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authorJamie Liu <jamieliu@google.com>2019-04-25 16:03:32 -0700
committerShentubot <shentubot@google.com>2019-04-25 16:05:13 -0700
commit6b76c172b48ecb2c342882c0fe6474b2b973dad0 (patch)
tree61295be888beb8cb9c024aad03b9debe44fc2e32 /test/syscalls
parent72197810405a462386ded05d3c7c60c320289223 (diff)
Don't enforce NAME_MAX in fs.Dirent.walk().
Maximum filename length is filesystem-dependent, and obtained via statfs::f_namelen. This limit is usually 255 bytes (NAME_MAX), but not always. For example, VFAT supports filenames of up to 255... UCS-2 characters, which Linux conservatively takes to mean UTF-8-encoded bytes: fs/fat/inode.c:fat_statfs(), FAT_LFN_LEN * NLS_MAX_CHARSET_SIZE. As a result, Linux's VFS does not enforce NAME_MAX: $ rg --maxdepth=1 '\WNAME_MAX\W' fs/ include/linux/ fs/libfs.c 38: buf->f_namelen = NAME_MAX; 64: if (dentry->d_name.len > NAME_MAX) include/linux/relay.h 74: char base_filename[NAME_MAX]; /* saved base filename */ include/linux/fscrypt.h 149: * filenames up to NAME_MAX bytes, since base64 encoding expands the length. include/linux/exportfs.h 176: * understanding that it is already pointing to a a %NAME_MAX+1 sized Remove this check from core VFS, and add it to ramfs (and by extension tmpfs), where it is actually applicable: mm/shmem.c:shmem_dir_inode_operations.lookup == simple_lookup *does* enforce NAME_MAX. PiperOrigin-RevId: 245324748 Change-Id: I17567c4324bfd60e31746a5270096e75db963fac
Diffstat (limited to 'test/syscalls')
-rw-r--r--test/syscalls/linux/chdir.cc5
-rw-r--r--test/syscalls/linux/statfs.cc1
2 files changed, 1 insertions, 5 deletions
diff --git a/test/syscalls/linux/chdir.cc b/test/syscalls/linux/chdir.cc
index 4905ffb23..a4b54f0ee 100644
--- a/test/syscalls/linux/chdir.cc
+++ b/test/syscalls/linux/chdir.cc
@@ -54,11 +54,6 @@ TEST(ChdirTest, NotDir) {
EXPECT_THAT(chdir(temp_file.path().c_str()), SyscallFailsWithErrno(ENOTDIR));
}
-TEST(ChdirTest, NameTooLong) {
- std::string name(NAME_MAX + 1, 'a');
- ASSERT_THAT(chdir(name.c_str()), SyscallFailsWithErrno(ENAMETOOLONG));
-}
-
TEST(ChdirTest, NotExist) {
EXPECT_THAT(chdir("/foo/bar"), SyscallFailsWithErrno(ENOENT));
}
diff --git a/test/syscalls/linux/statfs.cc b/test/syscalls/linux/statfs.cc
index 1fc9758c9..e1e7fc707 100644
--- a/test/syscalls/linux/statfs.cc
+++ b/test/syscalls/linux/statfs.cc
@@ -49,6 +49,7 @@ TEST(StatfsTest, NameLen) {
struct statfs st;
EXPECT_THAT(statfs("/dev/shm", &st), SyscallSucceeds());
+ // This assumes that /dev/shm is tmpfs.
EXPECT_EQ(st.f_namelen, NAME_MAX);
}