inotify, faccessat2, fsync for Linux programs, and D-Bus credentials
What installing and starting Epiphany ran into: - inotify: inotify_init/init1, add_watch, rm_watch, as a new kind of event descriptor. The filesystem reports creates, deletes, renames (with a cookie pairing MOVED_FROM and MOVED_TO), writes, close-after-write, truncation and attribute changes, to watches on the inode and on its directory with the name. ONESHOT, MASK_ADD, MASK_CREATE, ONLYDIR, DONT_FOLLOW, IGNORED on removal, Q_OVERFLOW, and Linux's coalescing of repeated events. The hooks cost one load when nothing is watched. Without it GLib found no file monitor and GNOME programs aborted. - FIONREAD on inotify descriptors and pipes (inotifywait sizes its buffer by it). - fsync and fdatasync had no Linux numbers since the first commit: GLib's atomic writes, gtk-update-icon-cache and dbus-uuidgen all got ENOSYS. - faccessat2, the flags-taking faccessat musl uses for any flags. - sendmsg accepts SCM_CREDENTIALS when they are the sender's own, as Linux checks; GDBus sends them in every handshake and was refused with EINVAL. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
This commit is contained in:
Nexoniarz
parent
c77841ce3d
commit
3113eff7fe
9 changed files with 590 additions and 9 deletions
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@ -15,6 +15,7 @@
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#include "core/uaccess.h"
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#include "core/kmem.h"
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#include "uapi/errno.h"
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#include "uapi/inotify.h"
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#include "fs/schfs.h" /* SCHFS_BLKSIZE, SCHFS_NAME_MAX — statfs reports them */
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#include "gfx/gfx.h" /* gfx_cols/gfx_rows — TIOCGWINSZ reports them */
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#include "dev/vt.h" /* the terminals the TIOC and VT_ ioctls act on */
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@ -370,10 +371,31 @@ createat_x(int dirfd, char *path, short type, short major, short minor,
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if (err) *err = r == -EINVAL ? EINVAL : ENOSPC;
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return 0;
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}
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inotify_event(dp->dev, dp->inum, IN_CREATE | (type == T_DIR ? IN_ISDIR : 0), name, 0);
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iunlockput(dp);
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return ip;
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}
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// The device and inode a path names, for inotify's watches. 0, or -errno.
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int
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path_identity(char *path, int follow, int onlydir, uint *dev, uint64 *inum)
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{
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struct inode *ip;
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int err = ENOENT, r = 0;
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begin_op();
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ip = follow ? at_nameif(AT_FDCWD, path, &err) : at_namei(AT_FDCWD, path);
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if (!ip) { end_op(); return -err; }
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ilock(ip);
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if (onlydir && ip->type != T_DIR)
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r = -ENOTDIR;
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*dev = ip->dev;
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*inum = ip->inum;
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iunlockput(ip);
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end_op();
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return r;
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}
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static struct inode*
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create(char *path, short type, short major, short minor)
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{
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@ -1079,6 +1101,8 @@ addr_t sys_link(void)
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if (dp->dev != ip->dev) { iunlockput(dp); err = EXDEV; goto bad_link; }
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if (dp->ops->no_hardlinks) { iunlockput(dp); err = EPERM; goto bad_link; }
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if (dirlink(dp, name, ip->inum) < 0) { iunlockput(dp); err = EEXIST; goto bad_link; }
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inotify_event(dp->dev, dp->inum, IN_CREATE, name, 0);
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inotify_event(ip->dev, ip->inum, IN_ATTRIB, 0, 0);
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iunlockput(dp); iput(ip); end_op();
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return 0;
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bad_link:
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@ -1107,6 +1131,17 @@ create_sock(char *path)
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return create(path, T_SOCK, 0, 0);
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}
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// A name removed from dp: IN_DELETE there, and for the inode itself either
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// IN_ATTRIB (a link went) or IN_DELETE_SELF (the last one did). Before the
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// caller drops nlink, so the last link is nlink == 1 here.
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static void
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inotify_unlinked(struct inode *dp, struct inode *ip, char *name)
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{
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inotify_event(dp->dev, dp->inum, IN_DELETE | (ip->type == T_DIR ? IN_ISDIR : 0), name, 0);
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inotify_event(ip->dev, ip->inum, ip->nlink <= 1 || ip->type == T_DIR
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? IN_DELETE_SELF : IN_ATTRIB, 0, 0);
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}
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// The body of unlink(2), by path. Factored out so that a failed bind can take
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// its own node back out without going through the syscall entry, and so there
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// is one implementation of what unlink means rather than two.
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@ -1129,6 +1164,7 @@ unlink_path(char *path)
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if (ip->type == T_DIR && dirempty(ip) != 1) { iunlockput(ip); err = ENOTEMPTY; goto bad; }
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if (dirunlink(dp, name, off) < 0) { iunlockput(ip); err = EIO; goto bad; }
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if (ip->type == T_DIR) { dp->nlink--; iupdate(dp); }
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inotify_unlinked(dp, ip, name);
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iunlockput(dp); ip->nlink--; iupdate(ip); iunlockput(ip);
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return 0;
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bad:
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@ -1185,6 +1221,7 @@ addr_t sys_ftruncate(void)
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begin_op(); ilock(f->ip);
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itrunc_to(f->ip, (uint64)length);
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iunlock(f->ip); end_op();
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inotify_file(f, IN_MODIFY);
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return 0;
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}
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@ -1200,6 +1237,7 @@ addr_t sys_truncate(void)
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if (!(ip = at_nameif(AT_FDCWD, path, &err))) { end_op(); return -err; }
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ilock(ip);
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itrunc_to(ip, (uint64)length);
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inotify_event(ip->dev, ip->inum, IN_MODIFY, 0, 0);
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iunlockput(ip); end_op();
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return 0;
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}
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@ -1255,6 +1293,8 @@ do_rename(int olddirfd, char *oldpath, int newdirfd, char *newpath)
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if (dp_new) iput(dp_new);
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goto bad_rename;
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}
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uint new_dev = dp_new->dev; // for inotify, after dp_new is put
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uint64 new_inum = dp_new->inum;
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// Clear the destination, if anything is there.
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ilock(dp_new);
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@ -1280,6 +1320,8 @@ do_rename(int olddirfd, char *oldpath, int newdirfd, char *newpath)
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iunlockput(ip_dst); iunlockput(dp_new); iput(dp_old);
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err = EIO; goto bad_rename;
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}
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if (ip_dst->nlink <= 1)
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inotify_event(ip_dst->dev, ip_dst->inum, IN_DELETE_SELF, 0, 0);
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ip_dst->nlink--; iupdate(ip_dst); iunlockput(ip_dst);
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}
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@ -1297,6 +1339,12 @@ do_rename(int olddirfd, char *oldpath, int newdirfd, char *newpath)
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if (dirunlink(dp_old, oldname, off) < 0) {
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iunlockput(dp_old); err = EIO; goto bad_rename;
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}
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{
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uint32 cookie = inotify_cookie();
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inotify_event(dp_old->dev, dp_old->inum, IN_MOVED_FROM, oldname, cookie);
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inotify_event(new_dev, new_inum, IN_MOVED_TO, newname, cookie);
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inotify_event(ip->dev, ip->inum, IN_MOVE_SELF, 0, 0);
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}
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iunlockput(dp_old);
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ilock(ip); ip->nlink--; iupdate(ip); iunlockput(ip);
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end_op(); return 0;
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@ -1575,6 +1623,12 @@ addr_t sys_ioctl(void)
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}
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if (request == 0x5452) // FIOASYNC
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return 0;
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if (request == FIONREAD && (f->type == FD_EVENT || f->type == FD_PIPE)) {
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int n = f->type == FD_PIPE ? pipe_avail(f->pipe) : ev_fionread(f->ev);
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if (n < 0)
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return n;
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return put_user(n, argp) < 0 ? -EFAULT : 0;
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}
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// /dev/fb0 (major 2) — geometry queries. This has to come before the
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// catch-all below, which answers every non-tty ioctl with 0: a program
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@ -1895,6 +1949,7 @@ chmod_inode(struct inode *ip, int mode)
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if (ip->mode == 0)
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ip->mode = 01000000; // "no bits", as distinct from "never set"
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iupdate(ip);
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inotify_event(ip->dev, ip->inum, IN_ATTRIB, 0, 0);
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iunlock(ip);
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return 0;
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}
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@ -2062,6 +2117,7 @@ addr_t sys_utimensat(void)
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}
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ip->ctime = (uint)now;
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iupdate(ip);
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inotify_event(ip->dev, ip->inum, IN_ATTRIB, 0, 0);
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iunlockput(ip);
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end_op();
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return 0;
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@ -2249,6 +2305,7 @@ addr_t sys_unlinkat(void)
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if (ip->type == T_DIR && dirempty(ip) != 1) { err = ENOTEMPTY; goto badip; }
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if (dirunlink(dp, name, off) < 0) { err = EIO; goto badip; }
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if (ip->type == T_DIR) { dp->nlink--; iupdate(dp); }
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inotify_unlinked(dp, ip, name);
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iunlockput(dp); ip->nlink--; iupdate(ip); iunlockput(ip);
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end_op();
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return 0;
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@ -2292,6 +2349,8 @@ addr_t sys_linkat(void)
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dirlink(dp, name, ip->inum) < 0) {
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iunlockput(dp); goto bad_linkat;
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}
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inotify_event(dp->dev, dp->inum, IN_CREATE, name, 0);
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inotify_event(ip->dev, ip->inum, IN_ATTRIB, 0, 0);
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iunlockput(dp); iput(ip); end_op();
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return 0;
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bad_linkat:
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@ -2365,6 +2424,37 @@ addr_t sys_faccessat(void)
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return 0;
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}
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// faccessat2: faccessat with the flags argument the original never had. musl
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// sends any faccessat with flags here, and without it GLib's every "does this
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// file exist" (F_OK, AT_SYMLINK_NOFOLLOW) failed with EINVAL. The mode is not
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// checked, as in faccessat above; AT_EACCESS changes nothing for the same
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// reason.
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addr_t sys_faccessat2(void)
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{
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int dirfd, mode, flags, err = ENOENT;
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char *path;
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struct inode *ip;
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argint(0, &dirfd);
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if (argstr(1, &path) < 0) return -EFAULT;
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argint(2, &mode);
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argint(3, &flags);
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if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS | AT_EMPTY_PATH))
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return -EINVAL;
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if ((flags & AT_EMPTY_PATH) && path[0] == '\0') {
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if (dirfd < 0 || dirfd >= NOFILE || !myproc()->files->ofile[dirfd])
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return -EBADF;
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return 0;
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}
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begin_op();
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ip = (flags & AT_SYMLINK_NOFOLLOW) ? at_namei(dirfd, path)
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: at_nameif(dirfd, path, &err);
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if (!ip) { end_op(); return -err; }
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iput(ip);
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end_op();
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return 0;
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}
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addr_t sys_fstatat(void)
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{
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int dirfd, flags;
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