diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/mds-base.c | 159 | ||||
| -rw-r--r-- | src/mds-base.h | 77 | ||||
| -rw-r--r-- | src/mds.c | 2 |
3 files changed, 237 insertions, 1 deletions
diff --git a/src/mds-base.c b/src/mds-base.c new file mode 100644 index 0000000..433564e --- /dev/null +++ b/src/mds-base.c @@ -0,0 +1,159 @@ +/** + * mds — A micro-display server + * Copyright © 2014 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include "mds-base.h" + +#include <libmdsserver/config.h> +#include <libmdsserver/macros.h> + +#include <stdlib.h> +#include <string.h> +#include <limits.h> +#include <stdio.h> +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <unistd.h> + + +#define try(INSTRUCTION) if ((r = INSTRUCTION)) return r + + +int argc; +char** argv; +int is_respawn = 0; +int is_reexec = 0; + +int socket_fd = -1; + + + +/** + * Parse command line arguments + * + * @return Non-zero on error + */ +static int parse_cmdline(void) +{ + int i; + for (i = 1; i < argc; i++) + { + char* arg = argv[i]; + int v; + if ((v = strequals(arg, "--initial-spawn")) || /* Initial spawn? */ + strequals(arg, "--respawn")) /* Respawning after crash? */ + { + exit_if (is_respawn == v, + eprintf("conflicting arguments %s and %s cannot be combined.", + "--initial-spawn", "--respawn");); + is_respawn = !v; + } + else if (strequals(arg, "--re-exec")) /* Re-exec state-marshal. */ + is_reexec = 1; + } + if (is_reexec) + { + is_respawn = 1; + eprint("re-exec performed."); + } + return 0; +} + + +/** + * Connect to the display + * + * @return Non-zero on error + */ +static int connect_to_display(void) +{ + char* display; + char pathname[PATH_MAX]; + struct sockaddr_un address; + + display = getenv("MDS_DISPLAY"); + exit_if ((display == NULL) || (strchr(display, ':') == NULL), + eprint("MDS_DISPLAY has not set.");); + exit_if (display[0] != ':', + eprint("Remote mds sessions are not supported.");); + xsnprintf(pathname, "%s/%s.socket", MDS_RUNTIME_ROOT_DIRECTORY, display + 1); + address.sun_family = AF_UNIX; + strcpy(address.sun_path, pathname); + fail_if ((socket_fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0); + fail_if (connect(socket_fd, (struct sockaddr*)(&address), sizeof(address)) < 0); + + return 0; + + pfail: + perror(*argv); + if (socket_fd >= 0) + close(socket_fd); + return 1; +} + + +/** + * Entry point of the server + * + * @param argc_ Number of elements in `argv_` + * @param argv_ Command line arguments + * @return Non-zero on error + */ +int main(int argc_, char** argv_) +{ + int r; + +#if (LIBEXEC_ARGC_EXTRA_LIMIT < 2) +# error LIBEXEC_ARGC_EXTRA_LIMIT is too small, need at least 2. +#endif + + + argc = argc_; + argv = argv_; + + + if (server_characteristics.require_privileges == 0) + /* Drop privileges like it's hot. */ + fail_if (drop_privileges()); + + + /* Sanity check the number of command line arguments. */ + exit_if (argc > ARGC_LIMIT + LIBEXEC_ARGC_EXTRA_LIMIT, + eprint("that number of arguments is ridiculous, I will not allow it.");); + + + /* Parse command line arguments. */ + try (parse_cmdline()); + + /* Connect to the display. */ + if (is_reexec == 0) + try (connect_to_display()); + + + close(socket_fd); + return 0; + + pfail: + perror(*argv); + if (socket_fd >= 0) + close(socket_fd); + return 1; +} + + +#undef try + diff --git a/src/mds-base.h b/src/mds-base.h new file mode 100644 index 0000000..26b9c17 --- /dev/null +++ b/src/mds-base.h @@ -0,0 +1,77 @@ +/** + * mds — A micro-display server + * Copyright © 2014 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef MDS_MDS_BASE_H +#define MDS_MDS_BASE_H + + +/** + * Characteristics of the server + */ +typedef struct server_characteristics +{ + /** + * Setting this to zero will cause the server to drop privileges as a security precaution + */ + int require_privileges; + +} server_characteristics_t; + + +/** + * This variable should declared by the actual server implementation. + * It must be configured before `main` is invoked. + * + * This tells the server-base how to behave. + */ +extern server_characteristics_t server_characteristics; + + +/** + * Number of elements in `argv` + */ +extern int argc; + +/** + * Command line arguments + */ +extern char** argv; + +/** + * Whether the server has been respawn + * rather than this being the initial spawn. + * This will be at least as true as `is_reexec`. + */ +extern int is_respawn; + +/** + * Whether the server is continuing + * from a self-reexecution + */ +extern int is_reexec; + + +/** + * The file descriptor of the socket + * that is connected to the server + */ +extern int socket_fd; + + + +#endif + @@ -167,7 +167,7 @@ int main(int argc_, char** argv_) address.sun_family = AF_UNIX; strcpy(address.sun_path, pathname); unlink(pathname); - fd = socket(AF_UNIX, SOCK_STREAM, 0); + fail_if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0); fail_if (fchmod(fd, S_IRWXU) < 0); fail_if (bind(fd, (struct sockaddr*)(&address), sizeof(address)) < 0); fail_if (chown(pathname, getuid(), NOBODY_GROUP_GID) < 0); |