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-rw-r--r--src/realpath/main.c247
1 files changed, 247 insertions, 0 deletions
diff --git a/src/realpath/main.c b/src/realpath/main.c
new file mode 100644
index 0000000..bfa2aa2
--- /dev/null
+++ b/src/realpath/main.c
@@ -0,0 +1,247 @@
+/*
+ * dpkg-realpath - print the resolved pathname with DPKG_ROOT support
+ *
+ * Copyright © 2020 Helmut Grohne <helmut@subdivi.de>
+ * Copyright © 2020-2024 Guillem Jover <guillem@debian.org>
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <compat.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#ifdef HAVE_LOCALE_H
+#include <locale.h>
+#endif
+#include <string.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <dpkg/i18n.h>
+#include <dpkg/dpkg.h>
+#include <dpkg/dpkg-db.h>
+#include <dpkg/debug.h>
+#include <dpkg/string.h>
+#include <dpkg/db-fsys.h>
+#include <dpkg/options.h>
+
+static const char printforhelp[] = N_(
+"Use --help for help about this utility.");
+
+static void DPKG_ATTR_NORET
+printversion(const struct cmdinfo *cip, const char *value)
+{
+ printf(_("Debian %s version %s.\n"), dpkg_get_progname(),
+ PACKAGE_RELEASE);
+
+ printf(_(
+"This is free software; see the GNU General Public License version 2 or\n"
+"later for copying conditions. There is NO warranty.\n"));
+
+ m_output(stdout, _("<standard output>"));
+
+ exit(0);
+}
+
+static void DPKG_ATTR_NORET
+usage(const struct cmdinfo *cip, const char *value)
+{
+ printf(_(
+"Usage: %s [<option>...] <pathname>\n"
+"\n"), dpkg_get_progname());
+
+ printf(_(
+"Options:\n"
+" -z, --zero end output line with NUL, not newline.\n"
+" --instdir <directory> set the root directory.\n"
+" --root <directory> set the root directory.\n"
+" --version show the version.\n"
+" --help show this help message.\n"
+"\n"));
+
+ m_output(stdout, _("<standard output>"));
+
+ exit(0);
+}
+
+static int opt_eol = '\n';
+
+static char *
+realpath_relative_to(const char *pathname, const char *rootdir)
+{
+ struct varbuf root = VARBUF_INIT;
+ struct varbuf src = VARBUF_INIT;
+ struct varbuf dst = VARBUF_INIT;
+ struct varbuf slink = VARBUF_INIT;
+ struct varbuf result = VARBUF_INIT;
+ struct varbuf prefix = VARBUF_INIT;
+ int loop = 0;
+
+ varbuf_init(&root, 32);
+ varbuf_init(&src, 32);
+ varbuf_init(&dst, 32);
+ varbuf_init(&result, 32);
+
+ varbuf_set_str(&root, rootdir);
+ varbuf_set_str(&src, pathname);
+ varbuf_set_str(&result, rootdir);
+
+ /* Check whether the path is relative, make it absolute otherwise. */
+ if (src.buf[0] != '/') {
+ struct varbuf abs_src = VARBUF_INIT;
+
+ file_getcwd(&abs_src);
+ varbuf_add_char(&abs_src, '/');
+ varbuf_add_varbuf(&abs_src, &src);
+
+ varbuf_set_varbuf(&src, &abs_src);
+ varbuf_destroy(&abs_src);
+
+ varbuf_trim_varbuf_prefix(&src, &root);
+ }
+
+ /* Remove prefixed slashes. */
+ varbuf_trim_char_prefix(&src, '/');
+
+ while (src.used) {
+ struct stat st;
+ const char *slash;
+
+ /* Get the first directory component. */
+ varbuf_set_varbuf(&prefix, &src);
+ slash = strchrnul(prefix.buf, '/');
+ varbuf_trunc(&prefix, slash - prefix.buf);
+
+ /* Remove the first directory component from src. */
+ varbuf_trim_varbuf_prefix(&src, &prefix);
+
+ /* Remove prefixed slashes. */
+ varbuf_trim_char_prefix(&src, '/');
+
+ varbuf_set_varbuf(&slink, &result);
+ varbuf_add_char(&slink, '/');
+ varbuf_add_varbuf(&slink, &prefix);
+
+ /* Resolve the first directory component. */
+ if (strcmp(prefix.buf, ".") == 0) {
+ /* Ignore, stay at the same directory. */
+ } else if (strcmp(prefix.buf, "..") == 0) {
+ /* Go up one directory. */
+ slash = strrchr(result.buf, '/');
+ if (slash != NULL)
+ varbuf_trunc(&result, slash - result.buf);
+
+ if (root.used && !varbuf_has_prefix(&result, &root))
+ varbuf_set_varbuf(&result, &root);
+ } else if (lstat(slink.buf, &st) == 0 && S_ISLNK(st.st_mode)) {
+ ssize_t linksize;
+
+ loop++;
+ if (loop > 25)
+ ohshit(_("too many levels of symbolic links"));
+
+ /* Resolve the symlink within result. */
+ linksize = file_readlink(slink.buf, &dst, st.st_size);
+ if (linksize < 0)
+ ohshite(_("cannot read link '%s'"), slink.buf);
+ else if ((off_t)linksize != st.st_size)
+ ohshit(_("symbolic link '%s' size has changed from %jd to %zd"),
+ slink.buf, (intmax_t)st.st_size, linksize);
+
+ if (dst.buf[0] == '/') {
+ /* Absolute pathname, reset result back to
+ * root. */
+ varbuf_set_varbuf(&result, &root);
+
+ if (src.used) {
+ varbuf_add_char(&dst, '/');
+ varbuf_add_varbuf(&dst, &src);
+ }
+ varbuf_set_varbuf(&src, &dst);
+
+ /* Remove prefixed slashes. */
+ varbuf_trim_char_prefix(&src, '/');
+ } else {
+ /* Relative pathname. */
+ if (src.used) {
+ varbuf_add_char(&dst, '/');
+ varbuf_add_varbuf(&dst, &src);
+ }
+ varbuf_set_varbuf(&src, &dst);
+ }
+ } else {
+ /* Otherwise append the prefix. */
+ varbuf_add_char(&result, '/');
+ varbuf_add_varbuf(&result, &prefix);
+ }
+ }
+
+ /* We are done, return the resolved pathname, w/o root. */
+ varbuf_trim_varbuf_prefix(&result, &root);
+
+ varbuf_destroy(&root);
+ varbuf_destroy(&src);
+ varbuf_destroy(&dst);
+ varbuf_destroy(&slink);
+ varbuf_destroy(&prefix);
+
+ return varbuf_detach(&result);
+}
+
+static const struct cmdinfo cmdinfos[] = {
+ { "zero", 'z', 0, &opt_eol, NULL, NULL, '\0' },
+ { "instdir", 0, 1, NULL, NULL, set_instdir, 0 },
+ { "root", 0, 1, NULL, NULL, set_instdir, 0 },
+ { "version", 0, 0, NULL, NULL, printversion },
+ { "help", '?', 0, NULL, NULL, usage },
+ { NULL, 0 }
+};
+
+int
+main(int argc, const char *const *argv)
+{
+ const char *instdir;
+ const char *pathname;
+ char *real_pathname;
+
+ dpkg_locales_init(PACKAGE);
+ dpkg_program_init("dpkg-realpath");
+ dpkg_options_parse(&argv, cmdinfos, printforhelp);
+
+ debug(dbg_general, "root=%s admindir=%s", dpkg_fsys_get_dir(), dpkg_db_get_dir());
+
+ pathname = argv[0];
+ if (str_is_unset(pathname))
+ badusage(_("need a pathname argument"));
+
+ instdir = dpkg_fsys_get_dir();
+ if (strlen(instdir) && strncmp(pathname, instdir, strlen(instdir)) == 0)
+ badusage(_("link '%s' includes root prefix '%s'"),
+ pathname, instdir);
+
+ real_pathname = realpath_relative_to(pathname, instdir);
+ printf("%s%c", real_pathname, opt_eol);
+ free(real_pathname);
+
+ dpkg_program_done();
+ dpkg_locales_done();
+
+ return 0;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-21 06:36:45 +0000