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* [glibc] hurd: Fix readlink() hanging on fifo
@ 2022-09-14 17:01 Samuel Thibault
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From: Samuel Thibault @ 2022-09-14 17:01 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9e5c991106cb04b489272de0ef6a7a6bcef50477
commit 9e5c991106cb04b489272de0ef6a7a6bcef50477
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:
---
sysdeps/mach/hurd/readlink.c | 5 ++++-
sysdeps/mach/hurd/readlinkat.c | 5 ++++-
2 files changed, 8 insertions(+), 2 deletions(-)
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;
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)
return -1;
@@ -41,6 +41,9 @@ __readlink (const char *file_name, char *buf, size_t len)
{
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)
{
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;
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)
return -1;
@@ -42,6 +42,9 @@ readlinkat (int fd, const char *file_name, char *buf, size_t len)
{
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)
{
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2022-09-14 17:01 [glibc] hurd: Fix readlink() hanging on fifo Samuel Thibault
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