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-rw-r--r--src/basic/memfd-util.c154
1 files changed, 154 insertions, 0 deletions
diff --git a/src/basic/memfd-util.c b/src/basic/memfd-util.c
new file mode 100644
index 0000000..0b8ecea
--- /dev/null
+++ b/src/basic/memfd-util.c
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#if HAVE_LINUX_MEMFD_H
+#include <linux/memfd.h>
+#endif
+#include <stdio.h>
+#include <sys/prctl.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "macro.h"
+#include "memfd-util.h"
+#include "missing_fcntl.h"
+#include "missing_mman.h"
+#include "missing_syscall.h"
+#include "string-util.h"
+#include "utf8.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 = strjoin("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;
+
+ return TAKE_FD(fd);
+}