view toys/posix/chmod.c @ 1531:3ff823086c99 draft

Teach ln -f to leave original target alone if link creation fails. Suggested by Ashwini Sharma, I wound up implementing it by creating the new link at a temporary name and renaming it over the old one instead of renaming the old file out of the way and putting it back if it failed. (Because "mkdir -p one/one/blah && ln -sf /bin/one one" would otherwise rename one/one out of the way and only notice it can't delete it way at the end when recovery's darn awkward, vs create new thing and if rename fails (including EISDIR) that's the main error path. And yes the temporary name is in the same directory as the destination so we never rename between mounts.) link over the old one instead of renaming the old file and renaming it back.
author Rob Landley <rob@landley.net>
date Wed, 22 Oct 2014 17:11:06 -0500
parents aae54dd82927
children
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/* chmod.c - Change file mode bits
 *
 * Copyright 2012 Rob Landley <rob@landley.net>
 *
 * See http://opengroup.org/onlinepubs/9699919799/utilities/chmod.html

USE_CHMOD(NEWTOY(chmod, "<2?vRf[-vf]", TOYFLAG_BIN))

config CHMOD
  bool "chmod"
  default y
  help
    usage: chmod [-R] MODE FILE...

    Change mode of listed file[s] (recursively with -R).

    MODE can be (comma-separated) stanzas: [ugoa][+-=][rwxstXugo]

    Stanzas are applied in order: For each category (u = user,
    g = group, o = other, a = all three, if none specified default is a),
    set (+), clear (-), or copy (=), r = read, w = write, x = execute.
    s = u+s = suid, g+s = sgid, o+s = sticky. (+t is an alias for o+s).
    suid/sgid: execute as the user/group who owns the file.
    sticky: can't delete files you don't own out of this directory
    X = x for directories or if any category already has x set.

    Or MODE can be an octal value up to 7777	ug uuugggooo	top +
    bit 1 = o+x, bit 1<<8 = u+w, 1<<11 = g+1	sstrwxrwxrwx	bottom

    Examples:
    chmod u+w file - allow owner of "file" to write to it.
    chmod 744 file - user can read/write/execute, everyone else read only
*/

#define FOR_chmod
#include "toys.h"

GLOBALS(
  char *mode;
)

int do_chmod(struct dirtree *try)
{
  mode_t mode;

  if (!dirtree_notdotdot(try)) return 0;

  mode = string_to_mode(TT.mode, try->st.st_mode);
  if (toys.optflags & FLAG_v) {
    char *s = dirtree_path(try, 0);
    printf("chmod '%s' to %04o\n", s, mode);
    free(s);
  }
  wfchmodat(dirtree_parentfd(try), try->name, mode);

  return (toys.optflags & FLAG_R) ? DIRTREE_RECURSE : 0;
}

void chmod_main(void)
{
  TT.mode = *toys.optargs;
  char **file;

  for (file = toys.optargs+1; *file; file++) dirtree_read(*file, do_chmod);
}