Centralise handling & ignoring of SIGPIPE in qcore_unix_p.h

We had two instances of this function in the Qt source code, one clearly
a copy of the other, so both had the same thread-safety issue. Instead,
let's have one copy and have both write_nosignal() and sendto() call
them.

(cherry-picked from qtbase commit cb7d64170d62c9cda11ced7e5047070af678338b)
Change-Id: I0f1354a8e9df8e6b10a02f86a940e3c6d1222087
Reviewed-by: Peter Hartmann <phartmann@rim.com>
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>

4 files changed, 33 insertions, 46 deletions

diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index 2feb6a5..88a3249 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -958,27 +958,9 @@ qint64 QProcessPrivate::readFromStderr(char *data, qint64 maxlen)
     return bytesRead;
 }
 
-static void qt_ignore_sigpipe()
-{
-    // Set to ignore SIGPIPE once only.
-    static QBasicAtomicInt atom = Q_BASIC_ATOMIC_INITIALIZER(0);
-    if (!atom) {
-        // More than one thread could turn off SIGPIPE at the same time
-        // But that's acceptable because they all would be doing the same
-        // action
-        struct sigaction noaction;
-        memset(&noaction, 0, sizeof(noaction));
-        noaction.sa_handler = SIG_IGN;
-        ::sigaction(SIGPIPE, &noaction, 0);
-        atom = 1;
-    }
-}
-
 qint64 QProcessPrivate::writeToStdin(const char *data, qint64 maxlen)
 {
-    qt_ignore_sigpipe();
-
-    qint64 written = qt_safe_write(stdinChannel.pipe[1], data, maxlen);
+    qint64 written = qt_safe_write_nosignal(stdinChannel.pipe[1], data, maxlen);
 #if defined QPROCESS_DEBUG
     qDebug("QProcessPrivate::writeToStdin(%p \"%s\", %lld) == %lld",
            data, qt_prettyDebug(data, maxlen, 16).constData(), maxlen, written);
diff --git a/src/corelib/kernel/qcore_unix_p.h b/src/corelib/kernel/qcore_unix_p.h
index 1672e1c..498a3d3 100644
--- a/src/corelib/kernel/qcore_unix_p.h
+++ b/src/corelib/kernel/qcore_unix_p.h
@@ -54,11 +54,13 @@
 //
 
 #include "qplatformdefs.h"
+#include "qatomic.h"
 
 #ifndef Q_OS_UNIX
 # error "qcore_unix_p.h included on a non-Unix system"
 #endif
 
+#include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -143,6 +145,27 @@ inline timeval operator*(const timeval &t1, int mul)
     return normalizedTimeval(tmp);
 }
 
+inline void qt_ignore_sigpipe()
+{
+#ifndef Q_NO_POSIX_SIGNALS
+    // Set to ignore SIGPIPE once only.
+    static QBasicAtomicInt atom = Q_BASIC_ATOMIC_INITIALIZER(0);
+    if (!atom) {
+        // More than one thread could turn off SIGPIPE at the same time
+        // But that's acceptable because they all would be doing the same
+        // action
+        struct sigaction noaction;
+        memset(&noaction, 0, sizeof(noaction));
+        noaction.sa_handler = SIG_IGN;
+        ::sigaction(SIGPIPE, &noaction, 0);
+        atom = 1;
+    }
+#else
+    // Posix signals are not supported by the underlying platform
+    // so we don't need to ignore sigpipe signal explicitly
+#endif
+}
+
 // don't call QT_OPEN or ::open
 // call qt_safe_open
 static inline int qt_safe_open(const char *pathname, int flags, mode_t mode = 0777)
@@ -265,6 +288,12 @@ static inline qint64 qt_safe_write(int fd, const void *data, qint64 len)
 #undef QT_WRITE
 #define QT_WRITE qt_safe_write
 
+static inline qint64 qt_safe_write_nosignal(int fd, const void *data, qint64 len)
+{
+    qt_ignore_sigpipe();
+    return qt_safe_write(fd, data, len);
+}
+
 static inline int qt_safe_close(int fd)
 {
     register int ret;
diff --git a/src/network/socket/qnativesocketengine_unix.cpp b/src/network/socket/qnativesocketengine_unix.cpp
index 640a627..aeba096 100644
--- a/src/network/socket/qnativesocketengine_unix.cpp
+++ b/src/network/socket/qnativesocketengine_unix.cpp
@@ -101,27 +101,6 @@ static QByteArray qt_prettyDebug(const char *data, int len, int maxSize)
 }
 #endif
 
-static void qt_ignore_sigpipe()
-{
-#ifndef Q_NO_POSIX_SIGNALS
-    // Set to ignore SIGPIPE once only.
-    static QBasicAtomicInt atom = Q_BASIC_ATOMIC_INITIALIZER(0);
-    if (!atom) {
-        // More than one thread could turn off SIGPIPE at the same time
-        // But that's acceptable because they all would be doing the same
-        // action
-        struct sigaction noaction;
-        memset(&noaction, 0, sizeof(noaction));
-        noaction.sa_handler = SIG_IGN;
-        ::sigaction(SIGPIPE, &noaction, 0);
-        atom = 1;
-    }
-#else
-    // Posix signals are not supported by the underlying platform
-    // so we don't need to ignore sigpipe signal explicitly
-#endif
-}
-
 /*
     Extracts the port and address from a sockaddr, and stores them in
     \a port and \a addr if they are non-null.
@@ -903,8 +882,6 @@ qint64 QNativeSocketEnginePrivate::nativeSendDatagram(const char *data, qint64 l
         sockAddrPtr = (struct sockaddr *)&sockAddrIPv4;
     }
 
-    // ignore the SIGPIPE signal
-    qt_ignore_sigpipe();
     ssize_t sentBytes = qt_safe_sendto(socketDescriptor, data, len,
                                        0, sockAddrPtr, sockAddrSize);
 
@@ -1011,11 +988,8 @@ qint64 QNativeSocketEnginePrivate::nativeWrite(const char *data, qint64 len)
 {
     Q_Q(QNativeSocketEngine);
 
-    // ignore the SIGPIPE signal
-    qt_ignore_sigpipe();
-
     ssize_t writtenBytes;
-    writtenBytes = qt_safe_write(socketDescriptor, data, len);
+    writtenBytes = qt_safe_write_nosignal(socketDescriptor, data, len);
 
     if (writtenBytes < 0) {
         switch (errno) {
diff --git a/src/network/socket/qnet_unix_p.h b/src/network/socket/qnet_unix_p.h
index dd13e3e..4b212c9 100644
--- a/src/network/socket/qnet_unix_p.h
+++ b/src/network/socket/qnet_unix_p.h
@@ -188,6 +188,8 @@ static inline int qt_safe_sendto(int sockfd, const void *buf, size_t len, int fl
 {
 #ifdef MSG_NOSIGNAL
     flags |= MSG_NOSIGNAL;
+#else
+    qt_ignore_sigpipe();
 #endif
 
     register int ret;