为什么 rl_bind_key 的自定义函数在 OSX/macOS 的 readline 中失败

Question

我构建了一个 shell 试图让制表符 (\t) 键使用 rl_bind_key() 做一些自定义的事情，但它在 macOS Sierra 中不起作用，但它有效在 Ubuntu、Fedora 和 CentOS 上。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 编译：

$ cc -lreadline cli.c -o cli

此行为的原因是什么，我该如何解决？

Answer 1

我正在使用标志 -lreadline，但我并不知道，Clang 似乎秘密地使用了 libedit（我也看到它叫做 editline）。在 libedit 中，出于某种原因（这值得另一个问题），rl_bind_key 似乎不适用于除 rl_insert.

之外的任何东西

所以我找到的一个解决方案是使用 Homebrew 安装 GNU Readline (brew install readline)，然后为了确保我使用那个版本，我这样编译：

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

事实上，当你安装 readline 时，它会在安装结束时告诉你这个，或者如果你这样做 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，rl_bind_key 函数是这样定义的：

/*
 * 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;
}

所以它似乎被设计为不适用于 rl_insert 以外的任何东西。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 rl_bind_key 的自定义函数在 OSX/macOS 的 readline 中失败

Why does rl_bind_key with custom function fail in readline on OSX/macOS

c

macos

shell

readline

macos-sierra

libedit 来源 rl_bind_key