more work on plugins

2 files changed, 156 insertions, 12 deletions

diff --git a/src/main.c b/src/main.c
index 50baf66..36eeaf7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4,6 +4,7 @@
 #include <stdarg.h>
 
 #include "pipeline.h"
+#include "plugins.h"
 
 PIPELINE_STAGE static int identity_stage_handle(const ptx_pipeline_ctx_t *ctx, const void *data, size_t sz)
 {
@@ -119,5 +120,15 @@ int main(void) {
 
   ptx_pipeline_free(pl);
 
+  ptx_plugin_manager_t *mgr = ptx_plugin_manager_new();
+  if (!mgr) {
+    fputs("Failed to allocate plugin manager\n", stderr);
+    return 1;
+  }
+
+  ptx_plugin_manager_load_dir(mgr, "plugins");
+
+  ptx_plugin_manager_free(mgr);
+
   return 0;
 }
diff --git a/src/plugins.c b/src/plugins.c
index f2f8d14..b96aade 100644
--- a/src/plugins.c
+++ b/src/plugins.c
@@ -3,19 +3,35 @@
 #include <stdio.h>
 #include <errno.h>
 #include <string.h>
-
+#include <assert.h>
+#include <dlfcn.h>
 #include <sys/types.h>
 #include <dirent.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
 
 struct ptx__plugin_manager_tag
 {
-  size_t sz_plugins;
-  ptx_plugin_t *plugins;
+  ptx_plugin_t *pl_head, *pl_tail;
 };
 
 struct ptx__plugin_handle_tag
 {
-  char *path;
+  /* what plugin manager is this plugin known to? */
+  ptx_plugin_manager_t *manager;
+
+  /* handle to library */
+  void *modp;
+  const struct ptx_plugin_desc *desc;
+
+  /* plugin list entries */
+  ptx_plugin_t *prev;
+  ptx_plugin_t *next;
+
+  int path_fd;
+  /* plugin filename */
+  char fname[1];
 };
 
 ptx_plugin_manager_t *ptx_plugin_manager_new(void)
@@ -24,40 +40,157 @@ ptx_plugin_manager_t *ptx_plugin_manager_new(void)
   if (!mgr) return NULL;
 
   /* do init */
-  mgr->sz_plugins = 0;
-  mgr->plugins = NULL;
+  mgr->pl_head = mgr->pl_tail = NULL;
 
   return mgr;
 }
 
+/* inform the plugin that it is about to be unloaded. It should clean up its resources. */
+static void deinit_plugin(ptx_plugin_t *plugin);
+
+/* unload/cleanup/free the plugin. */
+static void free_plugin(ptx_plugin_t *plugin);
+
 void ptx_plugin_manager_free(ptx_plugin_manager_t *mgr)
 {
   if (!mgr) return;
 
   /* do cleanup */
+  for (ptx_plugin_t *plugin = mgr->pl_head, *next; plugin; plugin = next) {
+    next = plugin->next;
+    deinit_plugin(plugin);
+    free_plugin(plugin);
+  }
 
   free(mgr);
   return;
 }
 
-int ptx_plugin_manager_load_dir(ptx_plugin_manager_t *mgr, const char *dirnam)
+static ptx_plugin_t *load_plugin(ptx_plugin_manager_t *manager, const char *plugin_file, const char *plugin_fname)
+{
+  /* define and initialize all variables to be cleaned up here! */
+  size_t fnamelen = strlen(plugin_fname);
+
+  ptx_plugin_t *plugin = NULL;
+  void *mod_dl = NULL;
+  const struct ptx_plugin_desc *pl_desc;
+
+  plugin = calloc(1, sizeof(ptx_plugin_t) + fnamelen);
+  if (!plugin) {
+    fprintf(stderr, "(plugin) malloc (loading %s): %s\n", plugin_file, strerror(errno));
+    /* FIXME: maybe abort() for these sorts of issues? */
+    goto cleanup;
+  }
+
+  plugin->manager = manager;
+  memcpy(plugin->fname, plugin_fname, fnamelen); /* NUL-termination achieved thanks to calloc */
+
+  mod_dl = dlopen(plugin_file, RTLD_NOW | RTLD_LOCAL);
+  if (!mod_dl) {
+    fprintf(stderr, "(plugin) dlopen: failed to load %s: %s\n", plugin_fname, dlerror());
+    goto cleanup;
+  }
+
+  plugin->modp = mod_dl;
+
+  pl_desc = dlsym(mod_dl, PTX_STR(PTX__INTERNAL_PLUGIN_DESC_SYM));
+  if (!pl_desc) {
+    fprintf(stderr, "(plugin) dlsym(descriptor): failed to load %s: %s\n", plugin_fname, dlerror());
+    goto cleanup;
+  }
+
+  plugin->desc = pl_desc;
+
+  return plugin;
+
+cleanup:
+  if (mod_dl) dlclose(mod_dl);
+  free(plugin);
+
+  return NULL;
+}
+
+#define PATHBUF_LEN (32)
+int ptx_plugin_manager_load_dir(ptx_plugin_manager_t *mgr, const char *dirname)
 {
   struct dirent *ent;
-  DIR *dir = opendir(dirnam);
+  char pl_pathbuf[PATHBUF_LEN] = { 0 };
+  struct stat st;
+
+  DIR *dir = opendir(dirname);
 
   if (!dir) {
-    fprintf(stderr, "Failed to load plugins from %s (opendir): %s\n", dirnam, strerror(errno));
+    fprintf(stderr, "Failed to load plugins from %s (opendir): %s\n", dirname, strerror(errno));
     return -1;
   }
 
+  int pl_dir_fd = dirfd(dir);
+  assert(pl_dir_fd >= 0);
+
   while ((errno = 0, ent = readdir(dir))) {
-    
+    int pl_fd = openat(pl_dir_fd, ent->d_name, O_PATH);
+    if (pl_fd < 0) {
+      fprintf(stderr, "(plugin) openat: failed to open %s/%s: %s\n", dirname, ent->d_name, strerror(errno));
+      continue;
+    }
+
+    if (fstat(pl_fd, &st) < 0) {
+      fprintf(stderr, "(plugin) fstat: failed to stat %s/%s: %s\n", dirname, ent->d_name, strerror(errno));
+      goto cleanup_iter;
+    }
+
+    if (!S_ISREG(st.st_mode)) {
+      goto cleanup_iter; /* not a file. skip silently */
+    }
+
+    int rlen = snprintf(pl_pathbuf, PATHBUF_LEN, "/proc/self/fd/%d", pl_fd);
+    assert(rlen < PATHBUF_LEN);
+    assert(pl_pathbuf[PATHBUF_LEN-1] == '\0');
+
+    ptx_plugin_t *plugin = load_plugin(mgr, pl_pathbuf, ent->d_name);
+    if (!plugin) goto cleanup_iter; /* error has been reported by load_plugin already. */
+
+    plugin->path_fd = pl_fd;
+
+    if (mgr->pl_head) {
+      assert(mgr->pl_tail);
+
+      mgr->pl_tail->next = plugin;
+      plugin->prev = mgr->pl_tail;
+      plugin->next = NULL;
+      mgr->pl_tail = plugin;
+    } else {
+      assert(!mgr->pl_tail);
+      plugin->prev = plugin->next = NULL;
+      mgr->pl_head = mgr->pl_tail = plugin;
+    }
+
+    continue;
+
+cleanup_iter:
+    close(pl_fd);
   }
 
-  if (errno != 0) {
-    fprintf(stderr, "Error reading entries from %s (readdir): %s\n", dirnam, strerror(errno));
+  int errno_save = errno;
+  closedir(dir);
+
+  if (errno_save != 0) {
+    fprintf(stderr, "Error reading entries from %s (readdir): %s\n", dirname, strerror(errno));
     return -1;
   }
 
   return 0;
 }
+
+static void deinit_plugin(ptx_plugin_t *plugin)
+{
+  /* TODO */
+  UNUSED(plugin);
+}
+
+static void free_plugin(ptx_plugin_t *plugin)
+{
+  dlclose(plugin->modp);
+  close(plugin->path_fd);
+  free(plugin);
+}