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7c4e78cf63
Enabling "set debug lin-lwp 1" with the MI interpreter doesn't work. When the sigchld_handler function wants to print a debug output ("sigchld\n"), it uses ui_file_write_async_safe. This ends up in the default implementation of ui_file::write_async_safe, which aborts GDB. This patch implements the write_async_safe method for mi_console_file. The "normal" MI output is line buffered, which means the output accumulates in m_buffer until a \n is written, at which point it's flushed in m_raw. The implementation of write_async_safe provided by this patch bypasses this buffer and writes directly to m_raw. There are two reasons for this: (1) Appending to m_buffer (therefore to an std::string) is probably not async-safe, as it may allocate memory. (2) We may have a partial output already in m_buffer, so that would lead to some nested MI output, not so great. There is probably still a chance to have bad MI output, if sigchld_handler is invoked in the middle of mi_console_file's flush, and the line being flushed is only partially sent to m_raw. The solution would probably be to block signals during flushing. Since this is only used for debug output, I don't know if it's worth the effort to do that. To implement write_async_safe, I needed to use the fputstrn_unfiltered, which does the necessary escaping (e.g. replace \n with \\n). I started by adding printchar's callback parameters to fputstrn_unfiltered, to be able to pass async-safe versions of them. It's not easy to provide an async-safe version of do_fprintf, but it turns out that we can easily replace printchar's callbacks with a single do_fputc quite easily. The async-safe version of do_fputc simply calls the underlying ui_file's write_async_safe method. gdb/ChangeLog: PR mi/22299 * mi/mi-console.c (do_fputc_async_safe): New. (mi_console_file::write_async_safe): New. (mi_console_file::flush): Adjust calls to fputstrn_unfiltered. * mi/mi-console.h (class mi_console_file) <write_async_safe>: New. * ui-file.c (ui_file::putstrn): Adjust call to fputstrn_unfiltered. * utils.c (printchar): Replace do_fputs and do_fprintf parameters by do_fputc. (fputstr_filtered): Adjust call to printchar. (fputstr_unfiltered): Likewise. (fputstrn_filtered): Likewise. (fputstrn_unfiltered): Add do_fputc parameter, pass to printchar. * utils.h (do_fputc_ftype): New typedef. (fputstrn_unfiltered): Add do_fputc parameter.
329 lines
5.8 KiB
C
329 lines
5.8 KiB
C
/* UI_FILE - a generic STDIO like output stream.
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Copyright (C) 1999-2018 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Implement the ``struct ui_file'' object. */
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#include "defs.h"
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#include "ui-file.h"
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#include "gdb_obstack.h"
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#include "gdb_select.h"
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#include "filestuff.h"
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null_file null_stream;
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ui_file::ui_file ()
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{}
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ui_file::~ui_file ()
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{}
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void
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ui_file::printf (const char *format, ...)
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{
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va_list args;
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va_start (args, format);
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vfprintf_unfiltered (this, format, args);
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va_end (args);
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}
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void
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ui_file::putstr (const char *str, int quoter)
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{
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fputstr_unfiltered (str, quoter, this);
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}
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void
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ui_file::putstrn (const char *str, int n, int quoter)
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{
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fputstrn_unfiltered (str, n, quoter, fputc_unfiltered, this);
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}
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int
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ui_file::putc (int c)
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{
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return fputc_unfiltered (c, this);
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}
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void
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ui_file::vprintf (const char *format, va_list args)
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{
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vfprintf_unfiltered (this, format, args);
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}
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void
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null_file::write (const char *buf, long sizeof_buf)
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{
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/* Discard the request. */
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}
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void
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null_file::puts (const char *)
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{
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/* Discard the request. */
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}
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void
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null_file::write_async_safe (const char *buf, long sizeof_buf)
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{
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/* Discard the request. */
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}
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void
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gdb_flush (struct ui_file *file)
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{
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file->flush ();
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}
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int
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ui_file_isatty (struct ui_file *file)
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{
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return file->isatty ();
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}
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void
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ui_file_write (struct ui_file *file,
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const char *buf,
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long length_buf)
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{
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file->write (buf, length_buf);
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}
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void
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ui_file_write_async_safe (struct ui_file *file,
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const char *buf,
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long length_buf)
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{
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file->write_async_safe (buf, length_buf);
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}
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long
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ui_file_read (struct ui_file *file, char *buf, long length_buf)
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{
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return file->read (buf, length_buf);
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}
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void
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fputs_unfiltered (const char *buf, struct ui_file *file)
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{
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file->puts (buf);
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}
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string_file::~string_file ()
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{}
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void
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string_file::write (const char *buf, long length_buf)
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{
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m_string.append (buf, length_buf);
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}
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stdio_file::stdio_file (FILE *file, bool close_p)
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{
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set_stream (file);
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m_close_p = close_p;
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}
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stdio_file::stdio_file ()
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: m_file (NULL),
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m_fd (-1),
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m_close_p (false)
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{}
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stdio_file::~stdio_file ()
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{
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if (m_close_p)
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fclose (m_file);
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}
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void
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stdio_file::set_stream (FILE *file)
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{
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m_file = file;
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m_fd = fileno (file);
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}
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bool
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stdio_file::open (const char *name, const char *mode)
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{
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/* Close the previous stream, if we own it. */
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if (m_close_p)
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{
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fclose (m_file);
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m_close_p = false;
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}
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gdb_file_up f = gdb_fopen_cloexec (name, mode);
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if (f == NULL)
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return false;
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set_stream (f.release ());
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m_close_p = true;
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return true;
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}
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void
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stdio_file::flush ()
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{
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fflush (m_file);
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}
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long
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stdio_file::read (char *buf, long length_buf)
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{
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/* Wait until at least one byte of data is available, or we get
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interrupted with Control-C. */
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{
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fd_set readfds;
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FD_ZERO (&readfds);
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FD_SET (m_fd, &readfds);
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if (interruptible_select (m_fd + 1, &readfds, NULL, NULL, NULL) == -1)
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return -1;
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}
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return ::read (m_fd, buf, length_buf);
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}
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void
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stdio_file::write (const char *buf, long length_buf)
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{
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/* Calling error crashes when we are called from the exception framework. */
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if (fwrite (buf, length_buf, 1, m_file))
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{
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/* Nothing. */
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}
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}
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void
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stdio_file::write_async_safe (const char *buf, long length_buf)
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{
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/* This is written the way it is to avoid a warning from gcc about not using the
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result of write (since it can be declared with attribute warn_unused_result).
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Alas casting to void doesn't work for this. */
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if (::write (m_fd, buf, length_buf))
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{
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/* Nothing. */
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}
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}
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void
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stdio_file::puts (const char *linebuffer)
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{
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/* Calling error crashes when we are called from the exception framework. */
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if (fputs (linebuffer, m_file))
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{
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/* Nothing. */
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}
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}
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bool
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stdio_file::isatty ()
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{
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return ::isatty (m_fd);
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}
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/* This is the implementation of ui_file method 'write' for stderr.
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gdb_stdout is flushed before writing to gdb_stderr. */
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void
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stderr_file::write (const char *buf, long length_buf)
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{
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gdb_flush (gdb_stdout);
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stdio_file::write (buf, length_buf);
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}
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/* This is the implementation of ui_file method 'puts' for stderr.
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gdb_stdout is flushed before writing to gdb_stderr. */
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void
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stderr_file::puts (const char *linebuffer)
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{
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gdb_flush (gdb_stdout);
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stdio_file::puts (linebuffer);
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}
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stderr_file::stderr_file (FILE *stream)
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: stdio_file (stream)
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{}
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tee_file::tee_file (ui_file *one, bool close_one,
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ui_file *two, bool close_two)
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: m_one (one),
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m_two (two),
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m_close_one (close_one),
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m_close_two (close_two)
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{}
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tee_file::~tee_file ()
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{
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if (m_close_one)
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delete m_one;
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if (m_close_two)
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delete m_two;
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}
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void
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tee_file::flush ()
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{
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m_one->flush ();
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m_two->flush ();
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}
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void
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tee_file::write (const char *buf, long length_buf)
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{
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m_one->write (buf, length_buf);
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m_two->write (buf, length_buf);
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}
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void
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tee_file::write_async_safe (const char *buf, long length_buf)
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{
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m_one->write_async_safe (buf, length_buf);
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m_two->write_async_safe (buf, length_buf);
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}
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void
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tee_file::puts (const char *linebuffer)
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{
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m_one->puts (linebuffer);
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m_two->puts (linebuffer);
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}
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bool
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tee_file::isatty ()
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{
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return m_one->isatty ();
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}
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