forked from Imagelibrary/rtems
2001-05-14 Till Straumann <strauman@slac.stanford.edu>
* Per PR212, added envlock support for newlib. This is used by at least getenv()/putenv() to avoid race conditions. * libc/envlock.c: New file. * libc/Makefile.am: Modified to reflect above.
This commit is contained in:
Joel Sherrill
@@ -34,6 +34,8 @@ DIRECTORY_SCAN_C_FILES = opendir.c closedir.c readdir.c rewinddir.c \
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MALLOC_C_FILES = malloc.c mallocfreespace.c __brk.c __sbrk.c
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ENVIRON_C_FILES = envlock.c
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PASSWORD_GROUP_C_FILES = getpwent.c getgrent.c
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TERMINAL_IDENTIFICATION_C_FILES = ctermid.c isatty.c ttyname.c ttyname_r.c
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@@ -44,7 +46,7 @@ LIBC_GLUE_C_FILES = __getpid.c __gettod.c __times.c truncate.c access.c \
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UNIX_LIBC_C_FILES = unixlibc.c hosterr.c
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COMMON_C_FILES = gxx_wrappers.c printk.c $(BASE_FS_C_FILES) \
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$(MALLOC_C_FILES) $(TERMIOS_C_FILES) $(ERROR_C_FILES) \
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$(MALLOC_C_FILES) $(ENVIRON_C_FILES) $(TERMIOS_C_FILES) $(ERROR_C_FILES) \
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$(ASSOCIATION_C_FILES)
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UNIX_C_FILES = $(UNIX_LIBC_C_FILES)
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82
c/src/exec/libcsupport/src/envlock.c
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82
c/src/exec/libcsupport/src/envlock.c
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@@ -0,0 +1,82 @@
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/*
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* $Id$
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*
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* Author: Till Straumann <strauman@slac.stanford.edu>, 3/2002
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*/
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/* provide locking for the global environment 'environ' */
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#if HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <rtems.h>
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#include <sys/reent.h>
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#include <assert.h>
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/*
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* NOTES:
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* - although it looks like a classical multiple-readers / single writer (MRSW)
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* locking problem, we still use a single lock for the following reasons:
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* 1) newlib has no provision / hook for calling different locking routines
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* from setenv/putenv and getenv, respectively.
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* 2) MRSW involves calling several semaphore-primitives, even in the most
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* likely case of a first-reader's access. This probably takes more CPU
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* time than just waiting until another reader is done; environment
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* access is fast.
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* - the lock implementation must allow nesting (same thread may call
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* lock-lock-unlock-unlock).
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* - NEWLIB-1.8.2 has an ugly BUG: if environ is NULL, _findenv_r() bails
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* out leaving the lock held :-(
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*
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*/
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static rtems_id envLock=0;
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static void
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__rtems_envlock_init(void)
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{
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extern char **environ;
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rtems_status_code rc;
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if (envLock) /* already initialized */
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return;
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assert(environ && "MUST have non-NULL 'environ' due to newlib bug");
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rc = rtems_semaphore_create(
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rtems_build_name('E','N','V','S'),
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1,
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RTEMS_BINARY_SEMAPHORE | RTEMS_PRIORITY | RTEMS_INHERIT_PRIORITY,
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0,
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&envLock);
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if (RTEMS_SUCCESSFUL!=rc)
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rtems_fatal_error_occurred(rc);
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}
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void
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__env_lock(struct _reent *r)
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{
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/* Do lazy init */
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if (!envLock)
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__rtems_envlock_init();
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/*
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* Must not use a semaphore before pre-tasking hook is called.
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* - it will corrupt memory :-(
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*/
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if (_Thread_Executing)
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rtems_semaphore_obtain(envLock, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
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}
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void
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__env_unlock(struct _reent *r)
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{
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/*
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* Must not use a semaphore before pre-tasking hook is called.
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* - it will corrupt memory :-(
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*/
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if (_Thread_Executing)
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rtems_semaphore_release(envLock);
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}
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@@ -1,3 +1,10 @@
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2001-05-14 Till Straumann <strauman@slac.stanford.edu>
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* Per PR212, added envlock support for newlib. This is used
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by at least getenv()/putenv() to avoid race conditions.
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* libc/envlock.c: New file.
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* libc/Makefile.am: Modified to reflect above.
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2002-05-03 Ralf Corsepius <corsepiu@faw.uni-ulm.de>
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* include/Makefile.am: Remove.
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@@ -34,6 +34,8 @@ DIRECTORY_SCAN_C_FILES = opendir.c closedir.c readdir.c rewinddir.c \
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MALLOC_C_FILES = malloc.c mallocfreespace.c __brk.c __sbrk.c
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ENVIRON_C_FILES = envlock.c
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PASSWORD_GROUP_C_FILES = getpwent.c getgrent.c
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TERMINAL_IDENTIFICATION_C_FILES = ctermid.c isatty.c ttyname.c ttyname_r.c
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@@ -44,7 +46,7 @@ LIBC_GLUE_C_FILES = __getpid.c __gettod.c __times.c truncate.c access.c \
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UNIX_LIBC_C_FILES = unixlibc.c hosterr.c
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COMMON_C_FILES = gxx_wrappers.c printk.c $(BASE_FS_C_FILES) \
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$(MALLOC_C_FILES) $(TERMIOS_C_FILES) $(ERROR_C_FILES) \
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$(MALLOC_C_FILES) $(ENVIRON_C_FILES) $(TERMIOS_C_FILES) $(ERROR_C_FILES) \
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$(ASSOCIATION_C_FILES)
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UNIX_C_FILES = $(UNIX_LIBC_C_FILES)
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82
c/src/lib/libc/envlock.c
Normal file
82
c/src/lib/libc/envlock.c
Normal file
@@ -0,0 +1,82 @@
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/*
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* $Id$
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*
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* Author: Till Straumann <strauman@slac.stanford.edu>, 3/2002
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*/
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/* provide locking for the global environment 'environ' */
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#if HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <rtems.h>
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#include <sys/reent.h>
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#include <assert.h>
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/*
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* NOTES:
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* - although it looks like a classical multiple-readers / single writer (MRSW)
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* locking problem, we still use a single lock for the following reasons:
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* 1) newlib has no provision / hook for calling different locking routines
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* from setenv/putenv and getenv, respectively.
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* 2) MRSW involves calling several semaphore-primitives, even in the most
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* likely case of a first-reader's access. This probably takes more CPU
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* time than just waiting until another reader is done; environment
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* access is fast.
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* - the lock implementation must allow nesting (same thread may call
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* lock-lock-unlock-unlock).
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* - NEWLIB-1.8.2 has an ugly BUG: if environ is NULL, _findenv_r() bails
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* out leaving the lock held :-(
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*
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*/
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static rtems_id envLock=0;
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static void
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__rtems_envlock_init(void)
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{
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extern char **environ;
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rtems_status_code rc;
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if (envLock) /* already initialized */
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return;
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assert(environ && "MUST have non-NULL 'environ' due to newlib bug");
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rc = rtems_semaphore_create(
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rtems_build_name('E','N','V','S'),
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1,
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RTEMS_BINARY_SEMAPHORE | RTEMS_PRIORITY | RTEMS_INHERIT_PRIORITY,
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0,
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&envLock);
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if (RTEMS_SUCCESSFUL!=rc)
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rtems_fatal_error_occurred(rc);
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}
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void
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__env_lock(struct _reent *r)
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{
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/* Do lazy init */
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if (!envLock)
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__rtems_envlock_init();
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/*
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* Must not use a semaphore before pre-tasking hook is called.
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* - it will corrupt memory :-(
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*/
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if (_Thread_Executing)
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rtems_semaphore_obtain(envLock, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
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}
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void
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__env_unlock(struct _reent *r)
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{
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/*
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* Must not use a semaphore before pre-tasking hook is called.
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* - it will corrupt memory :-(
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*/
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if (_Thread_Executing)
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rtems_semaphore_release(envLock);
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}
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82
cpukit/libcsupport/src/envlock.c
Normal file
82
cpukit/libcsupport/src/envlock.c
Normal file
@@ -0,0 +1,82 @@
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/*
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* $Id$
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*
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* Author: Till Straumann <strauman@slac.stanford.edu>, 3/2002
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*/
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/* provide locking for the global environment 'environ' */
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#if HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <rtems.h>
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#include <sys/reent.h>
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#include <assert.h>
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/*
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* NOTES:
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* - although it looks like a classical multiple-readers / single writer (MRSW)
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* locking problem, we still use a single lock for the following reasons:
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* 1) newlib has no provision / hook for calling different locking routines
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* from setenv/putenv and getenv, respectively.
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* 2) MRSW involves calling several semaphore-primitives, even in the most
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* likely case of a first-reader's access. This probably takes more CPU
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* time than just waiting until another reader is done; environment
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* access is fast.
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* - the lock implementation must allow nesting (same thread may call
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* lock-lock-unlock-unlock).
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* - NEWLIB-1.8.2 has an ugly BUG: if environ is NULL, _findenv_r() bails
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* out leaving the lock held :-(
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*
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*/
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static rtems_id envLock=0;
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static void
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__rtems_envlock_init(void)
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{
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extern char **environ;
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rtems_status_code rc;
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if (envLock) /* already initialized */
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return;
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assert(environ && "MUST have non-NULL 'environ' due to newlib bug");
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rc = rtems_semaphore_create(
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rtems_build_name('E','N','V','S'),
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1,
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RTEMS_BINARY_SEMAPHORE | RTEMS_PRIORITY | RTEMS_INHERIT_PRIORITY,
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0,
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&envLock);
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if (RTEMS_SUCCESSFUL!=rc)
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rtems_fatal_error_occurred(rc);
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}
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void
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__env_lock(struct _reent *r)
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{
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/* Do lazy init */
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if (!envLock)
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__rtems_envlock_init();
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/*
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* Must not use a semaphore before pre-tasking hook is called.
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* - it will corrupt memory :-(
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*/
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if (_Thread_Executing)
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rtems_semaphore_obtain(envLock, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
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}
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void
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__env_unlock(struct _reent *r)
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{
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/*
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* Must not use a semaphore before pre-tasking hook is called.
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* - it will corrupt memory :-(
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*/
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if (_Thread_Executing)
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rtems_semaphore_release(envLock);
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}
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Reference in New Issue
Block a user