android10/system/core/toolbox/toolbox.c

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define TOOL(name) int name##_main(int, char**);
#include "tools.h"
#undef TOOL

static struct {
    const char* name;
    int (*func)(int, char**);
} tools[] = {
#define TOOL(name) { #name, name##_main },
#include "tools.h"
#undef TOOL
    { 0, 0 },
};

static void SIGPIPE_handler(int signal) {
    // Those desktop Linux tools that catch SIGPIPE seem to agree that it's
    // a successful way to exit, not a failure. (Which makes sense --- we were
    // told to stop by a reader, rather than failing to continue ourselves.)
    _exit(0);
}

int main(int argc, char** argv) {
    // Let's assume that none of this code handles broken pipes. At least ls,
    // ps, and top were broken (though I'd previously added this fix locally
    // to top). We exit rather than use SIG_IGN because tools like top will
    // just keep on writing to nowhere forever if we don't stop them.
    signal(SIGPIPE, SIGPIPE_handler);

    char* cmd = strrchr(argv[0], '/');
    char* name = cmd ? (cmd + 1) : argv[0];

    for (size_t i = 0; tools[i].name; i++) {
        if (!strcmp(tools[i].name, name)) {
            return tools[i].func(argc, argv);
        }
    }

    printf("%s: no such tool\n", argv[0]);
    return 127;
}

int toolbox_main(int argc, char** argv) {
    // "toolbox foo ..." is equivalent to "foo ..."
    if (argc > 1) {
        return main(argc - 1, argv + 1);
    }

    // Plain "toolbox" lists the tools.
    for (size_t i = 1; tools[i].name; i++) {
        printf("%s%c", tools[i].name, tools[i+1].name ? ' ' : '\n');
    }
    return 0;
}