Question

我有以下程序导致程序崩溃：

void parseLinear(xmlDocPtr doc, xmlNodePtr node, struct daastXML *xmlFile){

// Set up Linear Property Here
struct daastLinear *Linear;
Linear = (struct daastLinear *) malloc (sizeof(struct daastLinear));

// Assign  Property
xmlFile->Ads->data->Inline->Creatives->data->linear = Linear;

// ***** THIS IS FINE HERE
struct daastMediaFile *newMediaFile;
newMediaFile = (struct daastMediaFile *) malloc (sizeof(struct daastMediaFile));

do {

    // ***** PROGRAM CRASHES IF I PUT IT HERE INSTEAD
    //struct daastMediaFile *newMediaFile;
    //newMediaFile = (struct daastMediaFile *) malloc (sizeof(struct daastMediaFile));


    if (xmlStrcmp (node->name, XMLSTR("Duration")) == 0){

        char *nodeValue = (char *) node->children->content;
        xmlFile->Ads->data->Inline->Creatives->data->linear->duration = malloc (sizeof(char));
        strcpy (xmlFile->Ads->data->Inline->Creatives->data->linear->duration, nodeValue);

    } else if (xmlStrcmp (node->name, XMLSTR("MediaFiles")) == 0){
        //
        parseMediaFiles(doc,node->children,xmlFile);
    }
} while ((node = node->next));

}

问题出在以下几行：

struct daastMediaFile *newMediaFile;
newMediaFile = (struct daastMediaFile *) malloc (sizeof(struct daastMediaFile));

如果我将这些放在循环之外，程序运行正常，但是如果我将它们放在循环中，它就会崩溃而且我看不到任何错误日志。

有谁知道这里发生了什么？

编辑和可能的修复？ 这是MediaFile的原始结构：

//THIS CAUSES A CRASH
struct daastMediaFile {
    char *id;
    char *delivery;
    char *type;
    char *url;
    char *bitRate;
};

但是添加一个int变量，它会起作用吗？

//THIS CAUSES A CRASH
struct daastMediaFile {
    char *id;
    char *delivery;
    char *type;
    char *url;
    char *bitRate;
    int MediaID;
};

Answer 1

xmlFile->Ads->data->Inline->Creatives->data->linear->duration = malloc (sizeof(char));

这只为一个字符分配内存。在C中，它可能只包含一个空字符串（因为最后一个字符是＆＃39; \ 0＆＃39;）。这是你的意图吗？

Answer 2

//Outside the loop
typedef struct daastMediaFile *daastMediaFiles;
daastMediaFiles newMediaFile;

//In the loop, if needed. free() is important in end of loop
newMediaFile = malloc(sizeof *newMediaFile);

...

free(newMediaFile);

malloc在循环中崩溃，但在循环外很好

2 个答案: