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Diffstat (limited to 'base/os_compat_android.cc')
-rw-r--r-- | base/os_compat_android.cc | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/base/os_compat_android.cc b/base/os_compat_android.cc new file mode 100644 index 0000000000..c1a2ac86dd --- /dev/null +++ b/base/os_compat_android.cc @@ -0,0 +1,178 @@ +// 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 <limits.h> +#include <math.h> +#include <sys/stat.h> +#include <sys/syscall.h> +#include <unistd.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" |