[PATCH 3/3] Implement remote_bfd_iovec_stat using vFile:fstat

Gary Benson
2015-03-09T11:58:29Z

This patch implements the function remote_bfd_iovec_stat using a
vFile:fstat hostio call to the remote target. If vFile:fstat is
not supported GDB creates a dummy result by zeroing the supplied
stat structure and then setting it's st_size field to INT_MAX.
This mimic's GDB's previous behaviour, with the exception that
GDB did not previously zero the structure so all other fields
would have been returned unchanged, which is to say very likely
populated with random values from the stack.

gdb/ChangeLog:

* remote-fileio.h (remote_fileio_to_host_stat): New declaration.
* remote-fileio.c (remote_fileio_to_host_uint): New function.
(remote_fileio_to_host_ulong): Likewise.
(remote_fileio_to_host_mode): Likewise.
(remote_fileio_to_host_time): Likewise.
(remote_fileio_to_host_stat): Likewise.
* remote.c (PACKET_vFile_fstat): New enum value.
(remote_protocol_features): Register the "vFile:fstat" feature.
(remote_hostio_fstat): New function.
(remote_bfd_iovec_stat): Use the above.
(_initialize_remote): Register new "set/show remote
hostio-fstat-packet" command.

gdb/doc/ChangeLog:

* gdb.texinfo (Remote Configuration): Document the
"set/show remote hostio-fstat-packet" command.
---
gdb/ChangeLog | 15 +++++++++
gdb/doc/ChangeLog | 5 +++
gdb/doc/gdb.texinfo | 4 ++
gdb/remote-fileio.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++
gdb/remote-fileio.h | 4 ++
gdb/remote.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++--
6 files changed, 183 insertions(+), 4 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 8d4af3c..552da31 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -19748,6 +19748,10 @@ are:
@tab @code{vFile:readlink}
@tab Host I/O

+@item @code{hostio-fstat-packet}
+@tab @code{vFile:fstat}
+@tab Host I/O
+
@item @code{noack-packet}
@tab @code{QStartNoAckMode}
@tab Packet acknowledgment
diff --git a/gdb/remote-fileio.c b/gdb/remote-fileio.c
index 0ce0714..aaf839d 100644
--- a/gdb/remote-fileio.c
+++ b/gdb/remote-fileio.c
@@ -1321,6 +1321,86 @@ remote_fileio_request (char *buf, int ctrlc_pending_p)

remote_fileio_sig_exit ();
}
+\f
+
+/* Unpack an fio_uint_t. */
+
+static unsigned int
+remote_fileio_to_host_uint (fio_uint_t fnum)
+{
+ gdb_byte *buf, *lim;
+ unsigned int num = 0;
+
+ for (buf = (gdb_byte *) fnum, lim = buf + 4; buf < lim; buf++)
+ {
+ num <<= 8;
+ num |= *buf;
+ }
+
+ return num;
+}
+
+/* Unpack an fio_ulong_t. */
+
+static ULONGEST
+remote_fileio_to_host_ulong (fio_ulong_t fnum)
+{
+ gdb_byte *buf, *lim;
+ ULONGEST num = 0;
+
+ for (buf = (gdb_byte *) fnum, lim = buf + 8; buf < lim; buf++)
+ {
+ num <<= 8;
+ num |= *buf;
+ }
+
+ return num;
+}
+
+/* Unpack an fio_mode_t. */
+
+static mode_t
+remote_fileio_to_host_mode (fio_mode_t fnum)
+{
+ return remote_fileio_mode_to_host (remote_fileio_to_host_uint (fnum),
+ 0);
+}
+
+/* Unpack an fio_time_t. */
+
+static time_t
+remote_fileio_to_host_time (fio_time_t fnum)
+{
+ return remote_fileio_to_host_uint (fnum);
+}
+
+
+/* See remote-fileio.h. */
+
+void
+remote_fileio_to_host_stat (struct fio_stat *fst, struct stat *st)
+{
+ memset (st, 0, sizeof (struct stat));
+
+ st->st_dev = remote_fileio_to_host_uint (fst->fst_dev);
+ st->st_ino = remote_fileio_to_host_uint (fst->fst_ino);
+ st->st_mode = remote_fileio_to_host_mode (fst->fst_mode);
+ st->st_nlink = remote_fileio_to_host_uint (fst->fst_nlink);
+ st->st_uid = remote_fileio_to_host_uint (fst->fst_uid);
+ st->st_gid = remote_fileio_to_host_uint (fst->fst_gid);
+ st->st_rdev = remote_fileio_to_host_uint (fst->fst_rdev);
+ st->st_size = remote_fileio_to_host_ulong (fst->fst_size);
+#ifdef HAVE_STRUCT_STAT_ST_BLKSIZE
+ st->st_blksize = remote_fileio_to_host_ulong (fst->fst_blksize);
+#endif
+#if HAVE_STRUCT_STAT_ST_BLOCKS
+ st->st_blocks = remote_fileio_to_host_ulong (fst->fst_blocks);
+#endif
+ st->st_atime = remote_fileio_to_host_time (fst->fst_atime);
+ st->st_mtime = remote_fileio_to_host_time (fst->fst_mtime);
+ st->st_ctime = remote_fileio_to_host_time (fst->fst_ctime);
+}
+\f

static void
set_system_call_allowed (char *args, int from_tty)
diff --git a/gdb/remote-fileio.h b/gdb/remote-fileio.h
index 8b32868..d30ae6a 100644
--- a/gdb/remote-fileio.h
+++ b/gdb/remote-fileio.h
@@ -38,4 +38,8 @@ extern void initialize_remote_fileio (
struct cmd_list_element *remote_set_cmdlist,
struct cmd_list_element *remote_show_cmdlist);

+/* Unpack a struct fio_stat. */
+extern void remote_fileio_to_host_stat (struct fio_stat *fst,
+ struct stat *st);
+
#endif
diff --git a/gdb/remote.c b/gdb/remote.c
index 495dfdc..69bcdd7 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -1253,6 +1253,7 @@ enum {
PACKET_vFile_close,
PACKET_vFile_unlink,
PACKET_vFile_readlink,
+ PACKET_vFile_fstat,
PACKET_qXfer_auxv,
PACKET_qXfer_features,
PACKET_qXfer_libraries,
@@ -4042,7 +4043,9 @@ static const struct protocol_feature remote_protocol_features[] = {
{ "Qbtrace-conf:bts:size", PACKET_DISABLE, remote_supported_packet,
PACKET_Qbtrace_conf_bts_size },
{ "swbreak", PACKET_DISABLE, remote_supported_packet, PACKET_swbreak_feature },
- { "hwbreak", PACKET_DISABLE, remote_supported_packet, PACKET_hwbreak_feature }
+ { "hwbreak", PACKET_DISABLE, remote_supported_packet, PACKET_hwbreak_feature },
+ { "vFile:fstat", PACKET_DISABLE, remote_supported_packet,
+ PACKET_vFile_fstat },
};

static char *remote_support_xml;
@@ -10059,6 +10062,55 @@ remote_hostio_readlink (struct target_ops *self,
return ret;
}

+/* Read information about the open file FD on the remote target
+ into ST. Return 0 on success, or -1 if an error occurs (and
+ set *REMOTE_ERRNO). */
+
+static int
+remote_hostio_fstat (struct target_ops *self,
+ int fd, struct stat *st,
+ int *remote_errno)
+{
+ struct remote_state *rs = get_remote_state ();
+ char *p = rs->buf;
+ int left = get_remote_packet_size ();
+ int attachment_len, ret;
+ char *attachment;
+ struct fio_stat fst;
+ int read_len;
+
+ if (packet_support (PACKET_vFile_fstat) != PACKET_ENABLE)
+ {
+ memset (st, 0, sizeof (struct stat));
+ st->st_size = INT_MAX;
+ return 0;
+ }
+
+ remote_buffer_add_string (&p, &left, "vFile:fstat:");
+
+ remote_buffer_add_int (&p, &left, fd);
+
+ ret = remote_hostio_send_command (p - rs->buf, PACKET_vFile_fstat,
+ remote_errno, &attachment,
+ &attachment_len);
+ if (ret < 0)
+ return ret;
+
+ read_len = remote_unescape_input ((gdb_byte *) attachment, attachment_len,
+ (gdb_byte *) &fst, sizeof (fst));
+
+ if (read_len != ret)
+ error (_("vFile:fstat returned %d, but %d bytes."), ret, read_len);
+
+ if (read_len != sizeof (fst))
+ error (_("vFile:fstat returned %d bytes, but expecting %d."),
+ read_len, (int) sizeof (fst));
+
+ remote_fileio_to_host_stat (&fst, st);
+
+ return 0;
+}
+
static int
remote_fileio_errno_to_host (int errnum)
{
@@ -10203,9 +10255,25 @@ remote_bfd_iovec_pread (struct bfd *abfd, void *stream, void *buf,
static int
remote_bfd_iovec_stat (struct bfd *abfd, void *stream, struct stat *sb)
{
- /* FIXME: We should probably implement remote_hostio_stat. */
- sb->st_size = INT_MAX;
- return 0;
+ int fd = *(int *) stream;
+ int remote_errno;
+ int result;
+ const char *filename;
+
+ filename = bfd_get_filename (abfd);
+ gdb_assert (remote_filename_p (filename));
+ filename += strlen (REMOTE_SYSROOT_PREFIX);
+
+ result = remote_hostio_fstat (find_target_at (process_stratum),
+ fd, sb, &remote_errno);
+
+ if (result == -1)
+ {
+ errno = remote_fileio_errno_to_host (remote_errno);
+ bfd_set_error (bfd_error_system_call);
+ }
+
+ return result;
}

int
@@ -12342,6 +12410,9 @@ Show the maximum size of the address (in bits) in a memory packet."), NULL,
add_packet_config_cmd (&remote_protocol_packets[PACKET_vFile_readlink],
"vFile:readlink", "hostio-readlink", 0);

+ add_packet_config_cmd (&remote_protocol_packets[PACKET_vFile_fstat],
+ "vFile:fstat", "hostio-fstat", 0);
+
add_packet_config_cmd (&remote_protocol_packets[PACKET_vAttach],
"vAttach", "attach", 0);

--
1.7.1