diff options
Diffstat (limited to '')
| -rw-r--r-- | src/mds.c | 212 |
1 files changed, 93 insertions, 119 deletions
@@ -69,9 +69,12 @@ int main(int argc_, char** argv_) char pathname[PATH_MAX]; char piddata[64]; unsigned int display; - FILE *f; + FILE* f; int rc; - int j; + int j, r; + + +#define exit_if(CONDITION, INSTRUCTION) if (CONDITION) { INSTRUCTION return 1; } argc = argc_; @@ -79,11 +82,8 @@ int main(int argc_, char** argv_) /* Sanity check the number of command line arguments. */ - if (argc > ARGC_LIMIT) - { - eprint("that number of arguments is ridiculous, I will not allow it."); - return 1; - } + exit_if (argc > ARGC_LIMIT, + eprint("that number of arguments is ridiculous, I will not allow it.");); /* Parse command line arguments. */ for (j = 1; j < argc; j++) @@ -91,29 +91,20 @@ int main(int argc_, char** argv_) char* arg = argv[j]; if (startswith(arg, "--master-server=")) /* Master server. */ { - if (got_master_server) - { - eprintf("duplicate declaration of %s.", "--master-server"); - return 1; - } + exit_if (got_master_server, + eprintf("duplicate declaration of %s.", "--master-server");); got_master_server = 1; master_server = arg + strlen("--master-server="); } } /* Stymied if the effective user is not root. */ - if (geteuid() != ROOT_USER_UID) - { - eprint("the effective user is not root, cannot continue."); - return 1; - } + exit_if (geteuid() != ROOT_USER_UID, + eprint("the effective user is not root, cannot continue.");); /* Set up to ignore SIGUSR1, used in mds for re-exec, but we cannot re-exec. */ if (xsigaction(SIGUSR1, SIG_IGN) < 0) - { - perror(*argv); - eprint("while ignoring the SIGUSR1 signal."); - } + perror(*argv); /* Create directory for socket files, PID files and such. */ if (create_directory_root(MDS_RUNTIME_ROOT_DIRECTORY)) @@ -127,88 +118,42 @@ int main(int argc_, char** argv_) fd = open(pathname, O_CREAT | O_EXCL); if (fd == -1) { - /* Reuse display index not no longer used. */ - size_t read_len; + /* Reuse display index if no longer used. */ f = fopen(pathname, "r"); if (f == NULL) /* Race, or error? */ { perror(*argv); - eprintf("while opening the file: %s", pathname); continue; } - read_len = fread(piddata, 1, sizeof(piddata) / sizeof(char), f); - if (ferror(f)) /* Failed to read. */ - { - perror(*argv); - eprintf("while reading the file: %s", pathname); - } - else if (feof(f) == 0) /* Did not read everything. */ - eprint("the content of a PID file is longer than expected."); - else - { - pid_t pid = 0; - size_t i, n = read_len - 1; - for (i = 0; i < n; i++) - { - char c = piddata[i]; - if (('0' <= c) && (c <= '9')) - pid = pid * 10 + (c & 15); - else - { - eprint("the content of a PID file is invalid."); - goto bad; - } - } - if (piddata[n] != '\n') - { - eprint("the content of a PID file is invalid."); - goto bad; - } - if (kill(pid, 0) < 0) /* Check if the PID is still allocated to any process. */ - if (errno == ESRCH) /* PID is not used. */ - { - fclose(f); - close(fd); - break; - } - } - bad: + r = is_pid_file_reusable(f); fclose(f); - continue; + if (r == 0) + continue; } close(fd); break; } - if (display == DISPLAY_MAX) - { - eprint("sorry, too many displays on the system."); - return 1; - /* Yes, the directory could have been removed, but it probably was not. */ - } + exit_if (display == DISPLAY_MAX, + eprint("sorry, too many displays on the system.");); + /* Yes, the directory could have been removed, but it probably was not. */ + +#undef exit_if /* Create PID file. */ - f = fopen(pathname, "w"); - if (f == NULL) - { - perror(*argv); - eprintf("while opening the file: %s", pathname); - return 1; - } + if ((f = fopen(pathname, "w")) == NULL) + goto pfail; xsnprintf(piddata, "%u\n", getpid()); if (fwrite(piddata, 1, strlen(piddata), f) < strlen(piddata)) { fclose(f); if (unlink(pathname) < 0) perror(*argv); - return -1; + return 1; } fflush(f); fclose(f); if (chmod(pathname, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) < 0) - { - perror(*argv); - eprintf("while setting permissions for PID file: %s", pathname); - } + perror(*argv); /* Create data storage directory. */ if (create_directory_root(MDS_STORAGE_ROOT_DIRECTORY)) @@ -228,32 +173,13 @@ int main(int argc_, char** argv_) strcpy(address.sun_path, pathname); unlink(pathname); fd = socket(AF_UNIX, SOCK_STREAM, 0); - if (fchmod(fd, S_IRWXU) < 0) - { - perror(*argv); - eprint("while making anonymous socket private to its owner."); - goto fail; - } - if (bind(fd, (struct sockaddr*)(&address), sizeof(address)) < 0) - { - perror(*argv); - eprintf("while binding socket to file: %s", pathname); - goto fail; - } - if (chown(pathname, getuid(), NOBODY_GROUP_GID) < 0) - { - perror(*argv); - eprint("while making socket private to the real user."); - goto fail; - } + if (fchmod(fd, S_IRWXU) < 0) goto pfail; + if (bind(fd, (struct sockaddr*)(&address), sizeof(address)) < 0) goto pfail; + if (chown(pathname, getuid(), NOBODY_GROUP_GID) < 0) goto pfail; /* Start listening on socket. */ if (listen(fd, SOMAXCONN) < 0) - { - perror(*argv); - eprintf("while setting up listening on socket: %s", pathname); - goto fail; - } + goto pfail; /* Start master server and respawn it if it crashes. */ rc = spawn_and_respawn_server(fd); @@ -279,6 +205,8 @@ int main(int argc_, char** argv_) return rc; + pfail: + perror(*argv); fail: rc = 1; goto done; @@ -286,6 +214,64 @@ int main(int argc_, char** argv_) /** + * Read a PID-file and determine whether it refers to an non-existing process + * + * @param f The PID-file + * @return Whether the PID-file is not longer used + */ +int is_pid_file_reusable(FILE* f) +{ + char piddata[64]; + size_t read_len; + + read_len = fread(piddata, 1, sizeof(piddata) / sizeof(char), f); + if (ferror(f)) /* Failed to read. */ + perror(*argv); + else if (feof(f) == 0) /* Did not read everything. */ + eprint("the content of a PID file is larger than expected."); + else + { + pid_t pid = parse_pid_t(piddata, read_len - 1); + if (pid == (pid_t)-1) + eprint("the content of a PID file is invalid."); + else + if (kill(pid, 0) < 0) /* Check if the PID is still allocated to any process. */ + return errno == ESRCH; /* PID is not used. */ + } + + return 0; +} + + +/** + * Parse an LF-terminated string as a non-negative `pid_t` + * + * @param str The string + * @param n The length of the string, excluding LF-termination + * @return The pid, `(pid_t)-1` if malformated + */ +pid_t parse_pid_t(const char* str, size_t n) +{ + pid_t pid = 0; + size_t i; + + for (i = 0; i < n; i++) + { + char c = str[i]; + if (('0' <= c) && (c <= '9')) + pid = pid * 10 + (c & 15); + else + return (pid_t)-1; + } + + if (str[n] != '\n') + return (pid_t)-1; + + return pid; +} + + +/** * Start master server and respawn it if it crashes * * @param fd The file descriptor of the socket @@ -322,7 +308,6 @@ int spawn_and_respawn_server(int fd) if (pid == (pid_t)-1) { perror(*argv); - eprint("while forking."); goto fail; } @@ -331,16 +316,12 @@ int spawn_and_respawn_server(int fd) /* Get the current time. (Start of child process.) */ time_error = (monotone(&time_start) < 0); if (time_error) - { - perror(*argv); - eprint("while reading a monotonic clock."); - } + perror(*argv); /* Wait for master server to die. */ if (waitpid(pid, &status, 0) == (pid_t)-1) { perror(*argv); - eprint("while waiting for child process to exit."); goto fail; } @@ -376,7 +357,6 @@ int spawn_and_respawn_server(int fd) if (child_args[argc + 0] == NULL) { perror(*argv); - eprint("while duplicating string."); goto fail; } } @@ -389,14 +369,12 @@ int spawn_and_respawn_server(int fd) if (drop_privileges()) { perror(*argv); - eprint("while dropping privileges."); goto fail; } /* Start master server. */ execv(master_server, child_args); perror(*argv); - eprint("while changing execution image."); goto fail; } } @@ -440,7 +418,6 @@ int create_directory_root(const char* pathname) if (errno != EEXIST) /* Unlikely race condition. */ { perror(*argv); - eprintf("while creating directory: %s", pathname); return 1; } } @@ -449,7 +426,6 @@ int create_directory_root(const char* pathname) if (chown(pathname, ROOT_USER_UID, ROOT_GROUP_GID) < 0) { perror(*argv); - eprintf("while changing owner of directory: %s", pathname); return 1; } } @@ -486,7 +462,6 @@ int create_directory_user(const char* pathname) if (errno != EEXIST) /* Unlikely race condition. */ { perror(*argv); - eprintf("while creating directory: %s", pathname); return 1; } } @@ -495,7 +470,6 @@ int create_directory_user(const char* pathname) if (chown(pathname, getuid(), NOBODY_GROUP_GID) < 0) { perror(*argv); - eprintf("while changing owner of directory: %s", pathname); return 1; } } @@ -516,6 +490,7 @@ int unlink_recursive(const char* pathname) int rc = 0; struct dirent* file; + /* Check that we could examine the directory. */ if (dir == NULL) { int errno_ = errno; @@ -524,10 +499,10 @@ int unlink_recursive(const char* pathname) return 0; errno = errno_; perror(*argv); - eprintf("while examining the content of directory: %s", pathname); return 1; } + /* Remove the content of the directory. */ while ((file = readdir(dir)) != NULL) if (strcmp(file->d_name, ".") && strcmp(file->d_name, "..")) if (unlink(file->d_name) < 0) @@ -537,17 +512,16 @@ int unlink_recursive(const char* pathname) else { perror(*argv); - eprintf("while unlinking file: %s", file->d_name); rc = 1; goto done; } eprint("pop"); } + /* Remvoe the drectory. */ if (rmdir(pathname) < 0) { perror(*argv); - eprintf("while removing directory: %s", pathname); rc = 1; } |