[PATCH 1/2] xfs_db: add a directory path lookup command

Darrick J. Wong
2020-11-16T17:40:28Z

From: Darrick J. Wong <darrick.wong@oracle.com>

Add a command to xfs_db so that we can navigate to inodes by path.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
db/Makefile | 2
db/command.c | 1
db/command.h | 1
db/namei.c | 223 +++++++++++++++++++++++++++++++++++++++++++++++++++++
man/man8/xfs_db.8 | 4 +
5 files changed, 230 insertions(+), 1 deletion(-)
create mode 100644 db/namei.c

diff --git a/db/Makefile b/db/Makefile
index 9bd9bf514f5d..67908a2c3c98 100644
--- a/db/Makefile
+++ b/db/Makefile
@@ -14,7 +14,7 @@ HFILES = addr.h agf.h agfl.h agi.h attr.h attrshort.h bit.h block.h bmap.h \
io.h logformat.h malloc.h metadump.h output.h print.h quit.h sb.h \
sig.h strvec.h text.h type.h write.h attrset.h symlink.h fsmap.h \
fuzz.h
-CFILES = $(HFILES:.h=.c) btdump.c btheight.c convert.c info.c
+CFILES = $(HFILES:.h=.c) btdump.c btheight.c convert.c info.c namei.c
LSRCFILES = xfs_admin.sh xfs_ncheck.sh xfs_metadump.sh

LLDLIBS = $(LIBXFS) $(LIBXLOG) $(LIBFROG) $(LIBUUID) $(LIBRT) $(LIBPTHREAD)
diff --git a/db/command.c b/db/command.c
index 0fb44efaec59..053097742b12 100644
--- a/db/command.c
+++ b/db/command.c
@@ -131,6 +131,7 @@ init_commands(void)
logformat_init();
io_init();
metadump_init();
+ namei_init();
output_init();
print_init();
quit_init();
diff --git a/db/command.h b/db/command.h
index b8499de0be17..bf130e63c85c 100644
--- a/db/command.h
+++ b/db/command.h
@@ -32,3 +32,4 @@ extern void convert_init(void);
extern void btdump_init(void);
extern void info_init(void);
extern void btheight_init(void);
+extern void namei_init(void);
diff --git a/db/namei.c b/db/namei.c
new file mode 100644
index 000000000000..13ae7f7d116b
--- /dev/null
+++ b/db/namei.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#include "libxfs.h"
+#include "command.h"
+#include "output.h"
+#include "init.h"
+#include "io.h"
+#include "type.h"
+#include "input.h"
+#include "faddr.h"
+#include "fprint.h"
+#include "field.h"
+#include "inode.h"
+
+/* Path lookup */
+
+/* Key for looking up metadata inodes. */
+struct dirpath {
+ /* Array of string pointers. */
+ char **path;
+
+ /* Number of strings in path. */
+ unsigned int depth;
+};
+
+static void
+path_free(
+ struct dirpath *dirpath)
+{
+ unsigned int i;
+
+ for (i = 0; i < dirpath->depth; i++)
+ free(dirpath->path[i]);
+ free(dirpath->path);
+ free(dirpath);
+}
+
+/* Chop a freeform string path into a structured path. */
+static struct dirpath *
+path_parse(
+ const char *path)
+{
+ struct dirpath *dirpath;
+ const char *p = path;
+ const char *endp = path + strlen(path);
+
+ dirpath = calloc(sizeof(*dirpath), 1);
+ if (!dirpath)
+ return NULL;
+
+ while (p < endp) {
+ char **new_path;
+ const char *next_slash;
+
+ next_slash = strchr(p, '/');
+ if (next_slash == p) {
+ p++;
+ continue;
+ }
+ if (!next_slash)
+ next_slash = endp;
+
+ new_path = realloc(dirpath->path,
+ (dirpath->depth + 1) * sizeof(char *));
+ if (!new_path) {
+ path_free(dirpath);
+ return NULL;
+ }
+
+ dirpath->path = new_path;
+ dirpath->path[dirpath->depth] = strndup(p, next_slash - p);
+ dirpath->depth++;
+
+ p = next_slash + 1;
+ }
+
+ return dirpath;
+}
+
+/* Given a directory and a structured path, walk the path and set the cursor. */
+static int
+path_navigate(
+ struct xfs_mount *mp,
+ xfs_ino_t rootino,
+ struct dirpath *dirpath)
+{
+ struct xfs_inode *dp;
+ xfs_ino_t ino = rootino;
+ unsigned int i;
+ int error;
+
+ error = -libxfs_iget(mp, NULL, ino, 0, &dp);
+ if (error)
+ return error;
+
+ for (i = 0; i < dirpath->depth; i++) {
+ struct xfs_name xname = {
+ .name = dirpath->path[i],
+ .len = strlen(dirpath->path[i]),
+ };
+
+ if (!S_ISDIR(VFS_I(dp)->i_mode)) {
+ error = ENOTDIR;
+ goto rele;
+ }
+
+ error = -libxfs_dir_lookup(NULL, dp, &xname, &ino, NULL);
+ if (error)
+ goto rele;
+ if (!xfs_verify_ino(mp, ino)) {
+ error = EFSCORRUPTED;
+ goto rele;
+ }
+
+ libxfs_irele(dp);
+ dp = NULL;
+
+ error = -libxfs_iget(mp, NULL, ino, 0, &dp);
+ switch (error) {
+ case EFSCORRUPTED:
+ case EFSBADCRC:
+ case 0:
+ break;
+ default:
+ return error;
+ }
+ }
+
+ set_cur_inode(ino);
+rele:
+ if (dp)
+ libxfs_irele(dp);
+ return error;
+}
+
+/* Walk a directory path to an inode and set the io cursor to that inode. */
+static int
+path_walk(
+ char *path)
+{
+ struct dirpath *dirpath;
+ char *p = path;
+ xfs_ino_t rootino = mp->m_sb.sb_rootino;
+ int error = 0;
+
+ if (*p == '/') {
+ /* Absolute path, start from the root inode. */
+ p++;
+ } else {
+ /* Relative path, start from current dir. */
+ if (iocur_top->typ != &typtab[TYP_INODE] ||
+ !S_ISDIR(iocur_top->mode))
+ return ENOTDIR;
+
+ rootino = iocur_top->ino;
+ }
+
+ dirpath = path_parse(p);
+ if (!dirpath)
+ return ENOMEM;
+
+ error = path_navigate(mp, rootino, dirpath);
+ if (error)
+ return error;
+
+ path_free(dirpath);
+ return 0;
+}
+
+static void
+path_help(void)
+{
+ dbprintf(_(
+"\n"
+" Navigate to an inode via directory path.\n"
+ ));
+}
+
+static int
+path_f(
+ int argc,
+ char **argv)
+{
+ int c;
+ int error;
+
+ while ((c = getopt(argc, argv, "")) != -1) {
+ switch (c) {
+ default:
+ path_help();
+ return 0;
+ }
+ }
+
+ error = path_walk(argv[optind]);
+ if (error) {
+ dbprintf("%s: %s\n", argv[optind], strerror(error));
+ exitcode = 1;
+ }
+
+ return 0;
+}
+
+static struct cmdinfo path_cmd = {
+ .name = "path",
+ .altname = NULL,
+ .cfunc = path_f,
+ .argmin = 1,
+ .argmax = 1,
+ .canpush = 0,
+ .args = "",
+ .help = path_help,
+};
+
+void
+namei_init(void)
+{
+ path_cmd.oneline = _("navigate to an inode by path");
+ add_command(&path_cmd);
+}
diff --git a/man/man8/xfs_db.8 b/man/man8/xfs_db.8
index 7f73d458cf76..d67e108a706a 100644
--- a/man/man8/xfs_db.8
+++ b/man/man8/xfs_db.8
@@ -831,6 +831,10 @@ See the
.B print
command.
.TP
+.BI "path " dir_path
+Walk the directory tree to an inode using the supplied path.
+Absolute and relative paths are supported.
+.TP
.B pop
Pop location from the stack.
.TP