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   if (source_styling && gdb_stdout->can_emit_style_escape ())
 182     {
 183 #ifdef HAVE_SOURCE_HIGHLIGHT
 184       bool already_styled = false;
 185       const char *lang_name = get_language_name (SYMTAB_LANGUAGE (s));
 186       if (lang_name != nullptr)
 187         {
 188           /* The global source highlight object, or null if one was
 189              never constructed.  This is stored here rather than in
 190              the class so that we don't need to include anything or do
 191              conditional compilation in source-cache.h.  */
 192           static srchilite::SourceHighlight *highlighter;
 193
 194           try
 195             {
 196               if (highlighter == nullptr)
 197                 {
 198                   highlighter = new srchilite::SourceHighlight ("esc.outlang");
 199                   highlighter->setStyleFile ("esc.style");
 200                 }
 201
 202               std::istringstream input (contents);
 203               std::ostringstream output;
 204               highlighter->highlight (input, output, lang_name, fullname);
 205               contents = output.str ();
 206               already_styled = true;
 207             }
 208           catch (...)
 209             {
 210               /* Source Highlight will throw an exception if
 211                  highlighting fails.  One possible reason it can fail
 212                  is if the language is unknown -- which matters to gdb
 213                  because Rust support wasn't added until after 3.1.8.
 214                  Ignore exceptions here and fall back to
 215                  un-highlighted text. */
 216             }
 217         }
 218
 219       if (!already_styled)
 220 #endif /* HAVE_SOURCE_HIGHLIGHT */
 221         {
 222           gdb::optional<std::string> ext_contents;
 223           ext_contents = ext_lang_colorize (fullname, contents);
 224           if (ext_contents.has_value ())
 225             contents = std::move (*ext_contents);
 226         }
 227     }
 228
 229   source_text result = { std::move (fullname), std::move (contents) };
 230   m_source_map.push_back (std::move (result));
 231
 232   if (m_source_map.size () > MAX_ENTRIES)
 233     m_source_map.erase (m_source_map.begin ());
 234
 235   return true;
 236 }
 237
 238 /* See source-cache.h.  */
 239
 240 bool
 241 source_cache::get_line_charpos (struct symtab *s,
 242                                 const std::vector<off_t> **offsets)
 243 {
 244   try
 245     {
 246       std::string fullname = symtab_to_fullname (s);
 247
 248       auto iter = m_offset_cache.find (fullname);
 249       if (iter == m_offset_cache.end ())
 250         {
 251           ensure (s);
 252           iter = m_offset_cache.find (fullname);
 253           /* cache_source_text ensured this was entered.  */
 254           gdb_assert (iter != m_offset_cache.end ());
 255         }
 256
 257       *offsets = &iter->second;
 258       return true;
 259     }
 260   catch (const gdb_exception_error &e)
 261     {
 262       return false;
 263     }
 264 }
 265
 266 /* A helper function that extracts the desired source lines from TEXT,
 267    putting them into LINES_OUT.  The arguments are as for
 268    get_source_lines.  Returns true on success, false if the line
 269    numbers are invalid.  */
 270
 271 static bool
 272 extract_lines (const std::string &text, int first_line, int last_line,
 273                std::string *lines_out)
 274 {
 275   int lineno = 1;
 276   std::string::size_type pos = 0;
 277   std::string::size_type first_pos = std::string::npos;
 278
 279   while (pos != std::string::npos && lineno <= last_line)
 280     {
 281       std::string::size_type new_pos = text.find ('\n', pos);
 282
 283       if (lineno == first_line)
 284         first_pos = pos;
 285
 286       pos = new_pos;
 287       if (lineno == last_line || pos == std::string::npos)
 288         {
 289           /* A newline at the end does not start a new line.  */
 290           if (first_pos == std::string::npos
 291               || first_pos == text.size ())
 292             return false;
 293           if (pos == std::string::npos)
 294             pos = text.size ();
 295           else
 296             ++pos;
 297           *lines_out = text.substr (first_pos, pos - first_pos);
 298           return true;
 299         }
 300       ++lineno;
 301       ++pos;
 302     }
 303
 304   return false;
 305 }
 306
 307 /* See source-cache.h.  */
 308
 309 bool
 310 source_cache::get_source_lines (struct symtab *s, int first_line,
 311                                 int last_line, std::string *lines)
 312 {
 313   if (first_line < 1 || last_line < 1 || first_line > last_line)
 314     return false;
 315
 316   if (!ensure (s))
 317     return false;
 318
 319   return extract_lines (m_source_map.back ().contents,
 320                         first_line, last_line, lines);
 321 }
 322
 323 #if GDB_SELF_TEST
 324 namespace selftests
 325 {
 326 static void extract_lines_test ()
 327 {
 328   std::string input_text = "abc\ndef\nghi\njkl\n";
 329   std::string result;
 330
 331   SELF_CHECK (extract_lines (input_text, 1, 1, &result)
 332               && result == "abc\n");
 333   SELF_CHECK (!extract_lines (input_text, 2, 1, &result));
 334   SELF_CHECK (extract_lines (input_text, 1, 2, &result)
 335               && result == "abc\ndef\n");
 336   SELF_CHECK (extract_lines ("abc", 1, 1, &result)
 337               && result == "abc");
 338 }
 339 }
 340 #endif
 341
 342 void _initialize_source_cache ();
 343 void
 344 _initialize_source_cache ()
 345 {
 346 #if GDB_SELF_TEST
 347   selftests::register_test ("source-cache", selftests::extract_lines_test);
 348 #endif
 349 }