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From: Samuel Thibault <sthibaul@sourceware.org>
To: glibc-cvs@sourceware.org
Subject: [glibc] hurd: Make readlink* just reopen the file used for stat
Date: Thu, 15 Sep 2022 19:55:31 +0000 (GMT) [thread overview]
Message-ID: <20220915195531.540743858C62@sourceware.org> (raw)
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5652e12cce80825297c3e0666991deb10310343c
commit 5652e12cce80825297c3e0666991deb10310343c
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Thu Sep 15 21:53:57 2022 +0200
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.
Diff:
---
sysdeps/mach/hurd/readlink.c | 32 ++++++++++++++++++++------------
sysdeps/mach/hurd/readlinkat.c | 32 ++++++++++++++++++++------------
2 files changed, 40 insertions(+), 24 deletions(-)
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);
diff --git a/sysdeps/mach/hurd/readlinkat.c b/sysdeps/mach/hurd/readlinkat.c
index 113b92b732..278a0b5b00 100644
--- a/sysdeps/mach/hurd/readlinkat.c
+++ b/sysdeps/mach/hurd/readlinkat.c
@@ -29,33 +29,41 @@ ssize_t
readlinkat (int fd, 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_at (fd, 0, file_name, O_NOLINK, 0);
- if (file == MACH_PORT_NULL)
+ file_stat = __file_name_lookup_at (fd, 0, 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_at (fd, 0, 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);
return err ? __hurd_fail (err) : len;
}
reply other threads:[~2022-09-15 19:55 UTC|newest]
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