gdb/source-cache.c

   1 /* Cache of styled source file text
   2    Copyright (C) 2018-2020 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include "defs.h"
  20 #include "source-cache.h"
  21 #include "gdbsupport/scoped_fd.h"
  22 #include "source.h"
  23 #include "cli/cli-style.h"
  24 #include "symtab.h"
  25 #include "gdbsupport/selftest.h"
  26 #include "objfiles.h"
  27 #include "exec.h"
  28
  29 #ifdef HAVE_SOURCE_HIGHLIGHT
  30 /* If Gnulib redirects 'open' and 'close' to its replacements
  31    'rpl_open' and 'rpl_close' via cpp macros, including <fstream>
  32    below with those macros in effect will cause unresolved externals
  33    when GDB is linked.  Happens, e.g., in the MinGW build.  */
  34 #undef open
  35 #undef close
  36 #include <sstream>
  37 #include <srchilite/sourcehighlight.h>
  38 #include <srchilite/langmap.h>
  39 #endif
  40
  41 /* The number of source files we'll cache.  */
  42
  43 #define MAX_ENTRIES 5
  44
  45 /* See source-cache.h.  */
  46
  47 source_cache g_source_cache;
  48
  49 /* See source-cache.h.  */
  50
  51 std::string
  52 source_cache::get_plain_source_lines (struct symtab *s,
  53                                       const std::string &fullname)
  54 {
  55   scoped_fd desc (open_source_file (s));
  56   if (desc.get () < 0)
  57     perror_with_name (symtab_to_filename_for_display (s));
  58
  59   struct stat st;
  60   if (fstat (desc.get (), &st) < 0)
  61     perror_with_name (symtab_to_filename_for_display (s));
  62
  63   std::string lines;
  64   lines.resize (st.st_size);
  65   if (myread (desc.get (), &lines[0], lines.size ()) < 0)
  66     perror_with_name (symtab_to_filename_for_display (s));
  67
  68   time_t mtime = 0;
  69   if (SYMTAB_OBJFILE (s) != NULL && SYMTAB_OBJFILE (s)->obfd != NULL)
  70     mtime = SYMTAB_OBJFILE (s)->mtime;
  71   else if (exec_bfd)
  72     mtime = exec_bfd_mtime;
  73
  74   if (mtime && mtime < st.st_mtime)
  75     warning (_("Source file is more recent than executable."));
  76
  77   std::vector<off_t> offsets;
  78   offsets.push_back (0);
  79   for (size_t offset = lines.find ('\n');
  80        offset != std::string::npos;
  81        offset = lines.find ('\n', offset))
  82     {
  83       ++offset;
  84       /* A newline at the end does not start a new line.  It would
  85          seem simpler to just strip the newline in this function, but
  86          then "list" won't print the final newline.  */
  87       if (offset != lines.size ())
  88         offsets.push_back (offset);
  89     }
  90
  91   offsets.shrink_to_fit ();
  92   m_offset_cache.emplace (fullname, std::move (offsets));
  93
  94   return lines;
  95 }
  96
  97 #ifdef HAVE_SOURCE_HIGHLIGHT
  98
  99 /* Return the Source Highlight language name, given a gdb language
 100    LANG.  Returns NULL if the language is not known.  */
 101
 102 static const char *
 103 get_language_name (enum language lang)
 104 {
 105   switch (lang)
 106     {
 107     case language_c:
 108     case language_objc:
 109       return "c.lang";
 110
 111     case language_cplus:
 112       return "cpp.lang";
 113
 114     case language_d:
 115       return "d.lang";
 116
 117     case language_go:
 118       return "go.lang";
 119
 120     case language_fortran:
 121       return "fortran.lang";
 122
 123     case language_m2:
 124       /* Not handled by Source Highlight.  */
 125       break;
 126
 127     case language_asm:
 128       return "asm.lang";
 129
 130     case language_pascal:
 131       return "pascal.lang";
 132
 133     case language_opencl:
 134       /* Not handled by Source Highlight.  */
 135       break;
 136
 137     case language_rust:
 138       return "rust.lang";
 139
 140     case language_ada:
 141       return "ada.lang";
 142
 143     default:
 144       break;
 145     }
 146
 147   return nullptr;
 148 }
 149
 150 #endif /* HAVE_SOURCE_HIGHLIGHT */
 151
 152 /* See source-cache.h.  */
 153
 154 bool
 155 source_cache::ensure (struct symtab *s)
 156 {
 157   std::string fullname = symtab_to_fullname (s);
 158
 159   size_t size = m_source_map.size ();
 160   for (int i = 0; i < size; ++i)
 161     {
 162       if (m_source_map[i].fullname == fullname)
 163         {
 164           /* This should always hold, because we create the file
 165              offsets when reading the file, and never free them
 166              without also clearing the contents cache.  */
 167           gdb_assert (m_offset_cache.find (fullname)
 168                       != m_offset_cache.end ());
 169           /* Not strictly LRU, but at least ensure that the most
 170              recently used entry is always the last candidate for
 171              deletion.  Note that this property is relied upon by at
 172              least one caller.  */
 173           if (i != size - 1)
 174             std::swap (m_source_map[i], m_source_map[size - 1]);
 175           return true;
 176         }
 177     }
 178
 179   std::string contents = get_plain_source_lines (s, fullname);
 180
 181 #ifdef HAVE_SOURCE_HIGHLIGHT
 182   if (source_styling && gdb_stdout->can_emit_style_escape ())
 183     {
 184       const char *lang_name = get_language_name (SYMTAB_LANGUAGE (s));
 185       if (lang_name != nullptr)
 186         {
 187           /* The global source highlight object, or null if one was
 188              never constructed.  This is stored here rather than in
 189              the class so that we don't need to include anything or do
 190              conditional compilation in source-cache.h.  */
 191           static srchilite::SourceHighlight *highlighter;
 192
 193           try
 194             {
 195               if (highlighter == nullptr)
 196                 {
 197                   highlighter = new srchilite::SourceHighlight ("esc.outlang");
 198                   highlighter->setStyleFile ("esc.style");
 199                 }
 200
 201               std::istringstream input (contents);
 202               std::ostringstream output;
 203               highlighter->highlight (input, output, lang_name, fullname);
 204               contents = output.str ();
 205             }
 206           catch (...)
 207             {
 208               /* Source Highlight will throw an exception if
 209                  highlighting fails.  One possible reason it can fail
 210                  is if the language is unknown -- which matters to gdb
 211                  because Rust support wasn't added until after 3.1.8.
 212                  Ignore exceptions here and fall back to
 213                  un-highlighted text. */
 214             }
 215         }
 216     }
 217 #endif /* HAVE_SOURCE_HIGHLIGHT */
 218
 219   source_text result = { std::move (fullname), std::move (contents) };
 220   m_source_map.push_back (std::move (result));
 221
 222   if (m_source_map.size () > MAX_ENTRIES)
 223     m_source_map.erase (m_source_map.begin ());
 224
 225   return true;
 226 }
 227
 228 /* See source-cache.h.  */
 229
 230 bool
 231 source_cache::get_line_charpos (struct symtab *s,
 232                                 const std::vector<off_t> **offsets)
 233 {
 234   try
 235     {
 236       std::string fullname = symtab_to_fullname (s);
 237
 238       auto iter = m_offset_cache.find (fullname);
 239       if (iter == m_offset_cache.end ())
 240         {
 241           ensure (s);
 242           iter = m_offset_cache.find (fullname);
 243           /* cache_source_text ensured this was entered.  */
 244           gdb_assert (iter != m_offset_cache.end ());
 245         }
 246
 247       *offsets = &iter->second;
 248       return true;
 249     }
 250   catch (const gdb_exception_error &e)
 251     {
 252       return false;
 253     }
 254 }
 255
 256 /* A helper function that extracts the desired source lines from TEXT,
 257    putting them into LINES_OUT.  The arguments are as for
 258    get_source_lines.  Returns true on success, false if the line
 259    numbers are invalid.  */
 260
 261 static bool
 262 extract_lines (const std::string &text, int first_line, int last_line,
 263                std::string *lines_out)
 264 {
 265   int lineno = 1;
 266   std::string::size_type pos = 0;
 267   std::string::size_type first_pos = std::string::npos;
 268
 269   while (pos != std::string::npos && lineno <= last_line)
 270     {
 271       std::string::size_type new_pos = text.find ('\n', pos);
 272
 273       if (lineno == first_line)
 274         first_pos = pos;
 275
 276       pos = new_pos;
 277       if (lineno == last_line || pos == std::string::npos)
 278         {
 279           /* A newline at the end does not start a new line.  */
 280           if (first_pos == std::string::npos
 281               || first_pos == text.size ())
 282             return false;
 283           if (pos == std::string::npos)
 284             pos = text.size ();
 285           else
 286             ++pos;
 287           *lines_out = text.substr (first_pos, pos - first_pos);
 288           return true;
 289         }
 290       ++lineno;
 291       ++pos;
 292     }
 293
 294   return false;
 295 }
 296
 297 /* See source-cache.h.  */
 298
 299 bool
 300 source_cache::get_source_lines (struct symtab *s, int first_line,
 301                                 int last_line, std::string *lines)
 302 {
 303   if (first_line < 1 || last_line < 1 || first_line > last_line)
 304     return false;
 305
 306   if (!ensure (s))
 307     return false;
 308
 309   return extract_lines (m_source_map.back ().contents,
 310                         first_line, last_line, lines);
 311 }
 312
 313 #if GDB_SELF_TEST
 314 namespace selftests
 315 {
 316 static void extract_lines_test ()
 317 {
 318   std::string input_text = "abc\ndef\nghi\njkl\n";
 319   std::string result;
 320
 321   SELF_CHECK (extract_lines (input_text, 1, 1, &result)
 322               && result == "abc\n");
 323   SELF_CHECK (!extract_lines (input_text, 2, 1, &result));
 324   SELF_CHECK (extract_lines (input_text, 1, 2, &result)
 325               && result == "abc\ndef\n");
 326   SELF_CHECK (extract_lines ("abc", 1, 1, &result)
 327               && result == "abc");
 328 }
 329 }
 330 #endif
 331
 332 void
 333 _initialize_source_cache ()
 334 {
 335 #if GDB_SELF_TEST
 336   selftests::register_test ("source-cache", selftests::extract_lines_test);
 337 #endif
 338 }