1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "base/os_compat_android.h"
6
7#include <asm/unistd.h>
8#include <errno.h>
9#include <math.h>
10#include <sys/stat.h>
11#include <sys/syscall.h>
12
13#if !defined(__LP64__)
14#include <time64.h>
15#endif
16
17#include "base/rand_util.h"
18#include "base/strings/string_piece.h"
19#include "base/strings/stringprintf.h"
20
21extern "C" {
22// There is no futimes() avaiable in Bionic, so we provide our own
23// implementation until it is there.
24int futimes(int fd, const struct timeval tv[2]) {
25  if (tv == NULL)
26    return syscall(__NR_utimensat, fd, NULL, NULL, 0);
27
28  if (tv[0].tv_usec < 0 || tv[0].tv_usec >= 1000000 ||
29      tv[1].tv_usec < 0 || tv[1].tv_usec >= 1000000) {
30    errno = EINVAL;
31    return -1;
32  }
33
34  // Convert timeval to timespec.
35  struct timespec ts[2];
36  ts[0].tv_sec = tv[0].tv_sec;
37  ts[0].tv_nsec = tv[0].tv_usec * 1000;
38  ts[1].tv_sec = tv[1].tv_sec;
39  ts[1].tv_nsec = tv[1].tv_usec * 1000;
40  return syscall(__NR_utimensat, fd, NULL, ts, 0);
41}
42
43#if !defined(__LP64__)
44// 32-bit Android has only timegm64() and not timegm().
45// We replicate the behaviour of timegm() when the result overflows time_t.
46time_t timegm(struct tm* const t) {
47  // time_t is signed on Android.
48  static const time_t kTimeMax = ~(1L << (sizeof(time_t) * CHAR_BIT - 1));
49  static const time_t kTimeMin = (1L << (sizeof(time_t) * CHAR_BIT - 1));
50  time64_t result = timegm64(t);
51  if (result < kTimeMin || result > kTimeMax)
52    return -1;
53  return result;
54}
55#endif
56
57// The following is only needed when building with GCC 4.6 or higher
58// (i.e. not with Android GCC 4.4.3, nor with Clang).
59//
60// GCC is now capable of optimizing successive calls to sin() and cos() into
61// a single call to sincos(). This means that source code that looks like:
62//
63//     double c, s;
64//     c = cos(angle);
65//     s = sin(angle);
66//
67// Will generate machine code that looks like:
68//
69//     double c, s;
70//     sincos(angle, &s, &c);
71//
72// Unfortunately, sincos() and friends are not part of the Android libm.so
73// library provided by the NDK for API level 9. When the optimization kicks
74// in, it makes the final build fail with a puzzling message (puzzling
75// because 'sincos' doesn't appear anywhere in the sources!).
76//
77// To solve this, we provide our own implementation of the sincos() function
78// and related friends. Note that we must also explicitely tell GCC to disable
79// optimizations when generating these. Otherwise, the generated machine code
80// for each function would simply end up calling itself, resulting in a
81// runtime crash due to stack overflow.
82//
83#if defined(__GNUC__) && !defined(__clang__) && \
84    !defined(ANDROID_SINCOS_PROVIDED)
85
86// For the record, Clang does not support the 'optimize' attribute.
87// In the unlikely event that it begins performing this optimization too,
88// we'll have to find a different way to achieve this. NOTE: Tested with O1
89// which still performs the optimization.
90//
91#define GCC_NO_OPTIMIZE  __attribute__((optimize("O0")))
92
93GCC_NO_OPTIMIZE
94void sincos(double angle, double* s, double *c) {
95  *c = cos(angle);
96  *s = sin(angle);
97}
98
99GCC_NO_OPTIMIZE
100void sincosf(float angle, float* s, float* c) {
101  *c = cosf(angle);
102  *s = sinf(angle);
103}
104
105#endif // __GNUC__ && !__clang__
106
107// An implementation of mkdtemp, since it is not exposed by the NDK
108// for native API level 9 that we target.
109//
110// For any changes in the mkdtemp function, you should manually run the unittest
111// OsCompatAndroidTest.DISABLED_TestMkdTemp in your local machine to check if it
112// passes. Please don't enable it, since it creates a directory and may be
113// source of flakyness.
114char* mkdtemp(char* path) {
115  if (path == NULL) {
116    errno = EINVAL;
117    return NULL;
118  }
119
120  const int path_len = strlen(path);
121
122  // The last six characters of 'path' must be XXXXXX.
123  const base::StringPiece kSuffix("XXXXXX");
124  const int kSuffixLen = kSuffix.length();
125  if (!base::StringPiece(path, path_len).ends_with(kSuffix)) {
126    errno = EINVAL;
127    return NULL;
128  }
129
130  // If the path contains a directory, as in /tmp/foo/XXXXXXXX, make sure
131  // that /tmp/foo exists, otherwise we're going to loop a really long
132  // time for nothing below
133  char* dirsep = strrchr(path, '/');
134  if (dirsep != NULL) {
135    struct stat st;
136    int ret;
137
138    *dirsep = '\0';  // Terminating directory path temporarily
139
140    ret = stat(path, &st);
141
142    *dirsep = '/';  // Restoring directory separator
143    if (ret < 0)  // Directory probably does not exist
144      return NULL;
145    if (!S_ISDIR(st.st_mode)) {  // Not a directory
146      errno = ENOTDIR;
147      return NULL;
148    }
149  }
150
151  // Max number of tries using different random suffixes.
152  const int kMaxTries = 100;
153
154  // Now loop until we CAN create a directory by that name or we reach the max
155  // number of tries.
156  for (int i = 0; i < kMaxTries; ++i) {
157    // Fill the suffix XXXXXX with a random string composed of a-z chars.
158    for (int pos = 0; pos < kSuffixLen; ++pos) {
159      char rand_char = static_cast<char>(base::RandInt('a', 'z'));
160      path[path_len - kSuffixLen + pos] = rand_char;
161    }
162    if (mkdir(path, 0700) == 0) {
163      // We just created the directory succesfully.
164      return path;
165    }
166    if (errno != EEXIST) {
167      // The directory doesn't exist, but an error occured
168      return NULL;
169    }
170  }
171
172  // We reached the max number of tries.
173  return NULL;
174}
175
176}  // extern "C"
177