misc: add stdbuf_cmdline

misc/stdbuf_cmdline.h

@@ -0,0 +1,75 @@
+/**
+ * @file stdbuf_cmdline.h
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * This file is part of BadVPN.
+ * 
+ * BadVPN is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ * 
+ * BadVPN 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * @section DESCRIPTION
+ * 
+ * Builds command line for running a program via stdbuf.
+ */
+
+#ifndef BADVPN_STDBUF_CMDLINE_H
+#define BADVPN_STDBUF_CMDLINE_H
+
+#include <misc/debug.h>
+#include <misc/cmdline.h>
+#include <misc/concat_strings.h>
+
+#define STDBUF_EXEC "/usr/bin/stdbuf"
+
+/**
+ * Builds the initial part of command line for calling a program via stdbuf
+ * with standard output buffering set to line-buffered.
+ * 
+ * @param out {@link CmdLine} to append the result to. Note than on failure, only
+ *            some part of the cmdline may have been appended.
+ * @param exec path to the executable
+ * @return 1 on success, 0 on failure
+ */
+static int build_stdbuf_cmdline (CmdLine *out, const char *exec) WARN_UNUSED;
+
+int build_stdbuf_cmdline (CmdLine *out, const char *exec)
+{
+    if (!CmdLine_AppendMulti(out, 3, STDBUF_EXEC, "-o", "L")) {
+        goto fail1;
+    }
+    
+    if (exec[0] == '/') {
+        if (!CmdLine_Append(out, exec)) {
+            goto fail1;
+        }
+    } else {
+        char *real_exec = concat_strings(2, "./", exec);
+        if (!real_exec) {
+            goto fail1;
+        }
+        int res = CmdLine_Append(out, real_exec);
+        free(real_exec);
+        if (!res) {
+            goto fail1;
+        }
+    }
+    
+    return 1;
+    
+fail1:
+    return 0;
+}
+
+#endif