htl: Get sem_open/sem_close/sem_unlink support [BZ #25524]

This just moves the existing nptl implementation to reuse as it is in
htl.

1 files changed, 320 insertions, 0 deletions

diff --git a/sysdeps/pthread/sem_open.c b/sysdeps/pthread/sem_open.c
new file mode 100644
index 0000000000..634bdf7425
--- /dev/null
+++ b/sysdeps/pthread/sem_open.c
@@ -0,0 +1,320 @@
+/* Copyright (C) 2002-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <search.h>
+#include <semaphore.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include "semaphoreP.h"
+#include <shm-directory.h>
+#include <futex-internal.h>
+#include <libc-lock.h>
+
+/* Comparison function for search of existing mapping.  */
+int
+attribute_hidden
+__sem_search (const void *a, const void *b)
+{
+  const struct inuse_sem *as = (const struct inuse_sem *) a;
+  const struct inuse_sem *bs = (const struct inuse_sem *) b;
+
+  if (as->ino != bs->ino)
+    /* Cannot return the difference the type is larger than int.  */
+    return as->ino < bs->ino ? -1 : (as->ino == bs->ino ? 0 : 1);
+
+  if (as->dev != bs->dev)
+    /* Cannot return the difference the type is larger than int.  */
+    return as->dev < bs->dev ? -1 : (as->dev == bs->dev ? 0 : 1);
+
+  return strcmp (as->name, bs->name);
+}
+
+
+/* The search tree for existing mappings.  */
+void *__sem_mappings attribute_hidden;
+
+/* Lock to protect the search tree.  */
+int __sem_mappings_lock attribute_hidden = LLL_LOCK_INITIALIZER;
+
+
+/* Search for existing mapping and if possible add the one provided.  */
+static sem_t *
+check_add_mapping (const char *name, size_t namelen, int fd, sem_t *existing)
+{
+  sem_t *result = SEM_FAILED;
+
+  /* Get the information about the file.  */
+  struct stat64 st;
+  if (__fstat64 (fd, &st) == 0)
+    {
+      /* Get the lock.  */
+      lll_lock (__sem_mappings_lock, LLL_PRIVATE);
+
+      /* Search for an existing mapping given the information we have.  */
+      struct inuse_sem *fake;
+      fake = (struct inuse_sem *) alloca (sizeof (*fake) + namelen);
+      memcpy (fake->name, name, namelen);
+      fake->dev = st.st_dev;
+      fake->ino = st.st_ino;
+
+      struct inuse_sem **foundp = __tfind (fake, &__sem_mappings,
+					   __sem_search);
+      if (foundp != NULL)
+	{
+	  /* There is already a mapping.  Use it.  */
+	  result = (*foundp)->sem;
+	  ++(*foundp)->refcnt;
+	}
+      else
+	{
+	  /* We haven't found a mapping.  Install ione.  */
+	  struct inuse_sem *newp;
+
+	  newp = (struct inuse_sem *) malloc (sizeof (*newp) + namelen);
+	  if (newp != NULL)
+	    {
+	      /* If the caller hasn't provided any map it now.  */
+	      if (existing == SEM_FAILED)
+		existing = (sem_t *) mmap (NULL, sizeof (sem_t),
+					   PROT_READ | PROT_WRITE, MAP_SHARED,
+					   fd, 0);
+
+	      newp->dev = st.st_dev;
+	      newp->ino = st.st_ino;
+	      newp->refcnt = 1;
+	      newp->sem = existing;
+	      memcpy (newp->name, name, namelen);
+
+	      /* Insert the new value.  */
+	      if (existing != MAP_FAILED
+		  && __tsearch (newp, &__sem_mappings, __sem_search) != NULL)
+		/* Successful.  */
+		result = existing;
+	      else
+		/* Something went wrong while inserting the new
+		   value.  We fail completely.  */
+		free (newp);
+	    }
+	}
+
+      /* Release the lock.  */
+      lll_unlock (__sem_mappings_lock, LLL_PRIVATE);
+    }
+
+  if (result != existing && existing != SEM_FAILED && existing != MAP_FAILED)
+    {
+      /* Do not disturb errno.  */
+      int save = errno;
+      munmap (existing, sizeof (sem_t));
+      errno = save;
+    }
+
+  return result;
+}
+
+
+sem_t *
+sem_open (const char *name, int oflag, ...)
+{
+  int fd;
+  sem_t *result;
+
+  /* Check that shared futexes are supported.  */
+  int err = futex_supports_pshared (PTHREAD_PROCESS_SHARED);
+  if (err != 0)
+    {
+      __set_errno (err);
+      return SEM_FAILED;
+    }
+
+  /* Create the name of the final file in local variable SHM_NAME.  */
+  SHM_GET_NAME (EINVAL, SEM_FAILED, SEM_SHM_PREFIX);
+
+  /* Disable asynchronous cancellation.  */
+#ifdef __libc_ptf_call
+  int state;
+  __libc_ptf_call (__pthread_setcancelstate,
+                   (PTHREAD_CANCEL_DISABLE, &state), 0);
+#endif
+
+  /* If the semaphore object has to exist simply open it.  */
+  if ((oflag & O_CREAT) == 0 || (oflag & O_EXCL) == 0)
+    {
+    try_again:
+      fd = __libc_open (shm_name,
+			(oflag & ~(O_CREAT|O_ACCMODE)) | O_NOFOLLOW | O_RDWR);
+
+      if (fd == -1)
+	{
+	  /* If we are supposed to create the file try this next.  */
+	  if ((oflag & O_CREAT) != 0 && errno == ENOENT)
+	    goto try_create;
+
+	  /* Return.  errno is already set.  */
+	}
+      else
+	/* Check whether we already have this semaphore mapped and
+	   create one if necessary.  */
+	result = check_add_mapping (name, namelen, fd, SEM_FAILED);
+    }
+  else
+    {
+      /* We have to open a temporary file first since it must have the
+	 correct form before we can start using it.  */
+      char *tmpfname;
+      mode_t mode;
+      unsigned int value;
+      va_list ap;
+
+    try_create:
+      va_start (ap, oflag);
+
+      mode = va_arg (ap, mode_t);
+      value = va_arg (ap, unsigned int);
+
+      va_end (ap);
+
+      if (value > SEM_VALUE_MAX)
+	{
+	  __set_errno (EINVAL);
+	  result = SEM_FAILED;
+	  goto out;
+	}
+
+      /* Create the initial file content.  */
+      union
+      {
+	sem_t initsem;
+	struct new_sem newsem;
+      } sem;
+
+      __new_sem_open_init (&sem.newsem, value);
+
+      /* Initialize the remaining bytes as well.  */
+      memset ((char *) &sem.initsem + sizeof (struct new_sem), '\0',
+	      sizeof (sem_t) - sizeof (struct new_sem));
+
+      tmpfname = __alloca (shm_dirlen + sizeof SEM_SHM_PREFIX + 6);
+      char *xxxxxx = __mempcpy (tmpfname, shm_dir, shm_dirlen);
+
+      int retries = 0;
+#define NRETRIES 50
+      while (1)
+	{
+	  /* Add the suffix for mktemp.  */
+	  strcpy (xxxxxx, "XXXXXX");
+
+	  /* We really want to use mktemp here.  We cannot use mkstemp
+	     since the file must be opened with a specific mode.  The
+	     mode cannot later be set since then we cannot apply the
+	     file create mask.  */
+	  if (__mktemp (tmpfname) == NULL)
+	    {
+	      result = SEM_FAILED;
+	      goto out;
+	    }
+
+	  /* Open the file.  Make sure we do not overwrite anything.  */
+	  fd = __libc_open (tmpfname, O_RDWR | O_CREAT | O_EXCL, mode);
+	  if (fd == -1)
+	    {
+	      if (errno == EEXIST)
+		{
+		  if (++retries < NRETRIES)
+		    continue;
+
+		  __set_errno (EAGAIN);
+		}
+
+	      result = SEM_FAILED;
+	      goto out;
+	    }
+
+	  /* We got a file.  */
+	  break;
+	}
+
+      if (TEMP_FAILURE_RETRY (__libc_write (fd, &sem.initsem, sizeof (sem_t)))
+	  == sizeof (sem_t)
+	  /* Map the sem_t structure from the file.  */
+	  && (result = (sem_t *) mmap (NULL, sizeof (sem_t),
+				       PROT_READ | PROT_WRITE, MAP_SHARED,
+				       fd, 0)) != MAP_FAILED)
+	{
+	  /* Create the file.  Don't overwrite an existing file.  */
+	  if (link (tmpfname, shm_name) != 0)
+	    {
+	      /* Undo the mapping.  */
+	      (void) munmap (result, sizeof (sem_t));
+
+	      /* Reinitialize 'result'.  */
+	      result = SEM_FAILED;
+
+	      /* This failed.  If O_EXCL is not set and the problem was
+		 that the file exists, try again.  */
+	      if ((oflag & O_EXCL) == 0 && errno == EEXIST)
+		{
+		  /* Remove the file.  */
+		  (void) unlink (tmpfname);
+
+		  /* Close the file.  */
+		  (void) __libc_close (fd);
+
+		  goto try_again;
+		}
+	    }
+	  else
+	    /* Insert the mapping into the search tree.  This also
+	       determines whether another thread sneaked by and already
+	       added such a mapping despite the fact that we created it.  */
+	    result = check_add_mapping (name, namelen, fd, result);
+	}
+
+      /* Now remove the temporary name.  This should never fail.  If
+	 it fails we leak a file name.  Better fix the kernel.  */
+      (void) unlink (tmpfname);
+    }
+
+  /* Map the mmap error to the error we need.  */
+  if (MAP_FAILED != (void *) SEM_FAILED && result == MAP_FAILED)
+    result = SEM_FAILED;
+
+  /* We don't need the file descriptor anymore.  */
+  if (fd != -1)
+    {
+      /* Do not disturb errno.  */
+      int save = errno;
+      __libc_close (fd);
+      errno = save;
+    }
+
+out:
+#ifdef __libc_ptf_call
+  __libc_ptf_call (__pthread_setcancelstate, (state, NULL), 0);
+#endif
+
+  return result;
+}