93fd817536
It has become a common idiom in sbase to check strlcat() and strlcpy()
using
if (strl{cat, cpy}(dst, src, siz) >= siz)
eprintf("path too long\n");
However, this was not carried out consistently and to this very day,
some tools employed unchecked calls to these functions, effectively
allowing silent truncations to happen, which in turn may lead to
security issues.
To finally put an end to this, the e*-functions detect truncation
automatically and the caller can lean back and enjoy coding without
trouble. :)
99 lines
1.7 KiB
C
99 lines
1.7 KiB
C
/* See LICENSE file for copyright and license details. */
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#include <sys/stat.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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#include <string.h>
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#include "util.h"
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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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}
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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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ARGBEGIN {
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case 'm':
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case 'e':
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case 'f':
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mefflag = ARGC();
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break;
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case 'n':
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nflag = 1;
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break;
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default:
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usage();
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} ARGEND;
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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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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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estrlcat(arg, argv[0], sizeof(arg));
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while ((p = strchr(p, '/'))) {
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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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lp = 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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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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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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if (!nflag)
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putchar('\n');
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return 0;
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}
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