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Merge "libcutils: route to ashmemd"

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Tri Vo 2019-02-05 21:38:50 +00:00 committed by Gerrit Code Review
commit 5bccd33e0b
1 changed files with 37 additions and 1 deletions
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38
libcutils/ashmem-dev.cpp
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@ -23,6 +23,9 @@
*/
#define LOG_TAG "ashmem"
#ifndef __ANDROID_VNDK__
#include <dlfcn.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <linux/ashmem.h>
@ -45,13 +48,46 @@ static dev_t __ashmem_rdev;
*/
static pthread_mutex_t __ashmem_lock = PTHREAD_MUTEX_INITIALIZER;
/*
* We use ashmemd to enforce that apps don't open /dev/ashmem directly. Vendor
* code can't access system aidl services per Treble requirements. So we limit
* ashmemd access to the system variant of libcutils.
*/
#ifndef __ANDROID_VNDK__
using openFdType = int (*)();
openFdType initOpenAshmemFd() {
openFdType openFd = nullptr;
void* handle = dlopen("libashmemd_client.so", RTLD_NOW);
if (!handle) {
ALOGE("Failed to dlopen() libashmemd_client.so: %s", dlerror());
return openFd;
}
openFd = reinterpret_cast<openFdType>(dlsym(handle, "openAshmemdFd"));
if (!openFd) {
ALOGE("Failed to dlsym() openAshmemdFd() function: %s", dlerror());
}
return openFd;
}
#endif
/* logistics of getting file descriptor for ashmem */
static int __ashmem_open_locked()
{
int ret;
struct stat st;
int fd = TEMP_FAILURE_RETRY(open(ASHMEM_DEVICE, O_RDWR | O_CLOEXEC));
int fd = -1;
#ifndef __ANDROID_VNDK__
static auto openFd = initOpenAshmemFd();
if (openFd) {
fd = openFd();
}
#endif
if (fd < 0) {
fd = TEMP_FAILURE_RETRY(open(ASHMEM_DEVICE, O_RDWR | O_CLOEXEC));
}
if (fd < 0) {
return fd;
}