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* [newlib-cygwin/main] Cygwin: lseek: improve seeking posix_getdents descriptors
@ 2024-03-01 14:44 Corinna Vinschen
0 siblings, 0 replies; only message in thread
From: Corinna Vinschen @ 2024-03-01 14:44 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=6d936915477ca8f64ecba31c9876103d69827fb2
commit 6d936915477ca8f64ecba31c9876103d69827fb2
Author: Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Fri Mar 1 15:16:44 2024 +0100
Commit: Corinna Vinschen <corinna@vinschen.de>
CommitDate: Fri Mar 1 15:32:39 2024 +0100
Cygwin: lseek: improve seeking posix_getdents descriptors
Transfer code lseeking on posix_getdents() directory descriptor
into its own static function and rework it so SEEK_END, SEEK_DATA
and SEEK_HOLE work here as expected, too.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Diff:
---
winsup/cygwin/syscalls.cc | 83 ++++++++++++++++++++++++++++++++++-------------
1 file changed, 61 insertions(+), 22 deletions(-)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 600c6c54e343..2c5bf7cbe08b 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -1596,6 +1596,66 @@ open (const char *unix_path, int flags, ...)
EXPORT_ALIAS (open, _open )
+static int
+posix_getdents_lseek (cygheap_fdget &cfd, off_t pos, int dir)
+{
+ long cur = cfd->telldir (cfd->getdents_dir ());
+ long abs_pos;
+
+ switch (dir)
+ {
+ case SEEK_CUR:
+ abs_pos = cur + pos;
+ break;
+ case SEEK_SET:
+ case SEEK_DATA:
+ abs_pos = pos;
+ break;
+ case SEEK_END:
+ case SEEK_HOLE:
+ /* First read full dir to learn end-of-dir position. */
+ while (::readdir (cfd->getdents_dir ()))
+ ;
+ long eod = cfd->telldir (cfd->getdents_dir ());
+ /* Seek back so it looks like nothing happend in error case */
+ cfd->seekdir (cfd->getdents_dir (), cur);
+ if (dir == SEEK_HOLE)
+ {
+ if (pos > eod)
+ {
+ set_errno (ENXIO);
+ return -1;
+ }
+ abs_pos = eod;
+ }
+ else
+ abs_pos = eod + pos;
+ break;
+ }
+ if (abs_pos < 0)
+ {
+ set_errno (EINVAL);
+ return -1;
+ }
+ if (abs_pos != cur)
+ {
+ cfd->seekdir (cfd->getdents_dir (), abs_pos);
+ /* In SEEK_DATA case, check that we didn't seek beyond EOF */
+ if (dir == SEEK_DATA || dir == SEEK_HOLE)
+ {
+ pos = cfd->telldir (cfd->getdents_dir ());
+ if (pos < abs_pos)
+ {
+ /* Seek back so it looks like nothing happend */
+ cfd->seekdir (cfd->getdents_dir (), cur);
+ set_errno (ENXIO);
+ return -1;
+ }
+ }
+ }
+ return abs_pos;
+}
+
extern "C" off_t
lseek (int fd, off_t pos, int dir)
{
@@ -1612,28 +1672,7 @@ lseek (int fd, off_t pos, int dir)
if (cfd < 0)
res = -1;
else if (cfd->getdents_dir ())
- {
- if (dir != SEEK_SET && dir != SEEK_CUR) /* No SEEK_END */
- {
- set_errno (EINVAL);
- res = -1;
- }
- else
- {
- long cur;
-
- cur = cfd->telldir (cfd->getdents_dir ());
- if (dir == SEEK_CUR && cur == 0)
- res = cur;
- else
- {
- if (dir == SEEK_CUR)
- pos = cur + pos;
- cfd->seekdir (cfd->getdents_dir (), pos);
- res = pos;
- }
- }
- }
+ res = posix_getdents_lseek (cfd, pos, dir);
else
res = cfd->lseek (pos, dir);
}
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