175 lines
3.9 KiB
C
175 lines
3.9 KiB
C
/***
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This file is part of systemd.
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Copyright 2013 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#if HAVE_LINUX_MEMFD_H
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#include <linux/memfd.h>
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#endif
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#include <stdio.h>
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#include <sys/mman.h>
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#include <sys/prctl.h>
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "macro.h"
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#include "memfd-util.h"
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#include "missing.h"
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#include "string-util.h"
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#include "utf8.h"
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int memfd_new(const char *name) {
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_cleanup_free_ char *g = NULL;
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int fd;
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if (!name) {
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char pr[17] = {};
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/* If no name is specified we generate one. We include
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* a hint indicating our library implementation, and
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* add the thread name to it */
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assert_se(prctl(PR_GET_NAME, (unsigned long) pr) >= 0);
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if (isempty(pr))
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name = "sd";
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else {
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_cleanup_free_ char *e = NULL;
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e = utf8_escape_invalid(pr);
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if (!e)
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return -ENOMEM;
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g = strappend("sd-", e);
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if (!g)
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return -ENOMEM;
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name = g;
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}
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}
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fd = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
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if (fd < 0)
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return -errno;
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return fd;
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}
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int memfd_map(int fd, uint64_t offset, size_t size, void **p) {
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void *q;
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int sealed;
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assert(fd >= 0);
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assert(size > 0);
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assert(p);
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sealed = memfd_get_sealed(fd);
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if (sealed < 0)
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return sealed;
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if (sealed)
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q = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, offset);
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else
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q = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, offset);
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if (q == MAP_FAILED)
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return -errno;
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*p = q;
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return 0;
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}
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int memfd_set_sealed(int fd) {
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int r;
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assert(fd >= 0);
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r = fcntl(fd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE | F_SEAL_SEAL);
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if (r < 0)
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return -errno;
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return 0;
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}
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int memfd_get_sealed(int fd) {
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int r;
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assert(fd >= 0);
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r = fcntl(fd, F_GET_SEALS);
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if (r < 0)
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return -errno;
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return r == (F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE | F_SEAL_SEAL);
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}
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int memfd_get_size(int fd, uint64_t *sz) {
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struct stat stat;
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int r;
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assert(fd >= 0);
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assert(sz);
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r = fstat(fd, &stat);
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if (r < 0)
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return -errno;
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*sz = stat.st_size;
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return 0;
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}
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int memfd_set_size(int fd, uint64_t sz) {
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int r;
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assert(fd >= 0);
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r = ftruncate(fd, sz);
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if (r < 0)
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return -errno;
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return 0;
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}
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int memfd_new_and_map(const char *name, size_t sz, void **p) {
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_cleanup_close_ int fd = -1;
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int r;
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assert(sz > 0);
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assert(p);
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fd = memfd_new(name);
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if (fd < 0)
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return fd;
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r = memfd_set_size(fd, sz);
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if (r < 0)
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return r;
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r = memfd_map(fd, 0, sz, p);
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if (r < 0)
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return r;
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r = fd;
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fd = -1;
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return r;
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}
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