lib/mmap-packet-seek.c

   1 #include "babeltrace/ctf/types.h"
   2 #include "babeltrace/ctf/metadata.h"
   3
   4 void ctf_move_mmap_pos_slow(struct ctf_stream_pos *pos, size_t offset, int whence)
   5 {
   6         struct ctf_file_stream *file_stream =
   7                 container_of(pos, struct ctf_file_stream, pos);
   8         int ret, err, i;
   9         off_t off;
  10         struct packet_index *index;
  11         int len_index;
  12         struct mmap_stream *iter, *tmp;
  13         struct mmap_stream tmp_snapshot;
  14
  15         /* first time we have to mmap the region */
  16         if (pos->mmap_len == 0) {
  17                 /* get the len of the mmap region */
  18                 ret = kernctl_get_mmap_len(pos->fd, &pos->mmap_len);
  19                 if (ret != 0) {
  20                         ret = errno;
  21                         perror("kernctl_get_mmap_len");
  22                         goto end;
  23                 }
  24                 pos->mmap_real_base = mmap(NULL, pos->mmap_len, PROT_READ, MAP_PRIVATE, pos->fd, 0);
  25                 if (pos->mmap_real_base == MAP_FAILED) {
  26                         perror("Error mmaping");
  27                         ret = -1;
  28                 }
  29         }
  30
  31         if (pos->base) {
  32                 /* FIXME : put_subbuf should work but fails after nb_subbuf get + put */
  33                 ret = kernctl_put_next_subbuf(pos->fd);
  34                 if (ret != 0) {
  35                         ret = errno;
  36                         perror("kernctl_put_subbuf");
  37                 }
  38                 pos->base = NULL;
  39         }
  40
  41 next_snapshot:
  42         tmp_snapshot.kconsumerd_fd = 0;
  43         for (i = 0; i < available_snapshots->len; i++) {
  44                 tmp = g_ptr_array_index(available_snapshots, 0);
  45                 if (tmp->kconsumerd_fd->wait_fd == pos->fd) {
  46                         tmp_snapshot.last_pos = tmp->last_pos;
  47                         tmp_snapshot.kconsumerd_fd = tmp->kconsumerd_fd;
  48                         g_ptr_array_remove_index(available_snapshots, i);
  49                         free(tmp);
  50                         break;
  51                 }
  52         }
  53         if (tmp_snapshot.kconsumerd_fd == 0) {
  54                 pos->offset = EOF;
  55                 return;
  56         }
  57 //      fprintf(stderr,"READING FROM SNAPSHOT ON FD %d at %lu\n",
  58 //                      tmp_snapshot.kconsumerd_fd->wait_fd, tmp_snapshot.last_pos);
  59         ret = kernctl_get_subbuf(tmp_snapshot.kconsumerd_fd->wait_fd, &tmp_snapshot.last_pos);
  60         if (ret != 0) {
  61                 ret = errno;
  62                 perror("kernctl_get_subbuf");
  63                 goto next_snapshot;
  64         }
  65
  66         ret = kernctl_get_mmap_read_offset(pos->fd, &(pos->mmap_offset));
  67         if (ret != 0) {
  68                 ret = errno;
  69                 perror("kernctl_get_mmap_read_offset");
  70                 goto end;
  71         }
  72
  73         /* read only the data in the subbuffer */
  74         err = kernctl_get_subbuf_size(pos->fd, &pos->content_size);
  75         if (err != 0) {
  76                 ret = errno;
  77                 perror("Getting sub-buffer len failed.");
  78                 goto end;
  79         }
  80         /* bits vs bytes */
  81         pos->content_size *= CHAR_BIT;
  82         /* read the whole subbuffer */
  83         err = kernctl_get_padded_subbuf_size(pos->fd, &pos->packet_size);
  84         if (err != 0) {
  85                 ret = errno;
  86                 perror("Getting sub-buffer len failed.");
  87                 goto end;
  88         }
  89         /* bits vs bytes */
  90         pos->packet_size *= CHAR_BIT;
  91
  92         pos->offset = 0;    /* will read headers */
  93
  94         /* map new base. Need mapping length from header. */
  95         pos->base = pos->mmap_real_base + pos->mmap_offset;
  96
  97         /* update trace_packet_header and stream_packet_context */
  98         if (pos->prot != PROT_WRITE && file_stream->parent.trace_packet_header) {
  99                 /* Read packet header */
 100                 ret = generic_rw(&pos->parent, &file_stream->parent.trace_packet_header->p);
 101                 assert(!ret);
 102         }
 103         if (pos->prot != PROT_WRITE && file_stream->parent.stream_packet_context) {
 104                 /* Read packet context */
 105                 ret = generic_rw(&pos->parent, &file_stream->parent.stream_packet_context->p);
 106                 assert(!ret);
 107         }
 108
 109         /* read timestamp begin from header */
 110         len_index = struct_declaration_lookup_field_index(
 111                         file_stream->parent.stream_packet_context->declaration,
 112                         g_quark_from_static_string("timestamp_begin"));
 113         if (len_index >= 0) {
 114                 struct definition_integer *defint;
 115                 struct definition *field;
 116
 117                 field = struct_definition_get_field_from_index(
 118                                 file_stream->parent.stream_packet_context, len_index);
 119                 assert(field->declaration->id == CTF_TYPE_INTEGER);
 120                 defint = container_of(field, struct definition_integer, p);
 121                 assert(defint->declaration->signedness == FALSE);
 122                 file_stream->parent.timestamp = defint->value._unsigned;
 123 //              fprintf(stderr, "READ TIMESTAMP : %lu\n", file_stream->parent.timestamp);
 124         }
 125
 126
 127 end:
 128         return;
 129 }
 130