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Avoid throwing exceptions during early boot if stdin is closed

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* libguile/fports.c (scm_i_fdes_is_valid): New internal helper.
  (scm_i_fdes_to_port): Use new helper.
* libguile/fports.h: Declare new helper.
* libguile/init.c (scm_standard_stream_to_port): Refactor to use
  scm_i_fdes_is_valid.
This commit is contained in:
Andy Wingo 2019-12-13 13:52:58 +01:00
parent cf693d862d
commit dbc93d6195
3 changed files with 37 additions and 55 deletions
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44
libguile/fports.c
View file

@ -401,6 +401,29 @@ SCM_DEFINE (scm_i_open_file, "open-file", 2, 0, 1,
/* Building Guile ports from a file descriptor. */
int
scm_i_fdes_is_valid (int fdes, long mode_bits)
{
#ifdef F_GETFL
int flags = fcntl (fdes, F_GETFL, 0);
if (flags == -1)
return 0;
flags &= O_ACCMODE;
if (flags == O_RDWR)
return 1;
if (flags != O_WRONLY && (mode_bits & SCM_WRTNG))
return 0;
if (flags != O_RDONLY && (mode_bits & SCM_RDNG))
return 0;
return 1;
#else
/* If we don't have F_GETFL, as on mingw, at least we can test that
it is a valid file descriptor. */
struct stat st;
return fstat (fdes, &st) == 0;
#endif
}
/* Build a Scheme port from an open file descriptor `fdes'.
MODE indicates whether FILE is open for reading or writing; it uses
the same notation as open-file's second argument.
@ -415,27 +438,14 @@ scm_i_fdes_to_port (int fdes, long mode_bits, SCM name, unsigned options)
if (options & SCM_FPORT_OPTION_VERIFY)
{
/* Check that the foreign FD is valid and matches the mode
bits. */
#ifdef F_GETFL
int flags = fcntl (fdes, F_GETFL, 0);
if (flags == -1)
SCM_SYSERROR;
flags &= O_ACCMODE;
if (flags != O_RDWR
&& ((flags != O_WRONLY && (mode_bits & SCM_WRTNG))
|| (flags != O_RDONLY && (mode_bits & SCM_RDNG))))
errno = 0;
if (!scm_i_fdes_is_valid (fdes, mode_bits))
{
if (errno)
SCM_SYSERROR;
SCM_MISC_ERROR ("requested file mode not available on fdes",
SCM_EOL);
}
#else
/* If we don't have F_GETFL, as on mingw, at least we can test that
it is a valid file descriptor. */
struct stat st;
if (fstat (fdes, &st) != 0)
SCM_SYSERROR;
#endif
}
fp = (scm_t_fport *) scm_gc_malloc_pointerless (sizeof (scm_t_fport),

4
libguile/fports.h
View file

@ -1,7 +1,7 @@
#ifndef SCM_FPORTS_H
#define SCM_FPORTS_H
/* Copyright 1995-2001,2006,2008-2009,2011-2012,2017-2018
/* Copyright 1995-2001,2006,2008-2009,2011-2012,2017-2019
Free Software Foundation, Inc.
This file is part of Guile.
@ -86,8 +86,10 @@ enum scm_fport_option
that case. */
SCM_FPORT_OPTION_NOT_SEEKABLE = 1U<<1
};
SCM_INTERNAL int scm_i_fdes_is_valid (int fdes, long mode_bits);
SCM_INTERNAL SCM scm_i_fdes_to_port (int fdes, long mode_bits, SCM name,
unsigned options);
#endif /* BUILDING_LIBGUILE */
#endif /* SCM_FPORTS_H */

44
libguile/init.c
View file

@ -156,49 +156,19 @@
/* initializing standard and current I/O ports */
typedef struct
{
int fdes;
char *mode;
} stream_body_data;
/* proc to be called in scope of exception handler stream_handler. */
static SCM
stream_body (void *data)
{
stream_body_data *body_data = (stream_body_data *) data;
SCM port = scm_fdes_to_port (body_data->fdes, body_data->mode, SCM_BOOL_F);
scm_set_port_revealed_x (port, SCM_INUM1);
return port;
}
/* exception handler for stream_body. */
static SCM
stream_handler (void *data SCM_UNUSED,
SCM tag SCM_UNUSED,
SCM throw_args SCM_UNUSED)
{
return SCM_BOOL_F;
}
/* Convert a file descriptor to a port, using scm_fdes_to_port.
- set the revealed count for FILE's file descriptor to 1, so
that fdes won't be closed when the port object is GC'd.
- catch exceptions: allow Guile to be able to start up even
if it has been handed bogus stdin/stdout/stderr. replace the
bad ports with void ports. */
that fdes won't be closed when the port object is GC'd. */
static SCM
scm_standard_stream_to_port (int fdes, char *mode)
{
SCM port;
stream_body_data body_data;
long mode_bits = scm_mode_bits (mode);
body_data.fdes = fdes;
body_data.mode = mode;
port = scm_internal_catch (SCM_BOOL_T, stream_body, &body_data,
stream_handler, NULL);
if (scm_is_false (port))
port = scm_void_port (mode);
if (!scm_i_fdes_is_valid (fdes, mode_bits))
return scm_void_port (mode);
SCM port = scm_i_fdes_to_port (fdes, mode_bits, SCM_BOOL_F, 0);
scm_set_port_revealed_x (port, SCM_INUM1);
return port;
}