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-rw-r--r--src/basic/memfd-util.c171
1 files changed, 171 insertions, 0 deletions
diff --git a/src/basic/memfd-util.c b/src/basic/memfd-util.c
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+++ b/src/basic/memfd-util.c
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+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2013 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+
+#ifdef HAVE_LINUX_MEMFD_H
+# include <linux/memfd.h>
+#endif
+
+#include "util.h"
+#include "memfd-util.h"
+#include "utf8.h"
+#include "missing.h"
+
+int memfd_new(const char *name) {
+ _cleanup_free_ char *g = NULL;
+ int fd;
+
+ if (!name) {
+ char pr[17] = {};
+
+ /* If no name is specified we generate one. We include
+ * a hint indicating our library implementation, and
+ * add the thread name to it */
+
+ assert_se(prctl(PR_GET_NAME, (unsigned long) pr) >= 0);
+
+ if (isempty(pr))
+ name = "sd";
+ else {
+ _cleanup_free_ char *e = NULL;
+
+ e = utf8_escape_invalid(pr);
+ if (!e)
+ return -ENOMEM;
+
+ g = strappend("sd-", e);
+ if (!g)
+ return -ENOMEM;
+
+ name = g;
+ }
+ }
+
+ fd = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ return fd;
+}
+
+int memfd_map(int fd, uint64_t offset, size_t size, void **p) {
+ void *q;
+ int sealed;
+
+ assert(fd >= 0);
+ assert(size > 0);
+ assert(p);
+
+ sealed = memfd_get_sealed(fd);
+ if (sealed < 0)
+ return sealed;
+
+ if (sealed)
+ q = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, offset);
+ else
+ q = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, offset);
+
+ if (q == MAP_FAILED)
+ return -errno;
+
+ *p = q;
+ return 0;
+}
+
+int memfd_set_sealed(int fd) {
+ int r;
+
+ assert(fd >= 0);
+
+ r = fcntl(fd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE | F_SEAL_SEAL);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+}
+
+int memfd_get_sealed(int fd) {
+ int r;
+
+ assert(fd >= 0);
+
+ r = fcntl(fd, F_GET_SEALS);
+ if (r < 0)
+ return -errno;
+
+ return r == (F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE | F_SEAL_SEAL);
+}
+
+int memfd_get_size(int fd, uint64_t *sz) {
+ struct stat stat;
+ int r;
+
+ assert(fd >= 0);
+ assert(sz);
+
+ r = fstat(fd, &stat);
+ if (r < 0)
+ return -errno;
+
+ *sz = stat.st_size;
+ return 0;
+}
+
+int memfd_set_size(int fd, uint64_t sz) {
+ int r;
+
+ assert(fd >= 0);
+
+ r = ftruncate(fd, sz);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+}
+
+int memfd_new_and_map(const char *name, size_t sz, void **p) {
+ _cleanup_close_ int fd = -1;
+ int r;
+
+ assert(sz > 0);
+ assert(p);
+
+ fd = memfd_new(name);
+ if (fd < 0)
+ return fd;
+
+ r = memfd_set_size(fd, sz);
+ if (r < 0)
+ return r;
+
+ r = memfd_map(fd, 0, sz, p);
+ if (r < 0)
+ return r;
+
+ r = fd;
+ fd = -1;
+
+ return r;
+}