PdfEditor.cpp revision 62ce332c141cf7bc7200c4c87d63e395874fc3ec 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "jni.h"
18#include "JNIHelp.h"
19#include "fpdfview.h"
20#include "fpdfedit.h"
21#include "fpdfsave.h"
22
23#include <android_runtime/AndroidRuntime.h>
24#include <vector>
25#include <utils/Log.h>
26#include <unistd.h>
27#include <sys/types.h>
28#include <unistd.h>
29
30namespace android {
31
32static Mutex sLock;
33
34static int sUnmatchedInitRequestCount = 0;
35
36static void initializeLibraryIfNeeded() {
37    Mutex::Autolock _l(sLock);
38    if (sUnmatchedInitRequestCount == 0) {
39        FPDF_InitLibrary(NULL);
40    }
41    sUnmatchedInitRequestCount++;
42}
43
44static void destroyLibraryIfNeeded() {
45    Mutex::Autolock _l(sLock);
46    sUnmatchedInitRequestCount--;
47    if (sUnmatchedInitRequestCount == 0) {
48       FPDF_DestroyLibrary();
49    }
50}
51
52static int getBlock(void* param, unsigned long position, unsigned char* outBuffer,
53        unsigned long size) {
54    const int fd = reinterpret_cast<intptr_t>(param);
55    const int readCount = pread(fd, outBuffer, size, position);
56    if (readCount < 0) {
57        ALOGE("Cannot read from file descriptor. Error:%d", errno);
58        return 0;
59    }
60    return 1;
61}
62
63static jlong nativeOpen(JNIEnv* env, jclass thiz, jint fd, jlong size) {
64    initializeLibraryIfNeeded();
65
66    FPDF_FILEACCESS loader;
67    loader.m_FileLen = size;
68    loader.m_Param = reinterpret_cast<void*>(intptr_t(fd));
69    loader.m_GetBlock = &getBlock;
70
71    FPDF_DOCUMENT document = FPDF_LoadCustomDocument(&loader, NULL);
72
73    if (!document) {
74        const long error = FPDF_GetLastError();
75        jniThrowException(env, "java/io/IOException",
76                "cannot create document. Error:" + error);
77        destroyLibraryIfNeeded();
78        return -1;
79    }
80
81    return reinterpret_cast<jlong>(document);
82}
83
84static void nativeClose(JNIEnv* env, jclass thiz, jlong documentPtr) {
85    FPDF_DOCUMENT document = reinterpret_cast<FPDF_DOCUMENT>(documentPtr);
86    FPDF_CloseDocument(document);
87    destroyLibraryIfNeeded();
88}
89
90static jint nativeGetPageCount(JNIEnv* env, jclass thiz, jlong documentPtr) {
91    FPDF_DOCUMENT document = reinterpret_cast<FPDF_DOCUMENT>(documentPtr);
92    return FPDF_GetPageCount(document);
93}
94
95static jint nativeRemovePage(JNIEnv* env, jclass thiz, jlong documentPtr, jint pageIndex) {
96    FPDF_DOCUMENT document = reinterpret_cast<FPDF_DOCUMENT>(documentPtr);
97    FPDFPage_Delete(document, pageIndex);
98    return FPDF_GetPageCount(document);
99}
100
101struct PdfToFdWriter : FPDF_FILEWRITE {
102    int dstFd;
103};
104
105static bool writeAllBytes(const int fd, const void* buffer, const size_t byteCount) {
106    char* writeBuffer = static_cast<char*>(const_cast<void*>(buffer));
107    size_t remainingBytes = byteCount;
108    while (remainingBytes > 0) {
109        ssize_t writtenByteCount = write(fd, writeBuffer, remainingBytes);
110        if (writtenByteCount == -1) {
111            if (errno == EINTR) {
112                continue;
113            }
114            __android_log_print(ANDROID_LOG_ERROR, LOG_TAG,
115                    "Error writing to buffer: %d", errno);
116            return false;
117        }
118        remainingBytes -= writtenByteCount;
119        writeBuffer += writtenByteCount;
120    }
121    return true;
122}
123
124static int writeBlock(FPDF_FILEWRITE* owner, const void* buffer, unsigned long size) {
125    const PdfToFdWriter* writer = reinterpret_cast<PdfToFdWriter*>(owner);
126    const bool success = writeAllBytes(writer->dstFd, buffer, size);
127    if (success < 0) {
128        ALOGE("Cannot write to file descriptor. Error:%d", errno);
129        return 0;
130    }
131    return 1;
132}
133
134static void nativeWrite(JNIEnv* env, jclass thiz, jlong documentPtr, jint fd) {
135    FPDF_DOCUMENT document = reinterpret_cast<FPDF_DOCUMENT>(documentPtr);
136    PdfToFdWriter writer;
137    writer.dstFd = fd;
138    writer.WriteBlock = &writeBlock;
139    const bool success = FPDF_SaveAsCopy(document, &writer, FPDF_NO_INCREMENTAL);
140    if (!success) {
141        jniThrowException(env, "java/io/IOException",
142                "cannot write to fd. Error:" + errno);
143        destroyLibraryIfNeeded();
144    }
145}
146
147static JNINativeMethod gPdfEditor_Methods[] = {
148    {"nativeOpen", "(IJ)J", (void*) nativeOpen},
149    {"nativeClose", "(J)V", (void*) nativeClose},
150    {"nativeGetPageCount", "(J)I", (void*) nativeGetPageCount},
151    {"nativeRemovePage", "(JI)I", (void*) nativeRemovePage},
152    {"nativeWrite", "(JI)V", (void*) nativeWrite}
153};
154
155int register_android_graphics_pdf_PdfEditor(JNIEnv* env) {
156    return android::AndroidRuntime::registerNativeMethods(
157            env, "android/graphics/pdf/PdfEditor", gPdfEditor_Methods,
158            NELEM(gPdfEditor_Methods));
159};
160
161};
162