view toys/posix/cat.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 fc1bb49e58a9
children f67b1e9e91b4
line wrap: on
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/* cat.c - copy inputs to stdout.
 *
 * Copyright 2006 Rob Landley <rob@landley.net>
 *
 * See http://opengroup.org/onlinepubs/9699919799/utilities/cat.html

USE_CAT(NEWTOY(cat, "u", TOYFLAG_BIN))

config CAT
  bool "cat"
  default y
  help
    usage: cat [-u] [file...]

    Copy (concatenate) files to stdout.  If no files listed, copy from stdin.
    Filename "-" is a synonym for stdin.

    -u	Copy one byte at a time (slow).
*/

#include "toys.h"

static void do_cat(int fd, char *name)
{
  int len, size=toys.optflags ? 1 : sizeof(toybuf);

  for (;;) {
    len = read(fd, toybuf, size);
    if (len<0) perror_msg("%s",name);
    if (len<1) break;
    xwrite(1, toybuf, len);
  }
}

void cat_main(void)
{
  loopfiles(toys.optargs, do_cat);
}