File content as of revision 2:531722036c0a:

#include "mbed.h"
#include "MSCFileSystem.h"
#include "EthernetInterface.h"
#include "HTTPClient.h"
#include "HTTPFile.h"
#include "BlinkLed.h"
#include "tinyxml2.h"

using namespace tinyxml2;

int GetFile(const char *path, const char *url);
int addNewLine(const char* dstPath, const char* srcPath);
int summarizeRss(const char* dstPath, const char* srcPath);
int removePhotos();
const char* getExtensionFromUrl(const char* url);

EthernetInterface eth;
HTTPClient http;
MSCFileSystem usb("usb");
BlinkLed led1(LED1, 0.02);
BlinkLed led2(LED2, 0.2);
BlinkLed ethGreen(p26, 0.02);
BlinkLed ethYellow(p25, 0.2);
DigitalOut fsusb30s(p9);
Timer timer;

/***** Please specify "albumRssUrl" *****/
const char* albumRssUrl  = "http://picasaweb.google.com/data/feed/base/user/*****/albumid/*****?alt=rss&kind=photo&authkey=*****&hl=ja";
const char* albumRssPath = "/usb/album.xml";
const char* tempPath     = "/usb/temp.xml";
const char* summaryPath  = "/usb/summary.xml";

int main()
{
    printf("\n\n================================\n");
    printf("mpod Picasa Photo frame\n");
    printf("================================\n\n");
    
    // FSUSB30 switches to HSD1 (mbed)
    printf("USB host was switched to HSD1(mbed).\n\n");
    fsusb30s = 0; // HSD1
    
    // Network setup
    printf("Setup EtherNet with DHCP.\n");
    eth.init(); //Use DHCP
    eth.connect();
    
    // Obtain original lastBuildDate
    char lastBuildDateOriginal[32] = {0};
    {
        XMLDocument docOriginal;
        if(XML_SUCCESS != docOriginal.LoadFile(summaryPath))
        {
            strcpy(lastBuildDateOriginal, "No original summary.xml in USB memory");
        }
        else
        {
            XMLElement* lastBuildDateOriginalElement = docOriginal.FirstChildElement("rss")->FirstChildElement("channel")->FirstChildElement("lastBuildDate");
            if(NULL == lastBuildDateOriginalElement)
            {
                strcpy(lastBuildDateOriginal, "No \"lastBuildDate\" element in original RSS");
            }
            else
            {
                strcpy(lastBuildDateOriginal, lastBuildDateOriginalElement->GetText());
            }
        }
    }
    printf("\nlastBuildDate (original): %s\n", lastBuildDateOriginal);
    
    // Download Album
    GetFile(albumRssPath, albumRssUrl);
    
    // Summarize RSS
    addNewLine(tempPath, albumRssPath);
    summarizeRss(summaryPath, tempPath);
    
    // Obtain current lastBuildDate 
    char lastBuildDateCurrent[32] = {0};
    
    XMLDocument docCurrent;
    if(XML_SUCCESS != docCurrent.LoadFile(summaryPath))
    {
        fsusb30s = 1; // HSD2
        error("No current summary.xml in USB memory.\n");
    }
    
    XMLElement* lastBuildDateCurrentElement = docCurrent.FirstChildElement("rss")->FirstChildElement("channel")->FirstChildElement("lastBuildDate");
    if(NULL == lastBuildDateCurrentElement)
    {
        fsusb30s = 1; // HSD2
        error("No \"lastBuildDate\" element in current RSS.\n");
    }
    strcpy(lastBuildDateCurrent, lastBuildDateCurrentElement->GetText());
    printf("\nlastBuildDate (current) : %s\n", lastBuildDateCurrent);
    
    if( strcmp(lastBuildDateOriginal, lastBuildDateCurrent) != 0 )
    {
        printf("lastBuildDate (original) != lastBuildDate (current)\n");
        if(removePhotos() < 0)
        {
            fsusb30s = 1; // HSD2
            error("No \"DCIM\" folder in MSD.\n");
        }
    
        char photoUrl[256] = {0};
        char photoPath[32] = {0};
        int photoNo = 1;
        XMLElement* itemElement = docCurrent.FirstChildElement("rss")->FirstChildElement("channel")->FirstChildElement("item");
        if(NULL == itemElement)
        {
            fsusb30s = 1; // HSD2
            error("No \"enclosure\" element in current RSS.\n");
        }
        strcpy(photoUrl, itemElement->FirstChildElement("enclosure")->Attribute("url"));
        const char* extension = getExtensionFromUrl(photoUrl);
        sprintf(photoPath, "/usb/DCIM/%08d.%s", photoNo, extension);
        GetFile(photoPath, photoUrl);
        ++photoNo;
    
        while( (itemElement = itemElement->NextSiblingElement( "item" ) ) != NULL )
        {
            strcpy(photoUrl, itemElement->FirstChildElement("enclosure")->Attribute("url"));
            sprintf(photoPath, "/usb/DCIM/%08d.jpg", photoNo);
            GetFile(photoPath, photoUrl);
            ++photoNo;
        }
    }
    else
    {
        printf("lastBuildDate (original) == lastBuildDate (current)\n");
    }
    
    // Wait for the completion of writing to USB Mass Storage Device.
    wait(1);
    
    // FSUSB30 switches to HSD2 (External Device)
    printf("\nUSB host was switched to HSD2(External Device).\n");
    fsusb30s = 1; // HSD2

    // blink LED
    led1.startBlink();
    ethGreen.startBlink();
    
    while(true){}
}

int GetFile(const char *path, const char *url)
{
    led2.startBlink();
    ethYellow.startBlink();
    printf("\nGetting %s\n", url);
    
    timer.stop();
    timer.reset();
    timer.start();
    
    HTTPFile file(path);
    HTTPResult retGet = http.get(url, &file);
    if (retGet != HTTP_OK)
    {
        fsusb30s = 1; // HSD2
        error("Error in http.get in GetFile(): %d\n", retGet);
    }
    file.clear();
    
    timer.stop();
    printf("timer.read_ms(): %d\n", timer.read_ms());
    
    led2.finishBlink();
    ethYellow.finishBlink();
    return (0);
}

int addNewLine(const char* dstPath, const char* srcPath)
{
    FILE* fpSrc = fopen(srcPath, "r");
    if (fpSrc == NULL)
    {
        return -1;
    }
    
    FILE* fpDst = fopen(dstPath, "w");
    if (fpDst == NULL)
    {
        return -1;
    }
    
    int src;
    int previous = '\0';
    while( (src = fgetc(fpSrc)) != EOF )
    {
        if(previous == '>' && src == '<')
        {
            fputc('\n', fpDst);
        }
        fputc(src, fpDst);
        previous = src;
    }
    
    fclose(fpDst);
    fclose(fpSrc);
    
    return 0;
}

int summarizeRss(const char* dstPath, const char* srcPath)
{
    FILE* fpSrc = fopen(srcPath, "r");
    if (fpSrc == NULL)
    {
        return -1;
    }
    
    FILE* fpDst = fopen(dstPath, "w");
    if (fpDst == NULL)
    {
        return -1;
    }
    
    char* ptn[] =
    {
        "<?xml",
        "<rss",
        "<channel",
        "<lastBuildDate",
        "<item",
        "<enclosure",
        "</item",
        "</channel",
        "</rss"
    };
    int ptnSize = sizeof(ptn) / sizeof(char*);
    
    char buff[1024] = {0};
    while( fgets(buff, 1024, fpSrc) != NULL )
    {
        for(int i = 0; i < ptnSize; ++i)
        {
            if( strncmp(buff, ptn[i], strlen(ptn[i])) == 0 )
            {
                fputs(buff, fpDst);
                break;
            }
        }
    }
    
    fclose(fpDst);
    fclose(fpSrc);
    
    return 0;
}

int removePhotos()
{
    if(DirHandle* dir = opendir("/usb/DCIM"))
    {
        int ret = 0;
        while(struct dirent* ent = dir->readdir())
        {
            char filename[32] = {0};
            sprintf(filename, "/usb/DCIM/%s", ent->d_name);
            printf("remove %s\n", filename);
            remove(filename);
            ++ret;
        }
        return ret;
    }
    else
    {
        return -1;
    }
}

const char* getExtensionFromUrl(const char* url)
{
    const char* tail = url;
    while('\0' != *tail)
    {
        ++tail;
    }
    
    for(const char* p = tail; p >= url; --p)
    {
        if ('/' == *p)
        {
            return tail;
        }
        if ( '.' == *p )
        {
            return p+1;
        }
    }
    return tail;
}