PHP fread 在成功 fopen、write 和 fclose 后无法工作

发布于 2024-12-02 13:39:50 字数 588 浏览 0 评论 0原文

现在是凌晨，我只是没有得到这个：

以下代码可以工作，并且文件被放置在服务器上：

$filename = $ioid . "_" . time();
$fp = fopen("$filename.csv", "w+");
foreach ($csv as $fields) {
    fputcsv($fp, $fields);
}
fclose($fp);

但这之后不起作用（文件为 105k）：

$fp2 = fopen("$filename.csv", "r");
$output = fread($fp2, 1000000000000);
header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=$filename.csv");
header("Pragma: no-cache");
header("Expires: 0");
echo $output;
fclose($fp2);

没有读取任何内容，也没有打印任何内容页面。

我做错了什么明显的事情？ :)

原文

It's early in the morning and I'm just not getting this:

The following code works, and file is placed on the server:

$filename = $ioid . "_" . time();
$fp = fopen("$filename.csv", "w+");
foreach ($csv as $fields) {
    fputcsv($fp, $fields);
}
fclose($fp);

But this doesn't work straight after (file is 105k):

$fp2 = fopen("$filename.csv", "r");
$output = fread($fp2, 1000000000000);
header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=$filename.csv");
header("Pragma: no-cache");
header("Expires: 0");
echo $output;
fclose($fp2);

Nothing is read, and nothing is printed to the page.

What obvious thing am I doing wrong? :)

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情绪失控 2024-12-09 13:39:50

您的问题是 fread($fp2, 1000000000000) 尝试分配 1 TB 大缓冲区来读入文件，并且显然达到了允许的内存限制，除非您使用的是发生整数溢出的 32 位平台。不管怎样，它都不起作用。

如果您想将整个文件读取到输出缓冲区并快速完成，请像这样使用readfile()：

header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=$filename.csv");
readfile("$filename.csv")

下次一定要检查错误日志。

另外，如果您不打算将生成的文件存储在磁盘上，我建议您重新制作脚本以使用更安全的方法：

$fp = tmpfile(); // creates a handle for a temporary file with a unique name
foreach ($csv as $fields) {
    fputcsv($fp, $fields);
}
rewind($fp);
header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=report.csv");
fpassthru($fp);
fclose($fp); // this removes the file

Your problem is that fread($fp2, 1000000000000) tries to allocate 1 terabyte big buffer to read the file into and obviously hits allowed memory limit, unless you're on a 32-bit platform where integer overflow occurs. Either way it isn't working.

If you want read a whole file to the output buffer and do that fast, use readfile() like so:

header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=$filename.csv");
readfile("$filename.csv")

Be sure to check the error log next time.

Also if you don't plan to store resulting files on disk I recommend you to remake your script to use a safer approach:

$fp = tmpfile(); // creates a handle for a temporary file with a unique name
foreach ($csv as $fields) {
    fputcsv($fp, $fields);
}
rewind($fp);
header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=report.csv");
fpassthru($fp);
fclose($fp); // this removes the file

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自在安然 2024-12-09 13:39:50

问题出在 fread 参数中。您的代码会产生：

Warning: fread() [function.fread]: Length parameter must be greater than 0

例如，当将 1000000000000 更改为 1000 时，它会起作用。所以：这样使用它：

$output = file_get_contents("filename.csv");
header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=$filename.csv");
header("Pragma: no-cache");
header("Expires: 0");
echo $output;

The probkem is in fread argument. Your code produces:

Warning: fread() [function.fread]: Length parameter must be greater than 0

when changing 1000000000000 to 1000 for example it works. so: use it this way:

$output = file_get_contents("filename.csv");
header("Content-type: application/csv");
header("Content-Disposition: attachment; filename=$filename.csv");
header("Pragma: no-cache");
header("Expires: 0");
echo $output;

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