| Message ID | 20230127172834.391311-3-adhemerval.zanella@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Fix opendir regression on some FS | expand |
* Adhemerval Zanella: > diff --git a/dirent/tst-seekdir.c b/dirent/tst-seekdir.c > index dcdd699b09..187eda7584 100644 > --- a/dirent/tst-seekdir.c > +++ b/dirent/tst-seekdir.c > @@ -41,6 +41,14 @@ do_test (void) > if (i == 400) > break; > } > + if (i < 3) > + { > + /* Non-lfs opendir skips entries that can not be represented (for > + instance if d_off is not an offset but rather an internal filesystem > + representation. For this case there is no point in continue the > + testcase. */ > + return 77; > + } > > printf ("going back past 4-th entry...\n"); I think this needs to check errno properly (set to zero before readdir, and if readdir fails, report a test error if errno is not zero). > index adcf8234f1..8f58a1c3a6 100644 > --- a/sysdeps/unix/sysv/linux/dirstream.h > +++ b/sysdeps/unix/sysv/linux/dirstream.h > @@ -22,6 +22,7 @@ > #include <sys/types.h> > > #include <libc-lock.h> > +#include <telldir.h> > > /* Directory stream type. > > @@ -38,13 +39,16 @@ struct __dirstream > size_t size; /* Total valid data in the block. */ > size_t offset; /* Current offset into the block. */ > > - off_t filepos; /* Position of next entry to read. */ > + off64_t filepos; /* Position of next entry to read. */ > > int errcode; /* Delayed error code. */ > > #if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T > struct dirent tdp; > #endif > +#if _DIRENT_OFFSET_TRANSLATION > + struct dirstream_loc_t locs; /* off64_t to long int map for telldir. */ > +#endif Please add a comment explaining the purpose of the new field. > diff --git a/sysdeps/unix/sysv/linux/readdir.c b/sysdeps/unix/sysv/linux/readdir.c > index cd0ccaf33a..7a7f484c36 100644 > --- a/sysdeps/unix/sysv/linux/readdir.c > +++ b/sysdeps/unix/sysv/linux/readdir.c > @@ -36,6 +36,15 @@ dirstream_entry (struct __dirstream *ds, const struct dirent64 *dp64) > if (dp64->d_reclen - offsetof (struct dirent64, d_name) > NAME_MAX) > return false; > > + /* telldir can not return an error, so preallocate the map if the entry can > + not be packed directly. */ > + if (telldir_need_dirstream (dp64->d_off)) > + { > + dirstream_loc_add (&ds->locs, dp64->d_off); > + if (dirstream_loc_has_failed (&ds->locs)) > + return false; > + } I recommend to reserve the space here (but only for d_off values that need it), and perform the assignment only if there is an actual telldir call. This avoids all the additional processing and allocations for the common case that telldir is never called. This will matter quite a bit for large directories. Reservation can be implemented by adding a 0 dummy value (offset 0 will never be recorded), unless the last element is already 0. I don't think we need to change dynarray for this. > diff --git a/sysdeps/unix/sysv/linux/seekdir.c b/sysdeps/unix/sysv/linux/seekdir.c > index 939ccc4447..30cce691a4 100644 > --- a/sysdeps/unix/sysv/linux/seekdir.c > +++ b/sysdeps/unix/sysv/linux/seekdir.c > + > + if (dirp->filepos != filepos) > + { > + __lseek64 (dirp->fd, filepos, SEEK_SET); > + dirp->filepos = filepos; > + dirp->offset = 0; > + dirp->size = 0; > + } I think we should seek unconditionally, just in case someone messed with dirfd directly. > diff --git a/sysdeps/unix/sysv/linux/telldir.c b/sysdeps/unix/sysv/linux/telldir.c > index 1e5c129e9f..c3ef14f3da 100644 > --- a/sysdeps/unix/sysv/linux/telldir.c > +++ b/sysdeps/unix/sysv/linux/telldir.c > @@ -15,9 +15,11 @@ > License along with the GNU C Library; if not, see > <https://www.gnu.org/licenses/>. */ > + else > + { > + dsp.l = -1; > + > + size_t i; > + for (i = 0; i < dirstream_loc_size (&dirp->locs); i++) > + if (*dirstream_loc_at (&dirp->locs, i) == dirp->filepos) > + break; > + /* It should be pre-allocated on readdir. */ > + assert (i != dirstream_loc_size (&dirp->locs)); This should overwrite the final 0 element if the offset could not be found. I think the quadratic behavior is acceptable in this case, given that we do not really expect telldir to be called. > diff --git a/sysdeps/unix/sysv/linux/telldir.h b/sysdeps/unix/sysv/linux/telldir.h > new file mode 100644 > index 0000000000..758bcb0eb3 > --- /dev/null > +++ b/sysdeps/unix/sysv/linux/telldir.h > @@ -0,0 +1,65 @@ > +/* Linux internal telldir definitions. > + Copyright (C) 2023 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +#ifndef _TELLDIR_H > +#define _TELLDIR_H 1 > + > +#if _DIRENT_OFFSET_TRANSLATION > +/* On platforms where 'long int' is smaller than 'off64_t' this is how the > + returned value is encoded and returned by 'telldir'. If the directory > + offset can be enconded in 31 bits it is returned in the 'info' member > + with 'is_packed' set to 1. > + > + Otherwise, the 'info' member describes an index in a dynamic array at > + 'DIR' structure. */ > + > +union dirstream_packed > +{ > + long int l; > + struct > + { > + unsigned long int is_packed:1; > + unsigned long int info:31; > + } p; > +}; Good explanation in the comment, but … can't you use negative values for indices, and ~ for encoding/decoding? I think that's a bit clearer. > +static __always_inline bool > +telldir_need_dirstream (__off64_t d_off) > +{ > + return d_off >= 1UL << 31; > +} Hmm, can d_off be negative? > diff --git a/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c b/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c > new file mode 100644 > index 0000000000..52e18171a7 > +static int > +do_test (void) > +{ > + DIR *dirp = opendir (dirname); > + TEST_VERIFY_EXIT (dirp != NULL); > + > + long int *tdirp = xmalloc (nfiles * sizeof (long int)); > + struct dirent **ddirp = xmalloc (nfiles * sizeof (struct dirent *)); xreallocarray? > + /* For non-LFS, the entry is skipped if it can not be converted. */ > + int count = 0; > + for (; count < nfiles; count++) > + { > + tdirp[count] = telldir (dirp); > + struct dirent *dp = readdir (dirp); > + if (dp == NULL) > + break; Should probably verify the count variable here (and check errno too?). > + ddirp[count] = xmalloc (dp->d_reclen); > + memcpy (ddirp[count], dp, dp->d_reclen); > + } > + > + closedir (dirp); > + > + /* Check against the getdents64 syscall. */ > + int fd = xopen (dirname, O_RDONLY | O_DIRECTORY, 0); > + int i = 0; > + while (true) If we create predictable file names (maybe just numbers?), this kind of checking becomes way easier. Thanks, Florian
On 20/02/23 15:39, Florian Weimer wrote: > * Adhemerval Zanella: > >> diff --git a/dirent/tst-seekdir.c b/dirent/tst-seekdir.c >> index dcdd699b09..187eda7584 100644 >> --- a/dirent/tst-seekdir.c >> +++ b/dirent/tst-seekdir.c >> @@ -41,6 +41,14 @@ do_test (void) >> if (i == 400) >> break; >> } >> + if (i < 3) >> + { >> + /* Non-lfs opendir skips entries that can not be represented (for >> + instance if d_off is not an offset but rather an internal filesystem >> + representation. For this case there is no point in continue the >> + testcase. */ >> + return 77; >> + } >> >> printf ("going back past 4-th entry...\n"); > > I think this needs to check errno properly (set to zero before readdir, > and if readdir fails, report a test error if errno is not zero). It can't in fact, since the entries will be ignored nad not reported as errors. Yes, it is subpar; but the whole non-LFS interface has similar corner cases and I think we can't paper over to much of its limitations. > >> index adcf8234f1..8f58a1c3a6 100644 >> --- a/sysdeps/unix/sysv/linux/dirstream.h >> +++ b/sysdeps/unix/sysv/linux/dirstream.h >> @@ -22,6 +22,7 @@ >> #include <sys/types.h> >> >> #include <libc-lock.h> >> +#include <telldir.h> >> >> /* Directory stream type. >> >> @@ -38,13 +39,16 @@ struct __dirstream >> size_t size; /* Total valid data in the block. */ >> size_t offset; /* Current offset into the block. */ >> >> - off_t filepos; /* Position of next entry to read. */ >> + off64_t filepos; /* Position of next entry to read. */ >> >> int errcode; /* Delayed error code. */ >> >> #if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T >> struct dirent tdp; >> #endif >> +#if _DIRENT_OFFSET_TRANSLATION >> + struct dirstream_loc_t locs; /* off64_t to long int map for telldir. */ >> +#endif > > Please add a comment explaining the purpose of the new field. Ack. > >> diff --git a/sysdeps/unix/sysv/linux/readdir.c b/sysdeps/unix/sysv/linux/readdir.c >> index cd0ccaf33a..7a7f484c36 100644 >> --- a/sysdeps/unix/sysv/linux/readdir.c >> +++ b/sysdeps/unix/sysv/linux/readdir.c >> @@ -36,6 +36,15 @@ dirstream_entry (struct __dirstream *ds, const struct dirent64 *dp64) >> if (dp64->d_reclen - offsetof (struct dirent64, d_name) > NAME_MAX) >> return false; >> >> + /* telldir can not return an error, so preallocate the map if the entry can >> + not be packed directly. */ >> + if (telldir_need_dirstream (dp64->d_off)) >> + { >> + dirstream_loc_add (&ds->locs, dp64->d_off); >> + if (dirstream_loc_has_failed (&ds->locs)) >> + return false; >> + } > > I recommend to reserve the space here (but only for d_off values that > need it), and perform the assignment only if there is an actual telldir > call. This avoids all the additional processing and allocations for the > common case that telldir is never called. This will matter quite a bit > for large directories. > > Reservation can be implemented by adding a 0 dummy value (offset 0 will > never be recorded), unless the last element is already 0. I don't think > we need to change dynarray for this. We need the d_off value, since it will be used by telldir to actually return the correct dynarray position to return as dirstream_packed union. > > >> diff --git a/sysdeps/unix/sysv/linux/seekdir.c b/sysdeps/unix/sysv/linux/seekdir.c >> index 939ccc4447..30cce691a4 100644 >> --- a/sysdeps/unix/sysv/linux/seekdir.c >> +++ b/sysdeps/unix/sysv/linux/seekdir.c > >> + >> + if (dirp->filepos != filepos) >> + { >> + __lseek64 (dirp->fd, filepos, SEEK_SET); >> + dirp->filepos = filepos; >> + dirp->offset = 0; >> + dirp->size = 0; >> + } > > I think we should seek unconditionally, just in case someone messed with > dirfd directly. Alright. > >> diff --git a/sysdeps/unix/sysv/linux/telldir.c b/sysdeps/unix/sysv/linux/telldir.c >> index 1e5c129e9f..c3ef14f3da 100644 >> --- a/sysdeps/unix/sysv/linux/telldir.c >> +++ b/sysdeps/unix/sysv/linux/telldir.c >> @@ -15,9 +15,11 @@ >> License along with the GNU C Library; if not, see >> <https://www.gnu.org/licenses/>. */ > >> + else >> + { >> + dsp.l = -1; >> + >> + size_t i; >> + for (i = 0; i < dirstream_loc_size (&dirp->locs); i++) >> + if (*dirstream_loc_at (&dirp->locs, i) == dirp->filepos) >> + break; >> + /* It should be pre-allocated on readdir. */ >> + assert (i != dirstream_loc_size (&dirp->locs)); > > This should overwrite the final 0 element if the offset could not be > found. > > I think the quadratic behavior is acceptable in this case, given that we > do not really expect telldir to be called. Ack. > >> diff --git a/sysdeps/unix/sysv/linux/telldir.h b/sysdeps/unix/sysv/linux/telldir.h >> new file mode 100644 >> index 0000000000..758bcb0eb3 >> --- /dev/null >> +++ b/sysdeps/unix/sysv/linux/telldir.h >> @@ -0,0 +1,65 @@ >> +/* Linux internal telldir definitions. >> + Copyright (C) 2023 Free Software Foundation, Inc. >> + This file is part of the GNU C Library. >> + >> + The GNU C Library is free software; you can redistribute it and/or >> + modify it under the terms of the GNU Lesser General Public >> + License as published by the Free Software Foundation; either >> + version 2.1 of the License, or (at your option) any later version. >> + >> + The GNU C Library is distributed in the hope that it will be useful, >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> + Lesser General Public License for more details. >> + >> + You should have received a copy of the GNU Lesser General Public >> + License along with the GNU C Library; if not, see >> + <https://www.gnu.org/licenses/>. */ >> + >> +#ifndef _TELLDIR_H >> +#define _TELLDIR_H 1 >> + >> +#if _DIRENT_OFFSET_TRANSLATION >> +/* On platforms where 'long int' is smaller than 'off64_t' this is how the >> + returned value is encoded and returned by 'telldir'. If the directory >> + offset can be enconded in 31 bits it is returned in the 'info' member >> + with 'is_packed' set to 1. >> + >> + Otherwise, the 'info' member describes an index in a dynamic array at >> + 'DIR' structure. */ >> + >> +union dirstream_packed >> +{ >> + long int l; >> + struct >> + { >> + unsigned long int is_packed:1; >> + unsigned long int info:31; >> + } p; >> +}; > > Good explanation in the comment, but … can't you use negative values for > indices, and ~ for encoding/decoding? I think that's a bit clearer. Do you mean remove the bitfield? > >> +static __always_inline bool >> +telldir_need_dirstream (__off64_t d_off) >> +{ >> + return d_off >= 1UL << 31; >> +} > > Hmm, can d_off be negative? But it is an unsigned comparion, so it should not matter afaiu. > >> diff --git a/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c b/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c >> new file mode 100644 >> index 0000000000..52e18171a7 > >> +static int >> +do_test (void) >> +{ >> + DIR *dirp = opendir (dirname); >> + TEST_VERIFY_EXIT (dirp != NULL); >> + >> + long int *tdirp = xmalloc (nfiles * sizeof (long int)); >> + struct dirent **ddirp = xmalloc (nfiles * sizeof (struct dirent *)); > > xreallocarray? Ack. > >> + /* For non-LFS, the entry is skipped if it can not be converted. */ >> + int count = 0; >> + for (; count < nfiles; count++) >> + { >> + tdirp[count] = telldir (dirp); >> + struct dirent *dp = readdir (dirp); >> + if (dp == NULL) >> + break; > > Should probably verify the count variable here (and check errno too?). The issue is we don't know if the entry will be skipped due overflow (the test check for non-LFS interface). And this lead me to add a test for LFS interface and realize that we need to use dirstream_packed for LFS as well if the ABI sets _DIRENT_OFFSET_TRANSLATION. > >> + ddirp[count] = xmalloc (dp->d_reclen); >> + memcpy (ddirp[count], dp, dp->d_reclen); >> + } >> + >> + closedir (dirp); >> + >> + /* Check against the getdents64 syscall. */ >> + int fd = xopen (dirname, O_RDONLY | O_DIRECTORY, 0); >> + int i = 0; >> + while (true) > > If we create predictable file names (maybe just numbers?), this kind of > checking becomes way easier. I am not sure because the test can have a 'count' less than 'nfiles'.
diff --git a/dirent/tst-seekdir.c b/dirent/tst-seekdir.c index dcdd699b09..187eda7584 100644 --- a/dirent/tst-seekdir.c +++ b/dirent/tst-seekdir.c @@ -41,6 +41,14 @@ do_test (void) if (i == 400) break; } + if (i < 3) + { + /* Non-lfs opendir skips entries that can not be represented (for + instance if d_off is not an offset but rather an internal filesystem + representation. For this case there is no point in continue the + testcase. */ + return 77; + } printf ("going back past 4-th entry...\n"); diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile index f298878e8f..33708f910b 100644 --- a/sysdeps/unix/sysv/linux/Makefile +++ b/sysdeps/unix/sysv/linux/Makefile @@ -465,6 +465,7 @@ ifeq ($(subdir),dirent) sysdep_routines += getdirentries getdirentries64 tests += \ tst-getdents64 \ + tst-opendir-nolfs \ tst-readdir64-compat \ # tests endif # $(subdir) == dirent diff --git a/sysdeps/unix/sysv/linux/alpha/bits/dirent.h b/sysdeps/unix/sysv/linux/alpha/bits/dirent.h index c8a0cfe93f..586d75586a 100644 --- a/sysdeps/unix/sysv/linux/alpha/bits/dirent.h +++ b/sysdeps/unix/sysv/linux/alpha/bits/dirent.h @@ -54,4 +54,7 @@ struct dirent64 /* Inform libc code that these two types are effectively identical. */ #define _DIRENT_MATCHES_DIRENT64 1 +/* alpha 'long int' is enough to handle off64_t. */ +#define _DIRENT_OFFSET_TRANSLATION 0 + #endif /* bits/dirent.h */ diff --git a/sysdeps/unix/sysv/linux/bits/dirent.h b/sysdeps/unix/sysv/linux/bits/dirent.h index ab34d986ff..bb02dcb70a 100644 --- a/sysdeps/unix/sysv/linux/bits/dirent.h +++ b/sysdeps/unix/sysv/linux/bits/dirent.h @@ -57,3 +57,7 @@ struct dirent64 #else # define _DIRENT_MATCHES_DIRENT64 0 #endif + +/* The telldir function returns long int, which may not be large enough to + store off64_t values. In this case, translation is required. */ +#define _DIRENT_OFFSET_TRANSLATION (LONG_WIDTH < 64) diff --git a/sysdeps/unix/sysv/linux/closedir.c b/sysdeps/unix/sysv/linux/closedir.c index f1c2608642..9585a6ca3a 100644 --- a/sysdeps/unix/sysv/linux/closedir.c +++ b/sysdeps/unix/sysv/linux/closedir.c @@ -47,6 +47,10 @@ __closedir (DIR *dirp) __libc_lock_fini (dirp->lock); #endif +#if _DIRENT_OFFSET_TRANSLATION + dirstream_loc_clear (&dirp->locs); +#endif + free ((void *) dirp); return __close_nocancel (fd); diff --git a/sysdeps/unix/sysv/linux/dirstream.h b/sysdeps/unix/sysv/linux/dirstream.h index adcf8234f1..8f58a1c3a6 100644 --- a/sysdeps/unix/sysv/linux/dirstream.h +++ b/sysdeps/unix/sysv/linux/dirstream.h @@ -22,6 +22,7 @@ #include <sys/types.h> #include <libc-lock.h> +#include <telldir.h> /* Directory stream type. @@ -38,13 +39,16 @@ struct __dirstream size_t size; /* Total valid data in the block. */ size_t offset; /* Current offset into the block. */ - off_t filepos; /* Position of next entry to read. */ + off64_t filepos; /* Position of next entry to read. */ int errcode; /* Delayed error code. */ #if !defined __OFF_T_MATCHES_OFF64_T || !defined __INO_T_MATCHES_INO64_T struct dirent tdp; #endif +#if _DIRENT_OFFSET_TRANSLATION + struct dirstream_loc_t locs; /* off64_t to long int map for telldir. */ +#endif /* Directory block. We must make sure that this block starts at an address that is aligned adequately enough to store diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c index 4336196a4d..3e2caabb9d 100644 --- a/sysdeps/unix/sysv/linux/opendir.c +++ b/sysdeps/unix/sysv/linux/opendir.c @@ -129,6 +129,9 @@ __alloc_dir (int fd, bool close_fd, int flags, dirp->offset = 0; dirp->filepos = 0; dirp->errcode = 0; +#if _DIRENT_OFFSET_TRANSLATION + dirstream_loc_init (&dirp->locs); +#endif return dirp; } diff --git a/sysdeps/unix/sysv/linux/readdir.c b/sysdeps/unix/sysv/linux/readdir.c index cd0ccaf33a..7a7f484c36 100644 --- a/sysdeps/unix/sysv/linux/readdir.c +++ b/sysdeps/unix/sysv/linux/readdir.c @@ -36,6 +36,15 @@ dirstream_entry (struct __dirstream *ds, const struct dirent64 *dp64) if (dp64->d_reclen - offsetof (struct dirent64, d_name) > NAME_MAX) return false; + /* telldir can not return an error, so preallocate the map if the entry can + not be packed directly. */ + if (telldir_need_dirstream (dp64->d_off)) + { + dirstream_loc_add (&ds->locs, dp64->d_off); + if (dirstream_loc_has_failed (&ds->locs)) + return false; + } + ds->filepos = dp64->d_off; ds->tdp.d_off = dp64->d_off; @@ -76,7 +85,7 @@ __readdir_unlocked (DIR *dirp) /* Reset the offset into the buffer. */ dirp->offset = 0; - } + } struct dirent64 *dp64 = (struct dirent64 *) &dirp->data[dirp->offset]; dirp->offset += dp64->d_reclen; diff --git a/sysdeps/unix/sysv/linux/rewinddir.c b/sysdeps/unix/sysv/linux/rewinddir.c index c0fb7aa765..1b158a584f 100644 --- a/sysdeps/unix/sysv/linux/rewinddir.c +++ b/sysdeps/unix/sysv/linux/rewinddir.c @@ -33,6 +33,11 @@ __rewinddir (DIR *dirp) dirp->offset = 0; dirp->size = 0; dirp->errcode = 0; + +#ifndef __LP64__ + dirstream_loc_clear (&dirp->locs); +#endif + #if IS_IN (libc) __libc_lock_unlock (dirp->lock); #endif diff --git a/sysdeps/unix/sysv/linux/seekdir.c b/sysdeps/unix/sysv/linux/seekdir.c index 939ccc4447..30cce691a4 100644 --- a/sysdeps/unix/sysv/linux/seekdir.c +++ b/sysdeps/unix/sysv/linux/seekdir.c @@ -22,14 +22,39 @@ #include <dirstream.h> /* Seek to position POS in DIRP. */ -/* XXX should be __seekdir ? */ void seekdir (DIR *dirp, long int pos) { + off64_t filepos; + __libc_lock_lock (dirp->lock); - (void) __lseek (dirp->fd, pos, SEEK_SET); - dirp->size = 0; - dirp->offset = 0; - dirp->filepos = pos; + +#if _DIRENT_OFFSET_TRANSLATION + union dirstream_packed dsp = { .l = pos }; + if (dsp.p.is_packed == 1) + filepos = dsp.p.info; + else + { + size_t index = dsp.p.info; + + if (index >= dirstream_loc_size (&dirp->locs)) + { + __libc_lock_unlock (dirp->lock); + return; + } + filepos = *dirstream_loc_at (&dirp->locs, index); + } +#else + filepos = pos; +#endif + + if (dirp->filepos != filepos) + { + __lseek64 (dirp->fd, filepos, SEEK_SET); + dirp->filepos = filepos; + dirp->offset = 0; + dirp->size = 0; + } + __libc_lock_unlock (dirp->lock); } diff --git a/sysdeps/unix/sysv/linux/telldir.c b/sysdeps/unix/sysv/linux/telldir.c index 1e5c129e9f..c3ef14f3da 100644 --- a/sysdeps/unix/sysv/linux/telldir.c +++ b/sysdeps/unix/sysv/linux/telldir.c @@ -15,9 +15,11 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +#include <assert.h> #include <dirent.h> #include <dirstream.h> +#include <telldir.h> /* Return the current position of DIRP. */ long int @@ -26,7 +28,40 @@ telldir (DIR *dirp) long int ret; __libc_lock_lock (dirp->lock); + +#if _DIRENT_OFFSET_TRANSLATION + /* If the directory position fits in the packet structure, returns it. + Otherwise, check if the position is already been recorded in the + dynamic array. If not, add the new record. */ + + union dirstream_packed dsp; + + if (!telldir_need_dirstream (dirp->filepos)) + { + dsp.p.is_packed = 1; + dsp.p.info = dirp->filepos; + } + else + { + dsp.l = -1; + + size_t i; + for (i = 0; i < dirstream_loc_size (&dirp->locs); i++) + if (*dirstream_loc_at (&dirp->locs, i) == dirp->filepos) + break; + /* It should be pre-allocated on readdir. */ + assert (i != dirstream_loc_size (&dirp->locs)); + + dsp.p.is_packed = 0; + /* This assignment might overflow, however most likely ENOME would + happen long before. */ + dsp.p.info = i; + } + + ret = dsp.l; +#else ret = dirp->filepos; +#endif __libc_lock_unlock (dirp->lock); return ret; diff --git a/sysdeps/unix/sysv/linux/telldir.h b/sysdeps/unix/sysv/linux/telldir.h new file mode 100644 index 0000000000..758bcb0eb3 --- /dev/null +++ b/sysdeps/unix/sysv/linux/telldir.h @@ -0,0 +1,65 @@ +/* Linux internal telldir definitions. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#ifndef _TELLDIR_H +#define _TELLDIR_H 1 + +#if _DIRENT_OFFSET_TRANSLATION +/* On platforms where 'long int' is smaller than 'off64_t' this is how the + returned value is encoded and returned by 'telldir'. If the directory + offset can be enconded in 31 bits it is returned in the 'info' member + with 'is_packed' set to 1. + + Otherwise, the 'info' member describes an index in a dynamic array at + 'DIR' structure. */ + +union dirstream_packed +{ + long int l; + struct + { + unsigned long int is_packed:1; + unsigned long int info:31; + } p; +}; + +_Static_assert (sizeof (long int) == sizeof (union dirstream_packed), + "sizeof (long int) != sizeof (union dirstream_packed)"); + +/* telldir maintains a list of offsets that describe the obtained diretory + position if it can fit this information in the returned 'dirstream_packed' + struct. */ + +# define DYNARRAY_STRUCT dirstream_loc_t +# define DYNARRAY_ELEMENT off64_t +# define DYNARRAY_PREFIX dirstream_loc_ +# include <malloc/dynarray-skeleton.c> + +static __always_inline bool +telldir_need_dirstream (__off64_t d_off) +{ + return d_off >= 1UL << 31; +} +#else + +_Static_assert (sizeof (long int) == sizeof (off64_t), + "sizeof (long int) != sizeof (off64_t)"); + +#endif /* __LP64__ */ + +#endif /* _TELLDIR_H */ diff --git a/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c b/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c new file mode 100644 index 0000000000..52e18171a7 --- /dev/null +++ b/sysdeps/unix/sysv/linux/tst-opendir-nolfs.c @@ -0,0 +1,146 @@ +/* Check multiple telldir and seekdir. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#include <dirent.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include <support/check.h> +#include <support/support.h> +#include <support/temp_file.h> +#include <support/xunistd.h> + +/* Some filesystems returns an arbitrary value for d_off direnty entry (ext4 + for instance, where the value is an internal hash key). The idea of create + a large number of file is to try trigger a overflow d_off value in a entry + to check if telldir/seekdir does work corretly in such case. */ +static const char *dirname; +/* The 2 extra files are '.' and '..'. */ +static const size_t nfiles = (1<<14) + 2; + +static inline bool +in_ino_t_range (ino64_t v) +{ + ino_t s = v; + return s == v; +} + +static inline bool +in_off_t_range (off64_t v) +{ + off_t s = v; + return s == v; +} + +static void +do_prepare (int argc, char *argv[]) +{ + dirname = support_create_temp_directory ("tst-opendir-nolfs-"); + + for (size_t i = 0; i < nfiles - 2; i++) + { + int fd = create_temp_file_in_dir ("tempfile.", dirname, NULL); + TEST_VERIFY_EXIT (fd > 0); + close (fd); + } +} +#define PREPARE do_prepare + +static int +do_test (void) +{ + DIR *dirp = opendir (dirname); + TEST_VERIFY_EXIT (dirp != NULL); + + long int *tdirp = xmalloc (nfiles * sizeof (long int)); + struct dirent **ddirp = xmalloc (nfiles * sizeof (struct dirent *)); + + /* For non-LFS, the entry is skipped if it can not be converted. */ + int count = 0; + for (; count < nfiles; count++) + { + tdirp[count] = telldir (dirp); + struct dirent *dp = readdir (dirp); + if (dp == NULL) + break; + ddirp[count] = xmalloc (dp->d_reclen); + memcpy (ddirp[count], dp, dp->d_reclen); + } + + closedir (dirp); + + /* Check against the getdents64 syscall. */ + int fd = xopen (dirname, O_RDONLY | O_DIRECTORY, 0); + int i = 0; + while (true) + { + struct + { + char buffer[1024]; + struct dirent64 pad; + } data; + + ssize_t ret = getdents64 (fd, &data.buffer, sizeof (data.buffer)); + if (ret < 0) + FAIL_EXIT1 ("getdents64: %m"); + if (ret == 0) + break; + + char *current = data.buffer; + char *end = data.buffer + ret; + while (current != end) + { + struct dirent64 entry; + memcpy (&entry, current, sizeof (entry)); + /* Truncate overlong strings. */ + entry.d_name[sizeof (entry.d_name) - 1] = '\0'; + TEST_VERIFY (strlen (entry.d_name) < sizeof (entry.d_name) - 1); + + if (in_ino_t_range (entry.d_ino) && in_off_t_range (entry.d_off)) + { + TEST_COMPARE_STRING (entry.d_name, ddirp[i]->d_name); + TEST_COMPARE (entry.d_ino, ddirp[i]->d_ino); + TEST_COMPARE (entry.d_off, ddirp[i]->d_off); + TEST_COMPARE (entry.d_type, ddirp[i]->d_type); + + /* Offset zero is reserved for the first entry. */ + TEST_VERIFY (entry.d_off != 0); + + TEST_VERIFY_EXIT (entry.d_reclen <= end - current); + i++; + } + + current += entry.d_reclen; + } + } + + /* direntries_read has been called more than once. */ + TEST_COMPARE (count, i); + + free (tdirp); + for (int i = 0; i < count; i++) + free (ddirp[i]); + free (ddirp); + + return 0; +} + +#include <support/test-driver.c>