+/*
+ * libringbuffer/shm.c
+ *
+ * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include "shm.h"
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h> /* For mode constants */
+#include <fcntl.h> /* For O_* constants */
+#include <assert.h>
+#include <ust/align.h>
+
+struct shm_object_table *shm_object_table_create(size_t max_nb_obj)
+{
+ struct shm_object_table *table;
+
+ table = zmalloc(sizeof(struct shm_object_table) +
+ max_nb_obj * sizeof(table->objects[0]));
+ table->size = max_nb_obj;
+ return table;
+}
+
+struct shm_object *shm_object_table_append(struct shm_object_table *table,
+ size_t memory_map_size)
+{
+ int shmfd, waitfd[2], ret, i;
+ struct shm_object *obj;
+ char *memory_map;
+
+ if (table->allocated_len >= table->size)
+ return NULL;
+ obj = &table->objects[table->allocated_len++];
+
+ /* wait_fd: create pipe */
+ ret = pipe(waitfd);
+ if (ret < 0) {
+ PERROR("pipe");
+ goto error_pipe;
+ }
+ for (i = 0; i < 2; i++) {
+ ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC);
+ if (ret < 0) {
+ PERROR("fcntl");
+ goto error_fcntl;
+ }
+ }
+ *obj->wait_fd = *waitfd;
+
+ /* shm_fd: create shm */
+
+ /*
+ * Allocate shm, and immediately unlink its shm oject, keeping
+ * only the file descriptor as a reference to the object. If it
+ * already exists (caused by short race window during which the
+ * global object exists in a concurrent shm_open), simply retry.
+ * We specifically do _not_ use the / at the beginning of the
+ * pathname so that some OS implementations can keep it local to
+ * the process (POSIX leaves this implementation-defined).
+ */
+ do {
+ shmfd = shm_open("ust-shm-tmp",
+ O_CREAT | O_EXCL | O_RDWR, 0700);
+ } while (shmfd < 0 && errno == EEXIST);
+ if (shmfd < 0) {
+ PERROR("shm_open");
+ goto error_shm_open;
+ }
+ ret = shm_unlink("ust-shm-tmp");
+ if (ret) {
+ PERROR("shm_unlink");
+ goto error_unlink;
+ }
+ ret = ftruncate(shmfd, memory_map_size);
+ if (ret) {
+ PERROR("ftruncate");
+ goto error_ftruncate;
+ }
+ obj->shm_fd = shmfd;
+
+ /* memory_map: mmap */
+ memory_map = mmap(NULL, memory_map_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED, shmfd, 0);
+ if (memory_map == MAP_FAILED) {
+ PERROR("mmap");
+ goto error_mmap;
+ }
+ obj->memory_map = memory_map;
+ obj->memory_map_size = memory_map_size;
+ obj->allocated_len = 0;
+ return obj;
+
+error_mmap:
+error_ftruncate:
+error_unlink:
+ ret = close(shmfd);
+ if (ret) {
+ PERROR("close");
+ assert(0);
+ }
+error_shm_open:
+error_fcntl:
+ for (i = 0; i < 2; i++) {
+ ret = close(waitfd[i]);
+ if (ret) {
+ PERROR("close");
+ assert(0);
+ }
+ }
+error_pipe:
+ free(obj);
+ return NULL;
+
+}
+
+static
+void shmp_object_destroy(struct shm_object *obj)
+{
+ int ret, i;
+
+ ret = munmap(obj->memory_map, obj->memory_map_size);
+ if (ret) {
+ PERROR("umnmap");
+ assert(0);
+ }
+ ret = close(obj->shm_fd);
+ if (ret) {
+ PERROR("close");
+ assert(0);
+ }
+ for (i = 0; i < 2; i++) {
+ ret = close(obj->wait_fd[i]);
+ if (ret) {
+ PERROR("close");
+ assert(0);
+ }
+ }
+}
+
+void shm_object_table_destroy(struct shm_object_table *table)
+{
+ int i;
+
+ for (i = 0; i < table->allocated_len; i++)
+ shmp_object_destroy(&table->objects[i]);
+ free(table);
+}
+
+/*
+ * zalloc_shm - allocate memory within a shm object.
+ *
+ * Shared memory is already zeroed by shmget.
+ * *NOT* multithread-safe (should be protected by mutex).
+ * Returns a -1, -1 tuple on error.
+ */
+struct shm_ref zalloc_shm(struct shm_object *obj, size_t len)
+{
+ struct shm_ref ref;
+ struct shm_ref shm_ref_error = { -1, -1 };
+
+ if (obj->memory_map_size - obj->allocated_len < len)
+ return shm_ref_error;
+ ref.index = obj->index;
+ ref.offset = obj->allocated_len;
+ obj->allocated_len += len;
+ return ref;
+}
+
+void align_shm(struct shm_object *obj, size_t align)
+{
+ size_t offset_len = offset_align(obj->allocated_len, align);
+ obj->allocated_len += offset_len;
+}