summaryrefslogtreecommitdiffstats
path: root/base/os_compat_android.cc
blob: b2756b2b2264dd44a35afb30c9ddfa4e21f8594a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/os_compat_android.h"

#include <asm/unistd.h>
#include <errno.h>
#include <math.h>
#include <sys/stat.h>
#include <sys/syscall.h>

#if !defined(__LP64__)
#include <time64.h>
#endif

#include "base/rand_util.h"
#include "base/strings/string_piece.h"
#include "base/strings/stringprintf.h"

extern "C" {
// There is no futimes() avaiable in Bionic, so we provide our own
// implementation until it is there.
int futimes(int fd, const struct timeval tv[2]) {
  if (tv == NULL)
    return syscall(__NR_utimensat, fd, NULL, NULL, 0);

  if (tv[0].tv_usec < 0 || tv[0].tv_usec >= 1000000 ||
      tv[1].tv_usec < 0 || tv[1].tv_usec >= 1000000) {
    errno = EINVAL;
    return -1;
  }

  // Convert timeval to timespec.
  struct timespec ts[2];
  ts[0].tv_sec = tv[0].tv_sec;
  ts[0].tv_nsec = tv[0].tv_usec * 1000;
  ts[1].tv_sec = tv[1].tv_sec;
  ts[1].tv_nsec = tv[1].tv_usec * 1000;
  return syscall(__NR_utimensat, fd, NULL, ts, 0);
}

#if !defined(__LP64__)
// 32-bit Android has only timegm64() and not timegm().
// We replicate the behaviour of timegm() when the result overflows time_t.
time_t timegm(struct tm* const t) {
  // time_t is signed on Android.
  static const time_t kTimeMax = ~(1L << (sizeof(time_t) * CHAR_BIT - 1));
  static const time_t kTimeMin = (1L << (sizeof(time_t) * CHAR_BIT - 1));
  time64_t result = timegm64(t);
  if (result < kTimeMin || result > kTimeMax)
    return -1;
  return result;
}
#endif

// The following is only needed when building with GCC 4.6 or higher
// (i.e. not with Android GCC 4.4.3, nor with Clang).
//
// GCC is now capable of optimizing successive calls to sin() and cos() into
// a single call to sincos(). This means that source code that looks like:
//
//     double c, s;
//     c = cos(angle);
//     s = sin(angle);
//
// Will generate machine code that looks like:
//
//     double c, s;
//     sincos(angle, &s, &c);
//
// Unfortunately, sincos() and friends are not part of the Android libm.so
// library provided by the NDK for API level 9. When the optimization kicks
// in, it makes the final build fail with a puzzling message (puzzling
// because 'sincos' doesn't appear anywhere in the sources!).
//
// To solve this, we provide our own implementation of the sincos() function
// and related friends. Note that we must also explicitely tell GCC to disable
// optimizations when generating these. Otherwise, the generated machine code
// for each function would simply end up calling itself, resulting in a
// runtime crash due to stack overflow.
//
#if defined(__GNUC__) && !defined(__clang__) && \
    !defined(ANDROID_SINCOS_PROVIDED)

// For the record, Clang does not support the 'optimize' attribute.
// In the unlikely event that it begins performing this optimization too,
// we'll have to find a different way to achieve this. NOTE: Tested with O1
// which still performs the optimization.
//
#define GCC_NO_OPTIMIZE  __attribute__((optimize("O0")))

GCC_NO_OPTIMIZE
void sincos(double angle, double* s, double *c) {
  *c = cos(angle);
  *s = sin(angle);
}

GCC_NO_OPTIMIZE
void sincosf(float angle, float* s, float* c) {
  *c = cosf(angle);
  *s = sinf(angle);
}

#endif // __GNUC__ && !__clang__

// An implementation of mkdtemp, since it is not exposed by the NDK
// for native API level 9 that we target.
//
// For any changes in the mkdtemp function, you should manually run the unittest
// OsCompatAndroidTest.DISABLED_TestMkdTemp in your local machine to check if it
// passes. Please don't enable it, since it creates a directory and may be
// source of flakyness.
char* mkdtemp(char* path) {
  if (path == NULL) {
    errno = EINVAL;
    return NULL;
  }

  const int path_len = strlen(path);

  // The last six characters of 'path' must be XXXXXX.
  const base::StringPiece kSuffix("XXXXXX");
  const int kSuffixLen = kSuffix.length();
  if (!base::StringPiece(path, path_len).ends_with(kSuffix)) {
    errno = EINVAL;
    return NULL;
  }

  // If the path contains a directory, as in /tmp/foo/XXXXXXXX, make sure
  // that /tmp/foo exists, otherwise we're going to loop a really long
  // time for nothing below
  char* dirsep = strrchr(path, '/');
  if (dirsep != NULL) {
    struct stat st;
    int ret;

    *dirsep = '\0';  // Terminating directory path temporarily

    ret = stat(path, &st);

    *dirsep = '/';  // Restoring directory separator
    if (ret < 0)  // Directory probably does not exist
      return NULL;
    if (!S_ISDIR(st.st_mode)) {  // Not a directory
      errno = ENOTDIR;
      return NULL;
    }
  }

  // Max number of tries using different random suffixes.
  const int kMaxTries = 100;

  // Now loop until we CAN create a directory by that name or we reach the max
  // number of tries.
  for (int i = 0; i < kMaxTries; ++i) {
    // Fill the suffix XXXXXX with a random string composed of a-z chars.
    for (int pos = 0; pos < kSuffixLen; ++pos) {
      char rand_char = static_cast<char>(base::RandInt('a', 'z'));
      path[path_len - kSuffixLen + pos] = rand_char;
    }
    if (mkdir(path, 0700) == 0) {
      // We just created the directory succesfully.
      return path;
    }
    if (errno != EEXIST) {
      // The directory doesn't exist, but an error occured
      return NULL;
    }
  }

  // We reached the max number of tries.
  return NULL;
}

}  // extern "C"