Fix one error in the example usage of the archive_write API and fill

in a few missing details.  The example code here is now a complete,
functioning example program.

lib/libarchive/archive_write.3

@@ -272,38 +272,17 @@ and
 .Xr close 2
 system calls.
 .Bd -literal -offset indent
-void
-write_archive(const char **filename)
-{
-  struct mydata *mydata = malloc(sizeof(struct mydata));
-  struct archive *a;
-  struct archive_entry *entry;
-  struct stat st;
-  char buff[8192];
-  int len;
+#include <sys/stat.h>
+#include <archive.h>
+#include <archive_entry.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
 
-  a = archive_write_new();
-  mydata->name = name;
-  archive_write_set_compression_gzip(a);
-  archive_write_set_format_ustar(a);
-  archive_write_open(a, mydata, myopen, mywrite, myclose);
-  while (*filename) {
-    stat(*filename, &st);
-    entry = archive_entry_new();
-    archive_entry_copy_stat(entry, &st);
-    archive_entry_set_pathname(entry, *filename);
-    archive_write_header(a, entry);
-    fd = open(*filename, O_RDONLY);
-    len = read(fd, buff, sizeof(buff));
-    while ( len >= 0 ) {
-	archive_write_data(a, buff, len);
-	len = read(fd, buff, sizeof(buff));
-    }
-    archive_entry_free(entry);
-    filename++;
-  }
-  archive_write_finish(a);
-}
+struct mydata {
+	const char *name;
+	int fd;
+};
 
 int
 myopen(struct archive *a, void *client_data)
@@ -311,7 +290,10 @@ myopen(struct archive *a, void *client_data)
   struct mydata *mydata = client_data;
 
   mydata->fd = open(mydata->name, O_WRONLY | O_CREAT, 0644);
-  return (mydata->fd >= 0);
+  if (mydata->fd >= 0)
+    return (ARCHIVE_OK);
+  else
+    return (ARCHIVE_FATAL);
 }
 
 ssize_t
@@ -331,6 +313,49 @@ myclose(struct archive *a, void *client_data)
     close(mydata->fd);
   return (0);
 }
+
+void
+write_archive(const char *outname, const char **filename)
+{
+  struct mydata *mydata = malloc(sizeof(struct mydata));
+  struct archive *a;
+  struct archive_entry *entry;
+  struct stat st;
+  char buff[8192];
+  int len;
+  int fd;
+
+  a = archive_write_new();
+  mydata->name = outname;
+  archive_write_set_compression_gzip(a);
+  archive_write_set_format_ustar(a);
+  archive_write_open(a, mydata, myopen, mywrite, myclose);
+  while (*filename) {
+    stat(*filename, &st);
+    entry = archive_entry_new();
+    archive_entry_copy_stat(entry, &st);
+    archive_entry_set_pathname(entry, *filename);
+    archive_write_header(a, entry);
+    fd = open(*filename, O_RDONLY);
+    len = read(fd, buff, sizeof(buff));
+    while ( len > 0 ) {
+	archive_write_data(a, buff, len);
+	len = read(fd, buff, sizeof(buff));
+    }
+    archive_entry_free(entry);
+    filename++;
+  }
+  archive_write_finish(a);
+}
+
+int main(int argc, const char **argv)
+{
+	const char *outname;
+	argv++;
+	outname = argv++;
+	write_archive(outname, argv);
+	return 0;
+}
 .Ed
 .Sh RETURN VALUES
 Most functions return zero on success, non-zero on error.