diff options
Diffstat (limited to 'src/bus.c')
| -rw-r--r-- | src/bus.c | 161 |
1 files changed, 123 insertions, 38 deletions
@@ -30,6 +30,9 @@ #include <errno.h> #include <string.h> #include <unistd.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> #include <sys/ipc.h> #include <sys/sem.h> @@ -40,37 +43,37 @@ /** * Semaphore used to signal `bus_write` that `bus_read` is ready */ -#define S 0 +#define S 0 /** * Semaphore for making `bus_write` wait while `bus_read` is reseting `S` */ -#define W 1 +#define W 1 /** * Binary semaphore for making `bus_write` exclusively locked */ -#define X 2 +#define X 2 /** * Semaphore used to cue `bus_read` that it may read the shared memory */ -#define Q 3 +#define Q 3 /** * The number of semaphores in the semaphore array */ -#define BUS_SEMAPHORES 4 +#define BUS_SEMAPHORES 4 /** * Decrease the value of a semaphore by 1 * - * @param bus:const bus_t * The bus - * @param semaphore:unsigned short The index of the semaphore, `S`, `W`, `X` or `Q` - * @param flags:short `SEM_UNDO` if the action should be undone when the program exits - * @return :int 0 on success, -1 on error + * @param bus:const bus_t * The bus + * @param semaphore:int The index of the semaphore, `S`, `W`, `X` or `Q` + * @param flags:int `SEM_UNDO` if the action should be undone when the program exits + * @return :int 0 on success, -1 on error */ #define acquire_semaphore(bus, semaphore, flags) \ semaphore_op(bus, semaphore, -1, flags) @@ -78,10 +81,10 @@ /** * Increase the value of a semaphore by 1 * - * @param bus:const bus_t * The bus - * @param semaphore:unsigned short The index of the semaphore, `S`, `W`, `X` or `Q` - * @param flags:short `SEM_UNDO` if the action should be undone when the program exits - * @return :int 0 on success, -1 on error + * @param bus:const bus_t * The bus + * @param semaphore:int The index of the semaphore, `S`, `W`, `X` or `Q` + * @param flags:int `SEM_UNDO` if the action should be undone when the program exits + * @return :int 0 on success, -1 on error */ #define release_semaphore(bus, semaphore, flags) \ semaphore_op(bus, semaphore, +1, flags) @@ -89,9 +92,9 @@ /** * Wait for the value of a semphore to become 0 * - * @param bus:const bus_t * The bus - * @param semaphore:unsigned short The index of the semaphore, `S`, `W`, `X` or `Q` - * @return :int 0 on success, -1 on error + * @param bus:const bus_t * The bus + * @param semaphore:int The index of the semaphore, `S`, `W`, `X` or `Q` + * @return :int 0 on success, -1 on error */ #define zero_semaphore(bus, semaphore) \ semaphore_op(bus, semaphore, 0, 0) @@ -167,7 +170,7 @@ create_semaphores(bus_t *bus) } /* Initialise the array. */ - values.array = calloc(BUS_SEMAPHORES, sizeof(unsigned short)); + values.array = calloc((size_t)BUS_SEMAPHORES, sizeof(unsigned short)); values.array[X] = 1; if (!values.array) goto fail; @@ -210,7 +213,7 @@ create_shared_memory(bus_t *bus) bus->key_shm = (key_t)r + 1; if (bus->key_shm == IPC_PRIVATE) continue; - id = shmget(bus->key_shm, BUS_MEMORY_SIZE, IPC_CREAT | IPC_EXCL | 0600); + id = shmget(bus->key_shm, (size_t)BUS_MEMORY_SIZE, IPC_CREAT | IPC_EXCL | 0600); if (id != -1) break; if ((errno != EEXIST) && (errno != EINTR)) @@ -252,7 +255,7 @@ static int remove_shared_memory(const bus_t *bus) { struct shmid_ds _info; - int id = shmget(bus->key_shm, BUS_MEMORY_SIZE, 0600); + int id = shmget(bus->key_shm, (size_t)BUS_MEMORY_SIZE, 0600); return ((id == -1) || (shmctl(id, IPC_RMID, &_info) == -1)) ? -1 : 0; } @@ -267,13 +270,13 @@ remove_shared_memory(const bus_t *bus) * @return 0 on success, -1 on error */ static int -semaphore_op(const bus_t *bus, unsigned short semaphore, short delta, short flags) +semaphore_op(const bus_t *bus, int semaphore, int delta, int flags) { struct sembuf op; - op.sem_op = delta; - op.sem_num = semaphore; - op.sem_flg = flags; - return semop(bus->sem_id, &op, 1); + op.sem_num = (unsigned short)semaphore; + op.sem_op = (short)delta; + op.sem_flg = (short)flags; + return semop(bus->sem_id, &op, (size_t)1); } @@ -286,11 +289,11 @@ semaphore_op(const bus_t *bus, unsigned short semaphore, short delta, short flag * @return 0 on success, -1 on error */ static int -write_semaphore(const bus_t *bus, unsigned short semaphore, int value) +write_semaphore(const bus_t *bus, unsigned semaphore, int value) { union semun semval; semval.val = value; - return semctl(bus->sem_id, semaphore, SETVAL, semval); + return semctl(bus->sem_id, (unsigned short)semaphore, SETVAL, semval); } @@ -306,7 +309,7 @@ open_shared_memory(bus_t *bus, int flags) { int id; void *address; - t(id = shmget(bus->key_shm, BUS_MEMORY_SIZE, 0600)); + t(id = shmget(bus->key_shm, (size_t)BUS_MEMORY_SIZE, 0600)); address = shmat(id, NULL, (flags & BUS_RDONLY) ? SHM_RDONLY : 0); if ((address == (void *)-1) || !address) goto fail; @@ -334,21 +337,48 @@ fail: } +/** + * Get a random ASCII letter or digit + * + * @return A random ASCII letter or digit + */ +static char +randomchar(void) +{ + int rint = rand(); + double r = (double)rint; + r /= (double)RAND_MAX + 1; + r *= 10 + 26 + 26; + return "0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM"[(int)r]; +} + + /** * Create a new bus * - * @param file The pathname of the bus, `NULL` to create a random one - * @param flags `BUS_EXCL` (if `file` is not `NULL`) to fail if the file - * already exists, otherwise if the file exists, nothing - * will happen - * @return The pathname of the bus, `NULL` on error + * @param file The pathname of the bus, `NULL` to create a random one + * @param flags `BUS_EXCL` (if `file` is not `NULL`) to fail if the file + * already exists, otherwise if the file exists, nothing + * will happen; + * `BUS_INTR` to fail if interrupted + * @param out_file Output parameter for the pathname of the bus + * @return 0 on success, -1 on error */ -const char * -bus_create(const char *file, int flags) +int +bus_create(const char *file, int flags, char **out_file) { - int saved_errno; + int fd = -1, saved_errno; bus_t bus; + char buf[1 + 2 * (3 * sizeof(ssize_t) + 2)]; + size_t ptr, len; + ssize_t wrote; + char *genfile = NULL; + const char *env; + + if (out_file) + *out_file = NULL; + bus.sem_id = -1; bus.key_sem = -1; bus.key_shm = -1; @@ -356,11 +386,60 @@ bus_create(const char *file, int flags) srand((unsigned int)time(NULL) + (unsigned int)rand()); - /* TODO */ (void) file; (void) flags; + if (file) { + fd = open(file, O_CREAT | O_EXCL); + if (fd == -1) { + if ((errno != EEXIST) || (flags & BUS_EXCL)) + return -1; + goto done; + } + } else { + env = getenv("XDG_RUNTIME_DIR"); + if (!env || !*env) + env = "/run"; + genfile = malloc((strlen(env) + 6 + 7 + 30) * sizeof(char)); + if (!genfile) + goto fail; + if (out_file) + *out_file = genfile; + sprintf(genfile, "%s/run/random.", env); + len = strlen(genfile); + genfile[len + 30] = '\0'; + retry: + for (ptr = 0; ptr < 30; ptr++) + genfile[len + ptr] = randomchar(); + fd = open(genfile, O_CREAT | O_EXCL); + if (fd == -1) { + if (errno == EEXIST) + goto retry; + return -1; + } + } t(create_semaphores(&bus)); t(create_shared_memory(&bus)); - return NULL; + + sprintf(buf, "%zi\n%zi\n", (ssize_t)(bus.key_sem), (ssize_t)(bus.key_shm)); + for (len = strlen(buf), ptr = 0; ptr < len;) { + wrote = write(fd, buf + ptr, len - ptr); + if (wrote < 0) { + if ((errno == EINTR) && (flags & BUS_INTR)) + goto fail; + } else { + ptr += (size_t)wrote; + } + } + close(fd); + +done: + if (out_file && !*out_file) { + len = strlen(file) + 1; + *out_file = malloc(len * sizeof(char)); + memcpy(*out_file, file, len * sizeof(char)); + } else if (!out_file) { + free(genfile); + } + return 0; fail: saved_errno = errno; @@ -368,8 +447,14 @@ fail: remove_semaphores(&bus); if (bus.key_shm) remove_shared_memory(&bus); + if (fd == -1) + close(fd); + if (out_file) + *out_file = NULL; + free(genfile); + unlink(file); errno = saved_errno; - return NULL; + return -1; } |