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Audit ln(1)

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1) Clarify behaviour when the f-flag is given and a target is in its
   own way.
2) Fix usage()-style.
3) Group local variable declarations.
4) reorder args
5) argc style, other boolean style changes
6) improve error messages
7) set argv[argc - 1] to NULL to allow argv-centric loop later
8) BUGFIX: POSIX specifies that when with the f-flag there's a
   situation where a file stands in its own way for linking it
   should be ignored.
9) Add weprintf() where possible, so we don't pussy out when there's
   a small issue. This is sbase ffs!
This commit is contained in:
FRIGN 2015-03-05 21:14:43 +01:00
parent aea256c288
commit ab26b5583e
3 changed files with 38 additions and 26 deletions
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2
README
View File

@ -39,7 +39,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
=*| hostname non-posix none
=* kill yes none
=*| link yes none
=* ln yes none
=*| ln yes none
=* logger yes none
=* logname yes none
= ls no (-C), -S, -f, -m, -s, -x

6
ln.1
View File

@ -1,4 +1,4 @@
.Dd January 26, 2015
.Dd March 5, 2015
.Dt LN 1
.Os sbase
.Sh NAME
@ -37,7 +37,9 @@ hardlinks them in the existing
.It Fl f
If
.Ar name
exists, remove it to allow the link.
exists and is not a
.Ar target ,
remove it to allow the link.
.It Fl L | Fl P
If
.Ar target

56
ln.c
View File

@ -1,6 +1,7 @@
/* See LICENSE file for copyright and license details. */
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <unistd.h>
@ -11,64 +12,73 @@ static void
usage(void)
{
eprintf("usage: %s [-f] [-L | -P | -s] target [name]\n"
" %s [-f] [-L | -P | -s] target ... directory\n",
argv0, argv0);
" %s [-f] [-L | -P | -s] target ... dir\n", argv0, argv0);
}
int
main(int argc, char *argv[])
{
char *fname, *to;
int sflag = 0;
int fflag = 0;
int hasto = 0;
int dirfd = AT_FDCWD;
int flags = AT_SYMLINK_FOLLOW;
struct stat st;
int sflag = 0, fflag = 0, hasto = 0, dirfd = AT_FDCWD, flags = AT_SYMLINK_FOLLOW;
struct stat st, tost;
ARGBEGIN {
case 'f':
fflag = 1;
break;
case 's':
sflag = 1;
break;
case 'L':
flags |= AT_SYMLINK_FOLLOW;
break;
case 'P':
flags &= ~AT_SYMLINK_FOLLOW;
break;
case 's':
sflag = 1;
break;
default:
usage();
} ARGEND;
if (argc == 0)
if (!argc)
usage();
fname = sflag ? "symlink" : "link";
if (argc >= 2) {
if (stat(argv[argc - 1], &st) == 0 && S_ISDIR(st.st_mode)) {
if (!stat(argv[argc - 1], &st) && S_ISDIR(st.st_mode)) {
if ((dirfd = open(argv[argc - 1], O_RDONLY)) < 0)
eprintf("open:");
eprintf("open %s:", argv[argc - 1]);
} else if (argc == 2) {
to = argv[1];
to = argv[argc - 1];
hasto = 1;
} else {
eprintf("destination is not a directory\n");
eprintf("%s: not a directory\n", argv[argc - 1]);
}
argv[argc - 1] = NULL;
argc--;
}
for (; argc > 0; argc--, argv++) {
for (; *argv; argc--, argv++) {
if (!hasto)
to = basename(argv[0]);
if (fflag)
unlinkat(dirfd, to, 0);
if ((!sflag ? linkat(AT_FDCWD, argv[0], dirfd, to, flags)
: symlinkat(argv[0], dirfd, to)) < 0) {
eprintf("%s %s <- %s:", fname, argv[0], to);
to = basename(*argv);
if (fflag) {
if (stat(*argv, &st) < 0) {
weprintf("stat %s:", *argv);
continue;
} else if (fstatat(dirfd, to, &tost, AT_SYMLINK_NOFOLLOW) < 0) {
if (errno != ENOENT)
eprintf("stat %s:", to);
} else {
if (st.st_dev == tost.st_dev && st.st_ino == tost.st_ino) {
weprintf("%s and %s are the same file\n", *argv, *argv);
continue;
}
unlinkat(dirfd, to, 0);
}
}
if ((!sflag ? linkat(AT_FDCWD, *argv, dirfd, to, flags)
: symlinkat(*argv, dirfd, to)) < 0) {
weprintf("%s %s <- %s:", fname, *argv, to);
}
}