Handle short writes.

[buftee] / buftee.c

diff --git a/buftee.c b/buftee.c
index 7ab731b..552a333 100644 (file)
--- a/buftee.c
+++ b/buftee.c
@@ -188,7 +188,7 @@ static void _nblog_helper(int want_errno,
                           const char* format,
                           ...);  // Forward.
 
-#define nblog(fmt...) _nblog_helper(1, __LINE__, __FUNCTION__, fmt)
+//#define nblog(fmt...) _nblog_helper(1, __LINE__, __FUNCTION__, fmt)
 #define nblogx(fmt...) _nblog_helper(0, __LINE__, __FUNCTION__, fmt)
 
 static void warn_time(const char* desc,
@@ -241,16 +241,17 @@ static void wait_until_writable(const int fd) {
     errx(1, "select() did not return writable fd = %d", fd);
 }
 
-static int xwrite(const int fd, struct buf* const buf) {
-  ssize_t write_ret;
-  int saved_errno;
-  struct timespec t0;
-  struct timespec t1;
+// Returns zero on EOF, dies on error, retries on short write.
+static int write_buf(const int fd, struct buf* const buf) {
+  char* data = buf->data;
+  size_t left = (size_t)buf->len;
 
   for (;;) {
+    struct timespec t0;
+    struct timespec t1;
     get_mono_time(&t0);
-    write_ret = write(fd, buf->data, (size_t)buf->len);
-    saved_errno = errno;
+    ssize_t write_ret = write(fd, data, left);
+    int saved_errno = errno;
     get_mono_time(&t1);
     warn_time("write()", &t0, &t1);
 
@@ -261,17 +262,21 @@ static int xwrite(const int fd, struct buf* const buf) {
         wait_until_writable(fd);
         continue;
       }
-      err(1, "write(fd = %d, count = %d) failed", fd, buf->len);
+      err(1, "write(fd = %d, count = %d) failed", fd, (int)left);
     }
-    if (write_ret == 0)
+    if (write_ret == 0) {
       return 0;  // EOF
+    }
     assert(write_ret >= 0);
-    if (write_ret < buf->len)
-      err(1, "write(fd = %d, count = %d) stopped short (returned %d)",
-          fd, buf->len, (int)write_ret);
-      // FIXME: handle this
-    assert(write_ret == buf->len);
-    return (int)write_ret;
+    if (write_ret < (ssize_t)left) {
+      nblogx("short write(fd = %d, count = %d): wrote %d",
+             fd, (int)left, (int)write_ret);
+      left -= write_ret;
+      data += write_ret;
+      continue;
+    }
+    assert(write_ret == (ssize_t)left);
+    return 1;
   }
 }
 
@@ -327,18 +332,18 @@ static void* writer_routine(void *arg) {
     }
 
     // Write.
-    int write_ret = xwrite(my->fd, buf);
-    if (write_ret == 0) {
+    if (write_buf(my->fd, buf) == 0) {
       errx(1, "fd %d hit EOF", my->fd);
     }
-    assert(write_ret == buf->len);
 
     // Unreference buffer, freeing it if we have to.
     lock(my->mutex);
     unref_buf(buf);
     buf = NULL;
   }
-  nblogx("thread exiting cleanly");
+  if (arg != logger) {
+    nblogx("thread exiting cleanly");
+  }
   return NULL;
 }
 
@@ -383,10 +388,7 @@ static void _nblog_helper(int want_errno,
                           const char* func,
                           const char* format,
                           ...) {
-  int saved_errno;
-  if (want_errno)
-    saved_errno = errno;
-
+  int saved_errno = errno;
   va_list va;
   va_start(va, format);
 
@@ -398,7 +400,7 @@ static void _nblog_helper(int want_errno,
 
   // Prefix.
   char buf[512];
-  size_t len;
+  int len;
   extern char *__progname;  // This is where glibc stashes argv[0].
   len = snprintf(buf, sizeof(buf), "%s:%d:%s(): tid %d at %d.%09d: ",
                  __progname, line, func, gettid(),
@@ -512,7 +514,9 @@ int main(int argc, char **argv) {
   while (!STAILQ_EMPTY(&writers)) {
     struct writer_thread* writer = STAILQ_FIRST(&writers);
     STAILQ_REMOVE_HEAD(&writers, entries);
-    // FIXME: free its queue?
+    if (!STAILQ_EMPTY(&writer->queue)) {
+      nblogx("queue for fd %d is not empty", writer->fd);
+    }
     free(writer);
   }
 
@@ -523,6 +527,10 @@ int main(int argc, char **argv) {
   xpthread_cond_broadcast(logger->cond);
   unlock(logger->mutex);
   xpthread_join(logger->thread);
+  pthread_mutex_destroy(logger->mutex);
+  free(logger->mutex);
+  pthread_cond_destroy(logger->cond);
+  free(logger->cond);
   free(logger);
 
   warnx("exiting cleanly");