memfd: move code from public library to src/shared

Don't expose generic kernel API via libsystemd, but keep the code internal
for our own usage.

2 files changed, 365 insertions, 0 deletions

diff --git a/src/shared/memfd.c b/src/shared/memfd.c
new file mode 100644
index 0000000000..4dd70a2473
--- /dev/null
+++ b/src/shared/memfd.c
@@ -0,0 +1,308 @@
+/*-*- 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/ioctl.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+
+#include "util.h"
+#include "bus-label.h"
+#include "missing.h"
+#include "memfd.h"
+
+#include "sd-bus.h"
+
+struct sd_memfd {
+        int fd;
+        FILE *f;
+};
+
+int sd_memfd_new(sd_memfd **m, const char *name) {
+
+        _cleanup_close_ int kdbus = -1;
+        _cleanup_free_ char *g = NULL;
+        sd_memfd *n;
+
+        assert_return(m, -EINVAL);
+
+        kdbus = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (kdbus < 0)
+                return -errno;
+
+        if (name) {
+                /* The kernel side is pretty picky about the character
+                 * set here, let's do the usual bus escaping to deal
+                 * with that. */
+
+                g = bus_label_escape(name);
+                if (!g)
+                        return -ENOMEM;
+
+                name = g;
+
+        } else {
+                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 = bus_label_escape(pr);
+                        if (!e)
+                                return -ENOMEM;
+
+                        g = strappend("sd-", e);
+                        if (!g)
+                                return -ENOMEM;
+
+                        name = g;
+                }
+        }
+
+        n = new0(struct sd_memfd, 1);
+        if (!n)
+                return -ENOMEM;
+
+        n->fd = memfd_create(name, 0, MFD_ALLOW_SEALING);
+        if (n->fd < 0) {
+                free(n);
+                return -errno;
+        }
+
+        *m = n;
+        return 0;
+}
+
+int sd_memfd_new_from_fd(sd_memfd **m, int fd) {
+        sd_memfd *n;
+
+        assert_return(m, -EINVAL);
+        assert_return(fd >= 0, -EINVAL);
+
+        /* Check if this is a sealable fd */
+        if (fcntl(fd, F_GET_SEALS) < 0)
+                return -ENOTTY;
+
+        n = new0(struct sd_memfd, 1);
+        if (!n)
+                return -ENOMEM;
+
+        n->fd = fd;
+        *m = n;
+
+        return 0;
+}
+
+void sd_memfd_free(sd_memfd *m) {
+        if (!m)
+                return;
+
+        if (m->f)
+                fclose(m->f);
+        else
+                safe_close(m->fd);
+
+        free(m);
+}
+
+int sd_memfd_get_fd(sd_memfd *m) {
+        assert_return(m, -EINVAL);
+
+        return m->fd;
+}
+
+int sd_memfd_get_file(sd_memfd *m, FILE **f) {
+        assert_return(m, -EINVAL);
+        assert_return(f, -EINVAL);
+
+        if (!m->f) {
+                m->f = fdopen(m->fd, "r+");
+                if (!m->f)
+                        return -errno;
+        }
+
+        *f = m->f;
+        return 0;
+}
+
+int sd_memfd_dup_fd(sd_memfd *m) {
+        int fd;
+
+        assert_return(m, -EINVAL);
+
+        fd = fcntl(m->fd, F_DUPFD_CLOEXEC, 3);
+        if (fd < 0)
+                return -errno;
+
+        return fd;
+}
+
+int sd_memfd_map(sd_memfd *m, uint64_t offset, size_t size, void **p) {
+        void *q;
+        int sealed;
+
+        assert_return(m, -EINVAL);
+        assert_return(size > 0, -EINVAL);
+        assert_return(p, -EINVAL);
+
+        sealed = sd_memfd_get_sealed(m);
+        if (sealed < 0)
+                return sealed;
+
+        q = mmap(NULL, size, sealed ? PROT_READ : PROT_READ|PROT_WRITE, MAP_PRIVATE, m->fd, offset);
+        if (q == MAP_FAILED)
+                return -errno;
+
+        *p = q;
+        return 0;
+}
+
+int sd_memfd_set_sealed(sd_memfd *m) {
+        int r;
+
+        assert_return(m, -EINVAL);
+
+        r = fcntl(m->fd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE);
+        if (r < 0)
+                return -errno;
+
+        return 0;
+}
+
+int sd_memfd_get_sealed(sd_memfd *m) {
+        int r;
+
+        assert_return(m, -EINVAL);
+
+        r = fcntl(m->fd, F_GET_SEALS);
+        if (r < 0)
+                return -errno;
+
+        return (r & (F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE)) ==
+                    (F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE);
+}
+
+int sd_memfd_get_size(sd_memfd *m, uint64_t *sz) {
+        int r;
+        struct stat stat;
+
+        assert_return(m, -EINVAL);
+        assert_return(sz, -EINVAL);
+
+        r = fstat(m->fd, &stat);
+        if (r < 0)
+                return -errno;
+
+        *sz = stat.st_size;
+        return r;
+}
+
+int sd_memfd_set_size(sd_memfd *m, uint64_t sz) {
+        int r;
+
+        assert_return(m, -EINVAL);
+
+        r = ftruncate(m->fd, sz);
+        if (r < 0)
+                return -errno;
+
+        return r;
+}
+
+int sd_memfd_new_and_map(sd_memfd **m, const char *name, size_t sz, void **p) {
+        sd_memfd *n;
+        int r;
+
+        r = sd_memfd_new(&n, name);
+        if (r < 0)
+                return r;
+
+        r = sd_memfd_set_size(n, sz);
+        if (r < 0) {
+                sd_memfd_free(n);
+                return r;
+        }
+
+        r = sd_memfd_map(n, 0, sz, p);
+        if (r < 0) {
+                sd_memfd_free(n);
+                return r;
+        }
+
+        *m = n;
+        return 0;
+}
+
+int sd_memfd_get_name(sd_memfd *m, char **name) {
+        char path[sizeof("/proc/self/fd/") + DECIMAL_STR_MAX(int)], buf[FILENAME_MAX+1], *e;
+        const char *delim, *end;
+        _cleanup_free_ char *n = NULL;
+        ssize_t k;
+
+        assert_return(m, -EINVAL);
+        assert_return(name, -EINVAL);
+
+        sprintf(path, "/proc/self/fd/%i", m->fd);
+
+        k = readlink(path, buf, sizeof(buf));
+        if (k < 0)
+                return -errno;
+
+        if ((size_t) k >= sizeof(buf))
+                return -E2BIG;
+
+        buf[k] = 0;
+
+        delim = strstr(buf, ":[");
+        if (!delim)
+                return -EIO;
+
+        delim = strchr(delim + 2, ':');
+        if (!delim)
+                return -EIO;
+
+        delim++;
+
+        end = strchr(delim, ']');
+        if (!end)
+                return -EIO;
+
+        n = strndup(delim, end - delim);
+        if (!n)
+                return -ENOMEM;
+
+        e = bus_label_unescape(n);
+        if (!e)
+                return -ENOMEM;
+
+        *name = e;
+
+        return 0;
+}
diff --git a/src/shared/memfd.h b/src/shared/memfd.h
new file mode 100644
index 0000000000..6de045c1d7
--- /dev/null
+++ b/src/shared/memfd.h
@@ -0,0 +1,57 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef foosdmemfdhfoo
+#define foosdmemfdhfoo
+
+/***
+  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 <inttypes.h>
+#include <sys/types.h>
+#include <stdio.h>
+
+#include "_sd-common.h"
+
+_SD_BEGIN_DECLARATIONS;
+
+typedef struct sd_memfd sd_memfd;
+
+int sd_memfd_new(sd_memfd **m, const char *name);
+int sd_memfd_new_from_fd(sd_memfd **m, int fd);
+int sd_memfd_new_and_map(sd_memfd **m, const char *name, size_t sz, void **p);
+
+void sd_memfd_free(sd_memfd *m);
+
+int sd_memfd_get_fd(sd_memfd *m);
+int sd_memfd_dup_fd(sd_memfd *n);
+int sd_memfd_get_file(sd_memfd *m, FILE **f);
+
+int sd_memfd_map(sd_memfd *m, uint64_t offset, size_t size, void **p);
+
+int sd_memfd_set_sealed(sd_memfd *m);
+int sd_memfd_get_sealed(sd_memfd *m);
+
+int sd_memfd_get_size(sd_memfd *m, uint64_t *sz);
+int sd_memfd_set_size(sd_memfd *m, uint64_t sz);
+
+int sd_memfd_get_name(sd_memfd *m, char **name);
+
+_SD_END_DECLARATIONS;
+
+#endif