The format plugins should implement this callback to tell whether they
are a good fit to read the given path or not. This allows to move
CTF-specific code from the core to ctf.c. This should be a step towards
having more than one input plugin.

The callback should return 1 if it wants to handle this path, 0 otherwise. It
should return -1 in case of catastrophic failure.

Signed-off-by: Simon Marchi <[email protected]>
---
 converter/babeltrace.c      | 91 ++++++++++++++++++++++-----------------------
 formats/ctf/ctf.c           | 50 +++++++++++++++++++++++++
 include/babeltrace/format.h |  1 +
 3 files changed, 95 insertions(+), 47 deletions(-)

diff --git a/converter/babeltrace.c b/converter/babeltrace.c
index d5a7040..d1a8aa3 100644
--- a/converter/babeltrace.c
+++ b/converter/babeltrace.c
@@ -416,7 +416,16 @@ end:
        return ret;
 }
 
-static GPtrArray *traversed_paths = 0;
+/*
+ * Since nftw doesn't pass a user data pointer to its callbacks, we
+ * have to resort to global variables.
+ */
+struct traverse_trace_dir_args {
+       struct bt_format *format;
+       GPtrArray *paths;
+};
+
+static struct traverse_trace_dir_args traverse_trace_dir_args = {NULL, NULL};
 
 /*
  * traverse_trace_dir() is the callback function for File Tree Walk (nftw).
@@ -429,53 +438,32 @@ static GPtrArray *traversed_paths = 0;
 static int traverse_trace_dir(const char *fpath, const struct stat *sb,
                        int tflag, struct FTW *ftwbuf)
 {
-       int dirfd, metafd;
-       int closeret;
+       int ret;
+       struct traverse_trace_dir_args args = traverse_trace_dir_args;
 
-       if (tflag != FTW_D)
-               return 0;
+       assert(args.format != NULL);
+       assert(args.paths != NULL);
 
-       dirfd = open(fpath, 0);
-       if (dirfd < 0) {
-               fprintf(stderr, "[error] [Context] Unable to open trace "
-                       "directory file descriptor.\n");
-               return 0;       /* partial error */
+       if (!args.format->read_fit) {
+               /* The plug-in needs to implement read_fit. */
+               return -1;
        }
-       metafd = openat(dirfd, "metadata", O_RDONLY);
-       if (metafd < 0) {
-               closeret = close(dirfd);
-               if (closeret < 0) {
-                       perror("close");
-                       return -1;
-               }
-               /* No meta data, just return */
-               return 0;
-       } else {
-               int err_close = 0;
 
-               closeret = close(metafd);
-               if (closeret < 0) {
-                       perror("close");
-                       err_close = 1;
-               }
-               closeret = close(dirfd);
-               if (closeret < 0) {
-                       perror("close");
-                       err_close = 1;
-               }
-               if (err_close) {
-                       return -1;
-               }
+       ret = args.format->read_fit(fpath, tflag == FTW_D);
 
-               /* Add path to the global list */
-               if (traversed_paths == NULL) {
-                       fprintf(stderr, "[error] [Context] Invalid open path 
array.\n");        
-                       return -1;
-               }
-               g_ptr_array_add(traversed_paths, g_string_new(fpath));
+       /*
+        * If ret is negative (means error), we return directly. This will
+        * interrupt the file tree walk. If ret is 0, the format is not 
interested
+        * by the path, we also return directly.
+        */
+
+       if (ret > 0) {
+               /* Format is interested. Add path to the global list */
+               g_ptr_array_add(args.paths, g_string_new(fpath));
+               ret = 0;
        }
 
-       return 0;
+       return ret;
 }
 
 /*
@@ -499,15 +487,22 @@ int bt_context_add_traces_recursive(struct bt_context 
*ctx, const char *path,
 
        /* Should lock traversed_paths mutex here if used in multithread */
 
-       traversed_paths = g_ptr_array_new();
+       struct bt_format *format = 
bt_lookup_format(g_quark_from_string(format_str));
+       if (!format) {
+               ret = -1;
+               goto error;
+       }
+
+       traverse_trace_dir_args.paths = g_ptr_array_new();
+       traverse_trace_dir_args.format = format;
        ret = nftw(path, traverse_trace_dir, 10, 0);
 
        /* Process the array if ntfw did not return a fatal error */
        if (ret >= 0) {
                int i;
 
-               for (i = 0; i < traversed_paths->len; i++) {
-                       GString *trace_path = g_ptr_array_index(traversed_paths,
+               for (i = 0; i < traverse_trace_dir_args.paths->len; i++) {
+                       GString *trace_path = 
g_ptr_array_index(traverse_trace_dir_args.paths,
                                                                i);
                        int trace_id = bt_context_add_trace(ctx,
                                                            trace_path->str,
@@ -527,8 +522,8 @@ int bt_context_add_traces_recursive(struct bt_context *ctx, 
const char *path,
                }
        }
 
-       g_ptr_array_free(traversed_paths, TRUE);
-       traversed_paths = NULL;
+       g_ptr_array_free(traverse_trace_dir_args.paths, TRUE);
+       traverse_trace_dir_args.paths = NULL;
 
        /* Should unlock traversed paths mutex here if used in multithread */
 
@@ -539,6 +534,8 @@ int bt_context_add_traces_recursive(struct bt_context *ctx, 
const char *path,
                fprintf(stderr, "[error] Cannot open any trace for 
reading.\n\n");
                ret = -ENOENT;          /* failure */
        }
+
+error:
        return ret;
 }
 
@@ -697,7 +694,7 @@ int main(int argc, char **argv)
                }
        }
        fmt_read = 
bt_lookup_format(g_quark_from_static_string(opt_input_format));
-       if (!fmt_read || fmt_read->name != g_quark_from_static_string("ctf")) {
+       if (!fmt_read) {
                fprintf(stderr, "[error] Format \"%s\" is not supported.\n\n",
                        opt_input_format);
                partial_error = 1;
diff --git a/formats/ctf/ctf.c b/formats/ctf/ctf.c
index 5fcfcdd..101eafb 100644
--- a/formats/ctf/ctf.c
+++ b/formats/ctf/ctf.c
@@ -111,6 +111,9 @@ static
 int ctf_convert_index_timestamp(struct bt_trace_descriptor *tdp);
 
 static
+int ctf_read_fit(const char *fpath, int is_dir);
+
+static
 rw_dispatch read_dispatch_table[] = {
        [ CTF_TYPE_INTEGER ] = ctf_integer_read,
        [ CTF_TYPE_FLOAT ] = ctf_float_read,
@@ -144,6 +147,7 @@ struct bt_format ctf_format = {
        .timestamp_begin = ctf_timestamp_begin,
        .timestamp_end = ctf_timestamp_end,
        .convert_index_timestamp = ctf_convert_index_timestamp,
+       .read_fit = ctf_read_fit,
 };
 
 static
@@ -2095,6 +2099,52 @@ int ctf_convert_index_timestamp(struct 
bt_trace_descriptor *tdp)
 }
 
 static
+int ctf_read_fit(const char *fpath, int is_dir)
+{
+       int dirfd, metafd;
+       int closeret;
+
+       if (!is_dir)
+                       return 0;
+
+       dirfd = open(fpath, 0);
+       if (dirfd < 0) {
+               fprintf(stderr, "[error] [Context] Unable to open trace "
+                       "directory file descriptor.\n");
+               return 0;       /* partial error */
+       }
+       metafd = openat(dirfd, "metadata", O_RDONLY);
+       if (metafd < 0) {
+               closeret = close(dirfd);
+               if (closeret < 0) {
+                       perror("close");
+                       return -1;
+               }
+               /* No meta data, just return */
+               return 0;
+       } else {
+               int err_close = 0;
+
+               closeret = close(metafd);
+               if (closeret < 0) {
+                       perror("close");
+                       err_close = 1;
+               }
+               closeret = close(dirfd);
+               if (closeret < 0) {
+                       perror("close");
+                       err_close = 1;
+               }
+               if (err_close) {
+                       return -1;
+               }
+       }
+
+       /* This path is interesting. */
+       return 1;
+}
+
+static
 int ctf_close_file_stream(struct ctf_file_stream *file_stream)
 {
        int ret;
diff --git a/include/babeltrace/format.h b/include/babeltrace/format.h
index 07e854f..588c0ff 100644
--- a/include/babeltrace/format.h
+++ b/include/babeltrace/format.h
@@ -77,6 +77,7 @@ struct bt_format {
        uint64_t (*timestamp_end)(struct bt_trace_descriptor *descriptor,
                        struct bt_trace_handle *handle, enum bt_clock_type 
type);
        int (*convert_index_timestamp)(struct bt_trace_descriptor *descriptor);
+       int (*read_fit)(const char *path, int is_dir);
 };
 
 extern struct bt_format *bt_lookup_format(bt_intern_str qname);
-- 
1.8.3.2


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