From fcd4a421e341d3f6fa3b9fb48acc3d52faf37805 Mon Sep 17 00:00:00 2001
From: Xiang Xiao <xiaoxiang@xiaomi.com>
Date: Wed, 11 Jan 2023 00:51:35 +0800
Subject: [PATCH] fs/mmap: Support the no backing file for anonymous mapping
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
---
fs/mmap/fs_anonmap.h | 2 +-
fs/mmap/fs_mmap.c | 33 +++++++++++++++++++--------------
2 files changed, 20 insertions(+), 15 deletions(-)
diff --git a/fs/mmap/fs_anonmap.h b/fs/mmap/fs_anonmap.h
index 70725c5623..1413d53bd5 100644
--- a/fs/mmap/fs_anonmap.h
+++ b/fs/mmap/fs_anonmap.h
@@ -55,7 +55,7 @@
#ifdef CONFIG_FS_ANONMAP
int map_anonymous(FAR struct mm_map_entry_s *entry, bool kernel);
#else
-#define map_anonymous(entry,kernel) (-ENOSYS)
+# define map_anonymous(entry, kernel) (-ENOSYS)
#endif /* CONFIG_FS_ANONMAP */
#endif /* __FS_MMAP_FS_ANONMAP_H */
diff --git a/fs/mmap/fs_mmap.c b/fs/mmap/fs_mmap.c
index a533602f76..8d7a3f6d2a 100644
--- a/fs/mmap/fs_mmap.c
+++ b/fs/mmap/fs_mmap.c
@@ -94,6 +94,22 @@ static int file_mmap_(FAR struct file *filep, FAR void *start,
}
#endif /* CONFIG_DEBUG_FEATURES */
+ /* Check if we are just be asked to allocate memory, i.e., MAP_ANONYMOUS
+ * set meaning that the memory is not backed up from a file. The file
+ * descriptor should be -1 (or refer to opened /dev/zero) in this case.
+ * The file descriptor is ignored in either case.
+ */
+
+ if ((flags & MAP_ANONYMOUS) != 0)
+ {
+ return map_anonymous(&entry, kernel);
+ }
+
+ if (filep == NULL)
+ {
+ return -EBADF;
+ }
+
if ((filep->f_oflags & O_WROK) == 0 && prot == PROT_WRITE)
{
ferr("ERROR: Unsupported options for read-only file descriptor,"
@@ -107,17 +123,6 @@ static int file_mmap_(FAR struct file *filep, FAR void *start,
return -EACCES;
}
- /* Check if we are just be asked to allocate memory, i.e., MAP_ANONYMOUS
- * set meaning that the memory is not backed up from a file. The file
- * descriptor should be -1 (or refer to opened /dev/zero) in this case.
- * The file descriptor is ignored in either case.
- */
-
- if ((flags & MAP_ANONYMOUS) != 0)
- {
- return map_anonymous(&entry, kernel);
- }
-
/* Call driver's mmap to get the base address of the file in 'mapped'
* in memory.
*/
@@ -218,7 +223,7 @@ int file_mmap(FAR struct file *filep, FAR void *start, size_t length,
* MAP_NORESERVE - Ignored
* MAP_POPULATE - Ignored
* MAP_NONBLOCK - Ignored
- * fd file descriptor of the backing file -- required.
+ * fd file descriptor of the backing file.
* offset The offset into the file to map
*
* Returned Value:
@@ -247,11 +252,11 @@ int file_mmap(FAR struct file *filep, FAR void *start, size_t length,
FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
int fd, off_t offset)
{
- FAR struct file *filep;
+ FAR struct file *filep = NULL;
FAR void *mapped;
int ret;
- if (fs_getfilep(fd, &filep) < 0)
+ if (fd != -1 && fs_getfilep(fd, &filep) < 0)
{
ferr("ERROR: Invalid file descriptor, fd=%d\n", fd);
ret = -EBADF;