system/Open: new UniqueFileDescriptor constructing library

Makefile.am

@@ -615,6 +615,7 @@ libsystem_a_SOURCES = \
 	src/system/FatalError.cxx src/system/FatalError.hxx \
 	src/system/FileDescriptor.cxx src/system/FileDescriptor.hxx \
 	src/system/UniqueFileDescriptor.hxx \
+	src/system/Open.cxx src/system/Open.hxx \
 	src/system/EventPipe.cxx src/system/EventPipe.hxx \
 	src/system/EventFD.cxx src/system/EventFD.hxx \
 	src/system/SignalFD.cxx src/system/SignalFD.hxx \

src/fs/io/FileReader.cxx

@@ -21,6 +21,7 @@
 #include "FileReader.hxx"
 #include "fs/FileInfo.hxx"
 #include "system/Error.hxx"
+#include "system/Open.hxx"
 
 #include <assert.h>
 
@@ -88,11 +89,8 @@ FileReader::Close() noexcept
 #else
 
 FileReader::FileReader(Path _path)
-	:path(_path)
+	:path(_path), fd(OpenReadOnly(path.c_str()))
 {
-	fd.OpenReadOnly(path.c_str());
-	if (!fd.IsDefined())
-		throw FormatErrno("Failed to open %s", path.ToUTF8().c_str());
 }
 
 FileInfo

src/system/Open.cxx

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2018 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "Open.hxx"
+#include "Error.hxx"
+#include "UniqueFileDescriptor.hxx"
+
+#include <fcntl.h>
+
+UniqueFileDescriptor
+OpenReadOnly(const char *path)
+{
+	UniqueFileDescriptor fd;
+	if (!fd.OpenReadOnly(path))
+		throw FormatErrno("Failed to open '%s'", path);
+
+	return fd;
+}
+
+#ifdef __linux__
+
+UniqueFileDescriptor
+OpenPath(const char *path, int flags)
+{
+	UniqueFileDescriptor fd;
+	if (!fd.Open(path, O_PATH|flags))
+		throw FormatErrno("Failed to open '%s'", path);
+
+	return fd;
+}
+
+UniqueFileDescriptor
+OpenPath(FileDescriptor directory, const char *name, int flags)
+{
+	UniqueFileDescriptor fd;
+	if (!fd.Open(directory, name, O_PATH|flags))
+		throw FormatErrno("Failed to open '%s'", name);
+
+	return fd;
+}
+
+UniqueFileDescriptor
+OpenReadOnly(FileDescriptor directory, const char *name, int flags)
+{
+	UniqueFileDescriptor fd;
+	if (!fd.Open(directory, name, O_RDONLY|flags))
+		throw FormatErrno("Failed to open '%s'", name);
+
+	return fd;
+}
+
+UniqueFileDescriptor
+OpenDirectory(FileDescriptor directory, const char *name, int flags)
+{
+	UniqueFileDescriptor fd;
+	if (!fd.Open(directory, name, O_DIRECTORY|O_RDONLY|flags))
+		throw FormatErrno("Failed to open '%s'", name);
+
+	return fd;
+}
+
+#endif

src/system/Open.hxx

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2018 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef OPEN_HXX
+#define OPEN_HXX
+
+class FileDescriptor;
+class UniqueFileDescriptor;
+
+UniqueFileDescriptor
+OpenReadOnly(const char *path);
+
+#ifdef __linux__
+
+UniqueFileDescriptor
+OpenPath(const char *path, int flags=0);
+
+UniqueFileDescriptor
+OpenPath(FileDescriptor directory, const char *name, int flags=0);
+
+UniqueFileDescriptor
+OpenReadOnly(FileDescriptor directory, const char *name, int flags=0);
+
+UniqueFileDescriptor
+OpenDirectory(FileDescriptor directory, const char *name, int flags=0);
+
+#endif
+
+#endif