Darwin 分配的 getline 缓冲区会怎样？

Question

假设我在 swift 中用这样的方式调用 getline：

import Darwin

let byLine = { (file : UnsafeMutablePointer<FILE>) in
    anyGenerator({ () -> String? in
        var input = UnsafeMutablePointer<Int8>()
        var lim = 0
        return getline(&input, &lim, file) > 0 ? String.fromCString(input) : nil
    })
}

请注意 ssize_t getline(char **lineptr, size_t *n, FILE *stream); 的特定文档：

If *lineptr is set to NULL and *n is set 0 before the call, then getline() will allocate a buffer for storing the line. This buffer should be freed by the user program even if getline() failed.

现在假设我有：

let fd = fopen("a_billion_lines_of_text.txt", "r")
for line in byLine(fd) {
    ...
}

当 for 循环逐行读取该文件时，十亿行文本会发生什么情况？

此代码确实适用于逐行读取文件，但是 getline 分配的每一行缓冲区会发生什么情况？ swift 释放它还是内存泄漏？

Answer 1

缓冲区泄漏。您需要在调用 getline 后释放内存。以下是您可以如何做到这一点。

let byLine = { (file : UnsafeMutablePointer<FILE>) in
    anyGenerator({ () -> String? in
        var input = UnsafeMutablePointer<Int8>()
        var lim = 0
        let numChars = getline(&input, &lim, file)
        defer {
            free(input)
        }            
        return numChars > 0 ? String.fromCString(input) : nil
    })
}

Darwin 分配的 getline 缓冲区会怎样？

What happens to Darwin allocated getline buffers?

c

darwin

swift

swift2.1