libcruft-util/io.cpp

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/*
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* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
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* http://www.apache.org/licenses/LICENSE-2.0
*
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* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2010-2018 Danny Robson <danny@nerdcruft.net>
*/
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#include "io.hpp"
#include "debug.hpp"
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#include "cast.hpp"
#include "format.hpp"
#include "posix/except.hpp"
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#include <cstdio>
#include <fcntl.h>
#include <sys/stat.h>
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#include <unistd.h>
#include <experimental/filesystem>
#include <stdexcept>
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using namespace util;
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//////////////////////////////////////////////////////////////////////////////
template <typename T>
std::vector<T>
util::slurp (const std::experimental::filesystem::path &path)
{
static_assert (
sizeof (T) == 1,
"slurp is designed for grabbing bytes, not complex structures"
);
posix::fd out (path, O_RDONLY | O_BINARY);
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// Calculate the total file size
off_t size = posix::error::try_value (lseek (out, 0, SEEK_END));
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posix::error::try_value (lseek (out, 0, SEEK_SET));
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// Allocate a buffer, and keep reading until it's full.
std::vector<T> buffer (size);
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CHECK_GE (size, 0);
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size_t remaining = (size_t)size;
T *cursor = buffer.data ();
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while (remaining) {
ssize_t consumed = posix::error::try_value(
::read (out, cursor, remaining)
);
CHECK_GT ( consumed, 0);
CHECK_LE ((size_t)consumed, remaining);
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remaining -= (size_t)consumed;
cursor += consumed;
}
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return buffer;
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}
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//-----------------------------------------------------------------------------
template std::vector<char> util::slurp (const std::experimental::filesystem::path&);
template std::vector<std::byte> util::slurp (const std::experimental::filesystem::path&);
///////////////////////////////////////////////////////////////////////////////
template <typename T>
std::vector<T>
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util::slurp (FILE *stream)
{
static_assert (
sizeof (T) == 1,
"slurp is designed for grabbing bytes, not complex structures"
);
// find how much data is in this file
const int desc = util::posix::error::try_value (fileno (stream));
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struct stat meta;
posix::error::try_value (fstat (desc, &meta));
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std::vector<T> buf;
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// we think we know the size, so try to do a simple read
if (meta.st_size) {
buf.resize (meta.st_size);
// read as much as possible, then resize to the actual length
auto res = fread (buf.data (), 1, meta.st_size, stream);
buf.resize (res);
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}
// try reading small chunks until we've hit the end. important for
// handling pipe streams (like from popen) which report a zero size.
constexpr size_t CHUNK_SIZE = 128;
size_t cursor = buf.size ();
while (!feof (stream) && !ferror (stream)) {
auto oldsize = buf.size ();
buf.resize (oldsize + CHUNK_SIZE);
auto res = fread (buf.data () + cursor, 1, CHUNK_SIZE, stream);
if (res != CHUNK_SIZE)
buf.resize (oldsize + res);
}
if (ferror (stream))
throw stream_error ();
return buf;
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}
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//-----------------------------------------------------------------------------
template std::vector<char> util::slurp (FILE*);
template std::vector<std::byte> util::slurp (FILE*);
///////////////////////////////////////////////////////////////////////////////
void
util::write (const posix::fd &out,
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const void *restrict data,
size_t bytes)
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{
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const char *restrict cursor = reinterpret_cast<const char*> (data);
size_t remaining = bytes;
while (remaining) {
ssize_t consumed = posix::error::try_value (::write (out, cursor, remaining));
remaining -= sign_cast<size_t> (consumed);
cursor += sign_cast<size_t> (consumed);
}
}
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//////////////////////////////////////////////////////////////////////////////
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int
indenter::overflow (int ch) {
if (m_line_start && ch != '\n')
m_dest->sputn (m_indent.data (), sign_cast<std::streamsize> (m_indent.size ()));
m_line_start = ch == '\n';
return m_dest->sputc (ch);
}
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//-----------------------------------------------------------------------------
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indenter::indenter (std::streambuf* _dest, size_t _indent)
: m_dest (_dest)
, m_line_start (true)
, m_indent (_indent, ' ')
, m_owner (NULL)
{ ; }
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//-----------------------------------------------------------------------------
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indenter::indenter (std::ostream& _dest, size_t _indent)
: m_dest (_dest.rdbuf())
, m_line_start (true)
, m_indent (_indent, ' ')
, m_owner (&_dest)
{
m_owner->rdbuf (this);
}
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//-----------------------------------------------------------------------------
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indenter::~indenter ()
{
if (m_owner != NULL)
m_owner->rdbuf (m_dest);
}
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//////////////////////////////////////////////////////////////////////////////
scoped_cwd::scoped_cwd ()
{
m_original.resize (16);
while (getcwd (&m_original[0], m_original.size ()) == nullptr && errno == ERANGE)
m_original.resize (m_original.size () * 2);
posix::error::try_code ();
}
//-----------------------------------------------------------------------------
scoped_cwd::~scoped_cwd ()
{
if (!chdir (m_original.c_str ()))
posix::error::throw_code ();
}
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///////////////////////////////////////////////////////////////////////////////
path_error::path_error (const std::experimental::filesystem::path &_path):
runtime_error (to_string (format::printf ("Unknown path: %!", m_path))),
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m_path (_path)
{ ; }
//-----------------------------------------------------------------------------
const std::experimental::filesystem::path&
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path_error::path (void) const noexcept
{
return m_path;
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}