Fix: Don't assume that PROT_WRITE grants read permissions

[babeltrace.git] / formats / ctf / ctf.c

diff --git a/formats/ctf/ctf.c b/formats/ctf/ctf.c
index e31808c3843d27380a63b0d173a949aa027e336e..58b5488920d006e71aafe96b764e5f49ec7c5b6d 100644 (file)
--- a/formats/ctf/ctf.c
+++ b/formats/ctf/ctf.c
@@ -763,7 +763,7 @@ int ctf_init_pos(struct ctf_stream_pos *pos, struct bt_trace_descriptor *trace,
                pos->parent.trace = trace;
                break;
        case O_RDWR:
-               pos->prot = PROT_WRITE; /* Write has priority */
+               pos->prot = PROT_READ | PROT_WRITE;
                pos->flags = MAP_SHARED;
                pos->parent.rw_table = write_dispatch_table;
                pos->parent.event_cb = ctf_write_event;
@@ -779,7 +779,7 @@ int ctf_init_pos(struct ctf_stream_pos *pos, struct bt_trace_descriptor *trace,
 
 int ctf_fini_pos(struct ctf_stream_pos *pos)
 {
-       if (pos->prot == PROT_WRITE && pos->content_size_loc)
+       if ((pos->prot & PROT_WRITE) && pos->content_size_loc)
                *pos->content_size_loc = pos->offset;
        if (pos->base_mma) {
                int ret;
@@ -873,7 +873,7 @@ void ctf_packet_seek(struct bt_stream_pos *stream_pos, size_t index, int whence)
                assert(0);
        }
 
-       if (pos->prot == PROT_WRITE && pos->content_size_loc)
+       if ((pos->prot & PROT_WRITE) && pos->content_size_loc)
                *pos->content_size_loc = pos->offset;
 
        if (pos->base_mma) {
@@ -891,7 +891,7 @@ void ctf_packet_seek(struct bt_stream_pos *stream_pos, size_t index, int whence)
         * The caller should never ask for ctf_move_pos across packets,
         * except to get exactly at the beginning of the next packet.
         */
-       if (pos->prot == PROT_WRITE) {
+       if (pos->prot & PROT_WRITE) {
                switch (whence) {
                case SEEK_CUR:
                        /* The writer will add padding */
@@ -1001,12 +1001,14 @@ void ctf_packet_seek(struct bt_stream_pos *stream_pos, size_t index, int whence)
        }
 
        /* update trace_packet_header and stream_packet_context */
-       if (pos->prot != PROT_WRITE && file_stream->parent.trace_packet_header) {
+       if (!(pos->prot & PROT_WRITE) &&
+               file_stream->parent.trace_packet_header) {
                /* Read packet header */
                ret = generic_rw(&pos->parent, &file_stream->parent.trace_packet_header->p);
                assert(!ret);
        }
-       if (pos->prot != PROT_WRITE && file_stream->parent.stream_packet_context) {
+       if (!(pos->prot & PROT_WRITE) &&
+               file_stream->parent.stream_packet_context) {
                /* Read packet context */
                ret = generic_rw(&pos->parent, &file_stream->parent.stream_packet_context->p);
                assert(!ret);
@@ -2245,13 +2247,17 @@ void ctf_init_mmap_pos(struct ctf_stream_pos *pos,
 
 static
 int prepare_mmap_stream_definition(struct ctf_trace *td,
-               struct ctf_file_stream *file_stream)
+               struct ctf_file_stream *file_stream,
+               void (*packet_seek)(struct bt_stream_pos *pos, size_t index,
+                       int whence))
 {
        struct ctf_stream_declaration *stream;
-       uint64_t stream_id = 0;
+       uint64_t stream_id;
        int ret;
 
-       file_stream->parent.stream_id = stream_id;
+       /* Ask for the first packet to get the stream_id. */
+       packet_seek(&file_stream->pos.parent, 0, SEEK_SET);
+       stream_id = file_stream->parent.stream_id;
        if (stream_id >= td->streams->len) {
                fprintf(stderr, "[error] Stream %" PRIu64 " is not declared "
                                "in metadata.\n", stream_id);
@@ -2281,6 +2287,7 @@ int ctf_open_mmap_stream_read(struct ctf_trace *td,
        struct ctf_file_stream *file_stream;
 
        file_stream = g_new0(struct ctf_file_stream, 1);
+       file_stream->parent.stream_id = -1ULL;
        file_stream->pos.last_offset = LAST_OFFSET_POISON;
        ctf_init_mmap_pos(&file_stream->pos, mmap_info);
 
@@ -2291,7 +2298,7 @@ int ctf_open_mmap_stream_read(struct ctf_trace *td,
                goto error_def;
        }
 
-       ret = prepare_mmap_stream_definition(td, file_stream);
+       ret = prepare_mmap_stream_definition(td, file_stream, packet_seek);
        if (ret)
                goto error_index;