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fs: Implement file_mmap and file_munmap API

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Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao 2021-03-20 05:06:08 +08:00 committed by Masayuki Ishikawa
parent 2b0b298ab6
commit 8612af4ae5
5 changed files with 346 additions and 234 deletions
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266
fs/mmap/fs_mmap.c
View File

@ -37,10 +37,156 @@
#include "inode/inode.h"
#include "fs_rammap.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: file_mmap_
****************************************************************************/
static int file_mmap_(FAR struct file *filep, FAR void *start,
size_t length, int prot, int flags,
off_t offset, bool kernel, FAR void **mapped)
{
FAR void *addr;
int ret;
/* Since only a tiny subset of mmap() functionality, we have to verify many
* things.
*/
#ifdef CONFIG_DEBUG_FEATURES
/* Fixed mappings and protections are not currently supported. These
* options could be supported in the KERNEL build with an MMU, but that
* logic is not in place.
*/
if ((flags & (MAP_FIXED | MAP_DENYWRITE)) != 0)
{
ferr("ERROR: Unsupported options, prot=%x flags=%04x\n", prot, flags);
return -ENOSYS;
}
#ifndef CONFIG_FS_RAMMAP
if ((flags & MAP_PRIVATE) != 0)
{
ferr("ERROR: MAP_PRIVATE is not supported without file mapping"
"emulation\n");
return -ENOSYS;
}
#endif /* CONFIG_FS_RAMMAP */
/* A length of 0 is invalid. */
if (length == 0)
{
ferr("ERROR: Invalid length, length=%zu\n", length);
return -EINVAL;
}
#endif /* CONFIG_DEBUG_FEATURES */
if ((filep->f_oflags & O_WROK) == 0 && prot == PROT_WRITE &&
(flags & MAP_SHARED) != 0)
{
ferr("ERROR: Unsupported options for read-only file descriptor,"
"prot=%x flags=%04x\n", prot, flags);
return -EACCES;
}
if ((filep->f_oflags & O_RDOK) == 0)
{
ferr("ERROR: File descriptor does not have read permission\n");
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)
{
/* REVISIT: Should reside outside of the heap. That is really the
* only purpose of MAP_ANONYMOUS: To get non-heap memory. In KERNEL
* build, this could be accomplished using pgalloc(), provided that
* you had logic in place to assign a virtual address to the mapping.
*/
*mapped = kernel ? kmm_zalloc(length) : kumm_zalloc(length);
if (*mapped == NULL)
{
ferr("ERROR: kumm_alloc() failed: %d\n", ret);
return -ENOMEM;
}
return OK;
}
if ((flags & MAP_PRIVATE) != 0)
{
#ifdef CONFIG_FS_RAMMAP
/* Allocate memory and copy the file into memory. We would, of course,
* do much better in the KERNEL build using the MMU.
*/
return rammap(filep, length, offset, kernel, mapped);
#endif
}
/* Perform the ioctl to get the base address of the file in 'mapped'
* in memory. (casting to uintptr_t first eliminates complaints on some
* architectures where the sizeof long is different from the size of
* a pointer).
*/
ret = file_ioctl(filep, FIOC_MMAP, (unsigned long)((uintptr_t)&addr));
if (ret < 0)
{
/* Not directly mappable, probably because the underlying media does
* not support random access.
*/
#ifdef CONFIG_FS_RAMMAP
/* Allocate memory and copy the file into memory. We would, of course,
* do much better in the KERNEL build using the MMU.
*/
return rammap(filep, length, offset, kernel, mapped);
#else
ferr("ERROR: file_ioctl(FIOC_MMAP) failed: %d\n", ret);
return ret;
#endif
}
/* Return the offset address */
*mapped = (FAR void *)(((FAR uint8_t *)addr) + offset);
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: file_mmap
*
* Description:
* Equivalent to the standard mmap() function except that is accepts
* a struct file instance instead of a file descriptor and it does not set
* the errno variable.
*
****************************************************************************/
int file_mmap(FAR struct file *filep, FAR void *start, size_t length,
int prot, int flags, off_t offset, FAR void **mapped)
{
return file_mmap_(filep, start, length,
prot, flags, offset, true, mapped);
}
/****************************************************************************
* Name: mmap
*
@ -118,47 +264,10 @@
FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
int fd, off_t offset)
{
FAR void *addr;
FAR struct file *filep;
FAR void *mapped;
int ret;
/* Since only a tiny subset of mmap() functionality, we have to verify many
* things.
*/
#ifdef CONFIG_DEBUG_FEATURES
/* Fixed mappings and protections are not currently supported. These
* options could be supported in the KERNEL build with an MMU, but that
* logic is not in place.
*/
if ((flags & (MAP_FIXED | MAP_DENYWRITE)) != 0)
{
ferr("ERROR: Unsupported options, prot=%x flags=%04x\n", prot, flags);
ret = -ENOSYS;
goto errout;
}
#ifndef CONFIG_FS_RAMMAP
if ((flags & MAP_PRIVATE) != 0)
{
ferr("ERROR: MAP_PRIVATE is not supported without file mapping"
"emulation\n");
ret = -ENOSYS;
goto errout;
}
#endif /* CONFIG_FS_RAMMAP */
/* A length of 0 is invalid. */
if (length == 0)
{
ferr("ERROR: Invalid length, length=%zu\n", length);
ret = -EINVAL;
goto errout;
}
#endif /* CONFIG_DEBUG_FEATURES */
if (fs_getfilep(fd, &filep) < 0)
{
ferr("ERROR: Invalid file descriptor, fd=%d\n", fd);
@ -166,89 +275,14 @@ FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
goto errout;
}
if ((filep->f_oflags & O_WROK) == 0 && prot == PROT_WRITE &&
(flags & MAP_SHARED) != 0)
{
ferr("ERROR: Unsupported options for read-only file descriptor,"
"fd=%d prot=%x flags=%04x\n", fd, prot, flags);
ret = -EACCES;
goto errout;
}
if ((filep->f_oflags & O_RDOK) == 0)
{
ferr("ERROR: File descriptor does not have read permission,"
"fd=%d\n", fd);
ret = -EACCES;
goto errout;
}
/* 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)
{
FAR void *alloc;
/* REVISIT: Should reside outside of the heap. That is really the
* only purpose of MAP_ANONYMOUS: To get non-heap memory. In KERNEL
* build, this could be accomplished using pgalloc(), provided that
* you had logic in place to assign a virtual address to the mapping.
*/
alloc = kumm_zalloc(length);
if (alloc == NULL)
{
ferr("ERROR: kumm_alloc() failed: %d\n", ret);
ret = -ENOMEM;
goto errout;
}
return alloc;
}
if ((flags & MAP_PRIVATE) != 0)
{
#ifdef CONFIG_FS_RAMMAP
/* Allocate memory and copy the file into memory. We would, of course,
* do much better in the KERNEL build using the MMU.
*/
return rammap(fd, length, offset);
#endif
}
/* Perform the ioctl to get the base address of the file in 'mapped'
* in memory. (casting to uintptr_t first eliminates complaints on some
* architectures where the sizeof long is different from the size of
* a pointer).
*/
ret = nx_ioctl(fd, FIOC_MMAP, (unsigned long)((uintptr_t)&addr));
ret = file_mmap_(filep, start, length,
prot, flags, offset, false, &mapped);
if (ret < 0)
{
/* Not directly mappable, probably because the underlying media does
* not support random access.
*/
#ifdef CONFIG_FS_RAMMAP
/* Allocate memory and copy the file into memory. We would, of course,
* do much better in the KERNEL build using the MMU.
*/
return rammap(fd, length, offset);
#else
ferr("ERROR: nx_ioctl(FIOC_MMAP) failed: %d\n", ret);
goto errout;
#endif
}
/* Return the offset address */
return (FAR void *)(((FAR uint8_t *)addr) + offset);
return mapped;
errout:
set_errno(-ret);

243
fs/mmap/fs_munmap.c
View File

@ -37,10 +37,149 @@
#include "inode/inode.h"
#include "fs_rammap.h"
/****************************************************************************
* Private Functions
****************************************************************************/
static int file_munmap_(FAR void *start, size_t length, bool kernel)
{
#ifdef CONFIG_FS_RAMMAP
FAR struct fs_rammap_s *prev;
FAR struct fs_rammap_s *curr;
FAR void *newaddr;
unsigned int offset;
int ret;
/* Find a region containing this start and length in the list of regions */
ret = nxsem_wait(&g_rammaps.exclsem);
if (ret < 0)
{
return ret;
}
/* Search the list of regions */
for (prev = NULL, curr = g_rammaps.head; curr;
prev = curr, curr = curr->flink)
{
/* Does this region include any part of the specified range? */
if ((uintptr_t)start < (uintptr_t)curr->addr + curr->length &&
(uintptr_t)start + length >= (uintptr_t)curr->addr)
{
break;
}
}
/* Did we find the region */
if (!curr)
{
ferr("ERROR: Region not found\n");
ret = -EINVAL;
goto errout_with_semaphore;
}
/* Get the offset from the beginning of the region and the actual number
* of bytes to "unmap". All mappings must extend to the end of the region.
* There is no support for free a block of memory but leaving a block of
* memory at the end. This is a consequence of using kumm_realloc() to
* simulate the unmapping.
*/
offset = start - curr->addr;
if (offset + length < curr->length)
{
ferr("ERROR: Cannot umap without unmapping to the end\n");
ret = -ENOSYS;
goto errout_with_semaphore;
}
/* Okay.. the region is beging umapped to the end. Make sure the length
* indicates that.
*/
length = curr->length - offset;
/* Are we unmapping the entire region (offset == 0)? */
if (length >= curr->length)
{
/* Yes.. remove the mapping from the list */
if (prev)
{
prev->flink = curr->flink;
}
else
{
g_rammaps.head = curr->flink;
}
/* Then free the region */
if (curr->kernel)
{
kmm_free(curr)
}
else
{
kumm_free(curr);
}
}
/* No.. We have been asked to "unmap' only a portion of the memory
* (offset > 0).
*/
else
{
if (kernel)
{
newaddr = kmm_realloc(curr->addr,
sizeof(struct fs_rammap_s) + length);
}
else
{
newaddr = kumm_realloc(curr->addr,
sizeof(struct fs_rammap_s) + length);
}
DEBUGASSERT(newaddr == (FAR void *)(curr->addr));
UNUSED(newaddr); /* May not be used */
curr->length = length;
}
nxsem_post(&g_rammaps.exclsem);
return OK;
errout_with_semaphore:
nxsem_post(&g_rammaps.exclsem);
return ret;
#else
return OK;
#endif /* CONFIG_FS_RAMMAP */
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: file_mummap
*
* Description:
* Equivalent to the standard file_mummap() function except it does not set
* the errno variable.
*
****************************************************************************/
int file_munmap(FAR void *start, size_t length)
{
return file_munmap_(start, length, true);
}
/****************************************************************************
* Name: munmap
*
@ -93,110 +232,14 @@
int munmap(FAR void *start, size_t length)
{
#ifdef CONFIG_FS_RAMMAP
FAR struct fs_rammap_s *prev;
FAR struct fs_rammap_s *curr;
FAR void *newaddr;
unsigned int offset;
int ret;
int errcode;
/* Find a region containing this start and length in the list of regions */
ret = nxsem_wait(&g_rammaps.exclsem);
ret = file_munmap_(start, length, false);
if (ret < 0)
{
errcode = ret;
goto errout;
set_errno(-ret);
ret = ERROR;
}
/* Search the list of regions */
for (prev = NULL, curr = g_rammaps.head; curr;
prev = curr, curr = curr->flink)
{
/* Does this region include any part of the specified range? */
if ((uintptr_t)start < (uintptr_t)curr->addr + curr->length &&
(uintptr_t)start + length >= (uintptr_t)curr->addr)
{
break;
}
}
/* Did we find the region */
if (!curr)
{
ferr("ERROR: Region not found\n");
errcode = EINVAL;
goto errout_with_semaphore;
}
/* Get the offset from the beginning of the region and the actual number
* of bytes to "unmap". All mappings must extend to the end of the region.
* There is no support for free a block of memory but leaving a block of
* memory at the end. This is a consequence of using kumm_realloc() to
* simulate the unmapping.
*/
offset = start - curr->addr;
if (offset + length < curr->length)
{
ferr("ERROR: Cannot umap without unmapping to the end\n");
errcode = ENOSYS;
goto errout_with_semaphore;
}
/* Okay.. the region is beging umapped to the end. Make sure the length
* indicates that.
*/
length = curr->length - offset;
/* Are we unmapping the entire region (offset == 0)? */
if (length >= curr->length)
{
/* Yes.. remove the mapping from the list */
if (prev)
{
prev->flink = curr->flink;
}
else
{
g_rammaps.head = curr->flink;
}
/* Then free the region */
kumm_free(curr);
}
/* No.. We have been asked to "unmap' only a portion of the memory
* (offset > 0).
*/
else
{
newaddr = kumm_realloc(curr->addr,
sizeof(struct fs_rammap_s) + length);
DEBUGASSERT(newaddr == (FAR void *)(curr->addr));
UNUSED(newaddr); /* May not be used */
curr->length = length;
}
nxsem_post(&g_rammaps.exclsem);
return OK;
errout_with_semaphore:
nxsem_post(&g_rammaps.exclsem);
errout:
set_errno(errcode);
return ERROR;
#else
return OK;
#endif /* CONFIG_FS_RAMMAP */
return ret;
}

37
fs/mmap/fs_rammap.c
View File

@ -62,14 +62,15 @@ struct fs_allmaps_s g_rammaps =
* Support simulation of memory mapped files by copying files into RAM.
*
* Input Parameters:
* fd file descriptor of the backing file -- required.
* filep file descriptor of the backing file -- required.
* length The length of the mapping. For exception #1 above, this length
* ignored: The entire underlying media is always accessible.
* offset The offset into the file to map
* kernel kmm_zalloc or kumm_zalloc
* mapped The pointer to the mapped area
*
* Returned Value:
* On success, rammmap() returns a pointer to the mapped area. On error,
* the value MAP_FAILED is returned, and errno is set appropriately.
* On success, rammmap returns 0. Otherwise errno is returned appropriately.
*
* EBADF
* 'fd' is not a valid file descriptor.
@ -80,7 +81,8 @@ struct fs_allmaps_s g_rammaps =
*
****************************************************************************/
FAR void *rammap(int fd, size_t length, off_t offset)
int rammap(FAR struct file *filep, size_t length,
off_t offset, bool kernel, FAR void **mapped)
{
FAR struct fs_rammap_s *map;
FAR uint8_t *alloc;
@ -104,12 +106,13 @@ FAR void *rammap(int fd, size_t length, off_t offset)
/* Allocate a region of memory of the specified size */
alloc = (FAR uint8_t *)kumm_malloc(sizeof(struct fs_rammap_s) + length);
alloc = (FAR uint8_t *)kernel ?
kmm_malloc(sizeof(struct fs_rammap_s) + length);
kumm_malloc(sizeof(struct fs_rammap_s) + length);
if (!alloc)
{
ferr("ERROR: Region allocation failed, length: %d\n", (int)length);
ret = -ENOMEM;
goto errout;
return -ENOMEM;
}
/* Initialize the region */
@ -122,7 +125,7 @@ FAR void *rammap(int fd, size_t length, off_t offset)
/* Seek to the specified file offset */
fpos = nx_seek(fd, offset, SEEK_SET);
fpos = file_seek(filep, offset, SEEK_SET);
if (fpos < 0)
{
/* Seek failed... errno has already been set, but EINVAL is probably
@ -139,7 +142,7 @@ FAR void *rammap(int fd, size_t length, off_t offset)
rdbuffer = map->addr;
while (length > 0)
{
nread = nx_read(fd, rdbuffer, length);
nread = file_read(filep, rdbuffer, length);
if (nread < 0)
{
/* Handle the special case where the read was interrupted by a
@ -187,14 +190,20 @@ FAR void *rammap(int fd, size_t length, off_t offset)
g_rammaps.head = map;
nxsem_post(&g_rammaps.exclsem);
return map->addr;
*mapped = map->addr;
return OK;
errout_with_region:
kumm_free(alloc);
if (kernel)
{
kmm_free(alloc);
}
else
{
kumm_free(alloc);
}
errout:
set_errno(-ret);
return MAP_FAILED;
return ret;
}
#endif /* CONFIG_FS_RAMMAP */

10
fs/mmap/fs_rammap.h
View File

@ -88,14 +88,15 @@ extern struct fs_allmaps_s g_rammaps;
* Support simulation of memory mapped files by copying files into RAM.
*
* Input Parameters:
* fd file descriptor of the backing file -- required.
* filep file descriptor of the backing file -- required.
* length The length of the mapping. For exception #1 above, this length
* ignored: The entire underlying media is always accessible.
* offset The offset into the file to map
* kernel kmm_zalloc or kumm_zalloc
* mapped The pointer to the mapped area
*
* Returned Value:
* On success, rammmap() returns a pointer to the mapped area. On error,
* the value MAP_FAILED is returned, and errno is set appropriately.
* On success rammmap returns 0. Otherwise errno is returned appropriately.
*
* EBADF
* 'fd' is not a valid file descriptor.
@ -106,7 +107,8 @@ extern struct fs_allmaps_s g_rammaps;
*
****************************************************************************/
FAR void *rammap(int fd, size_t length, off_t offset);
int rammap(FAR struct file *filep, size_t length,
off_t offset, bool kernel, FAR void **mapped);
#endif /* CONFIG_FS_RAMMAP */
#endif /* __FS_MMAP_RAMMAP_H */

24
include/nuttx/fs/fs.h
View File

@ -1168,6 +1168,30 @@ int file_fsync(FAR struct file *filep);
int file_truncate(FAR struct file *filep, off_t length);
#endif
/****************************************************************************
* Name: file_mmap
*
* Description:
* Equivalent to the standard mmap() function except that is accepts
* a struct file instance instead of a file descriptor and it does not set
* the errno variable.
*
****************************************************************************/
int file_mmap(FAR struct file *filep, FAR void *start, size_t length,
int prot, int flags, off_t offset, FAR void **mapped);
/****************************************************************************
* Name: file_mummap
*
* Description:
* Equivalent to the standard mummap() function except it does not set
* the errno variable.
*
****************************************************************************/
int file_munmap(FAR void *start, size_t length);
/****************************************************************************
* Name: file_ioctl
*