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Construct error messages for BinderService in native code
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The native side can describe better than the Java side what went wrong.
Needs adjustments on the Java side as well.
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@rovo89
rovo89 committed Mar 8, 2015
1 parent 5d02d5d commit f2e5529
Showing 1 changed file with 34 additions and 6 deletions.
40 changes: 34 additions & 6 deletions xposed_service.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include <binder/ProcessState.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <sys/mman.h>

#define UID_SYSTEM 1000
Expand Down Expand Up @@ -399,7 +400,8 @@ class IXposedService: public IInterface {
int64_t* size,
int64_t* mtime,
uint8_t** buffer,
int32_t* bytesRead) const = 0;
int32_t* bytesRead,
String16* errormsg) const = 0;

enum {
TEST_TRANSACTION = IBinder::FIRST_CALL_TRANSACTION,
Expand Down Expand Up @@ -470,7 +472,7 @@ class BpXposedService: public BpInterface<IXposedService> {
}

virtual status_t readFile(const String16& filename, int32_t offset, int32_t length,
int64_t* size, int64_t* mtime, uint8_t** buffer, int32_t* bytesRead) const {
int64_t* size, int64_t* mtime, uint8_t** buffer, int32_t* bytesRead, String16* errormsg) const {
Parcel data, reply;
data.writeInterfaceToken(IXposedService::getInterfaceDescriptor());
data.writeString16(filename);
Expand All @@ -487,12 +489,14 @@ class BpXposedService: public BpInterface<IXposedService> {
if (reply.readExceptionCode() != 0) return -1;

status_t err = reply.readInt32();
const String16& errormsg1(reply.readString16());
size1 = reply.readInt64();
mtime1 = reply.readInt64();
int32_t bytesRead1 = reply.readInt32();
if (size != NULL) *size = size1;
if (mtime != NULL) *mtime = mtime1;
if (bytesRead != NULL) *bytesRead = bytesRead1;
if (errormsg) *errormsg = errormsg1;

if (bytesRead1 > 0 && bytesRead1 <= (int32_t)reply.dataAvail()) {
*buffer = (uint8_t*) malloc(bytesRead1 + 1);
Expand Down Expand Up @@ -565,11 +569,13 @@ status_t BnXposedService::onTransact(uint32_t code, const Parcel& data, Parcel*
int64_t mtime = data.readInt64();
uint8_t* buffer = NULL;
int32_t bytesRead = -1;
String16 errormsg;

status_t err = readFile(filename, offset, length, &size, &mtime, &buffer, &bytesRead);
status_t err = readFile(filename, offset, length, &size, &mtime, &buffer, &bytesRead, &errormsg);

reply->writeNoException();
reply->writeInt32(err);
reply->writeString16(errormsg);
reply->writeInt64(size);
reply->writeInt64(mtime);
if (bytesRead > 0) {
Expand Down Expand Up @@ -610,12 +616,24 @@ class XposedService : public BnXposedService {
int64_t* size,
int64_t* mtime,
uint8_t** buffer,
int32_t* bytesRead) const;
int32_t* bytesRead,
String16* errormsg) const;

private:
bool isSystem;
};

static String16 formatToString16(const char* fmt, ...) {
char* message;
va_list args;
va_start(args, fmt);
int size = vasprintf(&message, fmt, args);
String16 result(message, size);
free(message);
va_end(args);
return result;
}

XposedService::XposedService(bool system)
: isSystem(system) {}

Expand Down Expand Up @@ -670,7 +688,7 @@ status_t XposedService::statFile(const String16& filename16, int64_t* size, int6
}

status_t XposedService::readFile(const String16& filename16, int32_t offset, int32_t length,
int64_t* size, int64_t* mtime, uint8_t** buffer, int32_t* bytesRead) const {
int64_t* size, int64_t* mtime, uint8_t** buffer, int32_t* bytesRead, String16* errormsg) const {

uid_t caller = IPCThreadState::self()->getCallingUid();
if (caller != UID_SYSTEM) {
Expand All @@ -685,10 +703,13 @@ status_t XposedService::readFile(const String16& filename16, int32_t offset, int
const char* filename = String8(filename16).string();
struct stat st;
if (stat(filename, &st) != 0) {
return errno;
status_t err = errno;
if (errormsg) *errormsg = formatToString16("%s during stat() on %s", strerror(err), filename);
return err;
}

if (S_ISDIR(st.st_mode)) {
if (errormsg) *errormsg = formatToString16("%s is a directory", filename);
return EISDIR;
}

Expand All @@ -702,12 +723,14 @@ status_t XposedService::readFile(const String16& filename16, int32_t offset, int

// Check range
if (offset > 0 && offset >= *size) {
if (errormsg) *errormsg = formatToString16("offset %d >= size %"PRId64" for %s", offset, *size, filename);
return EINVAL;
} else if (offset < 0) {
offset = 0;
}

if (length > 0 && (offset + length) > *size) {
if (errormsg) *errormsg = formatToString16("offset %d + length %d > size %"PRId64" for %s", offset, length, *size, filename);
return EINVAL;
} else if (*size == 0) {
*bytesRead = 0;
Expand All @@ -719,6 +742,7 @@ status_t XposedService::readFile(const String16& filename16, int32_t offset, int
// Allocate buffer
*buffer = (uint8_t*) malloc(length + 1);
if (*buffer == NULL) {
if (errormsg) *errormsg = formatToString16("allocating buffer with %d bytes failed", length + 1);
return ENOMEM;
}
(*buffer)[length] = 0;
Expand All @@ -729,13 +753,16 @@ status_t XposedService::readFile(const String16& filename16, int32_t offset, int
status_t err = errno;
free(*buffer);
*buffer = NULL;
if (errormsg) *errormsg = formatToString16("%s during fopen() on %s", strerror(err), filename);
return err;
}

// Seek to correct offset
if (offset > 0 && fseek(f, offset, SEEK_SET) != 0) {
free(*buffer);
*buffer = NULL;
status_t err = ferror(f);
if (errormsg) *errormsg = formatToString16("%s during fseek() to offset %d for %s", strerror(err), offset, filename);
return ferror(f);
}

Expand All @@ -746,6 +773,7 @@ status_t XposedService::readFile(const String16& filename16, int32_t offset, int
free(*buffer);
*buffer = NULL;
*bytesRead = -1;
if (errormsg) *errormsg = formatToString16("%s during fread(), read %d bytes for %s", strerror(err), *bytesRead, filename);
}

// Close the file
Expand Down

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