posix/mmap: Add support for file handler and MAP_ANON

Added a mmap file handler to struct _rtems_filesystem_file_handlers_r.
Updated each file handler object to support the default mmap handler.
Updated mmap() to call the mmap handler for MAP_SHARED.
Added a mmap file handler for shm

Added support for MAP_ANON in mmap().

Updates #2859

4 files changed, 53 insertions, 0 deletions

diff --git a/cpukit/libcsupport/include/rtems/libio.h b/cpukit/libcsupport/include/rtems/libio.h
index 4669cb52e1..8226d18ba2 100644
--- a/cpukit/libcsupport/include/rtems/libio.h
+++ b/cpukit/libcsupport/include/rtems/libio.h
@@ -977,6 +977,28 @@ typedef int (*rtems_filesystem_kqfilter_t)(
 );
 
 /**
+ * @brief MMAP support.
+ *
+ * @param[in, out] iop The IO pointer.
+ * @param[in, out] addr The starting address of the mapped memory.
+ * @param[in] len The maximum number of bytes to map.
+ * @param[in] prot The desired memory protection.
+ * @param[in] off The offset within the file descriptor to map.
+ *
+ * @retval 0 Successful operation.
+ * @retval error An error occurred.  This is usually EINVAL.
+ *
+ * @see rtems_filesystem_default_mmap().
+ */
+typedef int (*rtems_filesystem_mmap_t)(
+  rtems_libio_t *iop,
+  void **addr,
+  size_t len,
+  int prot,
+  off_t off
+);
+
+/**
  * @brief File system node operations table.
  */
 struct _rtems_filesystem_file_handlers_r {
@@ -995,6 +1017,7 @@ struct _rtems_filesystem_file_handlers_r {
   rtems_filesystem_kqfilter_t kqfilter_h;
   rtems_filesystem_readv_t readv_h;
   rtems_filesystem_writev_t writev_h;
+  rtems_filesystem_mmap_t mmap_h;
 };
 
 /**
@@ -1216,6 +1239,21 @@ int rtems_filesystem_default_kqfilter(
   struct knote *kn
 );
 
+/**
+ * @brief Default MMAP handler.
+ *
+ * @retval ENOTSUP Always.
+ *
+ * @see rtems_filesystem_mmap_t.
+ */
+int rtems_filesystem_default_mmap(
+  rtems_libio_t *iop,
+  void **addr,
+  size_t len,
+  int prot,
+  off_t off
+);
+
 /** @} */
 
 /**
diff --git a/cpukit/libcsupport/include/rtems/termiostypes.h b/cpukit/libcsupport/include/rtems/termiostypes.h
index e91faa7376..b3cac66e92 100644
--- a/cpukit/libcsupport/include/rtems/termiostypes.h
+++ b/cpukit/libcsupport/include/rtems/termiostypes.h
@@ -565,6 +565,19 @@ int rtems_termios_kqfilter(
 );
 
 /**
+ * @brief Termios mmap() filter filesystem node handler
+ *
+ * Real implementation is provided by libbsd.
+ */
+int rtems_termios_mmap(
+  rtems_libio_t *iop,
+  void         **addr,
+  size_t         len,
+  int            prot,
+  off_t          off
+);
+
+/**
  * @brief Termios poll() filesystem node handler.
  *
  * Real implementation is provided by libbsd.
diff --git a/cpukit/libcsupport/src/__usrenv.c b/cpukit/libcsupport/src/__usrenv.c
index a05295d642..611e0d7a92 100644
--- a/cpukit/libcsupport/src/__usrenv.c
+++ b/cpukit/libcsupport/src/__usrenv.c
@@ -56,6 +56,7 @@ const rtems_filesystem_file_handlers_r rtems_filesystem_null_handlers = {
   .fdatasync_h = rtems_filesystem_default_fsync_or_fdatasync,
   .fcntl_h = rtems_filesystem_default_fcntl,
   .kqfilter_h = rtems_filesystem_default_kqfilter,
+  .mmap_h = rtems_filesystem_default_mmap,
   .poll_h = rtems_filesystem_default_poll,
   .readv_h = rtems_filesystem_default_readv,
   .writev_h = rtems_filesystem_default_writev
diff --git a/cpukit/libcsupport/src/termios.c b/cpukit/libcsupport/src/termios.c
index a22ae95719..7d843495c5 100644
--- a/cpukit/libcsupport/src/termios.c
+++ b/cpukit/libcsupport/src/termios.c
@@ -2212,6 +2212,7 @@ static const rtems_filesystem_file_handlers_r rtems_termios_imfs_handler = {
   .fdatasync_h = rtems_filesystem_default_fsync_or_fdatasync,
   .fcntl_h = rtems_filesystem_default_fcntl,
   .kqfilter_h = rtems_termios_kqfilter,
+  .mmap_h = rtems_termios_mmap,
   .poll_h = rtems_termios_poll,
   .readv_h = rtems_filesystem_default_readv,
   .writev_h = rtems_filesystem_default_writev