gdb/source-cache.c

   1 /* Cache of styled source file text
   2    Copyright (C) 2018-2019 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           if (highlighter == nullptr)
 194             {
 195               highlighter = new srchilite::SourceHighlight ("esc.outlang");
 196               highlighter->setStyleFile ("esc.style");
 197             }
 198
 199           try
 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   std::string fullname = symtab_to_fullname (s);
 235
 236   auto iter = m_offset_cache.find (fullname);
 237   if (iter == m_offset_cache.end ())
 238     {
 239       ensure (s);
 240       iter = m_offset_cache.find (fullname);
 241       /* cache_source_text ensured this was entered.  */
 242       gdb_assert (iter != m_offset_cache.end ());
 243     }
 244
 245   *offsets = &iter->second;
 246   return true;
 247 }
 248
 249 /* A helper function that extracts the desired source lines from TEXT,
 250    putting them into LINES_OUT.  The arguments are as for
 251    get_source_lines.  Returns true on success, false if the line
 252    numbers are invalid.  */
 253
 254 static bool
 255 extract_lines (const std::string &text, int first_line, int last_line,
 256                std::string *lines_out)
 257 {
 258   int lineno = 1;
 259   std::string::size_type pos = 0;
 260   std::string::size_type first_pos = std::string::npos;
 261
 262   while (pos != std::string::npos && lineno <= last_line)
 263     {
 264       std::string::size_type new_pos = text.find ('\n', pos);
 265
 266       if (lineno == first_line)
 267         first_pos = pos;
 268
 269       pos = new_pos;
 270       if (lineno == last_line || pos == std::string::npos)
 271         {
 272           /* A newline at the end does not start a new line.  */
 273           if (first_pos == std::string::npos
 274               || first_pos == text.size ())
 275             return false;
 276           if (pos == std::string::npos)
 277             pos = text.size ();
 278           else
 279             ++pos;
 280           *lines_out = text.substr (first_pos, pos - first_pos);
 281           return true;
 282         }
 283       ++lineno;
 284       ++pos;
 285     }
 286
 287   return false;
 288 }
 289
 290 /* See source-cache.h.  */
 291
 292 bool
 293 source_cache::get_source_lines (struct symtab *s, int first_line,
 294                                 int last_line, std::string *lines)
 295 {
 296   if (first_line < 1 || last_line < 1 || first_line > last_line)
 297     return false;
 298
 299   if (!ensure (s))
 300     return false;
 301
 302   return extract_lines (m_source_map.back ().contents,
 303                         first_line, last_line, lines);
 304 }
 305
 306 #if GDB_SELF_TEST
 307 namespace selftests
 308 {
 309 static void extract_lines_test ()
 310 {
 311   std::string input_text = "abc\ndef\nghi\njkl\n";
 312   std::string result;
 313
 314   SELF_CHECK (extract_lines (input_text, 1, 1, &result)
 315               && result == "abc\n");
 316   SELF_CHECK (!extract_lines (input_text, 2, 1, &result));
 317   SELF_CHECK (extract_lines (input_text, 1, 2, &result)
 318               && result == "abc\ndef\n");
 319   SELF_CHECK (extract_lines ("abc", 1, 1, &result)
 320               && result == "abc");
 321 }
 322 }
 323 #endif
 324
 325 void
 326 _initialize_source_cache ()
 327 {
 328 #if GDB_SELF_TEST
 329   selftests::register_test ("source-cache", selftests::extract_lines_test);
 330 #endif
 331 }