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// Copyright 2019 Roman Perepelitsa.
//
// This file is part of GitStatus.
//
// GitStatus is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GitStatus is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with GitStatus. If not, see <https://www.gnu.org/licenses/>.
#include "dir.h"
#include <algorithm>
#include <atomic>
#include <cerrno>
#include <cstring>
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#ifdef __linux__
#include <endian.h>
#include <sys/syscall.h>
#endif
#ifdef __APPLE__
#include <iconv.h>
#endif
#include "bits.h"
#include "check.h"
#include "scope_guard.h"
#include "string_cmp.h"
#include "tribool.h"
namespace gitstatus {
namespace {
bool Dots(const char* name) {
if (name[0] == '.') {
if (name[1] == 0) return true;
if (name[1] == '.' && name[2] == 0) return true;
}
return false;
}
} // namespace
// The linux-specific implementation is about 20% faster than the generic (posix) implementation.
#ifdef __linux__
uint64_t Read64(const void* p) {
uint64_t res;
std::memcpy(&res, p, 8);
return res;
}
void Write64(uint64_t x, void* p) { std::memcpy(p, &x, 8); }
void SwapBytes(char** begin, char** end) {
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
for (; begin != end; ++begin) Write64(__builtin_bswap64(Read64(*begin)), *begin);
#elif __BYTE_ORDER__ != __ORDER_BIG_ENDIAN__
#error "sorry, not implemented"
#endif
}
template <bool kCaseSensitive>
void SortEntries(char** begin, char** end) {
static_assert(kCaseSensitive, "");
SwapBytes(begin, end);
std::sort(begin, end, [](const char* a, const char* b) {
uint64_t x = Read64(a);
uint64_t y = Read64(b);
// Add 5 for good luck.
return x < y || (x == y && std::memcmp(a + 5, b + 5, 256) < 0);
});
SwapBytes(begin, end);
}
template <>
void SortEntries<false>(char** begin, char** end) {
std::sort(begin, end, StrLt<false>());
}
bool ListDir(int dir_fd, Arena& arena, std::vector<char*>& entries, bool precompose_unicode,
bool case_sensitive) {
struct linux_dirent64 {
ino64_t d_ino;
off64_t d_off;
unsigned short d_reclen;
unsigned char d_type;
char d_name[];
};
constexpr size_t kBufSize = 8 << 10;
entries.clear();
while (true) {
char* buf = static_cast<char*>(arena.Allocate(kBufSize, alignof(linux_dirent64)));
// Save 256 bytes for the rainy day.
int n = syscall(SYS_getdents64, dir_fd, buf, kBufSize - 256);
if (n < 0) {
entries.clear();
return false;
}
for (int pos = 0; pos < n;) {
auto* ent = reinterpret_cast<linux_dirent64*>(buf + pos);
if (!Dots(ent->d_name)) entries.push_back(ent->d_name);
pos += ent->d_reclen;
}
if (n == 0) break;
// The following optimization relies on SYS_getdents64 always returning as many
// entries as would fit. This is not guaranteed by the specification and I don't
// know if this is true in practice. The optimization has no measurable effect on
// gitstatus performance, so it's turned off.
//
// if (n + sizeof(linux_dirent64) + 512 <= kBufSize) break;
}
if (case_sensitive) {
SortEntries<true>(entries.data(), entries.data() + entries.size());
} else {
SortEntries<false>(entries.data(), entries.data() + entries.size());
}
return true;
}
#else // __linux__
namespace {
char* DirentDup(Arena& arena, const struct dirent& ent, size_t len) {
char* p = arena.Allocate<char>(len + 2);
*p++ = ent.d_type;
std::memcpy(p, ent.d_name, len + 1);
return p;
}
#ifdef __APPLE__
std::atomic<bool> g_iconv_error(true);
Tribool IConvTry(char* inp, size_t ins, char* outp, size_t outs) {
if (outs == 0) return Tribool::kUnknown;
iconv_t ic = iconv_open("UTF-8", "UTF-8-MAC");
if (ic == (iconv_t)-1) {
if (g_iconv_error.load(std::memory_order_relaxed) &&
g_iconv_error.exchange(false, std::memory_order_relaxed)) {
LOG(ERROR) << "iconv_open(\"UTF-8\", \"UTF-8-MAC\") failed";
}
return Tribool::kFalse;
}
ON_SCOPE_EXIT(&) { CHECK(iconv_close(ic) == 0) << Errno(); };
--outs;
if (iconv(ic, &inp, &ins, &outp, &outs) >= 0) {
*outp = 0;
return Tribool::kTrue;
}
return errno == E2BIG ? Tribool::kUnknown : Tribool::kFalse;
}
char* DirenvConvert(Arena& arena, struct dirent& ent, bool do_convert) {
if (!do_convert) return DirentDup(arena, ent, std::strlen(ent.d_name));
size_t len = 0;
do_convert = false;
for (unsigned char c; (c = ent.d_name[len]); ++len) {
if (c & 0x80) do_convert = true;
}
if (!do_convert) return DirentDup(arena, ent, len);
size_t n = NextPow2(len + 2);
while (true) {
char* p = arena.Allocate<char>(n);
switch (IConvTry(ent.d_name, len, p + 1, n - 1)) {
case Tribool::kFalse:
return DirentDup(arena, ent, len);
case Tribool::kTrue:
*p = ent.d_type;
return p + 1;
case Tribool::kUnknown:
break;
}
n *= 2;
}
}
#else // __APPLE__
char* DirenvConvert(Arena& arena, struct dirent& ent, bool do_convert) {
return DirentDup(arena, ent, std::strlen(ent.d_name));
}
#endif // __APPLE__
} // namespace
bool ListDir(int dir_fd, Arena& arena, std::vector<char*>& entries, bool precompose_unicode,
bool case_sensitive) {
VERIFY((dir_fd = dup(dir_fd)) >= 0);
DIR* dir = fdopendir(dir_fd);
if (!dir) {
CHECK(!close(dir_fd)) << Errno();
return -1;
}
ON_SCOPE_EXIT(&) { CHECK(!closedir(dir)) << Errno(); };
entries.clear();
while (struct dirent* ent = (errno = 0, readdir(dir))) {
if (Dots(ent->d_name)) continue;
entries.push_back(DirenvConvert(arena, *ent, precompose_unicode));
}
if (errno) {
entries.clear();
return false;
}
StrSort(entries.data(), entries.data() + entries.size(), case_sensitive);
return true;
}
#endif // __linux__
} // namespace gitstatus
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