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#include "util/file_piece.hh"
#include "util/exception.hh"
#include <iostream>
#include <string>
#include <limits>
#include <assert.h>
#include <cstdlib>
#include <ctype.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
namespace util {
EndOfFileException::EndOfFileException() throw() {
*this << "End of file";
}
EndOfFileException::~EndOfFileException() throw() {}
ParseNumberException::ParseNumberException(StringPiece value) throw() {
*this << "Could not parse \"" << value << "\" into a float";
}
int OpenReadOrThrow(const char *name) {
int ret = open(name, O_RDONLY);
if (ret == -1) UTIL_THROW(ErrnoException, "in open (" << name << ") for reading");
return ret;
}
off_t SizeFile(int fd) {
struct stat sb;
if (fstat(fd, &sb) == -1 || (!sb.st_size && !S_ISREG(sb.st_mode))) return kBadSize;
return sb.st_size;
}
FilePiece::FilePiece(const char *name, std::ostream *show_progress, off_t min_buffer) :
file_(OpenReadOrThrow(name)), total_size_(SizeFile(file_.get())), page_(sysconf(_SC_PAGE_SIZE)),
progress_(total_size_ == kBadSize ? NULL : show_progress, std::string("Reading ") + name, total_size_) {
Initialize(name, show_progress, min_buffer);
}
FilePiece::FilePiece(const char *name, int fd, std::ostream *show_progress, off_t min_buffer) :
file_(fd), total_size_(SizeFile(file_.get())), page_(sysconf(_SC_PAGE_SIZE)),
progress_(total_size_ == kBadSize ? NULL : show_progress, std::string("Reading ") + name, total_size_) {
Initialize(name, show_progress, min_buffer);
}
void FilePiece::Initialize(const char *name, std::ostream *show_progress, off_t min_buffer) {
if (total_size_ == kBadSize) {
fallback_to_read_ = true;
if (show_progress)
*show_progress << "File " << name << " isn't normal. Using slower read() instead of mmap(). No progress bar." << std::endl;
} else {
fallback_to_read_ = false;
}
default_map_size_ = page_ * std::max<off_t>((min_buffer / page_ + 1), 2);
position_ = NULL;
position_end_ = NULL;
mapped_offset_ = 0;
at_end_ = false;
Shift();
}
float FilePiece::ReadFloat() throw(EndOfFileException, ParseNumberException) {
SkipSpaces();
while (last_space_ < position_) {
if (at_end_) {
// Hallucinate a null off the end of the file.
std::string buffer(position_, position_end_);
char *end;
float ret = std::strtof(buffer.c_str(), &end);
if (buffer.c_str() == end) throw ParseNumberException(buffer);
position_ += end - buffer.c_str();
return ret;
}
Shift();
}
char *end;
float ret = std::strtof(position_, &end);
if (end == position_) throw ParseNumberException(ReadDelimited());
position_ = end;
return ret;
}
void FilePiece::SkipSpaces() throw (EndOfFileException) {
for (; ; ++position_) {
if (position_ == position_end_) Shift();
if (!isspace(*position_)) return;
}
}
const char *FilePiece::FindDelimiterOrEOF() throw (EndOfFileException) {
for (const char *i = position_; i <= last_space_; ++i) {
if (isspace(*i)) return i;
}
while (!at_end_) {
size_t skip = position_end_ - position_;
Shift();
for (const char *i = position_ + skip; i <= last_space_; ++i) {
if (isspace(*i)) return i;
}
}
return position_end_;
}
StringPiece FilePiece::ReadLine(char delim) throw (EndOfFileException) {
const char *start = position_;
do {
for (const char *i = start; i < position_end_; ++i) {
if (*i == delim) {
StringPiece ret(position_, i - position_);
position_ = i + 1;
return ret;
}
}
size_t skip = position_end_ - position_;
Shift();
start = position_ + skip;
} while (!at_end_);
StringPiece ret(position_, position_end_ - position_);
position_ = position_end_;
return position_;
}
void FilePiece::Shift() throw(EndOfFileException) {
if (at_end_) throw EndOfFileException();
off_t desired_begin = position_ - data_.begin() + mapped_offset_;
progress_.Set(desired_begin);
if (!fallback_to_read_) MMapShift(desired_begin);
// Notice an mmap failure might set the fallback.
if (fallback_to_read_) ReadShift(desired_begin);
for (last_space_ = position_end_ - 1; last_space_ >= position_; --last_space_) {
if (isspace(*last_space_)) break;
}
}
void FilePiece::MMapShift(off_t desired_begin) throw() {
// Use mmap.
off_t ignore = desired_begin % page_;
// Duplicate request for Shift means give more data.
if (position_ == data_.begin() + ignore) {
default_map_size_ *= 2;
}
// Local version so that in case of failure it doesn't overwrite the class variable.
off_t mapped_offset = desired_begin - ignore;
off_t mapped_size;
if (default_map_size_ >= static_cast<size_t>(total_size_ - mapped_offset)) {
at_end_ = true;
mapped_size = total_size_ - mapped_offset;
} else {
mapped_size = default_map_size_;
}
// Forcibly clear the existing mmap first.
data_.reset();
data_.reset(mmap(NULL, mapped_size, PROT_READ, MAP_PRIVATE, *file_, mapped_offset), mapped_size, scoped_memory::MMAP_ALLOCATED);
if (data_.get() == MAP_FAILED) {
fallback_to_read_ = true;
if (desired_begin) {
if (((off_t)-1) == lseek(*file_, desired_begin, SEEK_SET)) UTIL_THROW(ErrnoException, "mmap failed even though it worked before. lseek failed too, so using read isn't an option either.");
}
return;
}
mapped_offset_ = mapped_offset;
position_ = data_.begin() + ignore;
position_end_ = data_.begin() + mapped_size;
}
void FilePiece::ReadShift(off_t desired_begin) throw() {
assert(fallback_to_read_);
if (data_.source() != scoped_memory::MALLOC_ALLOCATED) {
// First call.
data_.reset();
data_.reset(malloc(default_map_size_), default_map_size_, scoped_memory::MALLOC_ALLOCATED);
if (!data_.get()) UTIL_THROW(ErrnoException, "malloc failed for " << default_map_size_);
position_ = data_.begin();
position_end_ = position_;
}
// Bytes [data_.begin(), position_) have been consumed.
// Bytes [position_, position_end_) have been read into the buffer.
// Start at the beginning of the buffer if there's nothing useful in it.
if (position_ == position_end_) {
mapped_offset_ += (position_end_ - data_.begin());
position_ = data_.begin();
position_end_ = position_;
}
std::size_t already_read = position_end_ - data_.begin();
if (already_read == default_map_size_) {
if (position_ == data_.begin()) {
// Buffer too small.
std::size_t valid_length = position_end_ - position_;
default_map_size_ *= 2;
data_.call_realloc(default_map_size_);
if (!data_.get()) UTIL_THROW(ErrnoException, "realloc failed for " << default_map_size_);
position_ = data_.begin();
position_end_ = position_ + valid_length;
} else {
size_t moving = position_end_ - position_;
memmove(data_.get(), position_, moving);
position_ = data_.begin();
position_end_ = position_ + moving;
already_read = moving;
}
}
ssize_t read_return = read(file_.get(), static_cast<char*>(data_.get()) + already_read, default_map_size_ - already_read);
if (read_return == -1) UTIL_THROW(ErrnoException, "read failed");
if (read_return == 0) at_end_ = true;
position_end_ += read_return;
}
} // namespace util
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