gcc/libcody/buffer.cc

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// CODYlib -*- mode:c++ -*-
// Copyright (C) 2020 Nathan Sidwell, nathan@acm.org
// License: Apache v2.0
// Cody
#include "internal.hh"
// C++
#include <algorithm>
// C
#include <cstring>
// OS
#include <unistd.h>
#include <cerrno>
// MessageBuffer code
// Lines consist of words and end with a NEWLINE (0xa) char
// Whitespace characters are TAB (0x9) and SPACE (0x20)
// Words consist of non-whitespace chars separated by whitespace.
// Multiple lines in one transaction are indicated by ending non-final
// lines with a SEMICOLON (0x3b) word, immediately before the NEWLINE
// Continuations with ; preceding it
// Words matching regexp [-+_/%.a-zA-Z0-9]+ need no quoting.
// Quoting with '...'
// Anything outside of [-+_/%.a-zA-Z0-9] needs quoting
// Anything outside of <= <space> or DEL or \' or \\ needs escaping.
// Escapes are \\, \', \n, \t, \_, everything else as \<hex><hex>?
// Spaces separate words, UTF8 encoding for non-ascii chars
namespace Cody {
namespace Detail {
static const char CONTINUE = S2C(u8";");
void MessageBuffer::BeginLine ()
{
if (!buffer.empty ())
{
// Terminate the previous line with a continuation
buffer.reserve (buffer.size () + 3);
buffer.push_back (S2C(u8" "));
buffer.push_back (CONTINUE);
buffer.push_back (S2C(u8"\n"));
}
lastBol = buffer.size ();
}
// QUOTE means 'maybe quote', we search it for quote-needing chars
void MessageBuffer::Append (char const *str, bool quote, size_t len)
{
if (len == ~size_t (0))
len = strlen (str);
if (!len && !quote)
return;
// We want to quote characters outside of [-+_A-Za-z0-9/%.], anything
// that could remotely be shell-active. UTF8 encoding for non-ascii.
if (quote && len)
{
quote = false;
// Scan looking for quote-needing characters. We could just
// append until we find one, but that's probably confusing
for (size_t ix = len; ix--;)
{
unsigned char c = (unsigned char)str[ix];
if (!((c >= S2C(u8"a") && c <= S2C(u8"z"))
|| (c >= S2C(u8"A") && c <= S2C(u8"Z"))
|| (c >= S2C(u8"0") && c <= S2C(u8"9"))
|| c == S2C(u8"-") || c == S2C(u8"+") || c == S2C(u8"_")
|| c == S2C(u8"/") || c == S2C(u8"%") || c == S2C(u8".")))
{
quote = true;
break;
}
}
}
// Maximal length of appended string
buffer.reserve (buffer.size () + len * (quote ? 3 : 1) + 2);
if (quote)
buffer.push_back (S2C(u8"'"));
for (auto *end = str + len; str != end;)
{
auto *e = end;
if (quote)
// Look for next escape-needing char. More relaxed than
// the earlier needs-quoting check.
for (e = str; e != end; ++e)
{
unsigned char c = (unsigned char)*e;
if (c < S2C(u8" ") || c == 0x7f
|| c == S2C(u8"\\") || c == S2C(u8"'"))
break;
}
buffer.insert (buffer.end (), str, e);
str = e;
if (str == end)
break;
buffer.push_back (S2C(u8"\\"));
switch (unsigned char c = (unsigned char)*str++)
{
case S2C(u8"\t"):
c = S2C(u8"t");
goto append;
case S2C(u8"\n"):
c = S2C(u8"n");
goto append;
case S2C(u8"'"):
case S2C(u8"\\"):
append:
buffer.push_back (c);
break;
default:
// Full-on escape. Use 2 lower-case hex chars
for (unsigned shift = 8; shift;)
{
shift -= 4;
char nibble = (c >> shift) & 0xf;
nibble += S2C(u8"0");
if (nibble > S2C(u8"9"))
nibble += S2C(u8"a") - (S2C(u8"9") + 1);
buffer.push_back (nibble);
}
}
}
if (quote)
buffer.push_back (S2C(u8"'"));
}
void MessageBuffer::Append (char c)
{
buffer.push_back (c);
}
void MessageBuffer::AppendInteger (unsigned u)
{
// Sigh, even though std::to_string is C++11, we support building on
// gcc 4.8, which is a C++11 compiler lacking std::to_string. so
// have something horrible.
std::string v (20, 0);
size_t len = snprintf (const_cast<char *> (v.data ()), v.size (), "%u", u);
v.erase (len);
AppendWord (v);
}
int MessageBuffer::Write (int fd) noexcept
{
size_t limit = buffer.size () - lastBol;
ssize_t count = write (fd, &buffer.data ()[lastBol], limit);
int err = 0;
if (count < 0)
err = errno;
else
{
lastBol += count;
if (size_t (count) != limit)
err = EAGAIN;
}
if (err != EAGAIN && err != EINTR)
{
// Reset for next message
buffer.clear ();
lastBol = 0;
}
return err;
}
int MessageBuffer::Read (int fd) noexcept
{
constexpr size_t blockSize = 200;
size_t lwm = buffer.size ();
size_t hwm = buffer.capacity ();
if (hwm - lwm < blockSize / 2)
hwm += blockSize;
buffer.resize (hwm);
auto iter = buffer.begin () + lwm;
ssize_t count = read (fd, &*iter, hwm - lwm);
buffer.resize (lwm + (count >= 0 ? count : 0));
if (count < 0)
return errno;
if (!count)
// End of file
return -1;
bool more = true;
for (;;)
{
auto newline = std::find (iter, buffer.end (), S2C(u8"\n"));
if (newline == buffer.end ())
break;
more = newline != buffer.begin () && newline[-1] == CONTINUE;
iter = newline + 1;
if (iter == buffer.end ())
break;
if (!more)
{
// There is no continuation, but there are chars after the
// newline. Truncate the buffer and return an error
buffer.resize (iter - buffer.begin ());
return EINVAL;
}
}
return more ? EAGAIN : 0;
}
int MessageBuffer::Lex (std::vector<std::string> &result)
{
result.clear ();
if (IsAtEnd ())
return ENOENT;
Assert (buffer.back () == S2C(u8"\n"));
auto iter = buffer.begin () + lastBol;
for (std::string *word = nullptr;;)
{
char c = *iter;
++iter;
if (c == S2C(u8" ") || c == S2C(u8"\t"))
{
word = nullptr;
continue;
}
if (c == S2C(u8"\n"))
break;
if (c == CONTINUE)
{
// Line continuation
if (word || *iter != S2C(u8"\n"))
goto malformed;
++iter;
break;
}
if (c <= S2C(u8" ") || c >= 0x7f)
goto malformed;
if (!word)
{
result.emplace_back ();
word = &result.back ();
}
if (c == S2C(u8"'"))
{
// Quoted word
for (;;)
{
c = *iter;
if (c == S2C(u8"\n"))
{
malformed:;
result.clear ();
iter = std::find (iter, buffer.end (), S2C(u8"\n"));
auto back = iter;
if (back[-1] == CONTINUE && back[-2] == S2C(u8" "))
// Smells like a line continuation
back -= 2;
result.emplace_back (&buffer[lastBol],
back - buffer.begin () - lastBol);
++iter;
lastBol = iter - buffer.begin ();
return EINVAL;
}
if (c < S2C(u8" ") || c >= 0x7f)
goto malformed;
++iter;
if (c == S2C(u8"'"))
break;
if (c == S2C(u8"\\"))
// escape
switch (c = *iter)
{
case S2C(u8"\\"):
case S2C(u8"'"):
++iter;
break;
case S2C(u8"n"):
c = S2C(u8"\n");
++iter;
break;
case S2C(u8"_"):
// We used to escape SPACE as \_, so accept that
c = S2C(u8" ");
++iter;
break;
case S2C(u8"t"):
c = S2C(u8"\t");
++iter;
break;
default:
{
unsigned v = 0;
for (unsigned nibble = 0; nibble != 2; nibble++)
{
c = *iter;
if (c < S2C(u8"0"))
{
if (!nibble)
goto malformed;
break;
}
else if (c <= S2C(u8"9"))
c -= S2C(u8"0");
else if (c < S2C(u8"a"))
{
if (!nibble)
goto malformed;
break;
}
else if (c <= S2C(u8"f"))
c -= S2C(u8"a") - 10;
else
{
if (!nibble)
goto malformed;
break;
}
++iter;
v = (v << 4) | c;
}
c = v;
}
}
word->push_back (c);
}
}
else
// Unquoted character
word->push_back (c);
}
lastBol = iter - buffer.begin ();
if (result.empty ())
return ENOENT;
return 0;
}
void MessageBuffer::LexedLine (std::string &str)
{
if (lastBol)
{
size_t pos = lastBol - 1;
for (; pos; pos--)
if (buffer[pos-1] == S2C(u8"\n"))
break;
size_t end = lastBol - 1;
if (buffer[end-1] == CONTINUE && buffer[end-2] == S2C(u8" "))
// Strip line continuation
end -= 2;
str.append (&buffer[pos], end - pos);
}
}
} // Detail
} // Cody