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