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[libvirt] [PATCH 2/5] build: replace redundant header check with function check



Gnulib guarantees that pthread.h exists, but for now, it is a dummy
header with no support for most pthread_* functions.  Modify our
use of pthread to use function checks, rather than header checks,
to determine how much pthread support is present.

* configure.ac: Optimize function checks.  Add check for pthread
functions.
* src/remote/remote_driver.c (remoteIOEventLoop): Depend on
pthread_sigmask, now that gnulib guarantees pthread.h.
* src/util/util.c (virFork): Likewise.
* src/util/threads.c (threads-pthread.c): Depend on
pthread_mutexattr_init, as a witness of full pthread support.
* src/util/threads.h (threads-pthread.h): Likewise.
---
 configure.ac               |   13 +++++++++++--
 src/remote/remote_driver.c |    6 +++---
 src/util/threads.c         |    4 ++--
 src/util/threads.h         |    4 ++--
 src/util/util.c            |   10 +++++-----
 5 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/configure.ac b/configure.ac
index cfefc02..b5ff348 100644
--- a/configure.ac
+++ b/configure.ac
@@ -107,10 +107,19 @@ dnl Use --disable-largefile if you don't want this.
 AC_SYS_LARGEFILE

 dnl Availability of various common functions (non-fatal if missing).
-AC_CHECK_FUNCS([cfmakeraw regexec uname sched_getaffinity getuid getgid posix_fallocate mmap])
+AC_CHECK_FUNCS_ONCE([cfmakeraw regexec uname sched_getaffinity getuid getgid \
+ posix_fallocate mmap])

 dnl Availability of various not common threadsafe functions
-AC_CHECK_FUNCS([strerror_r strtok_r getmntent_r getgrnam_r getpwuid_r])
+AC_CHECK_FUNCS_ONCE([strerror_r strtok_r getmntent_r getgrnam_r getpwuid_r])
+
+dnl Availability of pthread functions (if missing, win32 threading is
+dnl assumed).  Because of $LIB_PTHREAD, we cannot use AC_CHECK_FUNCS_ONCE.
+dnl LIB_PTHREAD was set during gl_INIT by gnulib.
+old_LIBS=$LIBS
+LIBS="$LIBS $LIB_PTHREAD"
+AC_CHECK_FUNCS([pthread_sigmask pthread_mutexattr_init])
+LIBS=$old_libs

 dnl Availability of various common headers (non-fatal if missing).
 AC_CHECK_HEADERS([pwd.h paths.h regex.h sys/syslimits.h sys/utsname.h \
diff --git a/src/remote/remote_driver.c b/src/remote/remote_driver.c
index 1917f26..b798cdf 100644
--- a/src/remote/remote_driver.c
+++ b/src/remote/remote_driver.c
@@ -9487,7 +9487,7 @@ remoteIOEventLoop(virConnectPtr conn,
         struct remote_thread_call *tmp = priv->waitDispatch;
         struct remote_thread_call *prev;
         char ignore;
-#ifdef HAVE_PTHREAD_H
+#ifdef HAVE_PTHREAD_SIGMASK
         sigset_t oldmask, blockedsigs;
 #endif

@@ -9516,7 +9516,7 @@ remoteIOEventLoop(virConnectPtr conn,
          * after the call (RHBZ#567931).  Same for SIGCHLD and SIGPIPE
          * at the suggestion of Paolo Bonzini and Daniel Berrange.
          */
-#ifdef HAVE_PTHREAD_H
+#ifdef HAVE_PTHREAD_SIGMASK
         sigemptyset (&blockedsigs);
         sigaddset (&blockedsigs, SIGWINCH);
         sigaddset (&blockedsigs, SIGCHLD);
@@ -9529,7 +9529,7 @@ remoteIOEventLoop(virConnectPtr conn,
         if (ret < 0 && errno == EAGAIN)
             goto repoll;

-#ifdef HAVE_PTHREAD_H
+#ifdef HAVE_PTHREAD_SIGMASK
         ignore_value(pthread_sigmask(SIG_SETMASK, &oldmask, NULL));
 #endif

diff --git a/src/util/threads.c b/src/util/threads.c
index 18f8b64..8c0a91a 100644
--- a/src/util/threads.c
+++ b/src/util/threads.c
@@ -1,7 +1,7 @@
 /*
  * threads.c: basic thread synchronization primitives
  *
- * Copyright (C) 2009 Red Hat, Inc.
+ * Copyright (C) 2009-2010 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -23,7 +23,7 @@

 #include "threads.h"

-#ifdef HAVE_PTHREAD_H
+#ifdef HAVE_PTHREAD_MUTEXATTR_INIT
 # include "threads-pthread.c"
 #else
 # ifdef WIN32
diff --git a/src/util/threads.h b/src/util/threads.h
index 6e01082..8b2be8d 100644
--- a/src/util/threads.h
+++ b/src/util/threads.h
@@ -1,7 +1,7 @@
 /*
  * threads.h: basic thread synchronization primitives
  *
- * Copyright (C) 2009 Red Hat, Inc.
+ * Copyright (C) 2009-2010 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -61,7 +61,7 @@ int virThreadLocalInit(virThreadLocalPtr l,
 void *virThreadLocalGet(virThreadLocalPtr l);
 void virThreadLocalSet(virThreadLocalPtr l, void*);

-# ifdef HAVE_PTHREAD_H
+# ifdef HAVE_PTHREAD_MUTEXATTR_INIT
 #  include "threads-pthread.h"
 # else
 #  ifdef WIN32
diff --git a/src/util/util.c b/src/util/util.c
index 3958a11..c7d5c05 100644
--- a/src/util/util.c
+++ b/src/util/util.c
@@ -316,7 +316,7 @@ static int virClearCapabilities(void)

  */
 int virFork(pid_t *pid) {
-#  ifdef HAVE_PTHREAD_H
+#  ifdef HAVE_PTHREAD_SIGMASK
     sigset_t oldmask, newmask;
 #  endif
     struct sigaction sig_action;
@@ -328,7 +328,7 @@ int virFork(pid_t *pid) {
      * Need to block signals now, so that child process can safely
      * kill off caller's signal handlers without a race.
      */
-#  ifdef HAVE_PTHREAD_H
+#  ifdef HAVE_PTHREAD_SIGMASK
     sigfillset(&newmask);
     if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) {
         saved_errno = errno;
@@ -349,7 +349,7 @@ int virFork(pid_t *pid) {
     virLogUnlock();

     if (*pid < 0) {
-#  ifdef HAVE_PTHREAD_H
+#  ifdef HAVE_PTHREAD_SIGMASK
         /* attempt to restore signal mask, but ignore failure, to
            avoid obscuring the fork failure */
         ignore_value (pthread_sigmask(SIG_SETMASK, &oldmask, NULL));
@@ -363,7 +363,7 @@ int virFork(pid_t *pid) {

         /* parent process */

-#  ifdef HAVE_PTHREAD_H
+#  ifdef HAVE_PTHREAD_SIGMASK
         /* Restore our original signal mask now that the child is
            safely running */
         if (pthread_sigmask(SIG_SETMASK, &oldmask, NULL) != 0) {
@@ -407,7 +407,7 @@ int virFork(pid_t *pid) {
             sigaction(i, &sig_action, NULL);
         }

-#  ifdef HAVE_PTHREAD_H
+#  ifdef HAVE_PTHREAD_SIGMASK
         /* Unmask all signals in child, since we've no idea
            what the caller's done with their signal mask
            and don't want to propagate that to children */
-- 
1.6.6.1


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