200 lines
8.4 KiB
C
200 lines
8.4 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <syslog.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "architecture.h"
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#include "base-filesystem.h"
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#include "fd-util.h"
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#include "log.h"
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#include "macro.h"
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#include "nulstr-util.h"
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#include "path-util.h"
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#include "string-util.h"
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#include "umask-util.h"
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#include "user-util.h"
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typedef struct BaseFilesystem {
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const char *dir; /* directory or symlink to create */
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mode_t mode;
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const char *target; /* if non-NULL create as symlink to this target */
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const char *exists; /* conditionalize this entry on existence of this file */
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bool ignore_failure;
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} BaseFilesystem;
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static const BaseFilesystem table[] = {
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{ "bin", 0, "usr/bin\0", NULL },
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{ "lib", 0, "usr/lib\0", NULL },
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{ "root", 0750, NULL, NULL, true },
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{ "sbin", 0, "usr/sbin\0", NULL },
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{ "usr", 0755, NULL, NULL },
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{ "var", 0755, NULL, NULL },
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{ "etc", 0755, NULL, NULL },
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{ "proc", 0755, NULL, NULL, true },
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{ "sys", 0755, NULL, NULL, true },
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{ "dev", 0755, NULL, NULL, true },
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/* Various architecture ABIs define the path to the dynamic loader via the /lib64/ subdirectory of
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* the root directory. When booting from an otherwise empty root file system (where only /usr/ has
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* been mounted into) it is thus necessary to create a symlink pointing to the right subdirectory of
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* /usr/ first — otherwise we couldn't invoke any dynamic binary. Let's detect this case here, and
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* create the symlink as needed should it be missing. We prefer doing this consistently with Debian's
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* multiarch logic, but support Fedora-style multilib too.*/
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#if defined(__aarch64__)
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/* aarch64 ELF ABI actually says dynamic loader is in /lib/, but Fedora puts it in /lib64/ anyway and
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* just symlinks /lib/ld-linux-aarch64.so.1 to ../lib64/ld-linux-aarch64.so.1. For this to work
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* correctly, /lib64/ must be symlinked to /usr/lib64/. */
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld-linux-aarch64.so.1" },
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# define KNOW_LIB64_DIRS 1
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#elif defined(__alpha__)
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#elif defined(__arc__) || defined(__tilegx__)
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#elif defined(__arm__)
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/* No /lib64 on arm. The linker is /lib/ld-linux-armhf.so.3. */
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# define KNOW_LIB64_DIRS 1
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#elif defined(__i386__) || defined(__x86_64__)
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld-linux-x86-64.so.2" },
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# define KNOW_LIB64_DIRS 1
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#elif defined(__ia64__)
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#elif defined(__loongarch64)
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# define KNOW_LIB64_DIRS 1
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# if defined(__loongarch_double_float)
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld-linux-loongarch-lp64d.so.1" },
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# elif defined(__loongarch_single_float)
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld-linux-loongarch-lp64f.so.1" },
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# elif defined(__loongarch_soft_float)
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld-linux-loongarch-lp64s.so.1" },
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# else
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# error "Unknown LoongArch ABI"
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# endif
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#elif defined(__m68k__)
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/* No link needed. */
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# define KNOW_LIB64_DIRS 1
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#elif defined(_MIPS_SIM)
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# if _MIPS_SIM == _MIPS_SIM_ABI32
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# elif _MIPS_SIM == _MIPS_SIM_NABI32
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# elif _MIPS_SIM == _MIPS_SIM_ABI64
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# else
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# error "Unknown MIPS ABI"
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# endif
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#elif defined(__powerpc__)
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# if defined(__PPC64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld64.so.2" },
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# define KNOW_LIB64_DIRS 1
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# elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
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/* powerpc64-linux-gnu */
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# else
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/* powerpc-linux-gnu */
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# endif
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#elif defined(__riscv)
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# if __riscv_xlen == 32
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# elif __riscv_xlen == 64
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/* Same situation as for aarch64 */
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld-linux-riscv64-lp64d.so.1" },
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# define KNOW_LIB64_DIRS 1
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# else
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# error "Unknown RISC-V ABI"
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# endif
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#elif defined(__s390__)
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/* s390-linux-gnu */
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#elif defined(__s390x__)
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{ "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0"
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"usr/lib64\0", "ld-lsb-s390x.so.3" },
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# define KNOW_LIB64_DIRS 1
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#elif defined(__sparc__)
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#endif
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/* gcc doesn't allow pragma to be used within constructs, hence log about this separately below */
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};
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#ifndef KNOW_LIB64_DIRS
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# pragma message "Please add an entry above specifying whether your architecture uses /lib64/, /lib32/, or no such links."
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#endif
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int base_filesystem_create(const char *root, uid_t uid, gid_t gid) {
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_cleanup_close_ int fd = -1;
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int r;
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fd = open(root, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW);
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if (fd < 0)
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return log_error_errno(errno, "Failed to open root file system: %m");
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for (size_t i = 0; i < ELEMENTSOF(table); i++) {
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if (faccessat(fd, table[i].dir, F_OK, AT_SYMLINK_NOFOLLOW) >= 0)
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continue;
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if (table[i].target) {
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const char *target = NULL;
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/* check if one of the targets exists */
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NULSTR_FOREACH(s, table[i].target) {
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if (faccessat(fd, s, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
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continue;
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/* check if a specific file exists at the target path */
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if (table[i].exists) {
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_cleanup_free_ char *p = NULL;
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p = path_join(s, table[i].exists);
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if (!p)
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return log_oom();
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if (faccessat(fd, p, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
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continue;
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}
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target = s;
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break;
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}
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if (!target)
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continue;
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if (symlinkat(target, fd, table[i].dir) < 0) {
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log_full_errno(IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure ? LOG_DEBUG : LOG_ERR, errno,
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"Failed to create symlink at %s/%s: %m", root, table[i].dir);
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if (IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure)
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continue;
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return -errno;
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}
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if (uid_is_valid(uid) || gid_is_valid(gid))
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if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
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return log_error_errno(errno, "Failed to chown symlink at %s/%s: %m", root, table[i].dir);
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continue;
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}
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RUN_WITH_UMASK(0000)
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r = mkdirat(fd, table[i].dir, table[i].mode);
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if (r < 0) {
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log_full_errno(IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure ? LOG_DEBUG : LOG_ERR, errno,
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"Failed to create directory at %s/%s: %m", root, table[i].dir);
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if (IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure)
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continue;
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return -errno;
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}
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if (uid_is_valid(uid) || gid_is_valid(gid))
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if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
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return log_error_errno(errno, "Failed to chown directory at %s/%s: %m", root, table[i].dir);
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}
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return 0;
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}
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