--- Begin Message ---
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Subject: |
[PATCH] Port redirect-debugging-output to non-GNU/Linux |
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Date: |
Thu, 31 Mar 2016 13:25:34 -0700 |
Problem reported by Kylie McClain for musl in:
http://lists.gnu.org/archive/html/emacs-devel/2016-03/msg01592.html
* etc/DEBUG, etc/NEWS: Mention this.
* src/callproc.c (child_setup) [!MSDOS]:
* src/dispnew.c (init_display):
* src/emacs.c (main, Fdaemon_initialized):
* src/minibuf.c (read_minibuf_noninteractive):
* src/regex.c (xmalloc, xrealloc):
Prefer symbolic names like STDERR_FILENO to magic numbers like 2,
to make file-descriptor manipulation easier to follow.
* src/emacs.c (relocate_fd) [!WINDOWSNT]: Remove; no longer needed
now that we make sure stdin, stdout and stderr are open. All uses
removed.
(main): Make sure standard FDs are OK. Prefer symbolic names like
EXIT_FAILURE to magic numbers like 1. Use bool for boolean.
* src/lisp.h (init_standard_fds): New decl.
* src/print.c (WITH_REDIRECT_DEBUGGING_OUTPUT) [GNU_LINUX]:
Remove; no longer needed.
(Fredirect_debugging_output): Define on all platforms, not just
GNU/Linux. Redirect file descriptor, not stream, so that the code
works even if stderr is not an lvalue. Report an error if the
file arg is neither a string nor nil.
(syms_of_print): Always define redirect-debugging-output.
* src/sysdep.c (force_open, init_standard_fds): New functions.
---
etc/DEBUG | 8 ++++----
etc/NEWS | 3 +++
src/callproc.c | 58 +++-------------------------------------------------------
src/dispnew.c | 2 +-
src/emacs.c | 28 +++++++++++++++-------------
src/lisp.h | 1 +
src/minibuf.c | 12 ++++++------
src/print.c | 51 ++++++++++++++++++++++++---------------------------
src/regex.c | 4 ++--
src/sysdep.c | 29 +++++++++++++++++++++++++++++
10 files changed, 88 insertions(+), 108 deletions(-)
diff --git a/etc/DEBUG b/etc/DEBUG
index eef67da..d5d5829 100644
--- a/etc/DEBUG
+++ b/etc/DEBUG
@@ -144,8 +144,8 @@ These are displayed as integer values (or structures, if
you used the
"--enable-check-lisp-object-type" option at configure time) that are
hard to interpret, especially if they represent long lists. You can
use the 'pp' command to display them in their Lisp form. That command
-displays its output on the standard error stream (on GNU/Linux, you
-can redirect that to a file using "M-x redirect-debugging-output").
+displays its output on the standard error stream, which you
+can redirect to a file using "M-x redirect-debugging-output".
This means that if you attach GDB to a running Emacs that was invoked
from a desktop icon, chances are you will not see the output at all,
or it will wind up in an obscure place (check the documentation of
@@ -250,8 +250,8 @@ To see the current value of a Lisp Variable, use 'pv
variable'.
These commands send their output to stderr; if that is closed or
redirected to some file you don't know, you won't see their output.
This is particularly so for Emacs invoked on MS-Windows from the
-desktop shortcut. On GNU/Linux, you can use the command
-'redirect-debugging-output' to redirect stderr to a file.
+desktop shortcut. You can use the command 'redirect-debugging-output'
+to redirect stderr to a file.
Note: It is not a good idea to try 'pr', 'pp', or 'pv' if you know that Emacs
is in deep trouble: its stack smashed (e.g., if it encountered SIGSEGV
diff --git a/etc/NEWS b/etc/NEWS
index 726b4b9..e4d8a62 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -208,6 +208,9 @@ permanent and documented, and may be used by Lisp programs.
Its value
is a list of currently open parenthesis positions, starting with the
outermost parenthesis.
+** The function 'redirect-debugging-output' now works on platforms
+other than GNU/Linux.
+
* Changes in Emacs 25.2 on Non-Free Operating Systems
diff --git a/src/callproc.c b/src/callproc.c
index db602f5..8578556 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -1078,10 +1078,6 @@ usage: (call-process-region START END PROGRAM &optional
DELETE BUFFER DISPLAY &r
return unbind_to (count, val);
}
-#ifndef WINDOWSNT
-static int relocate_fd (int fd, int minfd);
-#endif
-
static char **
add_env (char **env, char **new_env, char *string)
{
@@ -1310,37 +1306,14 @@ child_setup (int in, int out, int err, char **new_argv,
bool set_pgrp,
return cpid;
#else /* not WINDOWSNT */
- /* Make sure that in, out, and err are not actually already in
- descriptors zero, one, or two; this could happen if Emacs is
- started with its standard in, out, or error closed, as might
- happen under X. */
- {
- int oin = in, oout = out;
-
- /* We have to avoid relocating the same descriptor twice! */
-
- in = relocate_fd (in, 3);
-
- if (out == oin)
- out = in;
- else
- out = relocate_fd (out, 3);
-
- if (err == oin)
- err = in;
- else if (err == oout)
- err = out;
- else
- err = relocate_fd (err, 3);
- }
#ifndef MSDOS
/* Redirect file descriptors and clear the close-on-exec flag on the
redirected ones. IN, OUT, and ERR are close-on-exec so they
need not be closed explicitly. */
- dup2 (in, 0);
- dup2 (out, 1);
- dup2 (err, 2);
+ dup2 (in, STDIN_FILENO);
+ dup2 (out, STDOUT_FILENO);
+ dup2 (err, STDERR_FILENO);
setpgid (0, 0);
tcsetpgrp (0, pid);
@@ -1359,31 +1332,6 @@ child_setup (int in, int out, int err, char **new_argv,
bool set_pgrp,
#endif /* not WINDOWSNT */
}
-#ifndef WINDOWSNT
-/* Move the file descriptor FD so that its number is not less than MINFD.
- If the file descriptor is moved at all, the original is closed on MSDOS,
- but not elsewhere as the caller will close it anyway. */
-static int
-relocate_fd (int fd, int minfd)
-{
- if (fd >= minfd)
- return fd;
- else
- {
- int new = fcntl (fd, F_DUPFD_CLOEXEC, minfd);
- if (new == -1)
- {
- emacs_perror ("while setting up child");
- _exit (EXIT_CANCELED);
- }
-#ifdef MSDOS
- emacs_close (fd);
-#endif
- return new;
- }
-}
-#endif /* not WINDOWSNT */
-
static bool
getenv_internal_1 (const char *var, ptrdiff_t varlen, char **value,
ptrdiff_t *valuelen, Lisp_Object env)
diff --git a/src/dispnew.c b/src/dispnew.c
index 3a0532a..51caa5b 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -6038,7 +6038,7 @@ init_display (void)
#endif
/* If no window system has been specified, try to use the terminal. */
- if (! isatty (0))
+ if (! isatty (STDIN_FILENO))
fatal ("standard input is not a tty");
#ifdef WINDOWSNT
diff --git a/src/emacs.c b/src/emacs.c
index 95d1905..c21c9e3 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -721,6 +721,7 @@ main (int argc, char **argv)
unexec_init_emacs_zone ();
#endif
+ init_standard_fds ();
atexit (close_output_streams);
#ifdef HAVE_MODULES
@@ -899,24 +900,25 @@ main (int argc, char **argv)
char *term;
if (argmatch (argv, argc, "-t", "--terminal", 4, &term, &skip_args))
{
- int result;
- emacs_close (0);
- emacs_close (1);
- result = emacs_open (term, O_RDWR, 0);
- if (result < 0 || fcntl (0, F_DUPFD_CLOEXEC, 1) < 0)
+ emacs_close (STDIN_FILENO);
+ emacs_close (STDOUT_FILENO);
+ int result = emacs_open (term, O_RDWR, 0);
+ if (result != STDIN_FILENO
+ || (fcntl (STDIN_FILENO, F_DUPFD_CLOEXEC, STDOUT_FILENO)
+ != STDOUT_FILENO))
{
char *errstring = strerror (errno);
fprintf (stderr, "%s: %s: %s\n", argv[0], term, errstring);
- exit (1);
+ exit (EXIT_FAILURE);
}
- if (! isatty (0))
+ if (! isatty (STDIN_FILENO))
{
fprintf (stderr, "%s: %s: not a tty\n", argv[0], term);
- exit (1);
+ exit (EXIT_FAILURE);
}
fprintf (stderr, "Using %s\n", term);
#ifdef HAVE_WINDOW_SYSTEM
- inhibit_window_system = 1; /* -t => -nw */
+ inhibit_window_system = true; /* -t => -nw */
#endif
}
else
@@ -1209,7 +1211,7 @@ Using an Emacs configured with --with-x-toolkit=lucid
does not have this problem
/* Started from GUI? */
/* FIXME: Do the right thing if getenv returns NULL, or if
chdir fails. */
- if (! inhibit_window_system && ! isatty (0) && ! ch_to_dir)
+ if (! inhibit_window_system && ! isatty (STDIN_FILENO) && ! ch_to_dir)
chdir (getenv ("HOME"));
if (skip_args < argc)
{
@@ -2357,9 +2359,9 @@ from the parent process and its tty file descriptors. */)
/* Get rid of stdin, stdout and stderr. */
nfd = emacs_open ("/dev/null", O_RDWR, 0);
err |= nfd < 0;
- err |= dup2 (nfd, 0) < 0;
- err |= dup2 (nfd, 1) < 0;
- err |= dup2 (nfd, 2) < 0;
+ err |= dup2 (nfd, STDIN_FILENO) < 0;
+ err |= dup2 (nfd, STDOUT_FILENO) < 0;
+ err |= dup2 (nfd, STDERR_FILENO) < 0;
err |= emacs_close (nfd) != 0;
/* Closing the pipe will notify the parent that it can exit.
diff --git a/src/lisp.h b/src/lisp.h
index 7c8b452..65335fb 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -4248,6 +4248,7 @@ struct tty_display_info;
struct terminal;
/* Defined in sysdep.c. */
+extern void init_standard_fds (void);
extern char *emacs_get_current_dir_name (void);
extern void stuff_char (char c);
extern void init_foreground_group (void);
diff --git a/src/minibuf.c b/src/minibuf.c
index 238a04a..41814c2 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -194,7 +194,7 @@ read_minibuf_noninteractive (Lisp_Object map, Lisp_Object
initial,
int c;
unsigned char hide_char = 0;
struct emacs_tty etty;
- bool etty_valid;
+ bool etty_valid IF_LINT (= false);
/* Check, whether we need to suppress echoing. */
if (CHARACTERP (Vread_hide_char))
@@ -203,10 +203,10 @@ read_minibuf_noninteractive (Lisp_Object map, Lisp_Object
initial,
/* Manipulate tty. */
if (hide_char)
{
- etty_valid = emacs_get_tty (fileno (stdin), &etty) == 0;
+ etty_valid = emacs_get_tty (STDIN_FILENO, &etty) == 0;
if (etty_valid)
- set_binary_mode (fileno (stdin), O_BINARY);
- suppress_echo_on_tty (fileno (stdin));
+ set_binary_mode (STDIN_FILENO, O_BINARY);
+ suppress_echo_on_tty (STDIN_FILENO);
}
fwrite (SDATA (prompt), 1, SBYTES (prompt), stdout);
@@ -240,8 +240,8 @@ read_minibuf_noninteractive (Lisp_Object map, Lisp_Object
initial,
fprintf (stdout, "\n");
if (etty_valid)
{
- emacs_set_tty (fileno (stdin), &etty, 0);
- set_binary_mode (fileno (stdin), O_TEXT);
+ emacs_set_tty (STDIN_FILENO, &etty, 0);
+ set_binary_mode (STDIN_FILENO, O_TEXT);
}
}
diff --git a/src/print.c b/src/print.c
index 2b53d75..db2918f 100644
--- a/src/print.c
+++ b/src/print.c
@@ -775,15 +775,6 @@ debug_output_compilation_hack (bool x)
print_output_debug_flag = x;
}
-#if defined (GNU_LINUX)
-
-/* This functionality is not vitally important in general, so we rely on
- non-portable ability to use stderr as lvalue. */
-
-#define WITH_REDIRECT_DEBUGGING_OUTPUT 1
-
-static FILE *initial_stderr_stream = NULL;
-
DEFUN ("redirect-debugging-output", Fredirect_debugging_output,
Sredirect_debugging_output,
1, 2,
"FDebug output file: \nP",
@@ -793,30 +784,38 @@ Optional arg APPEND non-nil (interactively, with prefix
arg) means
append to existing target file. */)
(Lisp_Object file, Lisp_Object append)
{
- if (initial_stderr_stream != NULL)
- {
- block_input ();
- fclose (stderr);
- unblock_input ();
- }
- stderr = initial_stderr_stream;
- initial_stderr_stream = NULL;
+ /* If equal to STDERR_FILENO, stderr has not been duplicated and is OK as-is.
+ Otherwise, this is a close-on-exec duplicate of the original stderr. */
+ static int stderr_dup = STDERR_FILENO;
+ int fd = stderr_dup;
- if (STRINGP (file))
+ if (! NILP (file))
{
file = Fexpand_file_name (file, Qnil);
- initial_stderr_stream = stderr;
- stderr = emacs_fopen (SSDATA (file), NILP (append) ? "w" : "a");
- if (stderr == NULL)
+
+ if (stderr_dup == STDERR_FILENO)
{
- stderr = initial_stderr_stream;
- initial_stderr_stream = NULL;
- report_file_error ("Cannot open debugging output stream", file);
+ int n = fcntl (STDERR_FILENO, F_DUPFD_CLOEXEC, STDERR_FILENO + 1);
+ if (n < 0)
+ report_file_error ("dup", file);
+ stderr_dup = n;
}
+
+ fd = emacs_open (SSDATA (ENCODE_FILE (file)),
+ (O_WRONLY | O_CREAT
+ | (! NILP (append) ? O_APPEND : O_TRUNC)),
+ 0666);
+ if (fd < 0)
+ report_file_error ("Cannot open debugging output stream", file);
}
+
+ fflush (stderr);
+ if (dup2 (fd, STDERR_FILENO) < 0)
+ report_file_error ("dup2", file);
+ if (fd != stderr_dup)
+ emacs_close (fd);
return Qnil;
}
-#endif /* GNU_LINUX */
/* This is the interface for debugging printing. */
@@ -2305,9 +2304,7 @@ priorities. */);
defsubr (&Sprint);
defsubr (&Sterpri);
defsubr (&Swrite_char);
-#ifdef WITH_REDIRECT_DEBUGGING_OUTPUT
defsubr (&Sredirect_debugging_output);
-#endif
DEFSYM (Qprint_escape_newlines, "print-escape-newlines");
DEFSYM (Qprint_escape_multibyte, "print-escape-multibyte");
diff --git a/src/regex.c b/src/regex.c
index d5c58ae..af37936 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -215,7 +215,7 @@ xmalloc (size_t size)
void *val = malloc (size);
if (!val && size)
{
- write (2, "virtual memory exhausted\n", 25);
+ write (STDERR_FILENO, "virtual memory exhausted\n", 25);
exit (1);
}
return val;
@@ -233,7 +233,7 @@ xrealloc (void *block, size_t size)
val = realloc (block, size);
if (!val && size)
{
- write (2, "virtual memory exhausted\n", 25);
+ write (STDERR_FILENO, "virtual memory exhausted\n", 25);
exit (1);
}
return val;
diff --git a/src/sysdep.c b/src/sysdep.c
index 6154c13..67c9bd9 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -130,6 +130,35 @@ static const int baud_convert[] =
1800, 2400, 4800, 9600, 19200, 38400
};
+/* If FD is not already open, arrange for it to be open with FLAGS. */
+static void
+force_open (int fd, int flags)
+{
+ if (dup2 (fd, fd) < 0 && errno == EBADF)
+ {
+ int n = open (NULL_DEVICE, flags);
+ if (n < 0 || (fd != n && (dup2 (n, fd) < 0 || emacs_close (n) != 0)))
+ {
+ emacs_perror (NULL_DEVICE);
+ exit (EXIT_FAILURE);
+ }
+ }
+}
+
+/* Make sure stdin, stdout, and stderr are open to something, so that
+ their file descriptors are not hijacked by later system calls. */
+void
+init_standard_fds (void)
+{
+ /* Open stdin for *writing*, and stdout and stderr for *reading*.
+ That way, any attempt to do normal I/O will result in an error,
+ just as if the files were closed, and the file descriptors will
+ not be reused by later opens. */
+ force_open (STDIN_FILENO, O_WRONLY);
+ force_open (STDOUT_FILENO, O_RDONLY);
+ force_open (STDERR_FILENO, O_RDONLY);
+}
+
/* Return the current working directory. The result should be freed
with 'free'. Return NULL on errors. */
char *
--
2.5.5
--- End Message ---