混合fdopen（）和open（） - GT;坏文件描述符 [英] Mixing fdopen() and open() -> bad file descriptor

问题描述

int source = open("hi", O_CREAT | O_RDONLY);
int dest = open("resultfile", O_CREAT | O_RDWR | O_TRUNC);

FILE* source1 = fdopen(source, "r");  
FILE* dest1 = fdopen(dest, "w+");

// outside of a testcase I would write something into 'resultfile' here

close(source);
close(dest);
fclose(source1);
fclose(dest1);

int sourcef = open("resultfile", O_RDONLY);
printf(strerror(errno)); // <--- Bad file descriptor

我不明白，为什么？我怎样才能成功地混合基于IO开放流（）？

I don't understand why? How can I successfully mix stream based IO with open()?

这是我仅有的工作库接受整数FD（和图书馆是关闭它，$ P $紧密psumably（）内部负责），但我仍然需要用文件来工作，我不T看看如何正确地是没有可能的f（）的调用，例如（FREAD（），FTELL（）等）

A library that I'm working with only accepts an integer fd (and the library is internally responsible for closing it, presumably with close()), but I still need to work with the file, and I don't see how that is properly possible without the f() calls like (fread(), ftell() etc)

推荐答案

FCLOSE 要求关闭为您服务。如果你想打电话后围绕保持FD FCLOSE ， DUP 的FD第一。

fclose calls close for you. If you want to keep the fd around after calling fclose, dup the fd first.

int fd = open(...);
int fd2 = dup(fd);
FILE *fp = fdopen(fd2);
fclose(fp);
// fd is still valid.

在你的榜样，坏的文件描述符错误消息是从 FCLOSE（dest1）通话挥之不去。

The bad file descriptor error message in your example is lingering from the fclose(dest1) call.

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