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fusefs: set d_off during VOP_READDIR

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This allows d_off to be used with lseek to position the file so that
getdirentries(2) will return the next entry.  It is not used by
readdir(3).

PR:		253411
Reported by:	John Millikin <jmillikin@gmail.com>
Reviewed by:	cem
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D28605
This commit is contained in:
Alan Somers 2021-02-11 18:01:10 -07:00
parent a375ec52a7
commit 71befc3506
3 changed files with 74 additions and 16 deletions
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13
sys/fs/fuse/fuse_internal.c
View File

@ -583,7 +583,7 @@ fuse_internal_readdir_processdata(struct uio *uio,
u_long **cookiesp)
{
int err = 0;
int bytesavail;
int oreclen;
size_t freclen;
struct dirent *de;
@ -620,10 +620,10 @@ fuse_internal_readdir_processdata(struct uio *uio,
err = EINVAL;
break;
}
bytesavail = GENERIC_DIRSIZ((struct pseudo_dirent *)
oreclen = GENERIC_DIRSIZ((struct pseudo_dirent *)
&fudge->namelen);
if (bytesavail > uio_resid(uio)) {
if (oreclen > uio_resid(uio)) {
/* Out of space for the dir so we are done. */
err = -1;
break;
@ -633,12 +633,13 @@ fuse_internal_readdir_processdata(struct uio *uio,
* the requested offset in the directory is found.
*/
if (*fnd_start != 0) {
fiov_adjust(cookediov, bytesavail);
bzero(cookediov->base, bytesavail);
fiov_adjust(cookediov, oreclen);
bzero(cookediov->base, oreclen);
de = (struct dirent *)cookediov->base;
de->d_fileno = fudge->ino;
de->d_reclen = bytesavail;
de->d_off = fudge->off;
de->d_reclen = oreclen;
de->d_type = fudge->type;
de->d_namlen = fudge->namelen;
memcpy((char *)cookediov->base + sizeof(struct dirent) -

3
tests/sys/fs/fusefs/Makefile
View File

@ -71,6 +71,9 @@ FUSEFS= ${SRCTOP}/sys/fs/fuse
MOUNT= ${SRCTOP}/sbin/mount
# Suppress warnings that GCC generates for the libc++ and gtest headers.
CXXWARNFLAGS.gcc+= -Wno-placement-new -Wno-attributes
# Suppress Wcast-align for readdir.cc, because it is unavoidable when using
# getdirentries.
CXXWARNFLAGS.readdir.cc+= -Wno-cast-align
.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 80000
CXXWARNFLAGS+= -Wno-class-memaccess
.endif

74
tests/sys/fs/fusefs/readdir.cc
View File

@ -62,6 +62,9 @@ void expect_lookup(const char *relpath, uint64_t ino)
}
};
const char dot[] = ".";
const char dotdot[] = "..";
/* FUSE_READDIR returns nothing but "." and ".." */
TEST_F(Readdir, dots)
{
@ -72,8 +75,6 @@ TEST_F(Readdir, dots)
struct dirent *de;
vector<struct dirent> ents(2);
vector<struct dirent> empty_ents(0);
const char dot[] = ".";
const char dotdot[] = "..";
expect_lookup(RELPATH, ino);
expect_opendir(ino);
@ -98,11 +99,6 @@ TEST_F(Readdir, dots)
de = readdir(dir);
ASSERT_NE(nullptr, de) << strerror(errno);
EXPECT_EQ(2ul, de->d_fileno);
/*
* fuse(4) doesn't actually set d_off, which is ok for now because
* nothing uses it.
*/
//EXPECT_EQ(2000, de->d_off);
EXPECT_EQ(DT_DIR, de->d_type);
EXPECT_EQ(sizeof(dotdot), de->d_namlen);
EXPECT_EQ(0, strcmp(dotdot, de->d_name));
@ -111,7 +107,6 @@ TEST_F(Readdir, dots)
de = readdir(dir);
ASSERT_NE(nullptr, de) << strerror(errno);
EXPECT_EQ(3ul, de->d_fileno);
//EXPECT_EQ(3000, de->d_off);
EXPECT_EQ(DT_DIR, de->d_type);
EXPECT_EQ(sizeof(dot), de->d_namlen);
EXPECT_EQ(0, strcmp(dot, de->d_name));
@ -153,8 +148,11 @@ TEST_F(Readdir, eio)
leakdir(dir);
}
/* getdirentries(2) can use a larger buffer size than readdir(3) */
TEST_F(Readdir, getdirentries)
/*
* getdirentries(2) can use a larger buffer size than readdir(3). It also has
* some additional non-standardized fields in the returned dirent.
*/
TEST_F(Readdir, getdirentries_empty)
{
const char FULLPATH[] = "mountpoint/some_dir";
const char RELPATH[] = "some_dir";
@ -186,6 +184,62 @@ TEST_F(Readdir, getdirentries)
leak(fd);
}
/*
* The dirent.d_off field can be used with lseek to position the directory so
* that getdirentries will return the subsequent dirent.
*/
TEST_F(Readdir, getdirentries_seek)
{
const char FULLPATH[] = "mountpoint/some_dir";
const char RELPATH[] = "some_dir";
vector<struct dirent> ents0(2);
vector<struct dirent> ents1(1);
uint64_t ino = 42;
int fd;
const size_t bufsize = 8192;
char buf[bufsize];
struct dirent *de0, *de1;
ssize_t r;
expect_lookup(RELPATH, ino);
expect_opendir(ino);
ents0[0].d_fileno = 2;
ents0[0].d_off = 2000;
ents0[0].d_namlen = sizeof(dotdot);
ents0[0].d_type = DT_DIR;
strncpy(ents0[0].d_name, dotdot, ents0[0].d_namlen);
expect_readdir(ino, 0, ents0);
ents0[1].d_fileno = 3;
ents0[1].d_off = 3000;
ents0[1].d_namlen = sizeof(dot);
ents0[1].d_type = DT_DIR;
ents1[0].d_fileno = 3;
ents1[0].d_off = 3000;
ents1[0].d_namlen = sizeof(dot);
ents1[0].d_type = DT_DIR;
strncpy(ents1[0].d_name, dot, ents1[0].d_namlen);
expect_readdir(ino, 0, ents0);
expect_readdir(ino, 2000, ents1);
fd = open(FULLPATH, O_DIRECTORY);
ASSERT_LE(0, fd) << strerror(errno);
r = getdirentries(fd, buf, sizeof(buf), 0);
ASSERT_LT(0, r) << strerror(errno);
de0 = (struct dirent*)&buf[0];
ASSERT_EQ(2000, de0->d_off);
ASSERT_LT(de0->d_reclen + offsetof(struct dirent, d_fileno), bufsize);
de1 = (struct dirent*)(&(buf[de0->d_reclen]));
ASSERT_EQ(3ul, de1->d_fileno);
r = lseek(fd, de0->d_off, SEEK_SET);
ASSERT_LE(0, r);
r = getdirentries(fd, buf, sizeof(buf), 0);
ASSERT_LT(0, r) << strerror(errno);
de0 = (struct dirent*)&buf[0];
ASSERT_EQ(3000, de0->d_off);
}
/*
* Nothing bad should happen if getdirentries is called on two file descriptors
* which were concurrently open, but one has already been closed.