_fd;
31  OutputFile *result = NULL;
32
33  // Allocate memory to hold the generated unique temporary filename.
34  tmp_filename =
35      new (std::nothrow) char [ pFileTemplate.length() + /* .XXXXXX */7 + 1 ];
36  if (tmp_filename == NULL) {
37    ALOGE("Out of memory when allocates memory for filename %s in "
38          "OutputFile::CreateTemporary()!", pFileTemplate.c_str());
39    return NULL;
40  }
41
42  // Construct filename template for mkstemp().
43  if (pFileTemplate.length() > 0)
44    ::memcpy(tmp_filename, pFileTemplate.c_str(), pFileTemplate.length());
45  ::strncpy(tmp_filename + pFileTemplate.length(), ".XXXXXX", 7);
46
47  // POSIX mkstemp() never returns EINTR.
48  tmp_fd = ::mkstemp(tmp_filename);
49  if (tmp_fd < 0) {
50    llvm::error_code err(errno, llvm::posix_category());
51    ALOGE("Failed to create temporary file using mkstemp() for %s! (%s)",
52          tmp_filename, err.message().c_str());
53    delete [] tmp_filename;
54    return NULL;
55  }
56
57  // Create result OutputFile.
58  result = new (std::nothrow) OutputFile(tmp_filename, pFlags);
59  if (result == NULL) {
60    ALOGE("Out of memory when creates OutputFile for %s!", tmp_filename);
61    // Fall through to the clean-up codes.
62  } else {
63    if (result->hasError()) {
64      ALOGE("Failed to open temporary output file %s! (%s)",
65            result->getName().c_str(), result->getErrorMessage().c_str());
66      delete result;
67      result = NULL;
68      // Fall through to the clean-up codes.
69    }
70  }
71
72  // Clean up.
73  delete [] tmp_filename;
74  ::close(tmp_fd);
75
76  return result;
77}
78
79OutputFile::OutputFile(const std::string &pFilename, unsigned pFlags)
80  : super(pFilename, pFlags) { }
81
82ssize_t OutputFile::write(const void *pBuf, size_t count) {
83  if ((mFD < 0) || hasError()) {
84    return -1;
85  }
86
87  if ((count <= 0) || (pBuf == NULL)) {
88    // Keep safe and issue a warning.
89    ALOGW("OutputFile::write: count = %zu, buffer = %p", count, pBuf);
90    return 0;
91  }
92
93  while (count > 0) {
94    ssize_t write_size = ::write(mFD, pBuf, count);
95
96    if (write_size > 0) {
97      return write_size;
98    } else if ((errno == EAGAIN) || (errno == EINTR)) {
99      // If the errno is EAGAIN or EINTR, then we try to write again.
100      //
101      // Fall-through
102    } else {
103      detectError();
104      return -1;
105    }
106  }
107  // unreachable
108  return 0;
109}
110
111void OutputFile::truncate() {
112  if (mFD < 0) {
113    return;
114  }
115
116  do {
117    if (::ftruncate(mFD, 0) == 0) {
118      return;
119    }
120  } while (errno == EINTR);
121  detectError();
122
123  return;
124}
125
126llvm::raw_fd_ostream *OutputFile::dup() {
127  int newfd;
128
129  do {
130    newfd = ::dup(mFD);
131    if (newfd < 0) {
132      if (errno != EINTR) {
133        detectError();
134        return NULL;
135      }
136      // EINTR
137      continue;
138    }
139    // dup() returns ok.
140    break;
141  } while (true);
142
143  llvm::raw_fd_ostream *result =
144      new (std::nothrow) llvm::raw_fd_ostream(newfd, /* shouldClose */true);
145
146  if (result == NULL) {
147    mError.assign(llvm::errc::not_enough_memory, llvm::system_category());
148  }
149
150  return result;
151}
152