1 /* UI_FILE - a generic STDIO like output stream.
2 Copyright (C) 1999-2022 Free Software Foundation, Inc.
4 This file is part of GDB.
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.
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.
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/>. */
25 /* The abstract ui_file base class. */
31 virtual ~ui_file () = 0;
33 /* Public non-virtual API. */
35 void printf (const char *, ...) ATTRIBUTE_PRINTF (2, 3);
37 /* Print a NUL-terminated string whose delimiter is QUOTER. Note
38 that these routines should only be called for printing things
39 which are independent of the language of the program being
42 This will normally escape backslashes and instances of QUOTER.
43 If QUOTER is 0, it won't escape backslashes or any quoting
44 character. As a side effect, if you pass the backslash character
45 as the QUOTER, this will escape backslashes as usual, but not any
46 other quoting character. */
47 void putstr (const char *str, int quoter);
49 /* Like putstr, but only print the first N characters of STR. If
50 ASYNC_SAFE is true, then the output is done via the
51 write_async_safe method. */
52 void putstrn (const char *str, int n, int quoter, bool async_safe = false);
56 void vprintf (const char *, va_list) ATTRIBUTE_PRINTF (2, 0);
58 /* Methods below are both public, and overridable by ui_file
61 virtual void write (const char *buf, long length_buf) = 0;
63 /* This version of "write" is safe for use in signal handlers. It's
64 not guaranteed that all existing output will have been flushed
65 first. Implementations are also free to ignore some or all of
66 the request. puts_async is not provided as the async versions
67 are rarely used, no point in having both for a rarely used
69 virtual void write_async_safe (const char *buf, long length_buf)
70 { gdb_assert_not_reached ("write_async_safe"); }
72 /* Some ui_files override this to provide a efficient implementation
73 that avoids a strlen. */
74 virtual void puts (const char *str)
75 { this->write (str, strlen (str)); }
77 virtual long read (char *buf, long length_buf)
78 { gdb_assert_not_reached ("can't read from this file type"); }
80 virtual bool isatty ()
83 /* true indicates terminal output behaviour such as cli_styling.
84 This default implementation indicates to do terminal output
85 behaviour if the UI_FILE is a tty. A derived class can override
86 TERM_OUT to have cli_styling behaviour without being a tty. */
87 virtual bool term_out ()
90 /* true if ANSI escapes can be used on STREAM. */
91 virtual bool can_emit_style_escape ()
97 /* If this object has an underlying file descriptor, then return it.
98 Otherwise, return -1. */
99 virtual int fd () const
102 /* Return true if this object supports paging, false otherwise. */
103 virtual bool can_page () const
105 /* Almost no file supports paging, which is why this is the
110 /* Indicate that if the next sequence of characters overflows the
111 line, a newline should be inserted here rather than when it hits
112 the end. If INDENT is non-zero, it is a number of spaces to be
113 printed to indent the wrapped part on the next line.
115 If the line is already overfull, we immediately print a newline and
116 the indentation, and disable further wrapping.
118 If we don't know the width of lines, but we know the page height,
119 we must not wrap words, but should still keep track of newlines
120 that were explicitly printed.
122 This routine is guaranteed to force out any output which has been
123 squirreled away in the wrap_buffer, so wrap_here (0) can be
124 used to force out output from the wrap_buffer. */
125 void wrap_here (int indent);
129 /* Helper function for putstr and putstrn. Print the character C on
130 this stream as part of the contents of a literal string whose
131 delimiter is QUOTER. */
132 void printchar (int c, int quoter, bool async_safe);
135 typedef std::unique_ptr<ui_file> ui_file_up;
137 /* A ui_file that writes to nowhere. */
139 class null_file : public ui_file
142 void write (const char *buf, long length_buf) override;
143 void write_async_safe (const char *buf, long sizeof_buf) override;
144 void puts (const char *str) override;
147 /* A preallocated null_file stream. */
148 extern null_file null_stream;
150 extern int gdb_console_fputs (const char *, FILE *);
152 /* A std::string-based ui_file. Can be used as a scratch buffer for
153 collecting output. */
155 class string_file : public ui_file
158 /* Construct a string_file to collect 'raw' output, i.e. without
159 'terminal' behaviour such as cli_styling. */
160 string_file () : m_term_out (false) {};
161 /* If TERM_OUT, construct a string_file with terminal output behaviour
163 else collect 'raw' output like the previous constructor. */
164 explicit string_file (bool term_out) : m_term_out (term_out) {};
165 ~string_file () override;
167 /* Override ui_file methods. */
169 void write (const char *buf, long length_buf) override;
171 long read (char *buf, long length_buf) override
172 { gdb_assert_not_reached ("a string_file is not readable"); }
174 bool term_out () override;
175 bool can_emit_style_escape () override;
177 /* string_file-specific public API. */
179 /* Accesses the std::string containing the entire output collected
181 const std::string &string () { return m_string; }
183 /* Return an std::string containing the entire output collected so far.
185 The internal buffer is cleared, such that it's ready to build a new
187 std::string release ()
189 std::string ret = std::move (m_string);
194 /* Provide a few convenience methods with the same API as the
195 underlying std::string. */
196 const char *data () const { return m_string.data (); }
197 const char *c_str () const { return m_string.c_str (); }
198 size_t size () const { return m_string.size (); }
199 bool empty () const { return m_string.empty (); }
200 void clear () { return m_string.clear (); }
203 /* The internal buffer. */
204 std::string m_string;
209 /* A ui_file implementation that maps directly onto <stdio.h>'s FILE.
210 A stdio_file can either own its underlying file, or not. If it
211 owns the file, then destroying the stdio_file closes the underlying
212 file, otherwise it is left open. */
214 class stdio_file : public ui_file
217 /* Create a ui_file from a previously opened FILE. CLOSE_P
218 indicates whether the underlying file should be closed when the
219 stdio_file is destroyed. */
220 explicit stdio_file (FILE *file, bool close_p = false);
222 /* Create an stdio_file that is not managing any file yet. Call
223 open to actually open something. */
226 ~stdio_file () override;
228 /* Open NAME in mode MODE, and own the resulting file. Returns true
229 on success, false otherwise. If the stdio_file previously owned
230 a file, it is closed. */
231 bool open (const char *name, const char *mode);
233 void flush () override;
235 void write (const char *buf, long length_buf) override;
237 void write_async_safe (const char *buf, long length_buf) override;
239 void puts (const char *) override;
241 long read (char *buf, long length_buf) override;
243 bool isatty () override;
245 bool can_emit_style_escape () override;
247 /* Return the underlying file descriptor. */
248 int fd () const override
251 virtual bool can_page () const override
253 return m_file == stdout;
257 /* Sets the internal stream to FILE, and saves the FILE's file
258 descriptor in M_FD. */
259 void set_stream (FILE *file);
264 /* The associated file descriptor is extracted ahead of time for
265 stdio_file::write_async_safe's benefit, in case fileno isn't
269 /* If true, M_FILE is closed on destruction. */
273 typedef std::unique_ptr<stdio_file> stdio_file_up;
275 /* Like stdio_file, but specifically for stderr.
277 This exists because there is no real line-buffering on Windows, see
278 <http://msdn.microsoft.com/en-us/library/86cebhfs%28v=vs.71%29.aspx>
279 so the stdout is either fully-buffered or non-buffered. We can't
280 make stdout non-buffered, because of two concerns:
282 1. Non-buffering hurts performance.
283 2. Non-buffering may change GDB's behavior when it is interacting
284 with a front-end, such as Emacs.
286 We leave stdout as fully buffered, but flush it first when
287 something is written to stderr.
289 Note that the 'write_async_safe' method is not overridden, because
290 there's no way to flush a stream in an async-safe manner.
291 Fortunately, it doesn't really matter, because:
293 1. That method is only used for printing internal debug output
294 from signal handlers.
296 2. Windows hosts don't have a concept of async-safeness. Signal
297 handlers run in a separate thread, so they can call the regular
298 non-async-safe output routines freely.
300 class stderr_file : public stdio_file
303 explicit stderr_file (FILE *stream);
305 /* Override the output routines to flush gdb_stdout before deferring
306 to stdio_file for the actual outputting. */
307 void write (const char *buf, long length_buf) override;
308 void puts (const char *linebuffer) override;
311 /* A ui_file implementation that maps onto two ui-file objects. */
313 class tee_file : public ui_file
316 /* Create a file which writes to both ONE and TWO. ONE will remain
317 open when this object is destroyed; but TWO will be closed. */
318 tee_file (ui_file *one, ui_file_up &&two);
319 ~tee_file () override;
321 void write (const char *buf, long length_buf) override;
322 void write_async_safe (const char *buf, long length_buf) override;
323 void puts (const char *) override;
325 bool isatty () override;
326 bool term_out () override;
327 bool can_emit_style_escape () override;
328 void flush () override;
330 virtual bool can_page () const override
332 /* If one of the underlying files can page, then we allow it
334 return m_one->can_page () || m_two->can_page ();
338 /* The two underlying ui_files. */
343 /* A ui_file implementation that filters out terminal escape
346 class no_terminal_escape_file : public stdio_file
349 no_terminal_escape_file ()
353 /* Like the stdio_file methods, but these filter out terminal escape
355 void write (const char *buf, long length_buf) override;
356 void puts (const char *linebuffer) override;