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libc: handle 'MAP_SHARED' flag in 'mmap()'

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Fixes #3857
This commit is contained in:
Christian Prochaska 2020-08-20 19:46:53 +02:00 committed by Norman Feske
parent f8f8b665c3
commit 9bc6b8be5a
3 changed files with 68 additions and 30 deletions
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2
repos/libports/src/lib/libc/internal/init.h
View File

@ -66,7 +66,7 @@ namespace Libc {
/**
* Virtual file system
*/
void init_vfs_plugin(Monitor &);
void init_vfs_plugin(Monitor &, Genode::Region_map &);
void init_file_operations(Cwd &);
/**

2
repos/libports/src/lib/libc/kernel.cc
View File

@ -534,7 +534,7 @@ Libc::Kernel::Kernel(Genode::Env &env, Genode::Allocator &heap)
*file_descriptor_allocator());
init_plugin(*this);
init_sleep(*this);
init_vfs_plugin(*this);
init_vfs_plugin(*this, _env.rm());
init_file_operations(*this);
init_time(*this, *this);
init_select(*this, *this, *this, _signal);

94
repos/libports/src/lib/libc/vfs_plugin.cc
View File

@ -46,12 +46,14 @@
#include <internal/current_time.h>
static Libc::Monitor *_monitor_ptr;
static Libc::Monitor *_monitor_ptr;
static Genode::Region_map *_region_map_ptr;
void Libc::init_vfs_plugin(Monitor &monitor)
void Libc::init_vfs_plugin(Monitor &monitor, Genode::Region_map &rm)
{
_monitor_ptr = &monitor;
_region_map_ptr = &rm;
}
@ -64,6 +66,15 @@ static Libc::Monitor & monitor()
}
static Genode::Region_map &region_map()
{
struct Missing_call_of_init_vfs_plugin : Genode::Exception { };
if (!_region_map_ptr)
throw Missing_call_of_init_vfs_plugin();
return *_region_map_ptr;
}
static Genode::Mutex &vfs_mutex()
{
static Genode::Mutex mutex;
@ -1634,7 +1645,7 @@ int Libc::Vfs_plugin::rename(char const *from_path, char const *to_path)
void *Libc::Vfs_plugin::mmap(void *addr_in, ::size_t length, int prot, int flags,
File_descriptor *fd, ::off_t offset)
{
if (prot != PROT_READ && !(prot == (PROT_READ | PROT_WRITE) && flags == MAP_PRIVATE)) {
if ((prot != PROT_READ) && (prot != (PROT_READ | PROT_WRITE))) {
error("mmap for prot=", Hex(prot), " not supported");
errno = EACCES;
return (void *)-1;
@ -1646,34 +1657,57 @@ void *Libc::Vfs_plugin::mmap(void *addr_in, ::size_t length, int prot, int flags
return (void *)-1;
}
/*
* XXX attempt to obtain memory mapping via
* 'Vfs::Directory_service::dataspace'.
*/
void *addr = nullptr;
void *addr = mem_alloc()->alloc(length, PAGE_SHIFT);
if (addr == (void *)-1) {
errno = ENOMEM;
return (void *)-1;
}
if (flags & MAP_PRIVATE) {
/* copy variables for complete read */
size_t read_remain = length;
size_t read_offset = offset;
char *read_addr = (char *)addr;
/*
* XXX attempt to obtain memory mapping via
* 'Vfs::Directory_service::dataspace'.
*/
while (read_remain > 0) {
ssize_t length_read = ::pread(fd->libc_fd, read_addr, read_remain, read_offset);
if (length_read < 0) { /* error */
error("mmap could not obtain file content");
::munmap(addr, length);
errno = EACCES;
addr = mem_alloc()->alloc(length, PAGE_SHIFT);
if (addr == (void *)-1) {
error("mmap out of memory");
errno = ENOMEM;
return (void *)-1;
} else if (length_read == 0) /* EOF */
break; /* done (length can legally be greater than the file length) */
read_remain -= length_read;
read_offset += length_read;
read_addr += length_read;
}
/* copy variables for complete read */
size_t read_remain = length;
size_t read_offset = offset;
char *read_addr = (char *)addr;
while (read_remain > 0) {
ssize_t length_read = ::pread(fd->libc_fd, read_addr, read_remain, read_offset);
if (length_read < 0) { /* error */
error("mmap could not obtain file content");
::munmap(addr, length);
errno = EACCES;
return (void *)-1;
} else if (length_read == 0) /* EOF */
break; /* done (length can legally be greater than the file length) */
read_remain -= length_read;
read_offset += length_read;
read_addr += length_read;
}
} else if (flags & MAP_SHARED) {
Genode::Dataspace_capability ds_cap;
Mutex::Guard guard(vfs_mutex());
monitor().monitor(vfs_mutex(), [&] {
ds_cap = _root_fs.dataspace(fd->fd_path);
return Fn::COMPLETE;
});
if (!ds_cap.valid()) {
Genode::error("mmap got invalid dataspace capability");
errno = ENODEV;
return (void*)-1;
}
addr = region_map().attach(ds_cap, length, offset);
}
return addr;
@ -1682,7 +1716,11 @@ void *Libc::Vfs_plugin::mmap(void *addr_in, ::size_t length, int prot, int flags
int Libc::Vfs_plugin::munmap(void *addr, ::size_t)
{
mem_alloc()->free(addr);
if (mem_alloc()->size_at(addr) > 0)
mem_alloc()->free(addr);
else
region_map().detach(addr);
return 0;
}