gdb/source-cache.c - binutils-gdb - Git at Google

 /* Cache of styled source file text
    Copyright (C) 2018-2021 Free Software Foundation, Inc.

    This file is part of GDB.

    This program 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.

    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

 #include "defs.h"
 #include "source-cache.h"
 #include "gdbsupport/scoped_fd.h"
 #include "source.h"
 #include "cli/cli-style.h"
 #include "symtab.h"
 #include "gdbsupport/selftest.h"
 #include "objfiles.h"
 #include "exec.h"

 #ifdef HAVE_SOURCE_HIGHLIGHT
 /* If Gnulib redirects 'open' and 'close' to its replacements
    'rpl_open' and 'rpl_close' via cpp macros, including <fstream>
    below with those macros in effect will cause unresolved externals
    when GDB is linked.  Happens, e.g., in the MinGW build.  */
 #undef open
 #undef close
 #include <sstream>
 #include <srchilite/sourcehighlight.h>
 #include <srchilite/langmap.h>
 #endif

 /* The number of source files we'll cache.  */

 #define MAX_ENTRIES 5

 /* See source-cache.h.  */

 source_cache g_source_cache;

 /* See source-cache.h.  */

 std::string
 source_cache::get_plain_source_lines (struct symtab *s,
 				      const std::string &fullname)
 {
   scoped_fd desc (open_source_file (s));
   if (desc.get () < 0)
     perror_with_name (symtab_to_filename_for_display (s));

   struct stat st;
   if (fstat (desc.get (), &st) < 0)
     perror_with_name (symtab_to_filename_for_display (s));

   std::string lines;
   lines.resize (st.st_size);
   if (myread (desc.get (), &lines[0], lines.size ()) < 0)
     perror_with_name (symtab_to_filename_for_display (s));

   time_t mtime = 0;
   if (SYMTAB_OBJFILE (s) != NULL && SYMTAB_OBJFILE (s)->obfd != NULL)
     mtime = SYMTAB_OBJFILE (s)->mtime;
   else if (current_program_space->exec_bfd ())
     mtime = current_program_space->ebfd_mtime;

   if (mtime && mtime < st.st_mtime)
     warning (_("Source file is more recent than executable."));

   std::vector<off_t> offsets;
   offsets.push_back (0);
   for (size_t offset = lines.find ('\n');
        offset != std::string::npos;
        offset = lines.find ('\n', offset))
     {
       ++offset;
       /* A newline at the end does not start a new line.  It would
 	 seem simpler to just strip the newline in this function, but
 	 then "list" won't print the final newline.  */
       if (offset != lines.size ())
 	offsets.push_back (offset);
     }

   offsets.shrink_to_fit ();
   m_offset_cache.emplace (fullname, std::move (offsets));

   return lines;
 }

 #ifdef HAVE_SOURCE_HIGHLIGHT

 /* Return the Source Highlight language name, given a gdb language
    LANG.  Returns NULL if the language is not known.  */

 static const char *
 get_language_name (enum language lang)
 {
   switch (lang)
     {
     case language_c:
     case language_objc:
       return "c.lang";

     case language_cplus:
       return "cpp.lang";

     case language_d:
       return "d.lang";

     case language_go:
       return "go.lang";

     case language_fortran:
       return "fortran.lang";

     case language_m2:
       /* Not handled by Source Highlight.  */
       break;

     case language_asm:
       return "asm.lang";

     case language_pascal:
       return "pascal.lang";

     case language_opencl:
       /* Not handled by Source Highlight.  */
       break;

     case language_rust:
       return "rust.lang";

     case language_ada:
       return "ada.lang";

     default:
       break;
     }

   return nullptr;
 }

 #endif /* HAVE_SOURCE_HIGHLIGHT */

 /* See source-cache.h.  */

 bool
 source_cache::ensure (struct symtab *s)
 {
   std::string fullname = symtab_to_fullname (s);

   size_t size = m_source_map.size ();
   for (int i = 0; i < size; ++i)
     {
       if (m_source_map[i].fullname == fullname)
 	{
 	  /* This should always hold, because we create the file
 	     offsets when reading the file, and never free them
 	     without also clearing the contents cache.  */
 	  gdb_assert (m_offset_cache.find (fullname)
 		      != m_offset_cache.end ());
 	  /* Not strictly LRU, but at least ensure that the most
 	     recently used entry is always the last candidate for
 	     deletion.  Note that this property is relied upon by at
 	     least one caller.  */
 	  if (i != size - 1)
 	    std::swap (m_source_map[i], m_source_map[size - 1]);
 	  return true;
 	}
     }

   std::string contents;
   try
     {
       contents = get_plain_source_lines (s, fullname);
     }
   catch (const gdb_exception_error &e)
     {
       /* If 's' is not found, an exception is thrown.  */
       return false;
     }

   if (source_styling && gdb_stdout->can_emit_style_escape ())
     {
 #ifdef HAVE_SOURCE_HIGHLIGHT
       bool already_styled = false;
       const char *lang_name = get_language_name (SYMTAB_LANGUAGE (s));
       if (lang_name != nullptr)
 	{
 	  /* The global source highlight object, or null if one was
 	     never constructed.  This is stored here rather than in
 	     the class so that we don't need to include anything or do
 	     conditional compilation in source-cache.h.  */
 	  static srchilite::SourceHighlight *highlighter;

 	  try
 	    {
 	      if (highlighter == nullptr)
 		{
 		  highlighter = new srchilite::SourceHighlight ("esc.outlang");
 		  highlighter->setStyleFile ("esc.style");
 		}

 	      std::istringstream input (contents);
 	      std::ostringstream output;
 	      highlighter->highlight (input, output, lang_name, fullname);
 	      contents = output.str ();
 	      already_styled = true;
 	    }
 	  catch (...)
 	    {
 	      /* Source Highlight will throw an exception if
 		 highlighting fails.  One possible reason it can fail
 		 is if the language is unknown -- which matters to gdb
 		 because Rust support wasn't added until after 3.1.8.
 		 Ignore exceptions here and fall back to
 		 un-highlighted text. */
 	    }
 	}

       if (!already_styled)
 #endif /* HAVE_SOURCE_HIGHLIGHT */
 	{
 	  gdb::optional<std::string> ext_contents;
 	  ext_contents = ext_lang_colorize (fullname, contents);
 	  if (ext_contents.has_value ())
 	    contents = std::move (*ext_contents);
 	}
     }

   source_text result = { std::move (fullname), std::move (contents) };
   m_source_map.push_back (std::move (result));

   if (m_source_map.size () > MAX_ENTRIES)
     m_source_map.erase (m_source_map.begin ());

   return true;
 }

 /* See source-cache.h.  */

 bool
 source_cache::get_line_charpos (struct symtab *s,
 				const std::vector<off_t> **offsets)
 {
   std::string fullname = symtab_to_fullname (s);

   auto iter = m_offset_cache.find (fullname);
   if (iter == m_offset_cache.end ())
     {
       if (!ensure (s))
 	return false;
       iter = m_offset_cache.find (fullname);
       /* cache_source_text ensured this was entered.  */
       gdb_assert (iter != m_offset_cache.end ());
     }

   *offsets = &iter->second;
   return true;
 }

 /* A helper function that extracts the desired source lines from TEXT,
    putting them into LINES_OUT.  The arguments are as for
    get_source_lines.  Returns true on success, false if the line
    numbers are invalid.  */

 static bool
 extract_lines (const std::string &text, int first_line, int last_line,
 	       std::string *lines_out)
 {
   int lineno = 1;
   std::string::size_type pos = 0;
   std::string::size_type first_pos = std::string::npos;

   while (pos != std::string::npos && lineno <= last_line)
     {
       std::string::size_type new_pos = text.find ('\n', pos);

       if (lineno == first_line)
 	first_pos = pos;

       pos = new_pos;
       if (lineno == last_line || pos == std::string::npos)
 	{
 	  /* A newline at the end does not start a new line.  */
 	  if (first_pos == std::string::npos
 	      || first_pos == text.size ())
 	    return false;
 	  if (pos == std::string::npos)
 	    pos = text.size ();
 	  else
 	    ++pos;
 	  *lines_out = text.substr (first_pos, pos - first_pos);
 	  return true;
 	}
       ++lineno;
       ++pos;
     }

   return false;
 }

 /* See source-cache.h.  */

 bool
 source_cache::get_source_lines (struct symtab *s, int first_line,
 				int last_line, std::string *lines)
 {
   if (first_line < 1 || last_line < 1 || first_line > last_line)
     return false;

   if (!ensure (s))
     return false;

   return extract_lines (m_source_map.back ().contents,
 			first_line, last_line, lines);
 }

 #if GDB_SELF_TEST
 namespace selftests
 {
 static void extract_lines_test ()
 {
   std::string input_text = "abc\ndef\nghi\njkl\n";
   std::string result;

   SELF_CHECK (extract_lines (input_text, 1, 1, &result)
 	      && result == "abc\n");
   SELF_CHECK (!extract_lines (input_text, 2, 1, &result));
   SELF_CHECK (extract_lines (input_text, 1, 2, &result)
 	      && result == "abc\ndef\n");
   SELF_CHECK (extract_lines ("abc", 1, 1, &result)
 	      && result == "abc");
 }
 }
 #endif

 void _initialize_source_cache ();
 void
 _initialize_source_cache ()
 {
 #if GDB_SELF_TEST
   selftests::register_test ("source-cache", selftests::extract_lines_test);
 #endif
 }
	/* Cache of styled source file text
	Copyright (C) 2018-2021 Free Software Foundation, Inc.

	This file is part of GDB.

	This program 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.

	This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */

	#include "defs.h"
	#include "source-cache.h"
	#include "gdbsupport/scoped_fd.h"
	#include "source.h"
	#include "cli/cli-style.h"
	#include "symtab.h"
	#include "gdbsupport/selftest.h"
	#include "objfiles.h"
	#include "exec.h"

	#ifdef HAVE_SOURCE_HIGHLIGHT
	/* If Gnulib redirects 'open' and 'close' to its replacements
	'rpl_open' and 'rpl_close' via cpp macros, including <fstream>
	below with those macros in effect will cause unresolved externals
	when GDB is linked. Happens, e.g., in the MinGW build. */
	#undef open
	#undef close
	#include <sstream>
	#include <srchilite/sourcehighlight.h>
	#include <srchilite/langmap.h>
	#endif

	/* The number of source files we'll cache. */

	#define MAX_ENTRIES 5

	/* See source-cache.h. */

	source_cache g_source_cache;

	/* See source-cache.h. */

	std::string
	source_cache::get_plain_source_lines (struct symtab *s,
	const std::string &fullname)
	{
	scoped_fd desc (open_source_file (s));
	if (desc.get () < 0)
	perror_with_name (symtab_to_filename_for_display (s));

	struct stat st;
	if (fstat (desc.get (), &st) < 0)
	perror_with_name (symtab_to_filename_for_display (s));

	std::string lines;
	lines.resize (st.st_size);
	if (myread (desc.get (), &lines[0], lines.size ()) < 0)
	perror_with_name (symtab_to_filename_for_display (s));

	time_t mtime = 0;
	if (SYMTAB_OBJFILE (s) != NULL && SYMTAB_OBJFILE (s)->obfd != NULL)
	mtime = SYMTAB_OBJFILE (s)->mtime;
	else if (current_program_space->exec_bfd ())
	mtime = current_program_space->ebfd_mtime;

	if (mtime && mtime < st.st_mtime)
	warning (_("Source file is more recent than executable."));

	std::vector<off_t> offsets;
	offsets.push_back (0);
	for (size_t offset = lines.find ('\n');
	offset != std::string::npos;
	offset = lines.find ('\n', offset))
	{
	++offset;
	/* A newline at the end does not start a new line. It would
	seem simpler to just strip the newline in this function, but
	then "list" won't print the final newline. */
	if (offset != lines.size ())
	offsets.push_back (offset);
	}

	offsets.shrink_to_fit ();
	m_offset_cache.emplace (fullname, std::move (offsets));

	return lines;
	}

	#ifdef HAVE_SOURCE_HIGHLIGHT

	/* Return the Source Highlight language name, given a gdb language
	LANG. Returns NULL if the language is not known. */

	static const char *
	get_language_name (enum language lang)
	{
	switch (lang)
	{
	case language_c:
	case language_objc:
	return "c.lang";

	case language_cplus:
	return "cpp.lang";

	case language_d:
	return "d.lang";

	case language_go:
	return "go.lang";

	case language_fortran:
	return "fortran.lang";

	case language_m2:
	/* Not handled by Source Highlight. */
	break;

	case language_asm:
	return "asm.lang";

	case language_pascal:
	return "pascal.lang";

	case language_opencl:
	/* Not handled by Source Highlight. */
	break;

	case language_rust:
	return "rust.lang";

	case language_ada:
	return "ada.lang";

	default:
	break;
	}

	return nullptr;
	}

	#endif /* HAVE_SOURCE_HIGHLIGHT */

	/* See source-cache.h. */

	bool
	source_cache::ensure (struct symtab *s)
	{
	std::string fullname = symtab_to_fullname (s);

	size_t size = m_source_map.size ();
	for (int i = 0; i < size; ++i)
	{
	if (m_source_map[i].fullname == fullname)
	{
	/* This should always hold, because we create the file
	offsets when reading the file, and never free them
	without also clearing the contents cache. */
	gdb_assert (m_offset_cache.find (fullname)
	!= m_offset_cache.end ());
	/* Not strictly LRU, but at least ensure that the most
	recently used entry is always the last candidate for
	deletion. Note that this property is relied upon by at
	least one caller. */
	if (i != size - 1)
	std::swap (m_source_map[i], m_source_map[size - 1]);
	return true;
	}
	}

	std::string contents;
	try
	{
	contents = get_plain_source_lines (s, fullname);
	}
	catch (const gdb_exception_error &e)
	{
	/* If 's' is not found, an exception is thrown. */
	return false;
	}

	if (source_styling && gdb_stdout->can_emit_style_escape ())
	{
	#ifdef HAVE_SOURCE_HIGHLIGHT
	bool already_styled = false;
	const char *lang_name = get_language_name (SYMTAB_LANGUAGE (s));
	if (lang_name != nullptr)
	{
	/* The global source highlight object, or null if one was
	never constructed. This is stored here rather than in
	the class so that we don't need to include anything or do
	conditional compilation in source-cache.h. */
	static srchilite::SourceHighlight *highlighter;

	try
	{
	if (highlighter == nullptr)
	{
	highlighter = new srchilite::SourceHighlight ("esc.outlang");
	highlighter->setStyleFile ("esc.style");
	}

	std::istringstream input (contents);
	std::ostringstream output;
	highlighter->highlight (input, output, lang_name, fullname);
	contents = output.str ();
	already_styled = true;
	}
	catch (...)
	{
	/* Source Highlight will throw an exception if
	highlighting fails. One possible reason it can fail
	is if the language is unknown -- which matters to gdb
	because Rust support wasn't added until after 3.1.8.
	Ignore exceptions here and fall back to
	un-highlighted text. */
	}
	}

	if (!already_styled)
	#endif /* HAVE_SOURCE_HIGHLIGHT */
	{
	gdb::optional<std::string> ext_contents;
	ext_contents = ext_lang_colorize (fullname, contents);
	if (ext_contents.has_value ())
	contents = std::move (*ext_contents);
	}
	}

	source_text result = { std::move (fullname), std::move (contents) };
	m_source_map.push_back (std::move (result));

	if (m_source_map.size () > MAX_ENTRIES)
	m_source_map.erase (m_source_map.begin ());

	return true;
	}

	/* See source-cache.h. */

	bool
	source_cache::get_line_charpos (struct symtab *s,
	const std::vector<off_t> **offsets)
	{
	std::string fullname = symtab_to_fullname (s);

	auto iter = m_offset_cache.find (fullname);
	if (iter == m_offset_cache.end ())
	{
	if (!ensure (s))
	return false;
	iter = m_offset_cache.find (fullname);
	/* cache_source_text ensured this was entered. */
	gdb_assert (iter != m_offset_cache.end ());
	}

	*offsets = &iter->second;
	return true;
	}

	/* A helper function that extracts the desired source lines from TEXT,
	putting them into LINES_OUT. The arguments are as for
	get_source_lines. Returns true on success, false if the line
	numbers are invalid. */

	static bool
	extract_lines (const std::string &text, int first_line, int last_line,
	std::string *lines_out)
	{
	int lineno = 1;
	std::string::size_type pos = 0;
	std::string::size_type first_pos = std::string::npos;

	while (pos != std::string::npos && lineno <= last_line)
	{
	std::string::size_type new_pos = text.find ('\n', pos);

	if (lineno == first_line)
	first_pos = pos;

	pos = new_pos;
	if (lineno == last_line \|\| pos == std::string::npos)
	{
	/* A newline at the end does not start a new line. */
	if (first_pos == std::string::npos
	\|\| first_pos == text.size ())
	return false;
	if (pos == std::string::npos)
	pos = text.size ();
	else
	++pos;
	*lines_out = text.substr (first_pos, pos - first_pos);
	return true;
	}
	++lineno;
	++pos;
	}

	return false;
	}

	/* See source-cache.h. */

	bool
	source_cache::get_source_lines (struct symtab *s, int first_line,
	int last_line, std::string *lines)
	{
	if (first_line < 1 \|\| last_line < 1 \|\| first_line > last_line)
	return false;

	if (!ensure (s))
	return false;

	return extract_lines (m_source_map.back ().contents,
	first_line, last_line, lines);
	}

	#if GDB_SELF_TEST
	namespace selftests
	{
	static void extract_lines_test ()
	{
	std::string input_text = "abc\ndef\nghi\njkl\n";
	std::string result;

	SELF_CHECK (extract_lines (input_text, 1, 1, &result)
	&& result == "abc\n");
	SELF_CHECK (!extract_lines (input_text, 2, 1, &result));
	SELF_CHECK (extract_lines (input_text, 1, 2, &result)
	&& result == "abc\ndef\n");
	SELF_CHECK (extract_lines ("abc", 1, 1, &result)
	&& result == "abc");
	}
	}
	#endif

	void _initialize_source_cache ();
	void
	_initialize_source_cache ()
	{
	#if GDB_SELF_TEST
	selftests::register_test ("source-cache", selftests::extract_lines_test);
	#endif
	}