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Commit e42ad945 authored by Samuel Thibault's avatar Samuel Thibault
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hurd-i386/git-readlink-fifo.diff: Fix atomicity

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debian/patches/hurd-i386/git-readlink-fifo.diff
+ 105
− 30
View file @ e42ad945
commit 9e5c991106cb04b489272de0ef6a7a6bcef50477
commit 9e5c991106cb04b489272de0ef6a7a6bcef50477 (origin/master, origin/HEAD)
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Wed Sep 14 18:52:52 2022 +0200
hurd: Fix readlink() hanging on fifo
readlink() opens the target with O_READ to be able to read the symlink
content. When the target is actually a fifo, that would hang waiting for a
writer (caught in the coreutils testsuite). We thus have to first lookup the
target without O_READ to perform io_stat and lookout for fifos, and only
after checking the symlink type, we can re-lookup with O_READ.
diff --git a/sysdeps/mach/hurd/readlink.c b/sysdeps/mach/hurd/readlink.c
index 770462714f..2d75ef7725 100644
--- a/sysdeps/mach/hurd/readlink.c
+++ b/sysdeps/mach/hurd/readlink.c
@@ -31,7 +31,7 @@ __readlink (const char *file_name, char *buf, size_t len)
file_t file;
commit 5652e12cce80825297c3e0666991deb10310343c (HEAD -> master, origin-rw/master)
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.
Index: glibc-2.36/sysdeps/mach/hurd/readlink.c
===================================================================
--- glibc-2.36.orig/sysdeps/mach/hurd/readlink.c
+++ glibc-2.36/sysdeps/mach/hurd/readlink.c
@@ -28,30 +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_READ | O_NOLINK, 0);
+ file = __file_name_lookup (file_name, O_NOLINK, 0);
if (file == MACH_PORT_NULL)
- if (file == MACH_PORT_NULL)
+ file_stat = __file_name_lookup (file_name, O_NOLINK, 0);
+ if (file_stat == MACH_PORT_NULL)
return -1;
@@ -41,6 +41,9 @@ __readlink (const char *file_name, char *buf, size_t len)
- 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 = __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)
{
diff --git a/sysdeps/mach/hurd/readlinkat.c b/sysdeps/mach/hurd/readlinkat.c
index 059aad9f58..113b92b732 100644
--- a/sysdeps/mach/hurd/readlinkat.c
+++ b/sysdeps/mach/hurd/readlinkat.c
@@ -32,7 +32,7 @@ readlinkat (int fd, const char *file_name, char *buf, size_t len)
file_t file;
- 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);
Index: glibc-2.36/sysdeps/mach/hurd/readlinkat.c
===================================================================
--- glibc-2.36.orig/sysdeps/mach/hurd/readlinkat.c
+++ glibc-2.36/sysdeps/mach/hurd/readlinkat.c
@@ -29,30 +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_READ | O_NOLINK, 0);
+ file = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0);
if (file == MACH_PORT_NULL)
- 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;
@@ -42,6 +42,9 @@ readlinkat (int fd, const char *file_name, char *buf, size_t len)
- 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 = __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;
}
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