[svn] Rewrite path_simplify.

Published in <sxspu5nx2yi.fsf@florida.arsdigita.de>.
This commit is contained in:
hniksic 2001-12-09 17:58:37 -08:00
parent 233fcbc44d
commit 0e72aa6e13
2 changed files with 191 additions and 131 deletions

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@ -1,3 +1,8 @@
2001-12-10 Hrvoje Niksic <hniksic@arsdigita.com>
* utils.c (path_simplify): Rewrite, with better comments, and
without the use of strcpy to move overlapping blocks.
2001-12-09 Hrvoje Niksic <hniksic@arsdigita.com> 2001-12-09 Hrvoje Niksic <hniksic@arsdigita.com>
* init.c (cmd_spec_progress): Resurrect. Check whether VAL is a * init.c (cmd_spec_progress): Resurrect. Check whether VAL is a

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@ -473,163 +473,125 @@ fork_to_background (void)
} }
#endif /* not WINDOWS */ #endif /* not WINDOWS */
#if 0 /* Resolve "." and ".." elements of PATH by destructively modifying
/* debug */ PATH. "." is resolved by removing that path element, and ".." is
char * resolved by removing the preceding path element. Leading and
ps (char *orig) trailing slashes are preserved.
{
char *r = xstrdup (orig);
path_simplify (r);
return r;
}
#endif
/* Canonicalize PATH, and return a new path. The new path differs from PATH Return non-zero if any changes have been made.
in that:
Multple `/'s are collapsed to a single `/'.
Leading `./'s and trailing `/.'s are removed.
Trailing `/'s are removed.
Non-leading `../'s and trailing `..'s are handled by removing
portions of the path.
E.g. "a/b/c/./../d/.." will yield "a/b/". This function originates For example, "a/b/c/./../d/.." will yield "a/b/". More exhaustive
from GNU Bash and has been mutilated to unrecognition for use in test examples are provided below. If you change anything in this
Wget. function, run test_path_simplify to make sure you haven't broken a
test case.
Changes for Wget: A previous version of this function was based on path_simplify()
Always use '/' as stub_char. from GNU Bash, but it has been rewritten for Wget 1.8.1. */
Don't check for local things using canon_stat.
Change the original string instead of strdup-ing.
React correctly when beginning with `./' and `../'.
Don't zip out trailing slashes.
Return a value indicating whether any modifications took place.
If you dare change this function, take a careful look at the test
cases below, and make sure that they pass. */
int int
path_simplify (char *path) path_simplify (char *path)
{ {
register int i, start; int change = 0;
int changes = 0; char *p, *end;
if (!*path)
return 0;
if (path[0] == '/') if (path[0] == '/')
/* Preserve initial '/'. */ ++path; /* preserve the leading '/'. */
++path;
/* Nix out leading `.' or `..' with. */ p = path;
if ((path[0] == '.' && path[1] == '\0') end = p + strlen (p) + 1; /* position past the terminating zero. */
|| (path[0] == '.' && path[1] == '.' && path[2] == '\0'))
{
path[0] = '\0';
changes = 1;
return changes;
}
/* Walk along PATH looking for things to compact. */
i = 0;
while (1) while (1)
{ {
if (!path[i]) again:
break; /* P should point to the beginning of a path element. */
while (path[i] && path[i] != '/') if (*p == '.' && (*(p + 1) == '/' || *(p + 1) == '\0'))
i++;
start = i++;
/* If we didn't find any slashes, then there is nothing left to do. */
if (!path[start])
break;
/* Handle multiple `/'s in a row. */
while (path[i] == '/')
i++;
if ((start + 1) != i)
{ {
strcpy (path + start + 1, path + i); /* Handle "./foo" by moving "foo" two characters to the
i = start + 1; left. */
changes = 1; if (*(p + 1) == '/')
}
/* Check for `../', `./' or trailing `.' by itself. */
if (path[i] == '.')
{
/* Handle trailing `.' by itself. */
if (!path[i + 1])
{ {
path[--i] = '\0'; change = 1;
changes = 1; memmove (p, p + 2, end - p);
end -= 2;
goto again;
}
else
{
change = 1;
*p = '\0';
break;
}
}
else if (*p == '.' && *(p + 1) == '.'
&& (*(p + 2) == '/' || *(p + 2) == '\0'))
{
/* Handle "../foo" by moving "foo" one path element to the
left. */
char *b = p;
/* Backtrack by one path element, but not past the beginning
of PATH. */
/* foo/bar/../baz */
/* ^ p */
/* ^ b */
if (b > path + 1)
{
/* Find the character preceded by slash or by the
beginning of path. */
for (--b; b > path && *(b - 1) != '/'; b--)
;
}
change = 1;
if (*(p + 2) == '/')
{
memmove (b, p + 3, end - (p + 3));
end -= (p + 3) - b;
p = b;
}
else
{
*b = '\0';
break; break;
} }
/* Handle `./'. */ goto again;
if (path[i + 1] == '/') }
else if (*p == '/')
{
/* Remove empty path elements. Not mandated by rfc1808 et
al, but empty path elements are not all that useful, and
the rest of Wget might not deal with them well. */
char *q = p;
while (*q == '/')
++q;
change = 1;
if (*q == '\0')
{ {
strcpy (path + i, path + i + 1); *p = '\0';
i = (start < 0) ? 0 : start; break;
changes = 1;
continue;
} }
memmove (p, q, end - q);
end -= q - p;
goto again;
}
/* Handle `../' or trailing `..' by itself. */ /* Skip to the next path element. */
if (path[i + 1] == '.' && while (*p && *p != '/')
(path[i + 2] == '/' || !path[i + 2])) ++p;
{ if (*p == '\0')
while (--start > -1 && path[start] != '/');
strcpy (path + start + 1, path + i + 2 + (start == -1 && path[i + 2]));
i = (start < 0) ? 0 : start;
changes = 1;
continue;
}
} /* path == '.' */
} /* while */
/* Addition: Remove all `./'-s and `../'-s preceding the string. */
i = 0;
while (1)
{
if (path[i] == '.' && path[i + 1] == '/')
i += 2;
else if (path[i] == '.' && path[i + 1] == '.' && path[i + 2] == '/')
i += 3;
else
break; break;
}
if (i) /* Make sure P points to the beginning of the next path element,
{ which is location after the slash. */
strcpy (path, path + i - 0); ++p;
changes = 1;
} }
return changes; return change;
} }
/* Test cases:
ps("") -> ""
ps("/") -> "/"
ps(".") -> ""
ps("..") -> ""
ps("/.") -> "/"
ps("/..") -> "/"
ps("foo") -> "foo"
ps("foo/bar") -> "foo/bar"
ps("foo//bar") -> "foo/bar" (possibly a bug)
ps("foo/../bar") -> "bar"
ps("foo/bar/..") -> "foo/"
ps("foo/bar/../x") -> "foo/x"
ps("foo/bar/../x/") -> "foo/x/"
ps("foo/..") -> ""
ps("/foo/..") -> "/"
ps("a/b/../../c") -> "c"
ps("/a/b/../../c") -> "/c"
ps("./a/../b") -> "b"
ps("/./a/../b") -> "/b"
*/
/* "Touch" FILE, i.e. make its atime and mtime equal to the time /* "Touch" FILE, i.e. make its atime and mtime equal to the time
specified with TM. */ specified with TM. */
@ -1846,3 +1808,96 @@ debug_test_md5 (char *buf)
return res; return res;
} }
#endif #endif
#if 0
/* Debugging and testing support for path_simplify. */
/* Debug: run path_simplify on PATH and return the result in a new
string. Useful for calling from the debugger. */
static char *
ps (char *path)
{
char *copy = xstrdup (path);
path_simplify (copy);
return copy;
}
static void
run_test (char *test, char *expected_result, int expected_change)
{
char *test_copy = xstrdup (test);
int modified = path_simplify (test_copy);
if (0 != strcmp (test_copy, expected_result))
{
printf ("Failed path_simplify(\"%s\"): expected \"%s\", got \"%s\".\n",
test, expected_result, test_copy);
}
if (modified != expected_change)
{
if (expected_change == 1)
printf ("Expected no modification with path_simplify(\"%s\").\n",
test);
else
printf ("Expected modification with path_simplify(\"%s\").\n",
test);
}
xfree (test_copy);
}
static void
test_path_simplify (void)
{
static struct {
char *test, *result;
int should_modify;
} tests[] = {
{ "", "", 0 },
{ ".", "", 1 },
{ "..", "", 1 },
{ "foo", "foo", 0 },
{ "foo/bar", "foo/bar", 0 },
{ "foo///bar", "foo/bar", 1 },
{ "foo/.", "foo/", 1 },
{ "foo/./", "foo/", 1 },
{ "foo./", "foo./", 0 },
{ "foo/../bar", "bar", 1 },
{ "foo/../bar/", "bar/", 1 },
{ "foo/bar/..", "foo/", 1 },
{ "foo/bar/../x", "foo/x", 1 },
{ "foo/bar/../x/", "foo/x/", 1 },
{ "foo/..", "", 1 },
{ "foo/../..", "", 1 },
{ "a/b/../../c", "c", 1 },
{ "./a/../b", "b", 1 }
};
int i;
for (i = 0; i < ARRAY_SIZE (tests); i++)
{
char *test = tests[i].test;
char *expected_result = tests[i].result;
int expected_change = tests[i].should_modify;
run_test (test, expected_result, expected_change);
}
/* Now run all the tests with a leading slash before the test case,
to prove that the slash is being preserved. */
for (i = 0; i < ARRAY_SIZE (tests); i++)
{
char *test, *expected_result;
int expected_change = tests[i].should_modify;
test = xmalloc (1 + strlen (tests[i].test) + 1);
sprintf (test, "/%s", tests[i].test);
expected_result = xmalloc (1 + strlen (tests[i].result) + 1);
sprintf (expected_result, "/%s", tests[i].result);
run_test (test, expected_result, expected_change);
xfree (test);
xfree (expected_result);
}
}
#endif