src/libds/allocator/shm.c

   1 #include <assert.h>
   2 #include <stdlib.h>
   3 #include <sys/mman.h>
   4 #include <unistd.h>
   5
   6 #include <drm_fourcc.h>
   7 #include <wayland-server.h>
   8
   9 #include "libds/allocator/shm.h"
  10 #include "libds/interfaces/allocator.h"
  11 #include "libds/interfaces/buffer.h"
  12 #include "libds/log.h"
  13 #include "util.h"
  14
  15 struct ds_shm_allocator
  16 {
  17     struct ds_allocator base;
  18 };
  19
  20 struct ds_shm_buffer
  21 {
  22     struct ds_buffer base;
  23     struct ds_shm_attributes shm;
  24     void *data;
  25     size_t size;
  26 };
  27
  28 static const struct ds_allocator_interface shm_allocator_iface;
  29
  30 WL_EXPORT struct ds_allocator *
  31 ds_shm_allocator_create(void)
  32 {
  33     struct ds_shm_allocator *alloc;
  34
  35     alloc = calloc(1, sizeof *alloc);
  36     if (!alloc)
  37         return NULL;
  38
  39     ds_allocator_init(&alloc->base, &shm_allocator_iface,
  40             DS_BUFFER_CAP_DATA_PTR | DS_BUFFER_CAP_SHM);
  41
  42     ds_dbg("Shm allocator(%p) created", alloc);
  43
  44     return &alloc->base;
  45 }
  46
  47 static struct ds_shm_allocator *
  48 shm_allocator_from_allocator(struct ds_allocator *ds_allocator)
  49 {
  50     assert(ds_allocator->iface == &shm_allocator_iface);
  51     return (struct ds_shm_allocator *)ds_allocator;
  52 }
  53
  54 static void
  55 shm_allocator_destroy(struct ds_allocator *ds_allocator)
  56 {
  57     struct ds_shm_allocator *alloc;
  58
  59     alloc = shm_allocator_from_allocator(ds_allocator);
  60     ds_dbg("Destroy Shm allocator(%p)", alloc);
  61     free(alloc);
  62 }
  63
  64 static const struct ds_buffer_interface shm_buffer_interface;
  65
  66 static struct ds_shm_buffer *
  67 shm_buffer_from_buffer(struct ds_buffer *buffer)
  68 {
  69     assert(buffer->iface == &shm_buffer_interface);
  70     return (struct ds_shm_buffer *)buffer;
  71 }
  72
  73 static void
  74 shm_buffer_destroy(struct ds_buffer *ds_buffer)
  75 {
  76     struct ds_shm_buffer *buffer;
  77
  78     buffer = shm_buffer_from_buffer(ds_buffer);
  79
  80     ds_dbg("Destroy shm buffer(%p)", buffer);
  81
  82     munmap(buffer->data, buffer->size);
  83     close(buffer->shm.fd);
  84     free(buffer);
  85 }
  86
  87 static bool
  88 shm_buffer_get_shm(struct ds_buffer *ds_buffer, struct ds_shm_attributes *shm)
  89 {
  90     struct ds_shm_buffer *buffer;
  91
  92     buffer = shm_buffer_from_buffer(ds_buffer);
  93     memcpy(shm, &buffer->shm, sizeof *shm);
  94     return true;
  95 }
  96
  97 static bool
  98 shm_buffer_begin_data_ptr_access(struct ds_buffer *ds_buffer, uint32_t flags,
  99         void **data, uint32_t *format, size_t *stride)
 100 {
 101     struct ds_shm_buffer *buffer;
 102
 103     buffer = shm_buffer_from_buffer(ds_buffer);
 104     *data = buffer->data;
 105     *format = buffer->shm.format;
 106     *stride = buffer->shm.stride;
 107     return true;
 108 }
 109
 110 static void
 111 shm_buffer_end_data_ptr_access(struct ds_buffer *buffer)
 112 {
 113     (void) buffer;
 114
 115     // This space is intentionally left blank
 116 }
 117
 118 static const struct ds_buffer_interface shm_buffer_interface =
 119 {
 120     .destroy = shm_buffer_destroy,
 121     .get_shm = shm_buffer_get_shm,
 122     .begin_data_ptr_access = shm_buffer_begin_data_ptr_access,
 123     .end_data_ptr_access = shm_buffer_end_data_ptr_access,
 124 };
 125
 126 static struct ds_buffer *
 127 shm_allocator_create_buffer(struct ds_allocator *ds_allocator,
 128         int width, int height, uint32_t format)
 129 {
 130     struct ds_shm_buffer *buffer;
 131     int bytes_per_pixel, stride;
 132
 133     buffer = calloc(1, sizeof *buffer);
 134     if (!buffer)
 135         return NULL;
 136
 137     ds_buffer_init(&buffer->base, &shm_buffer_interface, width, height);
 138
 139     // FIXME
 140     bytes_per_pixel = 4;
 141     stride = width * bytes_per_pixel;
 142     buffer->size = stride * height;
 143     buffer->shm.fd = allocate_shm_file(buffer->size);
 144     if (buffer->shm.fd < 0) {
 145         free(buffer);
 146         return NULL;
 147     }
 148
 149     buffer->shm.format = format;
 150     buffer->shm.width = width;
 151     buffer->shm.height = height;
 152     buffer->shm.stride = stride;
 153     buffer->shm.offset = 0;
 154
 155     buffer->data = mmap(NULL, buffer->size, PROT_READ | PROT_WRITE, MAP_SHARED,
 156             buffer->shm.fd, 0);
 157     if (buffer->data == MAP_FAILED) {
 158         ds_log_errno(DS_ERR, "mmap failed");
 159         close(buffer->shm.fd);
 160         free(buffer);
 161         return NULL;
 162     }
 163
 164     ds_dbg("Shm buffer(%p) created: size(%dx%d)", buffer, width, height);
 165
 166     return &buffer->base;
 167 }
 168
 169 static const struct ds_allocator_interface shm_allocator_iface =
 170 {
 171     .destroy = shm_allocator_destroy,
 172     .create_buffer = shm_allocator_create_buffer,
 173 };