[vlc-devel] [PATCH 1/2] filesystem: add vlc_dup2() wrapper

[remi at remlab.net]

From: Rémi Denis-Courmont <remi at remlab.net>

---
 include/vlc_fs.h       | 17 +++++++++++++++++
 src/libvlccore.sym     |  1 +
 src/posix/filesystem.c | 12 ++++++++++++
 src/win32/filesystem.c |  8 ++++++++
 4 files changed, 38 insertions(+)

diff --git a/include/vlc_fs.h b/include/vlc_fs.h
index 4a50288be0..9ad2028053 100644
--- a/include/vlc_fs.h
+++ b/include/vlc_fs.h
@@ -110,6 +110,23 @@ VLC_API int vlc_mkstemp( char * );
  */
 VLC_API int vlc_dup(int oldfd) VLC_USED;
 
+/**
+ * Replaces a file descriptor.
+ *
+ * This function duplicates a file descriptor to a specified file descriptor.
+ * This is primarily used to atomically replace a described file.
+ *
+ * @param oldfd source file descriptor to copy
+ * @param newfd destination file descriptor to replace
+ *
+ * @note Contrary to standard dup2(), the new file descriptor has the
+ * close-on-exec descriptor flag preset.
+ *
+ * @retval newfd success
+ * @retval -1 failure (see @c errno)
+ */
+VLC_API int vlc_dup2(int oldfd, int newfd);
+
 /**
  * Creates a pipe (see "man pipe" for further reference). The new file
  * descriptors have the close-on-exec flag preset.
diff --git a/src/libvlccore.sym b/src/libvlccore.sym
index e3a2de9f6d..2cfe0d376c 100644
--- a/src/libvlccore.sym
+++ b/src/libvlccore.sym
@@ -448,6 +448,7 @@ vlc_unlink
 vlc_rename
 vlc_getcwd
 vlc_dup
+vlc_dup2
 vlc_pipe
 vlc_write
 vlc_writev
diff --git a/src/posix/filesystem.c b/src/posix/filesystem.c
index 60a997d9e0..18105a643c 100644
--- a/src/posix/filesystem.c
+++ b/src/posix/filesystem.c
@@ -178,6 +178,18 @@ int vlc_dup (int oldfd)
     return fcntl (oldfd, F_DUPFD_CLOEXEC, 0);
 }
 
+int vlc_dup2(int oldfd, int newfd)
+{
+#ifdef HAVE_DUP3
+    return dup3(oldfd, newfd, O_CLOEXEC);
+#else
+    int ret = dup2(oldfd, newfd);
+    if (ret >= 0)
+        vlc_cloexec(newfd);
+    return ret;
+#endif
+}
+
 int vlc_pipe (int fds[2])
 {
 #ifdef HAVE_PIPE2
diff --git a/src/win32/filesystem.c b/src/win32/filesystem.c
index d8e3cc1127..09b8ec70d3 100644
--- a/src/win32/filesystem.c
+++ b/src/win32/filesystem.c
@@ -304,6 +304,14 @@ int vlc_dup (int oldfd)
     return fd;
 }
 
+int vlc_dup2(int oldfd, int newfd)
+{
+    int fd = dup2(oldfd, newfd);
+    if (fd != -1)
+        setmode(fd, O_BINARY);
+    return fd;
+}
+
 int vlc_pipe (int fds[2])
 {
 #if VLC_WINSTORE_APP
-- 
2.29.2