c - fopen/fclose 上的段错误

Question

我有一个正在创建多个文件的程序。每个正在创建的文件都有一个函数。在每个函数中都有完全相同的代码来创建文件名、打开/创建要写入的文件、设置其权限并在最后关闭文件。我决定制作一个用于打开文件和关闭文件的函数，这样我就可以调用它而不是每次都使用相同的代码。之前的代码在每个函数中看起来如下所示:

void WriteFile1(char *name) {
   FILE *file;
   char *filename; //This is being malloc'ed because it initially consisted of multiple strings

   if (!(filename = malloc(sizeof(char *) * (strlen(name) + 1)))) MallocError();
   if (!(file = fopen(filename, "w"))) {
       fprintf(stderr, "Unable to open %s. Exiting \n", filename);
       exit(1);
   }
   fchmod(fileno(file), S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH);

   //a bunch of fprintf statements here

   if (fclose(file)) {
       fprintf(stderr, "Error closing %s. Exiting...\n", filename);
       exit(1);
   }
}

这工作得很好。我没有问题。现在看起来像下面这样:

void WriteFile1() {
FILE *file;

OpenFile(file, "filename.asdf");
//fprintf statements
CloseFile(file, "filename.asdf");
}

void OpenFile(FILE *file, char *name) {
   if (!(file = fopen(name, "w"))) {
      fprintf(stderr, "Unable to open %s. Exiting... \n", name);
      exit(1);
   }
   fchmod(fileno(file), S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH);
}
void CloseFile(FILE *file, char *name) {
    if (fclose(file)) {
        fprintf(stderr, "Error closing %s. Exiting...\n", name);
        exit(1);
    }
}

当我到达 WriteFile1() 中的第一个 fprintf 语句时，它会立即出现段错误。我对 FILE 变量做错了什么吗？看起来它应该像以前一样工作。唯一的区别是文件名字符串的 malloc，我将其作为名称传递并在引号中给出实际值。

谢谢

Answer 1

这段代码是错误的:

void OpenFile(FILE *file, char *name) {
   if (!(file = fopen(name, "w"))) {

在这里你只是分配给本地 file 变量。您必须返回 file，这样您的 WriteFile1() 函数才能使用该 FILE*

void WriteFile1() {
FILE *file;

file = OpenFile("filename.asdf");
//fprintf statements
CloseFile(file, "filename.asdf");
}

FILE * OpenFile(char *name) {
   FILE * file;
   if (!(file = fopen(name, "w"))) {
      fprintf(stderr, "Unable to open %s. Exiting... \n", name);
      exit(1);
   }
   fchmod(fileno(file), S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH);
   return file;
}