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| author | Florian Weimer <fweimer@redhat.com> | 2018-12-10 14:14:45 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2018-12-10 16:25:09 +0100 |
| commit | 8d20a2f414fa52aceef8a0e3675415df54a840db (patch) | |
| tree | 5b2999ee9361ad4b89d85a51253a8e6bfd5d242f | |
| parent | 80472e2fba099c8da559bd524486354636ed0c4f (diff) | |
| download | glibc-8d20a2f414fa52aceef8a0e3675415df54a840db.tar.gz | |
compat getdents64: Use correct offset for retry [BZ #23972]
d_off is the offset of the *next* entry, not the offset of the current
entry.
| -rw-r--r-- | ChangeLog | 10 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/getdents64.c | 16 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/tst-readdir64-compat.c | 4 |
3 files changed, 27 insertions, 3 deletions
@@ -1,3 +1,13 @@ +2018-12-10 Florian Weimer <fweimer@redhat.com> + + [BZ #23972] + * sysdeps/unix/sysv/linux/getdents64.c (handle_overflow): Check + offset instead of count for clarity. Fix typo in comment. + (__old_getdents64): Keep track of previous offset. Use it to call + handle_overflow. + * sysdeps/unix/sysv/linux/tst-readdir64-compat.c (do_test): Check + that d_off is never zero. + 2018-12-10 Andreas Schwab <schwab@suse.de> * sysdeps/unix/sysv/linux/powerpc/powerpc64/*-le.abilist: Move to diff --git a/sysdeps/unix/sysv/linux/getdents64.c b/sysdeps/unix/sysv/linux/getdents64.c index bc140b5a7f..46eb5f4419 100644 --- a/sysdeps/unix/sysv/linux/getdents64.c +++ b/sysdeps/unix/sysv/linux/getdents64.c @@ -41,14 +41,14 @@ handle_overflow (int fd, __off64_t offset, ssize_t count) { /* If this is the first entry in the buffer, we can report the error. */ - if (count == 0) + if (offset == 0) { __set_errno (EOVERFLOW); return -1; } /* Otherwise, seek to the overflowing entry, so that the next call - will report the error, and return the data read so far.. */ + will report the error, and return the data read so far. */ if (__lseek64 (fd, offset, SEEK_SET) != 0) return -1; return count; @@ -70,6 +70,15 @@ __old_getdents64 (int fd, char *buf, size_t nbytes) ssize_t retval = INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes); if (retval > 0) { + /* This is the marker for the first entry. Offset 0 is reserved + for the first entry (see rewinddir). Here, we use it as a + marker for the first entry in the buffer. We never actually + seek to offset 0 because handle_overflow reports the error + directly, so it does not matter that the offset is incorrect + if entries have been read from the descriptor before (so that + the descriptor is not actually at offset 0). */ + __off64_t previous_offset = 0; + char *p = buf; char *end = buf + retval; while (p < end) @@ -84,7 +93,7 @@ __old_getdents64 (int fd, char *buf, size_t nbytes) /* Check for ino_t overflow. */ if (__glibc_unlikely (ino != source->d_ino)) - return handle_overflow (fd, offset, p - buf); + return handle_overflow (fd, previous_offset, p - buf); /* Convert to the target layout. Use a separate struct and memcpy to side-step aliasing issues. */ @@ -107,6 +116,7 @@ __old_getdents64 (int fd, char *buf, size_t nbytes) reclen - offsetof (struct dirent64, d_name)); p += reclen; + previous_offset = offset; } } return retval; diff --git a/sysdeps/unix/sysv/linux/tst-readdir64-compat.c b/sysdeps/unix/sysv/linux/tst-readdir64-compat.c index 43c4a8477c..cb78bc9be4 100644 --- a/sysdeps/unix/sysv/linux/tst-readdir64-compat.c +++ b/sysdeps/unix/sysv/linux/tst-readdir64-compat.c @@ -88,6 +88,10 @@ do_test (void) else TEST_VERIFY_EXIT (entry_test != NULL); + /* d_off is never zero because it is the offset of the next + entry (not the current entry). */ + TEST_VERIFY (entry_reference->d_off > 0); + /* Check that the entries are the same. */ TEST_COMPARE_BLOB (entry_reference->d_name, strlen (entry_reference->d_name), |