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authorFlorian Weimer <fweimer@redhat.com>2021-02-03 08:55:13 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2021-02-08 14:10:42 -0300
commite9fed2438a1ff475821864f906286dc58907f06b (patch)
tree185b4a49e256ef312e65eafebf836ba17ea2ccef /NEWS
parent7f61f785f16d22f185de77086c44a88218436cfb (diff)
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linux: Require /dev/shm as the shared memory file system
Previously, glibc would pick an arbitrary tmpfs file system from
/proc/mounts if /dev/shm was not available.  This could lead to
an unsuitable file system being picked for the backing storage for
shm_open, sem_open, and related functions.

This patch introduces a new function, __shm_get_name, which builds
the file name under the appropriate (now hard-coded) directory.  It is
called from the various shm_* and sem_* function.  Unlike the
SHM_GET_NAME macro it replaces, the callers handle the return values
and errno updates.  shm-directory.c is moved directly into the posix
subdirectory because it can be implemented directly using POSIX
functionality.  It resides in libc because it is needed by both
librt and nptl/htl.

In the sem_open implementation, tmpfname is initialized directly
from a string constant.  This happens to remove one alloca call.

Checked on x86_64-linux-gnu.
Diffstat (limited to 'NEWS')
-rw-r--r--NEWS5
1 files changed, 4 insertions, 1 deletions
diff --git a/NEWS b/NEWS
index 1ca12bc1a2..85e84fe536 100644
--- a/NEWS
+++ b/NEWS
@@ -20,7 +20,10 @@ Deprecated and removed features, and other changes affecting compatibility:
 
 Changes to build and runtime requirements:
 
-  [Add changes to build and runtime requirements here]
+* On Linux, the shm_open, sem_open, and related functions now expect the
+  file shared memory file system to be mounted at /dev/shm.  These functions
+  no longer search among the system's mount points for a suitable
+  replacement if /dev/shm is not available.
 
 Security related changes: