discover: separate file-reading code into file.c

[petitboot] / discover / file.c

diff --git a/discover/file.c b/discover/file.c
new file mode 100644 (file)
index 0000000..269421c
--- /dev/null
+++ b/discover/file.c
@@ -0,0 +1,77 @@
+/*
+ *  Copyright (C) 2013 Jeremy Kerr <jk@ozlabs.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <talloc/talloc.h>
+
+#include "file.h"
+
+static const int max_file_size = 1024 * 1024;
+
+int read_file(void *ctx, const char *filename, char **bufp, int *lenp)
+{
+       struct stat statbuf;
+       int rc, fd, i, len;
+       char *buf;
+
+       fd = open(filename, O_RDONLY);
+       if (fd < 0)
+               return -1;
+
+       rc = fstat(fd, &statbuf);
+       if (rc < 0)
+               goto err_close;
+
+       len = statbuf.st_size;
+       if (len > max_file_size)
+               goto err_close;
+
+       buf = talloc_array(ctx, char, len + 1);
+       if (!buf)
+               goto err_close;
+
+       for (i = 0; i < len; i += rc) {
+               rc = read(fd, buf + i, len - i);
+
+               /* unexpected EOF: trim and return */
+               if (rc == 0) {
+                       len = i;
+                       break;
+               }
+
+               if (rc < 0)
+                       goto err_free;
+
+       }
+
+       buf[len] = '\0';
+
+       close(fd);
+       *bufp = buf;
+       *lenp = len;
+       return 0;
+
+err_free:
+       talloc_free(buf);
+err_close:
+       close(fd);
+       return -1;
+}