1 /* UI_FILE - a generic STDIO like output stream.
2 Copyright (C) 1999-2021 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 string whose delimiter is QUOTER. Note that these
38 routines should only be called for printing things which are
39 independent of the language of the program being debugged. */
40 void putstr (const char *str
, int quoter
);
42 void putstrn (const char *str
, int n
, int quoter
);
46 void vprintf (const char *, va_list) ATTRIBUTE_PRINTF (2, 0);
48 /* Methods below are both public, and overridable by ui_file
51 virtual void write (const char *buf
, long length_buf
) = 0;
53 /* This version of "write" is safe for use in signal handlers. It's
54 not guaranteed that all existing output will have been flushed
55 first. Implementations are also free to ignore some or all of
56 the request. puts_async is not provided as the async versions
57 are rarely used, no point in having both for a rarely used
59 virtual void write_async_safe (const char *buf
, long length_buf
)
60 { gdb_assert_not_reached ("write_async_safe"); }
62 /* Some ui_files override this to provide a efficient implementation
63 that avoids a strlen. */
64 virtual void puts (const char *str
)
65 { this->write (str
, strlen (str
)); }
67 virtual long read (char *buf
, long length_buf
)
68 { gdb_assert_not_reached ("can't read from this file type"); }
70 virtual bool isatty ()
73 /* true indicates terminal output behaviour such as cli_styling.
74 This default implementation indicates to do terminal output
75 behaviour if the UI_FILE is a tty. A derived class can override
76 TERM_OUT to have cli_styling behaviour without being a tty. */
77 virtual bool term_out ()
80 /* true if ANSI escapes can be used on STREAM. */
81 virtual bool can_emit_style_escape ()
87 /* If this object has an underlying file descriptor, then return it.
88 Otherwise, return -1. */
89 virtual int fd () const
92 /* Return true if this object supports paging, false otherwise. */
93 virtual bool can_page () const
95 /* Almost no file supports paging, which is why this is the
101 typedef std::unique_ptr
<ui_file
> ui_file_up
;
103 /* A ui_file that writes to nowhere. */
105 class null_file
: public ui_file
108 void write (const char *buf
, long length_buf
) override
;
109 void write_async_safe (const char *buf
, long sizeof_buf
) override
;
110 void puts (const char *str
) override
;
113 /* A preallocated null_file stream. */
114 extern null_file null_stream
;
116 extern int gdb_console_fputs (const char *, FILE *);
118 /* A std::string-based ui_file. Can be used as a scratch buffer for
119 collecting output. */
121 class string_file
: public ui_file
124 /* Construct a string_file to collect 'raw' output, i.e. without
125 'terminal' behaviour such as cli_styling. */
126 string_file () : m_term_out (false) {};
127 /* If TERM_OUT, construct a string_file with terminal output behaviour
129 else collect 'raw' output like the previous constructor. */
130 explicit string_file (bool term_out
) : m_term_out (term_out
) {};
131 ~string_file () override
;
133 /* Override ui_file methods. */
135 void write (const char *buf
, long length_buf
) override
;
137 long read (char *buf
, long length_buf
) override
138 { gdb_assert_not_reached ("a string_file is not readable"); }
140 bool term_out () override
;
141 bool can_emit_style_escape () override
;
143 /* string_file-specific public API. */
145 /* Accesses the std::string containing the entire output collected
148 Returns a non-const reference so that it's easy to move the
149 string contents out of the string_file. E.g.:
154 return std::move (buf.string ());
156 std::string
&string () { return m_string
; }
158 /* Provide a few convenience methods with the same API as the
159 underlying std::string. */
160 const char *data () const { return m_string
.data (); }
161 const char *c_str () const { return m_string
.c_str (); }
162 size_t size () const { return m_string
.size (); }
163 bool empty () const { return m_string
.empty (); }
164 void clear () { return m_string
.clear (); }
167 /* The internal buffer. */
168 std::string m_string
;
173 /* A ui_file implementation that maps directly onto <stdio.h>'s FILE.
174 A stdio_file can either own its underlying file, or not. If it
175 owns the file, then destroying the stdio_file closes the underlying
176 file, otherwise it is left open. */
178 class stdio_file
: public ui_file
181 /* Create a ui_file from a previously opened FILE. CLOSE_P
182 indicates whether the underlying file should be closed when the
183 stdio_file is destroyed. */
184 explicit stdio_file (FILE *file
, bool close_p
= false);
186 /* Create an stdio_file that is not managing any file yet. Call
187 open to actually open something. */
190 ~stdio_file () override
;
192 /* Open NAME in mode MODE, and own the resulting file. Returns true
193 on success, false otherwise. If the stdio_file previously owned
194 a file, it is closed. */
195 bool open (const char *name
, const char *mode
);
197 void flush () override
;
199 void write (const char *buf
, long length_buf
) override
;
201 void write_async_safe (const char *buf
, long length_buf
) override
;
203 void puts (const char *) override
;
205 long read (char *buf
, long length_buf
) override
;
207 bool isatty () override
;
209 bool can_emit_style_escape () override
;
211 /* Return the underlying file descriptor. */
212 int fd () const override
215 virtual bool can_page () const override
217 return m_file
== stdout
;
221 /* Sets the internal stream to FILE, and saves the FILE's file
222 descriptor in M_FD. */
223 void set_stream (FILE *file
);
228 /* The associated file descriptor is extracted ahead of time for
229 stdio_file::write_async_safe's benefit, in case fileno isn't
233 /* If true, M_FILE is closed on destruction. */
237 typedef std::unique_ptr
<stdio_file
> stdio_file_up
;
239 /* Like stdio_file, but specifically for stderr.
241 This exists because there is no real line-buffering on Windows, see
242 <http://msdn.microsoft.com/en-us/library/86cebhfs%28v=vs.71%29.aspx>
243 so the stdout is either fully-buffered or non-buffered. We can't
244 make stdout non-buffered, because of two concerns:
246 1. Non-buffering hurts performance.
247 2. Non-buffering may change GDB's behavior when it is interacting
248 with a front-end, such as Emacs.
250 We leave stdout as fully buffered, but flush it first when
251 something is written to stderr.
253 Note that the 'write_async_safe' method is not overridden, because
254 there's no way to flush a stream in an async-safe manner.
255 Fortunately, it doesn't really matter, because:
257 1. That method is only used for printing internal debug output
258 from signal handlers.
260 2. Windows hosts don't have a concept of async-safeness. Signal
261 handlers run in a separate thread, so they can call the regular
262 non-async-safe output routines freely.
264 class stderr_file
: public stdio_file
267 explicit stderr_file (FILE *stream
);
269 /* Override the output routines to flush gdb_stdout before deferring
270 to stdio_file for the actual outputting. */
271 void write (const char *buf
, long length_buf
) override
;
272 void puts (const char *linebuffer
) override
;
275 /* A ui_file implementation that maps onto two ui-file objects. */
277 class tee_file
: public ui_file
280 /* Create a file which writes to both ONE and TWO. ONE will remain
281 open when this object is destroyed; but TWO will be closed. */
282 tee_file (ui_file
*one
, ui_file_up
&&two
);
283 ~tee_file () override
;
285 void write (const char *buf
, long length_buf
) override
;
286 void write_async_safe (const char *buf
, long length_buf
) override
;
287 void puts (const char *) override
;
289 bool isatty () override
;
290 bool term_out () override
;
291 bool can_emit_style_escape () override
;
292 void flush () override
;
294 virtual bool can_page () const override
296 /* If one of the underlying files can page, then we allow it
298 return m_one
->can_page () || m_two
->can_page ();
302 /* The two underlying ui_files. */
307 /* A ui_file implementation that filters out terminal escape
310 class no_terminal_escape_file
: public stdio_file
313 no_terminal_escape_file ()
317 /* Like the stdio_file methods, but these filter out terminal escape
319 void write (const char *buf
, long length_buf
) override
;
320 void puts (const char *linebuffer
) override
;