From 5652e12cce80825297c3e0666991deb10310343c Mon Sep 17 00:00:00 2001 From: Samuel Thibault Date: Thu, 15 Sep 2022 21:53:57 +0200 Subject: hurd: Make readlink* just reopen the file used for stat 9e5c991106cb ("hurd: Fix readlink() hanging on fifo") separated opening the file for the stat call from opening the file for the read call. That however opened a small window for the file to change. Better make this atomic by reopening the file with O_READ. --- sysdeps/mach/hurd/readlink.c | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-) (limited to 'sysdeps/mach/hurd/readlink.c') diff --git a/sysdeps/mach/hurd/readlink.c b/sysdeps/mach/hurd/readlink.c index 2d75ef7725..34f132cb92 100644 --- a/sysdeps/mach/hurd/readlink.c +++ b/sysdeps/mach/hurd/readlink.c @@ -28,33 +28,41 @@ ssize_t __readlink (const char *file_name, char *buf, size_t len) { error_t err; - file_t file; + file_t file_stat; struct stat64 st; - file = __file_name_lookup (file_name, O_NOLINK, 0); - if (file == MACH_PORT_NULL) + file_stat = __file_name_lookup (file_name, O_NOLINK, 0); + if (file_stat == MACH_PORT_NULL) return -1; - err = __io_stat (file, &st); + err = __io_stat (file_stat, &st); if (! err) if (S_ISLNK (st.st_mode)) { + enum retry_type doretry; + char retryname[1024]; + file_t file; char *rbuf = buf; - __mach_port_deallocate (__mach_task_self (), file); - file = __file_name_lookup (file_name, O_READ | O_NOLINK, 0); - - err = __io_read (file, &rbuf, &len, 0, len); - if (!err && rbuf != buf) + err = __dir_lookup (file_stat, "", O_READ | O_NOLINK, 0, &doretry, retryname, &file); + if (! err && (doretry != FS_RETRY_NORMAL || retryname[0] != '\0')) + err = EGRATUITOUS; + if (! err) { - memcpy (buf, rbuf, len); - __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + err = __io_read (file, &rbuf, &len, 0, len); + if (!err && rbuf != buf) + { + memcpy (buf, rbuf, len); + __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len); + } + + __mach_port_deallocate (__mach_task_self (), file); } } else err = EINVAL; - __mach_port_deallocate (__mach_task_self (), file); + __mach_port_deallocate (__mach_task_self (), file_stat); if (err) return __hurd_fail (err); -- cgit v1.2.3