Question

我构建了一个shell，试图让tab（\t）键使用rl_bind_key()做一些自定义的东西，但它在macOS Sierra中不起作用，但是它适用于Ubuntu，Fedora和CentOS的。这是mcve：

#include <stdlib.h>
#include <stdio.h>
#include <readline/readline.h>

static int cmd_complete(int count, int key)
{
        printf("\nCustom tab action goes here...\n");
        rl_forced_update_display();
        return 0;
}

char *interactive_input()
{
        char *buffer = readline(" > ");
        return buffer;
}

int main(int argc, char **argv)
{
        rl_bind_key('\t', cmd_complete); // this doesn't seem to work in macOS
        char *buffer = 0;
        while (!buffer || strncmp(buffer, "exit", 4)) {
                if (buffer) { free(buffer); buffer=0; }
                // get command
                buffer = interactive_input();
                printf("awesome command: %s\n", buffer);
        }
        free(buffer);
        return 0;
}

我像这样使用Clang进行编译：

$ cc -lreadline cli.c -o cli

此行为的原因是什么？如何解决？

Answer 1

我正在使用旗帜-lreadline，但我不知道，Clang似乎秘密使用了libedit（我也看过它也称为editline）。在libedit中，出于某种原因（值得提出另一个问题），rl_bind_key似乎不适用于rl_insert以外的所有内容。

所以我找到的一个解决方案是使用Homebrew来安装GNU Readline（brew install readline），然后为了确保我使用该版本，我编译：

$ cc -lreadline cli.c -o cli -L/usr/local/opt/readline/lib -I/usr/local/opt/readline/include

事实上，当您安装readline时，它会在安装结束时告诉您，或者您执行brew info readline：

gns-mac1:~ gns$ brew info readline
readline: stable 7.0.3 (bottled) [keg-only]
Library for command-line editing
https://tiswww.case.edu/php/chet/readline/rltop.html
/usr/local/Cellar/readline/7.0.3_1 (46 files, 1.5MB)
  Poured from bottle on 2017-10-24 at 12:21:35
From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/readline.rb
==> Caveats
This formula is keg-only, which means it was not symlinked into /usr/local,
because macOS provides the BSD libedit library, which shadows libreadline.
In order to prevent conflicts when programs look for libreadline we are
defaulting this GNU Readline installation to keg-only..

For compilers to find this software you may need to set:
    LDFLAGS:  -L/usr/local/opt/readline/lib
    CPPFLAGS: -I/usr/local/opt/readline/include

libedit来源rl_bind_key

所以这就是它在libedit中不起作用的原因。我下载了源代码，这就是rl_bind_key函数的定义方式：

/*
 * bind key c to readline-type function func
 */
int
rl_bind_key(int c, rl_command_func_t *func)
{
    int retval = -1;

    if (h == NULL || e == NULL)
        rl_initialize();

    if (func == rl_insert) {
        /* XXX notice there is no range checking of ``c'' */
        e->el_map.key[c] = ED_INSERT;
        retval = 0;
    }
    return retval;
}

所以它似乎不适用于除rl_insert之外的任何内容。这似乎是一个错误，而不是一个功能。我希望我知道如何成为libedit的贡献者。

为什么带有自定义函数的rl_bind_key在OSX / macOS上的readline中失败

1 个答案:

libedit来源rl_bind_key