From ea8bf8f588310b0d7fd3297d74907602705bba1d Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 2 Dec 2017 17:03:10 +0200
Subject: [PATCH] Implement controls for file descriptor inheritance

---
 source/core/unix/process.cpp |  1 +
 source/io/base.h             |  6 ++++++
 source/io/buffered.cpp       |  5 +++++
 source/io/buffered.h         |  1 +
 source/io/console.cpp        |  6 ++++++
 source/io/console.h          |  1 +
 source/io/file.cpp           | 11 +++++++++++
 source/io/file.h             |  2 ++
 source/io/handle.h           |  1 +
 source/io/memory.cpp         |  5 +++++
 source/io/memory.h           |  1 +
 source/io/mode.h             |  3 ++-
 source/io/pipe.cpp           |  7 +++++++
 source/io/pipe.h             |  1 +
 source/io/serial.cpp         |  6 ++++++
 source/io/serial.h           |  1 +
 source/io/slice.cpp          |  5 +++++
 source/io/slice.h            |  1 +
 source/io/unix/file.cpp      |  2 ++
 source/io/unix/handle.cpp    |  6 ++++++
 source/io/windows/file.cpp   |  5 +++++
 source/io/windows/handle.cpp |  4 ++++
 source/io/zlibcompressed.cpp |  5 +++++
 source/io/zlibcompressed.h   |  1 +
 24 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/source/core/unix/process.cpp b/source/core/unix/process.cpp
index 76141b0..99be2e1 100644
--- a/source/core/unix/process.cpp
+++ b/source/core/unix/process.cpp
@@ -39,6 +39,7 @@ void Process::execute(const string &command, bool path_search, const Arguments &
 
 			if(redirect)
 			{
+				// dup2 clears O_CLOEXEC
 				if(cin)
 					IO::cin.redirect(*cin);
 				if(cout)
diff --git a/source/io/base.h b/source/io/base.h
index 1fe143e..a6a8827 100644
--- a/source/io/base.h
+++ b/source/io/base.h
@@ -59,6 +59,12 @@ public:
 	Blocking is enabled by default. */
 	virtual void set_block(bool) = 0;
 
+	/** Sets inheritance mode.  When inheritance is enabled, the file descriptor
+	will persist through Process::execute.
+
+	Inheritance is disabled by default. */
+	virtual void set_inherit(bool) = 0;
+
 	/** Returns the current mode flags. */
 	Mode get_mode() const { return mode; }
 
diff --git a/source/io/buffered.cpp b/source/io/buffered.cpp
index 6567fff..2836e4b 100644
--- a/source/io/buffered.cpp
+++ b/source/io/buffered.cpp
@@ -37,6 +37,11 @@ void Buffered::set_block(bool)
 	throw logic_error("Buffered::set_block");
 }
 
+void Buffered::set_inherit(bool)
+{
+	throw logic_error("Buffered::set_block");
+}
+
 void Buffered::flush()
 {
 	if(cur_op==M_WRITE)
diff --git a/source/io/buffered.h b/source/io/buffered.h
index c88f0f8..da917e0 100644
--- a/source/io/buffered.h
+++ b/source/io/buffered.h
@@ -22,6 +22,7 @@ public:
 	~Buffered();
 
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 	void flush();
 
diff --git a/source/io/console.cpp b/source/io/console.cpp
index e70f31d..a7417ed 100644
--- a/source/io/console.cpp
+++ b/source/io/console.cpp
@@ -22,6 +22,12 @@ void Console::set_block(bool b)
 	sys_set_blocking(handle, b);
 }
 
+void Console::set_inherit(bool i)
+{
+	adjust_mode(mode, M_INHERIT, i);
+	sys_set_inherit(handle, i);
+}
+
 unsigned Console::do_write(const char *buf, unsigned len)
 {
 	check_access(M_WRITE);
diff --git a/source/io/console.h b/source/io/console.h
index e2b5d53..8feccfd 100644
--- a/source/io/console.h
+++ b/source/io/console.h
@@ -32,6 +32,7 @@ public:
 	~Console();
 
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 	
 	/** If local echo is enabled, characters will appear on the console as they
 	are typed.  Can only be used on an input Console.  */
diff --git a/source/io/file.cpp b/source/io/file.cpp
index ab957c9..74b9f9f 100644
--- a/source/io/file.cpp
+++ b/source/io/file.cpp
@@ -32,6 +32,12 @@ void File::set_block(bool b)
 	sys_set_blocking(handle, b);
 }
 
+void File::set_inherit(bool i)
+{
+	adjust_mode(mode, M_INHERIT, i);
+	sys_set_inherit(handle, i);
+}
+
 unsigned File::do_write(const char *buf, unsigned size)
 {
 	check_access(M_WRITE);
@@ -96,6 +102,11 @@ void BufferedFile::set_block(bool b)
 	file.set_block(b);
 }
 
+void BufferedFile::set_inherit(bool)
+{
+	throw logic_error("BufferedFile::set_inherit");
+}
+
 unsigned BufferedFile::do_write(const char *buf, unsigned size)
 {
 	unsigned ret = buffer.write(buf, size);
diff --git a/source/io/file.h b/source/io/file.h
index ececa8d..85075d0 100644
--- a/source/io/file.h
+++ b/source/io/file.h
@@ -58,6 +58,7 @@ public:
 	virtual ~File();
 
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 protected:
 	virtual unsigned do_write(const char *, unsigned);
@@ -93,6 +94,7 @@ public:
 	BufferedFile(const std::string &, Mode = M_READ, File::CreateMode = File::C_OVERWRITE);
 
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 protected:
 	virtual unsigned do_write(const char *, unsigned);
diff --git a/source/io/handle.h b/source/io/handle.h
index 8a9db50..4b311f5 100644
--- a/source/io/handle.h
+++ b/source/io/handle.h
@@ -29,6 +29,7 @@ public:
 
 
 void sys_set_blocking(Handle &, bool);
+void sys_set_inherit(Handle &, bool);
 unsigned sys_read(Handle &, char *, unsigned);
 unsigned sys_write(Handle &, const char *, unsigned);
 void sys_close(Handle &);
diff --git a/source/io/memory.cpp b/source/io/memory.cpp
index c5aee1e..eaaaeb1 100644
--- a/source/io/memory.cpp
+++ b/source/io/memory.cpp
@@ -42,6 +42,11 @@ void Memory::set_block(bool)
 	throw logic_error("Memory::set_block");
 }
 
+void Memory::set_inherit(bool)
+{
+	throw logic_error("Memory::set_inherit");
+}
+
 unsigned Memory::do_write(const char *buf, unsigned size)
 {
 	check_access(M_WRITE);
diff --git a/source/io/memory.h b/source/io/memory.h
index 4df2aa3..4a6eca2 100644
--- a/source/io/memory.h
+++ b/source/io/memory.h
@@ -23,6 +23,7 @@ private:
 
 public:
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 private:
 	virtual unsigned do_write(const char *, unsigned);
diff --git a/source/io/mode.h b/source/io/mode.h
index 2e7527d..0f7bb4f 100644
--- a/source/io/mode.h
+++ b/source/io/mode.h
@@ -13,7 +13,8 @@ enum Mode
 	M_WRITE = 2,
 	M_RDWR = M_READ|M_WRITE,
 	M_APPEND = 4,
-	M_NONBLOCK = 8
+	M_NONBLOCK = 8,
+	M_INHERIT = 16
 };
 
 inline Mode operator|(Mode m, Mode n)
diff --git a/source/io/pipe.cpp b/source/io/pipe.cpp
index 444f8c7..1301b3a 100644
--- a/source/io/pipe.cpp
+++ b/source/io/pipe.cpp
@@ -47,6 +47,13 @@ void Pipe::set_block(bool b)
 	sys_set_blocking(write_handle, b);
 }
 
+void Pipe::set_inherit(bool i)
+{
+	adjust_mode(mode, M_INHERIT, i);
+	sys_set_inherit(read_handle, i);
+	sys_set_inherit(write_handle, i);
+}
+
 unsigned Pipe::do_write(const char *buf, unsigned size)
 {
 	if(size==0)
diff --git a/source/io/pipe.h b/source/io/pipe.h
index 2b2b76e..098e119 100644
--- a/source/io/pipe.h
+++ b/source/io/pipe.h
@@ -24,6 +24,7 @@ public:
 
 	void set_mode(Mode);
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 protected:
 	virtual unsigned do_write(const char *, unsigned);
diff --git a/source/io/serial.cpp b/source/io/serial.cpp
index b4cfaab..09a9768 100644
--- a/source/io/serial.cpp
+++ b/source/io/serial.cpp
@@ -46,6 +46,12 @@ void Serial::set_block(bool b)
 	sys_set_blocking(handle, b);
 }
 
+void Serial::set_inherit(bool i)
+{
+	adjust_mode(mode, M_INHERIT, i);
+	sys_set_inherit(handle, i);
+}
+
 void Serial::set_baud_rate(unsigned rate)
 {
 	DeviceState state;
diff --git a/source/io/serial.h b/source/io/serial.h
index b219482..dbc7a77 100644
--- a/source/io/serial.h
+++ b/source/io/serial.h
@@ -36,6 +36,7 @@ private:
 
 public:
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 	void set_baud_rate(unsigned);
 	void set_data_bits(unsigned);
diff --git a/source/io/slice.cpp b/source/io/slice.cpp
index d53a63b..3fbfc57 100644
--- a/source/io/slice.cpp
+++ b/source/io/slice.cpp
@@ -26,6 +26,11 @@ void Slice::set_block(bool)
 	throw logic_error("Slice::set_block");
 }
 
+void Slice::set_inherit(bool)
+{
+	throw logic_error("Slice::set_inherit");
+}
+
 void Slice::flush()
 {
 	sync_position = true;
diff --git a/source/io/slice.h b/source/io/slice.h
index fb45014..d5f0f74 100644
--- a/source/io/slice.h
+++ b/source/io/slice.h
@@ -29,6 +29,7 @@ public:
 	Slice(Seekable &, SeekOffset, SeekOffset);
 
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 private:
 	void flush();
diff --git a/source/io/unix/file.cpp b/source/io/unix/file.cpp
index b2c9089..6092cb7 100644
--- a/source/io/unix/file.cpp
+++ b/source/io/unix/file.cpp
@@ -35,6 +35,8 @@ void File::platform_init(const string &fn, CreateMode cm)
 		flags |= O_APPEND;
 	if(mode&M_NONBLOCK)
 		flags |= O_NONBLOCK;
+	if(!(mode&M_INHERIT))
+		flags |= O_CLOEXEC;
 
 	*handle = ::open(fn.c_str(), flags, 0666);
 	if(!handle)
diff --git a/source/io/unix/handle.cpp b/source/io/unix/handle.cpp
index cb3ce4c..cbffa48 100644
--- a/source/io/unix/handle.cpp
+++ b/source/io/unix/handle.cpp
@@ -14,6 +14,12 @@ void sys_set_blocking(Handle &handle, bool b)
 	fcntl(*handle, F_SETFL, (flags&~O_NONBLOCK)|(b?0:O_NONBLOCK));
 }
 
+void sys_set_inherit(Handle &handle, bool i)
+{
+	int flags = fcntl(*handle, F_GETFD);
+	fcntl(*handle, F_SETFD, (flags&~O_CLOEXEC)|(i?O_CLOEXEC:0));
+}
+
 unsigned sys_read(Handle &handle, char *buf, unsigned size)
 {
 	int ret = read(*handle, buf, size);
diff --git a/source/io/windows/file.cpp b/source/io/windows/file.cpp
index b973375..f6943ad 100644
--- a/source/io/windows/file.cpp
+++ b/source/io/windows/file.cpp
@@ -33,6 +33,11 @@ void File::platform_init(const string &fn, CreateMode cm)
 	else
 		share_flags = FILE_SHARE_READ;
 
+	SECURITY_ATTRIBUTES sec_attr;
+	sec_attr.nLength = sizeof(SECURITY_ATTRIBUTES);
+	sec_attr.lpSecurityDescriptor = 0;
+	sec_attr.bInheritHandle = !!(mode&M_INHERIT);
+
 	*handle = CreateFile(fn.c_str(), flags, share_flags, 0, create_flags, FILE_ATTRIBUTE_NORMAL, 0);
 	if(!handle)
 	{
diff --git a/source/io/windows/handle.cpp b/source/io/windows/handle.cpp
index 2dac33f..e59de27 100644
--- a/source/io/windows/handle.cpp
+++ b/source/io/windows/handle.cpp
@@ -9,6 +9,10 @@ void sys_set_blocking(Handle &, bool)
 {
 }
 
+void sys_set_inherit(Handle &, bool)
+{
+}
+
 unsigned sys_read(Handle &handle, char *buf, unsigned size)
 {
 	DWORD ret;
diff --git a/source/io/zlibcompressed.cpp b/source/io/zlibcompressed.cpp
index 99ae7f8..3ad4f22 100644
--- a/source/io/zlibcompressed.cpp
+++ b/source/io/zlibcompressed.cpp
@@ -118,6 +118,11 @@ void ZlibCompressed::set_block(bool)
 	throw logic_error("ZlibCompressed::set_block");
 }
 
+void ZlibCompressed::set_inherit(bool)
+{
+	throw logic_error("ZlibCompressed::set_inherit");
+}
+
 void ZlibCompressed::flush()
 {
 #ifdef WITH_ZLIB
diff --git a/source/io/zlibcompressed.h b/source/io/zlibcompressed.h
index fc559fe..af75aec 100644
--- a/source/io/zlibcompressed.h
+++ b/source/io/zlibcompressed.h
@@ -57,6 +57,7 @@ public:
 	virtual ~ZlibCompressed();
 
 	virtual void set_block(bool);
+	virtual void set_inherit(bool);
 
 	void flush();
 
-- 
2.45.2