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// file : libbutl/manifest-rewriter.cxx -*- C++ -*-
// license : MIT; see accompanying LICENSE file
#include <libbutl/manifest-rewriter.hxx>
#include <string>
#include <cassert>
#include <cstdint> // uint64_t
#include <cstddef> // size_t
#include <libbutl/utility.hxx> // utf8_length()
#include <libbutl/manifest-serializer.hxx>
using namespace std;
namespace butl
{
manifest_rewriter::
manifest_rewriter (path p, bool long_lines)
: path_ (move (p)),
long_lines_ (long_lines),
fd_ (fdopen (path_,
fdopen_mode::in |
fdopen_mode::out |
fdopen_mode::exclusive))
{
}
// Seek the file descriptor to the specified logical position and truncate
// the file. Return the file suffix (cached prior to truncating) starting
// from the specified position.
//
static string
truncate (auto_fd& fd, uint64_t pos, uint64_t suffix_pos)
{
string r;
{
// Temporary move the descriptor into the stream.
//
ifdstream is (move (fd));
fdstreambuf& buf (static_cast<fdstreambuf&> (*is.rdbuf ()));
// Read suffix.
//
buf.seekg (suffix_pos);
r = is.read_text ();
// Seek to the specified position and move the file descriptor back.
//
buf.seekg (pos);
fd = is.release ();
}
// Truncate the file starting from the current position. Note that we need
// to use the physical position rather than logical.
//
fdtruncate (fd.get (), fdseek (fd.get (), 0, fdseek_mode::cur));
return r;
}
void manifest_rewriter::
replace (const manifest_name_value& nv)
{
assert (nv.colon_pos != 0); // Sanity check.
// Truncate right after the value colon.
//
string suffix (truncate (fd_, nv.colon_pos + 1, nv.end_pos));
// Temporary move the descriptor into the stream.
//
ofdstream os (move (fd_));
if (!nv.value.empty ())
{
os << ' ';
manifest_serializer s (os, path_.string (), long_lines_);
// Note that the name can be surrounded with the ASCII whitespace
// characters and the start_pos refers to the first character in the
// line.
//
// Also note that we assume the already serialized name to be a valid
// UTF-8 byte string and so utf8_length() may not throw.
//
s.write_value (nv.value,
static_cast<size_t> (nv.colon_pos - nv.start_pos) -
(nv.name.size () - utf8_length (nv.name)) + 2);
}
os << suffix;
// Move the file descriptor back.
//
fd_ = os.release (); // Note: flushes the buffer.
}
void manifest_rewriter::
insert (const manifest_name_value& pos, const manifest_name_value& nv)
{
assert (pos.end_pos != 0); // Sanity check.
// We could have just started writing over the suffix but the truncation
// doesn't hurt.
//
string suffix (truncate (fd_, pos.end_pos, pos.end_pos));
// Temporary move the descriptor into the stream.
//
ofdstream os (move (fd_));
os << '\n';
manifest_serializer s (os, path_.string (), long_lines_);
size_t n (s.write_name (nv.name));
os << ':';
if (!nv.value.empty ())
{
os << ' ';
// Note that the name can be surrounded with the ASCII whitespace
// characters and the start_pos refers to the first character in the
// line.
//
s.write_value (nv.value,
static_cast<size_t> (nv.colon_pos - nv.start_pos) -
(nv.name.size () - n) + 2);
}
os << suffix;
// Move the file descriptor back.
//
fd_ = os.release (); // Note: flushes the buffer.
}
}
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