Audit readlink(1)
1) Properly document e, f and m-flags in the manpage.
2) Clear up the code for the m-flag-handling. Add idiomatic
'/'-path-traversal as already seen in mkdir(1).
3) Unwrap the SWAP_BUF()-macro.
4) BUGFIX: Actually handle the f-flag properly. Only resolve
the dirname and append the basename later.
5) Use fputs() instead of printf("%s", ...).
This commit is contained in:
FRIGN
parent
e6c20fe367
commit
a531865fe5
2
README
2
README
@ -55,7 +55,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
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=*| printenv non-posix none
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#*| printf yes none
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=*| pwd yes none
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= readlink non-posix none
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=*| readlink non-posix none
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=*| renice yes none
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=*| rm yes none (-i)
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=*| rmdir yes none
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31
readlink.1
31
readlink.1
@ -1,4 +1,4 @@
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.Dd January 31, 2015
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.Dd March 20, 2015
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.Dt READLINK 1
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.Os sbase
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.Sh NAME
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@ -6,30 +6,27 @@
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.Nd print symbolic link target or canonical file name
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.Sh SYNOPSIS
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.Nm
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.Op Fl fn
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.Ar name
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.Op Fl e | Fl f | Fl m
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.Op Fl n
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.Ar path
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.Sh DESCRIPTION
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If
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.Ar name
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is a symbolic link,
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.Nm
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writes its target to stdout.
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If
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.Fl f
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is not set and
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.Ar name
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is not a symbolic link,
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writes the target of
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.Ar path ,
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if it is a symbolic link, to stdout.
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If not,
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.Nm
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exits with a nonzero exit code without printing anything.
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exits with a non-zero return value.
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.Sh OPTIONS
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.Bl -tag -width Ds
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.It Fl f
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.It Fl e | Fl f | Fl m
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Canonicalize
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.Ar name ,
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which does not need to be a symlink,
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by recursively following every symlink in its components.
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which needn't be a symlink,
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by recursively following every symlink in its path components.
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All | All but the last | No path components must exist.
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.It Fl n
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Do not output the trailing newline.
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Do not print the terminating newline.
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.El
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.Sh SEE ALSO
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.Xr readlink 2 ,
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55
readlink.c
55
readlink.c
@ -1,6 +1,7 @@
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/* See LICENSE file for copyright and license details. */
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#include <sys/stat.h>
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#include <libgen.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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@ -11,18 +12,17 @@
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static void
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usage(void)
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{
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eprintf("usage: %s [-efmn] name\n", argv0);
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eprintf("usage: %s [-e | -f | -m] [-n] path\n", argv0);
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}
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int
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main(int argc, char *argv[])
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{
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char buf1[PATH_MAX], buf2[PATH_MAX], arg[PATH_MAX];
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int nflag = 0;
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int mefflag = 0;
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ssize_t n;
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struct stat st;
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char *p = arg, *lp = NULL, *b = buf1;
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ssize_t n;
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int nflag = 0, mefflag = 0;
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char buf1[PATH_MAX], buf2[PATH_MAX], arg[PATH_MAX],
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*p, *slash, *prefix, *lp, *b = buf1;
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ARGBEGIN {
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case 'm':
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@ -40,57 +40,54 @@ main(int argc, char *argv[])
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if (argc != 1)
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usage();
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if (strlen(argv[0]) > PATH_MAX - 1)
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if (strlen(argv[0]) >= PATH_MAX)
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eprintf("path too long\n");
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#define SWAP_BUF() (b = (b == buf1 ? buf2 : buf1));
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switch (mefflag) {
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case 'm':
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if (argv[0][0] == '/') { /* case when path is on '/' */
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arg[0] = '/';
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arg[1] = '\0';
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p++;
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} else if (!strchr(argv[0], '/')) { /* relative path */
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arg[0] = '.';
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arg[1] = '/';
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arg[2] = '\0';
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} else
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arg[0] = '\0';
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slash = strchr(argv[0], '/');
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prefix = (slash == argv[0]) ? "/" : (!slash) ? "./" : "";
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estrlcpy(arg, prefix, sizeof(arg));
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estrlcat(arg, argv[0], sizeof(arg));
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while ((p = strchr(p, '/'))) {
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for (lp = "", p = arg + (argv[0][0] == '/'); *p; p++) {
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if (*p != '/')
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continue;
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*p = '\0';
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if (!realpath(arg, b)) {
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*p = '/';
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goto mdone;
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}
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SWAP_BUF();
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b = (b == buf1) ? buf2 : buf1;
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lp = p;
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*p++ = '/';
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*p = '/';
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}
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if (!realpath(arg, b)) {
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mdone:
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SWAP_BUF();
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if (lp) {
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/* drop the extra '/' on root */
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lp += (argv[0][0] == '/' &&
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lp - arg == 1);
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b = (b == buf1) ? buf2 : buf1;
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estrlcat(b, lp, sizeof(arg));
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}
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}
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break;
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case 'e':
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if (stat(argv[0], &st) < 0)
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eprintf("stat %s:", argv[0]);
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case 'f': /* fallthrough */
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if (!realpath(argv[0], b))
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eprintf("realpath %s:", argv[0]);
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break;
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case 'f':
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p = dirname(estrdup(argv[0]));
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if (!realpath(p, b))
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eprintf("realpath %s:", p);
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estrlcat(b, "/", sizeof(arg));
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estrlcat(b, basename(estrdup(argv[0])), sizeof(arg));
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break;
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default:
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if ((n = readlink(argv[0], b, PATH_MAX - 1)) < 0)
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eprintf("readlink %s:", argv[0]);
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b[n] = '\0';
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}
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printf("%s", b);
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fputs(b, stdout);
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if (!nflag)
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putchar('\n');
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