hw/9pfs: consolidate name validation with check_name()
Add a new, shared helper function check_name() that consolidates the name validation logic (illegal name check and "." / ".." rejection) currently spread over multiple 9p handlers, unnecessarily duplicating code. This is pure refactoring with no behavior change. The existing error code semantics are preserved: rename operations return -EISDIR, create operations return -EEXIST. Note: These current error codes actually differ from native Linux system calls (e.g. rename() returns -EBUSY, open(O_CREAT) returns -EISDIR). The 9P protocol does not mandate specific error codes for these validation errors. Hence consolidating to a single error code (e.g., -EINVAL) for all cases could be considered in the future for simplicity reason. This change reduces code duplication across 9 functions: - v9fs_lcreate - v9fs_create - v9fs_symlink - v9fs_link - v9fs_rename - v9fs_renameat - v9fs_wstat - v9fs_mknod - v9fs_mkdir Link: https://lore.kernel.org/qemu-devel/0573103880129eb543f07b68c77e86f2f572f6bf.1780072238.git.qemu_oss@crudebyte.com Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Christian Schoenebeck committed
May 29, 2026 at 18:29 UTC
116db2986b11c914217bbd1547815b6c7efb944a
1 file changed
+39
-61
hw/9pfs/9p.c
+39
-61
@@ -1823,6 +1823,25 @@ static bool name_is_illegal(const char *name)
1823
return !*name || strchr(name, '/') != NULL;
1824
}
1825
1826
+static int check_name(const char *name, V9fsPDU *pdu)
1827
+{
1828
+ int request_type = pdu->id;
1829
+
1830
+ if (name_is_illegal(name)) {
1831
+ return -ENOENT;
1832
+ }
1833
+ if (!strcmp(name, ".") || !strcmp(name, "..")) {
1834
+ /*
1835
+ * TODO: The different error codes here are just there to preserve
1836
+ * pre-existing behaviour of 9p server. In future it might make sense to
1837
+ * consolidate this and e.g. just return -EINVAL for everyone.
1838
+ */
1839
+ return (request_type == P9_TRENAME || request_type == P9_TRENAMEAT ||
1840
+ request_type == P9_TWSTAT) ? -EISDIR : -EEXIST;
1841
+ }
1842
+ return 0;
1843
+}
1844
+
1845
static bool same_stat_id(const struct stat *a, const struct stat *b)
1846
{
1847
return a->st_dev == b->st_dev && a->st_ino == b->st_ino;
@@ -2173,13 +2192,8 @@ static void coroutine_fn v9fs_lcreate(void *opaque)
2192
}
2193
trace_v9fs_lcreate(pdu->tag, pdu->id, dfid, flags, mode, gid);
2194
2176
- if (name_is_illegal(name.data)) {
2177
- err = -ENOENT;
2178
- goto out_nofid;
2179
- }
2180
-
2181
- if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
2182
- err = -EEXIST;
2195
+ err = check_name(name.data, pdu);
2196
+ if (err < 0) {
2197
goto out_nofid;
2198
}
2199
@@ -2861,13 +2875,8 @@ static void coroutine_fn v9fs_create(void *opaque)
2875
}
2876
trace_v9fs_create(pdu->tag, pdu->id, fid, name.data, perm, mode);
2877
2864
- if (name_is_illegal(name.data)) {
2865
- err = -ENOENT;
2866
- goto out_nofid;
2867
- }
2868
-
2869
- if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
2870
- err = -EEXIST;
2878
+ err = check_name(name.data, pdu);
2879
+ if (err < 0) {
2880
goto out_nofid;
2881
}
2882
@@ -3055,13 +3064,8 @@ static void coroutine_fn v9fs_symlink(void *opaque)
3064
}
3065
trace_v9fs_symlink(pdu->tag, pdu->id, dfid, name.data, symname.data, gid);
3066
3058
- if (name_is_illegal(name.data)) {
3059
- err = -ENOENT;
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- goto out_nofid;
3061
- }
3062
-
3063
- if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
3064
- err = -EEXIST;
3067
+ err = check_name(name.data, pdu);
3068
+ if (err < 0) {
3069
goto out_nofid;
3070
}
3071
@@ -3148,13 +3152,8 @@ static void coroutine_fn v9fs_link(void *opaque)
3152
}
3153
trace_v9fs_link(pdu->tag, pdu->id, dfid, oldfid, name.data);
3154
3151
- if (name_is_illegal(name.data)) {
3152
- err = -ENOENT;
3153
- goto out_nofid;
3154
- }
3155
-
3156
- if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
3157
- err = -EEXIST;
3155
+ err = check_name(name.data, pdu);
3156
+ if (err < 0) {
3157
goto out_nofid;
3158
}
3159
@@ -3385,13 +3384,8 @@ static void coroutine_fn v9fs_rename(void *opaque)
3384
goto out_nofid;
3385
}
3386
3388
- if (name_is_illegal(name.data)) {
3389
- err = -ENOENT;
3390
- goto out_nofid;
3391
- }
3392
-
3393
- if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
3394
- err = -EISDIR;
3387
+ err = check_name(name.data, pdu);
3388
+ if (err < 0) {
3389
goto out_nofid;
3390
}
3391
@@ -3526,14 +3520,12 @@ static void coroutine_fn v9fs_renameat(void *opaque)
3520
goto out_err;
3521
}
3522
3529
- if (name_is_illegal(old_name.data) || name_is_illegal(new_name.data)) {
3530
- err = -ENOENT;
3523
+ err = check_name(old_name.data, pdu);
3524
+ if (err < 0) {
3525
goto out_err;
3526
}
3533
-
3534
- if (!strcmp(".", old_name.data) || !strcmp("..", old_name.data) ||
3535
- !strcmp(".", new_name.data) || !strcmp("..", new_name.data)) {
3536
- err = -EISDIR;
3527
+ err = check_name(new_name.data, pdu);
3528
+ if (err < 0) {
3529
goto out_err;
3530
}
3531
@@ -3638,12 +3630,8 @@ static void coroutine_fn v9fs_wstat(void *opaque)
3630
err = -EOPNOTSUPP;
3631
goto out;
3632
}
3641
- if (name_is_illegal(v9stat.name.data)) {
3642
- err = -ENOENT;
3643
- goto out;
3644
- }
3645
- if (!strcmp(".", v9stat.name.data) || !strcmp("..", v9stat.name.data)) {
3646
- err = -EISDIR;
3633
+ err = check_name(v9stat.name.data, pdu);
3634
+ if (err < 0) {
3635
goto out;
3636
}
3637
@@ -3776,13 +3764,8 @@ static void coroutine_fn v9fs_mknod(void *opaque)
3764
}
3765
trace_v9fs_mknod(pdu->tag, pdu->id, fid, mode, major, minor);
3766
3779
- if (name_is_illegal(name.data)) {
3780
- err = -ENOENT;
3781
- goto out_nofid;
3782
- }
3783
-
3784
- if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
3785
- err = -EEXIST;
3767
+ err = check_name(name.data, pdu);
3768
+ if (err < 0) {
3769
goto out_nofid;
3770
}
3771
@@ -3938,13 +3921,8 @@ static void coroutine_fn v9fs_mkdir(void *opaque)
3921
}
3922
trace_v9fs_mkdir(pdu->tag, pdu->id, fid, name.data, mode, gid);
3923
3941
- if (name_is_illegal(name.data)) {
3942
- err = -ENOENT;
3943
- goto out_nofid;
3944
- }
3945
-
3946
- if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
3947
- err = -EEXIST;
3924
+ err = check_name(name.data, pdu);
3925
+ if (err < 0) {
3926
goto out_nofid;
3927
}
3928