Adding upstream version 2.38.1.upstream/2.38.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 249 insertions, 0 deletions

diff --git a/lib/canonicalize.c b/lib/canonicalize.c
new file mode 100644
index 0000000..6f85b47
--- /dev/null
+++ b/lib/canonicalize.c
@@ -0,0 +1,249 @@
+/*
+ * canonicalize.c -- canonicalize pathname by removing symlinks
+ *
+ * This file may be distributed under the terms of the
+ * GNU Lesser General Public License.
+ *
+ * Copyright (C) 2009-2013 Karel Zak <kzak@redhat.com>
+ */
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+#include "canonicalize.h"
+#include "pathnames.h"
+#include "all-io.h"
+
+/*
+ * Converts private "dm-N" names to "/dev/mapper/<name>"
+ *
+ * Since 2.6.29 (patch 784aae735d9b0bba3f8b9faef4c8b30df3bf0128) kernel sysfs
+ * provides the real DM device names in /sys/block/<ptname>/dm/name
+ */
+char *__canonicalize_dm_name(const char *prefix, const char *ptname)
+{
+	FILE	*f;
+	size_t	sz;
+	char	path[256], name[sizeof(path) - sizeof(_PATH_DEV_MAPPER)], *res = NULL;
+
+	if (!ptname || !*ptname)
+		return NULL;
+
+	if (!prefix)
+		prefix = "";
+
+	snprintf(path, sizeof(path), "%s/sys/block/%s/dm/name", prefix, ptname);
+	if (!(f = fopen(path, "r" UL_CLOEXECSTR)))
+		return NULL;
+
+	/* read "<name>\n" from sysfs */
+	if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) {
+		name[sz - 1] = '\0';
+		snprintf(path, sizeof(path), _PATH_DEV_MAPPER "/%s", name);
+
+		if ((prefix && *prefix) || access(path, F_OK) == 0)
+			res = strdup(path);
+	}
+	fclose(f);
+	return res;
+}
+
+char *canonicalize_dm_name(const char *ptname)
+{
+	return __canonicalize_dm_name(NULL, ptname);
+}
+
+static int is_dm_devname(char *canonical, char **name)
+{
+	struct stat sb;
+	char *p = strrchr(canonical, '/');
+
+	*name = NULL;
+
+	if (!p
+	    || strncmp(p, "/dm-", 4) != 0
+	    || !isdigit(*(p + 4))
+	    || stat(canonical, &sb) != 0
+	    || !S_ISBLK(sb.st_mode))
+		return 0;
+
+	*name = p + 1;
+	return 1;
+}
+
+/*
+ * This function does not canonicalize the path! It just prepends CWD before a
+ * relative path. If the path is no relative than returns NULL. The path does
+ * not have to exist.
+ */
+char *absolute_path(const char *path)
+{
+	char cwd[PATH_MAX], *res, *p;
+	size_t psz, csz;
+
+	if (!is_relative_path(path)) {
+		errno = EINVAL;
+		return NULL;
+	}
+	if (!getcwd(cwd, sizeof(cwd)))
+		return NULL;
+
+	/* simple clean up */
+	if (startswith(path, "./"))
+		path += 2;
+	else if (strcmp(path, ".") == 0)
+		path = NULL;
+
+	if (!path || !*path)
+		return strdup(cwd);
+
+	csz = strlen(cwd);
+	psz = strlen(path);
+
+	p = res = malloc(csz + 1 + psz + 1);
+	if (!res)
+		return NULL;
+
+	memcpy(p, cwd, csz);
+	p += csz;
+	*p++ = '/';
+	memcpy(p, path, psz + 1);
+
+	return res;
+}
+
+char *canonicalize_path(const char *path)
+{
+	char *canonical, *dmname;
+
+	if (!path || !*path)
+		return NULL;
+
+	canonical = realpath(path, NULL);
+	if (!canonical)
+		return strdup(path);
+
+	if (is_dm_devname(canonical, &dmname)) {
+		char *dm = canonicalize_dm_name(dmname);
+		if (dm) {
+			free(canonical);
+			return dm;
+		}
+	}
+
+	return canonical;
+}
+
+char *canonicalize_path_restricted(const char *path)
+{
+	char *canonical = NULL;
+	int errsv = 0;
+	int pipes[2];
+	ssize_t len;
+	pid_t pid;
+
+	if (!path || !*path)
+		return NULL;
+
+	if (pipe(pipes) != 0)
+		return NULL;
+
+	/*
+	 * To accurately assume identity of getuid() we must use setuid()
+	 * but if we do that, we lose ability to reassume euid of 0, so
+	 * we fork to do the check to keep euid intact.
+	 */
+	pid = fork();
+	switch (pid) {
+	case -1:
+		close(pipes[0]);
+		close(pipes[1]);
+		return NULL;			/* fork error */
+	case 0:
+		close(pipes[0]);		/* close unused end */
+		pipes[0] = -1;
+		errno = 0;
+
+		if (drop_permissions() != 0)
+			canonical = NULL;	/* failed */
+		else {
+			char *dmname = NULL;
+
+			canonical = realpath(path, NULL);
+			if (canonical && is_dm_devname(canonical, &dmname)) {
+				char *dm = canonicalize_dm_name(dmname);
+				if (dm) {
+					free(canonical);
+					canonical = dm;
+				}
+			}
+		}
+
+		len = canonical ? (ssize_t) strlen(canonical) :
+		          errno ? -errno : -EINVAL;
+
+		/* send length or errno */
+		write_all(pipes[1], (char *) &len, sizeof(len));
+		if (canonical)
+			write_all(pipes[1], canonical, len);
+		exit(0);
+	default:
+		break;
+	}
+
+	close(pipes[1]);		/* close unused end */
+	pipes[1] = -1;
+
+	/* read size or -errno */
+	if (read_all(pipes[0], (char *) &len, sizeof(len)) != sizeof(len))
+		goto done;
+	if (len < 0) {
+		errsv = -len;
+		goto done;
+	}
+
+	canonical = malloc(len + 1);
+	if (!canonical) {
+		errsv = ENOMEM;
+		goto done;
+	}
+	/* read path */
+	if (read_all(pipes[0], canonical, len) != len) {
+		errsv = errno;
+		goto done;
+	}
+	canonical[len] = '\0';
+done:
+	if (errsv) {
+		free(canonical);
+		canonical = NULL;
+	}
+	close(pipes[0]);
+
+	/* We make a best effort to reap child */
+	waitpid(pid, NULL, 0);
+
+	errno = errsv;
+	return canonical;
+}
+
+
+#ifdef TEST_PROGRAM_CANONICALIZE
+int main(int argc, char **argv)
+{
+	if (argc < 2) {
+		fprintf(stderr, "usage: %s <device>\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	fprintf(stdout, "orig: %s\n", argv[1]);
+	fprintf(stdout, "real: %s\n", canonicalize_path(argv[1]));
+	exit(EXIT_SUCCESS);
+}
+#endif