A3 🎉

A2/fhistogram-mt.c

@@ -0,0 +1,87 @@
+// Setting _DEFAULT_SOURCE is necessary to activate visibility of
+// certain header file contents on GNU/Linux systems.
+#define _DEFAULT_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+#include <stdint.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fts.h>
+
+#include "job_queue.h"
+
+pthread_mutex_t stdout_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+// err.h contains various nonstandard BSD extensions, but they are
+// very handy.
+#include <err.h>
+
+#include "histogram.h"
+
+int main(int argc, char * const *argv) {
+  if (argc < 2) {
+    err(1, "usage: paths...");
+    exit(1);
+  }
+
+  int num_threads = 1;
+  char * const *paths = &argv[1];
+
+  if (argc > 3 && strcmp(argv[1], "-n") == 0) {
+    // Since atoi() simply returns zero on syntax errors, we cannot
+    // distinguish between the user entering a zero, or some
+    // non-numeric garbage.  In fact, we cannot even tell whether the
+    // given option is suffixed by garbage, i.e. '123foo' returns
+    // '123'.  A more robust solution would use strtol(), but its
+    // interface is more complicated, so here we are.
+    num_threads = atoi(argv[2]);
+
+    if (num_threads < 1) {
+      err(1, "invalid thread count: %s", argv[2]);
+    }
+
+    paths = &argv[3];
+  } else {
+    paths = &argv[1];
+  }
+
+  assert(0); // Initialise the job queue and some worker threads here.
+
+  // FTS_LOGICAL = follow symbolic links
+  // FTS_NOCHDIR = do not change the working directory of the process
+  //
+  // (These are not particularly important distinctions for our simple
+  // uses.)
+  int fts_options = FTS_LOGICAL | FTS_NOCHDIR;
+
+  FTS *ftsp;
+  if ((ftsp = fts_open(paths, fts_options, NULL)) == NULL) {
+    err(1, "fts_open() failed");
+    return -1;
+  }
+
+  FTSENT *p;
+  while ((p = fts_read(ftsp)) != NULL) {
+    switch (p->fts_info) {
+    case FTS_D:
+      break;
+    case FTS_F:
+      assert(0); // Process the file p->fts_path, somehow.
+      break;
+    default:
+      break;
+    }
+  }
+
+  fts_close(ftsp);
+
+  assert(0); // Shut down the job queue and the worker threads here.
+
+  move_lines(9);
+
+  return 0;
+}