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Associate target_ops with target_fileio file descriptors

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Various target_fileio_* functions use integer file descriptors to
refer to open files.  File operation functions are looked up from
the target stack as they are used, which causes problems if the
target stack changes after the file is opened.

For example, if a file is opened on a remote target and the remote
target disconnects or closes the remote target will be popped off
the stack.  If target_fileio_close is then called on that file and
"set auto-connect-native-target" is "on" (the default) then the
native target's close method will be called.  If the file opened
on the remote happens to share the same number with a file open in
GDB then that file will be closed by mistake.

This commit changes target_fileio_open to store newly opened file
descriptors in a table together with the target_ops used to open
them.  The index into the table is returned and used as the file
descriptor argument to all target_fileio_* functions that accept
file descriptor arguments.

gdb/ChangeLog:

	* target.c (fileio_ft_t): New typedef, define object vector.
	(fileio_fhandles): New static variable.
	(is_closed_fileio_fh): New macro.
	(lowest_closed_fd): New static variable.
	(acquire_fileio_fd): New function.
	(release_fileio_fd): Likewise.
	(fileio_fd_to_fh): New macro.
	(target_fileio_open): Wrap the file descriptor on success.
	(target_fileio_pwrite): Updated to use wrapped file descriptor.
	(target_fileio_pread): Likewise.
	(target_fileio_close): Likewise.
This commit is contained in:
Gary Benson 2015-03-25 11:26:43 +00:00
parent d422d1c433
commit 1c4b552ba5
2 changed files with 132 additions and 52 deletions
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15
gdb/ChangeLog
View file

@ -1,3 +1,18 @@
2015-03-25 Gary Benson <gbenson@redhat.com>
Pedro Alves <palves@redhat.com>
* target.c (fileio_ft_t): New typedef, define object vector.
(fileio_fhandles): New static variable.
(is_closed_fileio_fh): New macro.
(lowest_closed_fd): New static variable.
(acquire_fileio_fd): New function.
(release_fileio_fd): Likewise.
(fileio_fd_to_fh): New macro.
(target_fileio_open): Wrap the file descriptor on success.
(target_fileio_pwrite): Updated to use wrapped file descriptor.
(target_fileio_pread): Likewise.
(target_fileio_close): Likewise.
2015-03-24 Pedro Alves <palves@redhat.com>
* thread.c (thread_apply_all_command): Take exited threads into

169
gdb/target.c
View file

@ -2684,6 +2684,78 @@ default_fileio_target (void)
return find_default_run_target ("file I/O");
}
/* File handle for target file operations. */
typedef struct
{
/* The target on which this file is open. */
struct target_ops *t;
/* The file descriptor on the target. */
int fd;
} fileio_fh_t;
DEF_VEC_O (fileio_fh_t);
/* Vector of currently open file handles. The value returned by
target_fileio_open and passed as the FD argument to other
target_fileio_* functions is an index into this vector. This
vector's entries are never freed; instead, files are marked as
closed, and the handle becomes available for reuse. */
static VEC (fileio_fh_t) *fileio_fhandles;
/* Macro to check whether a fileio_fh_t represents a closed file. */
#define is_closed_fileio_fh(fd) ((fd) < 0)
/* Index into fileio_fhandles of the lowest handle that might be
closed. This permits handle reuse without searching the whole
list each time a new file is opened. */
static int lowest_closed_fd;
/* Acquire a target fileio file descriptor. */
static int
acquire_fileio_fd (struct target_ops *t, int fd)
{
fileio_fh_t *fh, buf;
gdb_assert (!is_closed_fileio_fh (fd));
/* Search for closed handles to reuse. */
for (;
VEC_iterate (fileio_fh_t, fileio_fhandles,
lowest_closed_fd, fh);
lowest_closed_fd++)
if (is_closed_fileio_fh (fh->fd))
break;
/* Push a new handle if no closed handles were found. */
if (lowest_closed_fd == VEC_length (fileio_fh_t, fileio_fhandles))
fh = VEC_safe_push (fileio_fh_t, fileio_fhandles, NULL);
/* Fill in the handle. */
fh->t = t;
fh->fd = fd;
/* Return its index, and start the next lookup at
the next index. */
return lowest_closed_fd++;
}
/* Release a target fileio file descriptor. */
static void
release_fileio_fd (int fd, fileio_fh_t *fh)
{
fh->fd = -1;
lowest_closed_fd = min (lowest_closed_fd, fd);
}
/* Return a pointer to the fileio_fhandle_t corresponding to FD. */
#define fileio_fd_to_fh(fd) \
VEC_index (fileio_fh_t, fileio_fhandles, (fd))
/* Open FILENAME on the target, using FLAGS and MODE. Return a
target file descriptor, or -1 if an error occurs (and set
*TARGET_ERRNO). */
@ -2699,6 +2771,11 @@ target_fileio_open (const char *filename, int flags, int mode,
{
int fd = t->to_fileio_open (t, filename, flags, mode, target_errno);
if (fd < 0)
fd = -1;
else
fd = acquire_fileio_fd (t, fd);
if (targetdebug)
fprintf_unfiltered (gdb_stdlog,
"target_fileio_open (%s,0x%x,0%o) = %d (%d)\n",
@ -2719,27 +2796,22 @@ int
target_fileio_pwrite (int fd, const gdb_byte *write_buf, int len,
ULONGEST offset, int *target_errno)
{
struct target_ops *t;
fileio_fh_t *fh = fileio_fd_to_fh (fd);
int ret = -1;
for (t = default_fileio_target (); t != NULL; t = t->beneath)
{
if (t->to_fileio_pwrite != NULL)
{
int ret = t->to_fileio_pwrite (t, fd, write_buf, len, offset,
target_errno);
if (is_closed_fileio_fh (fh->fd))
*target_errno = EBADF;
else
ret = fh->t->to_fileio_pwrite (fh->t, fh->fd, write_buf,
len, offset, target_errno);
if (targetdebug)
fprintf_unfiltered (gdb_stdlog,
"target_fileio_pwrite (%d,...,%d,%s) "
"= %d (%d)\n",
fd, len, pulongest (offset),
ret, ret != -1 ? 0 : *target_errno);
return ret;
}
}
*target_errno = FILEIO_ENOSYS;
return -1;
if (targetdebug)
fprintf_unfiltered (gdb_stdlog,
"target_fileio_pwrite (%d,...,%d,%s) "
"= %d (%d)\n",
fd, len, pulongest (offset),
ret, ret != -1 ? 0 : *target_errno);
return ret;
}
/* Read up to LEN bytes FD on the target into READ_BUF.
@ -2749,27 +2821,22 @@ int
target_fileio_pread (int fd, gdb_byte *read_buf, int len,
ULONGEST offset, int *target_errno)
{
struct target_ops *t;
fileio_fh_t *fh = fileio_fd_to_fh (fd);
int ret = -1;
for (t = default_fileio_target (); t != NULL; t = t->beneath)
{
if (t->to_fileio_pread != NULL)
{
int ret = t->to_fileio_pread (t, fd, read_buf, len, offset,
target_errno);
if (is_closed_fileio_fh (fh->fd))
*target_errno = EBADF;
else
ret = fh->t->to_fileio_pread (fh->t, fh->fd, read_buf,
len, offset, target_errno);
if (targetdebug)
fprintf_unfiltered (gdb_stdlog,
"target_fileio_pread (%d,...,%d,%s) "
"= %d (%d)\n",
fd, len, pulongest (offset),
ret, ret != -1 ? 0 : *target_errno);
return ret;
}
}
*target_errno = FILEIO_ENOSYS;
return -1;
if (targetdebug)
fprintf_unfiltered (gdb_stdlog,
"target_fileio_pread (%d,...,%d,%s) "
"= %d (%d)\n",
fd, len, pulongest (offset),
ret, ret != -1 ? 0 : *target_errno);
return ret;
}
/* Close FD on the target. Return 0, or -1 if an error occurs
@ -2777,24 +2844,22 @@ target_fileio_pread (int fd, gdb_byte *read_buf, int len,
int
target_fileio_close (int fd, int *target_errno)
{
struct target_ops *t;
fileio_fh_t *fh = fileio_fd_to_fh (fd);
int ret = -1;
for (t = default_fileio_target (); t != NULL; t = t->beneath)
if (is_closed_fileio_fh (fh->fd))
*target_errno = EBADF;
else
{
if (t->to_fileio_close != NULL)
{
int ret = t->to_fileio_close (t, fd, target_errno);
if (targetdebug)
fprintf_unfiltered (gdb_stdlog,
"target_fileio_close (%d) = %d (%d)\n",
fd, ret, ret != -1 ? 0 : *target_errno);
return ret;
}
ret = fh->t->to_fileio_close (fh->t, fh->fd, target_errno);
release_fileio_fd (fd, fh);
}
*target_errno = FILEIO_ENOSYS;
return -1;
if (targetdebug)
fprintf_unfiltered (gdb_stdlog,
"target_fileio_close (%d) = %d (%d)\n",
fd, ret, ret != -1 ? 0 : *target_errno);
return ret;
}
/* Unlink FILENAME on the target. Return 0, or -1 if an error