diff options
Diffstat (limited to 'src/shared/memfd.c')
| -rw-r--r-- | src/shared/memfd.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/src/shared/memfd.c b/src/shared/memfd.c new file mode 100644 index 0000000000..2b0d26d9ed --- /dev/null +++ b/src/shared/memfd.c @@ -0,0 +1,229 @@ +/*-*- 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" + +int memfd_new(int *fd, const char *name) { + + _cleanup_free_ char *g = NULL; + int n; + + assert_return(fd, -EINVAL); + + 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 = memfd_create(name, MFD_ALLOW_SEALING); + if (n < 0) + return -errno; + + *fd = n; + return 0; +} + +int memfd_map(int fd, uint64_t offset, size_t size, void **p) { + void *q; + int sealed; + + assert_return(fd >= 0, -EINVAL); + assert_return(size > 0, -EINVAL); + assert_return(p, -EINVAL); + + 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_return(fd >= 0, -EINVAL); + + r = fcntl(fd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE); + if (r < 0) + return -errno; + + return 0; +} + +int memfd_get_sealed(int fd) { + int r; + + assert_return(fd >= 0, -EINVAL); + + r = fcntl(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 memfd_get_size(int fd, uint64_t *sz) { + int r; + struct stat stat; + + assert_return(fd >= 0, -EINVAL); + assert_return(sz, -EINVAL); + + r = fstat(fd, &stat); + if (r < 0) + return -errno; + + *sz = stat.st_size; + return r; +} + +int memfd_set_size(int fd, uint64_t sz) { + int r; + + assert_return(fd >= 0, -EINVAL); + + r = ftruncate(fd, sz); + if (r < 0) + return -errno; + + return r; +} + +int memfd_new_and_map(int *fd, const char *name, size_t sz, void **p) { + _cleanup_close_ int n = -1; + int r; + + r = memfd_new(&n, name); + if (r < 0) + return r; + + r = memfd_set_size(n, sz); + if (r < 0) + return r; + + r = memfd_map(n, 0, sz, p); + if (r < 0) + return r; + + *fd = n; + n = -1; + return 0; +} + +int memfd_get_name(int fd, 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(fd >= 0, -EINVAL); + assert_return(name, -EINVAL); + + sprintf(path, "/proc/self/fd/%i", 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; +} |