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fs/mmap/fs_mmap.c: Add support for MAP_PRIVATE.

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Xiang Xiao 2019-11-23 08:07:04 -06:00 committed by Gregory Nutt
parent e0307fcd8f
commit afb40d87fb
1 changed files with 16 additions and 16 deletions
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32
fs/mmap/fs_mmap.c
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@ -90,8 +90,8 @@
* PROT_WRITE - PROT_READ and PROT_EXEC also assumed * PROT_WRITE - PROT_READ and PROT_EXEC also assumed
* PROT_EXEC - PROT_READ and PROT_WRITE also assumed * PROT_EXEC - PROT_READ and PROT_WRITE also assumed
* flags See the MAP_* definitions in sys/mman.h. * flags See the MAP_* definitions in sys/mman.h.
* MAP_SHARED - Required * MAP_SHARED - MAP_PRIVATE or MAP_SHARED required
* MAP_PRIVATE - Will cause an error * MAP_PRIVATE - MAP_PRIVATE or MAP_SHARED required
* MAP_FIXED - Will cause an error * MAP_FIXED - Will cause an error
* MAP_FILE - Ignored * MAP_FILE - Ignored
* MAP_ANONYMOUS - Optional * MAP_ANONYMOUS - Optional
@ -128,33 +128,31 @@ FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
{ {
FAR void *addr; FAR void *addr;
int errcode; int errcode;
int ret; int ret = -1;
/* Since only a tiny subset of mmap() functionality, we have to verify many /* Since only a tiny subset of mmap() functionality, we have to verify many
* things. * things.
*/ */
#ifdef CONFIG_DEBUG_FEATURES #ifdef CONFIG_DEBUG_FEATURES
/* Private mappings and protections are not currently supported. These /* Fixed mappings and protections are not currently supported. These
* options could be supported in the KERNEL build with an MMU, but that * options could be supported in the KERNEL build with an MMU, but that
* logic is not in place. * logic is not in place.
*/ */
if (prot == PROT_NONE || if (prot == PROT_NONE ||
(flags & (MAP_PRIVATE | MAP_FIXED | MAP_DENYWRITE)) != 0) (flags & (MAP_FIXED | MAP_DENYWRITE)) != 0)
{ {
ferr("ERROR: Unsupported options, prot=%x flags=%04x\n", prot, flags); ferr("ERROR: Unsupported options, prot=%x flags=%04x\n", prot, flags);
errcode = ENOSYS; errcode = ENOSYS;
goto errout; goto errout;
} }
/* A length of 0 is invalid. Currently only shared mappings are supported. /* A length of 0 is invalid. */
* Non-shared could be implemented in the KERNEL build with an MMU.
*/
if (length == 0 || (flags & MAP_SHARED) == 0) if (length == 0)
{ {
ferr("ERROR: Invalid options, length=%d flags=%04x\n", length, flags); ferr("ERROR: Invalid length, length=%d\n", length);
errcode = EINVAL; errcode = EINVAL;
goto errout; goto errout;
} }
@ -187,16 +185,17 @@ FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
return alloc; return alloc;
} }
/* Okay now we can assume a shared mapping from a file. This is the /* Perform the ioctl to get the base address of the file in 'mapped'
* only other option supported
*
* Perform the ioctl to get the base address of the file in 'mapped'
* in memory. (casting to uintptr_t first eliminates complaints on some * in memory. (casting to uintptr_t first eliminates complaints on some
* architectures where the sizeof long is different from the size of * architectures where the sizeof long is different from the size of
* a pointer). * a pointer).
*/ */
ret = ioctl(fd, FIOC_MMAP, (unsigned long)((uintptr_t)&addr)); if ((flags & MAP_PRIVATE) == 0)
{
ret = ioctl(fd, FIOC_MMAP, (unsigned long)((uintptr_t)&addr));
}
if (ret < 0) if (ret < 0)
{ {
/* Not directly mappable, probably because the underlying media does /* Not directly mappable, probably because the underlying media does
@ -213,7 +212,8 @@ FAR void *mmap(FAR void *start, size_t length, int prot, int flags,
/* Error out. The errno value was already set by ioctl() */ /* Error out. The errno value was already set by ioctl() */
ferr("ERROR: ioctl(FIOC_MMAP) failed: %d\n", get_errno()); ferr("ERROR: ioctl(FIOC_MMAP) failed: %d\n", get_errno());
return MAP_FAILED; errcode = ENOSYS;
goto errout;
#endif #endif
} }