view main.c @ 1572:da1bf31ed322 draft

Tweak the "ignoring return value" fortify workaround for readlinkat. We zero the buffer and if the link read fails that's left alone, so it's ok for the symlink not to be there. Unfortunately, typecasting the return value to (void) doesn't shut up gcc, and having an if(); with the semicolon on the same line doesn't shut up llvm. (The semicolon on a new line would, but C does not have significant whitespace and I'm not going to humor llvm if it plans to start.) So far, empty curly brackets consistently get the warning to shut up.
author Rob Landley <rob@landley.net>
date Mon, 24 Nov 2014 17:23:23 -0600
parents 3c77af6f81cc
children a35ea98b4972
line wrap: on
line source

/* Toybox infrastructure.
 *
 * Copyright 2006 Rob Landley <rob@landley.net>
 */

#include "toys.h"

// Populate toy_list[].

#undef NEWTOY
#undef OLDTOY
#define NEWTOY(name, opts, flags) {#name, name##_main, opts, flags},
#define OLDTOY(name, oldname, opts, flags) {#name, oldname##_main, opts, flags},

struct toy_list toy_list[] = {
#include "generated/newtoys.h"
};

// global context for this command.

struct toy_context toys;
union global_union this;
char toybuf[4096], libbuf[4096];

struct toy_list *toy_find(char *name)
{
  int top, bottom, middle;

  if (!CFG_TOYBOX) return 0;

  // If the name starts with "toybox" accept that as a match.  Otherwise
  // skip the first entry, which is out of order.

  if (!strncmp(name,"toybox",6)) return toy_list;
  bottom = 1;

  // Binary search to find this command.

  top = ARRAY_LEN(toy_list)-1;
  for (;;) {
    int result;

    middle = (top+bottom)/2;
    if (middle<bottom || middle>top) return NULL;
    result = strcmp(name,toy_list[middle].name);
    if (!result) return toy_list+middle;
    if (result<0) top=--middle;
    else bottom = ++middle;
  }
}

// Figure out whether or not anything is using the option parsing logic,
// because the compiler can't figure out whether or not to optimize it away
// on its' own.  NEED_OPTIONS becomes a constant allowing if() to optimize
// stuff out via dead code elimination.

#undef NEWTOY
#undef OLDTOY
#define NEWTOY(name, opts, flags) opts ||
#define OLDTOY(name, oldname, opts, flags) opts ||
static const int NEED_OPTIONS =
#include "generated/newtoys.h"
0;  // Ends the opts || opts || opts...

// Subset of init needed by singlemain
static void toy_singleinit(struct toy_list *which, char *argv[])
{
  toys.which = which;
  toys.argv = argv;

  if (CFG_TOYBOX_I18N) setlocale(LC_ALL, "C"+!!(which->flags & TOYFLAG_LOCALE));

  if (CFG_TOYBOX_HELP_DASHDASH && argv[1] && !strcmp(argv[1], "--help")) {
    if (CFG_TOYBOX && toys.which == toy_list && toys.argv[2])
      if (!(toys.which = toy_find(toys.argv[2]))) return;
    show_help();
    xexit();
  }

  if (NEED_OPTIONS && which->options) get_optflags();
  else {
    toys.optargs = argv+1;
    for (toys.optc=0; toys.optargs[toys.optc]; toys.optc++);
  }
  toys.old_umask = umask(0);
  if (!(which->flags & TOYFLAG_UMASK)) umask(toys.old_umask);
  toys.signalfd--;
  toys.toycount = ARRAY_LEN(toy_list);
}

// Setup toybox global state for this command.

void toy_init(struct toy_list *which, char *argv[])
{
  // Drop permissions for non-suid commands.

  if (CFG_TOYBOX_SUID) {
    uid_t uid = getuid(), euid = geteuid();

    if (!(which->flags & TOYFLAG_STAYROOT)) {
      if (uid != euid) {
        if (!setuid(uid)) perror_exit("setuid %d->%d", euid, uid); // drop root
        else euid = uid;
      }
    } else if (CFG_TOYBOX_DEBUG && uid && which != toy_list)
      error_msg("Not installed suid root");

    if ((which->flags & TOYFLAG_NEEDROOT) && euid) {
      toys.exithelp++;
      error_exit("Not root");
    }
  }

  // Free old toys contents (to be reentrant), but leave rebound if any

  if (toys.optargs != toys.argv+1) free(toys.optargs);
  memset(&toys, 0, offsetof(struct toy_context, rebound));

  // Subset of init needed by singlemain.
  toy_singleinit(which, argv);
}

// Like exec() but runs an internal toybox command instead of another file.
// Only returns if it can't run command internally, otherwise exit() when done.
void toy_exec(char *argv[])
{
  struct toy_list *which;

  // Return if we can't find it, or need to re-exec to acquire root,
  // or if stack depth is getting silly.
  if (!(which = toy_find(argv[0]))) return;
  if (toys.recursion && (which->flags & TOYFLAG_ROOTONLY) && getuid()) return;
  if (toys.recursion++ > 5) return;

  // Run command
  toy_init(which, argv);
  if (toys.which) toys.which->toy_main();
  if (fflush(NULL) || ferror(stdout)) perror_exit("write");
  xexit();
}

// Multiplexer command, first argument is command to run, rest are args to that.
// If first argument starts with - output list of command install paths.

void toybox_main(void)
{
  static char *toy_paths[]={"usr/","bin/","sbin/",0};
  int i, len = 0;

  toys.which = toy_list;
  if (toys.argv[1]) {
    toys.optc = 0;
    toy_exec(toys.argv+1);
    if (toys.argv[1][0] == '-') goto list;
    
    error_exit("Unknown command %s",toys.argv[1]);
  }

list:
  // Output list of command.
  for (i=1; i<ARRAY_LEN(toy_list); i++) {
    int fl = toy_list[i].flags;
    if (fl & TOYMASK_LOCATION) {
      if (toys.argv[1]) {
        int j;
        for (j=0; toy_paths[j]; j++)
          if (fl & (1<<j)) len += printf("%s", toy_paths[j]);
      }
      len += printf("%s",toy_list[i].name);
      if (++len > 65) len = 0;
      xputc(len ? ' ' : '\n');
    }
  }
  xputc('\n');
}

int main(int argc, char *argv[])
{
  if (CFG_TOYBOX) {
    // Trim path off of command name
    *argv = basename(*argv);

    // Call the multiplexer, adjusting this argv[] to be its' argv[1].
    // (It will adjust it back before calling toy_exec().)
    toys.argv = argv-1;
    toybox_main();
  } else {
    // a single toybox command built standalone with no multiplexer
    toy_singleinit(toy_list, argv);
    toy_list->toy_main();
    if (fflush(NULL) || ferror(stdout)) perror_exit("write");
  }

  return toys.exitval;
}