1 files changed, 108 insertions, 0 deletions
diff --git a/host/lib/include/subprocess.h b/host/lib/include/subprocess.h
new file mode 100644
index 00000000..cddcf05c
--- /dev/null
+++ b/host/lib/include/subprocess.h
@@ -0,0 +1,108 @@
+/* Copyright 2019 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Library for creating subprocesses in a high level manner. */
+
+#ifndef VBOOT_REFERENCE_SUBPROCESS_H_
+#define VBOOT_REFERENCE_SUBPROCESS_H_
+
+#include <stdio.h>
+#include <stdlib.h>
+
+/**
+ * subprocess_target is the "mini language" of the subprocess
+ * library. It describes where to read or write data from the process.
+ *
+ * There are currently five target of targets:
+ *
+ * - TARGET_NULL: /dev/null, no need to describe any other fields.
+ *
+ * - TARGET_FD: file descriptor, put the fd in the fd field.
+ *
+ * - TARGET_FILE: FILE *, put the FILE pointer in the file field.
+ *
+ * - TARGET_BUFFER: read to, or write from, a buffer. Fields:
+ *   - buffer->buf: the buffer
+ *   - buffer->size: the size of that buffer
+ *   - buffer->bytes_consumed: do not fill out this field.
+ *     subprocess_run will set it to the number of bytes read from the
+ *     process (if writing to a buffer). Goes unused when reading from
+ *     a buffer.
+ *
+ * - TARGET_BUFFER_NULL_TERMINATED: when reading from a buffer, don't
+ *   fill out the size field and subprocess_run will strlen for you.
+ *   When writing to a buffer, subprocess_run will reserve one byte of
+ *   the size for a null terminator and guarantee that the output is
+ *   always NULL terminated.
+ */
+struct subprocess_target {
+	enum {
+		TARGET_NULL,
+		TARGET_FD,
+		TARGET_FILE,
+		TARGET_BUFFER,
+		TARGET_BUFFER_NULL_TERMINATED,
+	} type;
+	union {
+		int fd;
+		FILE *file;
+		struct {
+			char *buf;
+			size_t size;
+
+			/* This variable is used internally by "run" and
+			 * shouldn't be operated on by the caller.
+			 */
+			int _pipefd[2];
+
+			/* This variable is the output of the number of bytes
+			 * read or written. It should be read by the caller, not
+			 * set.
+			 */
+			size_t bytes_consumed;
+		} buffer;
+	};
+};
+
+/**
+ * A convenience subprocess target which uses TARGET_NULL.
+ */
+struct subprocess_target subprocess_null;
+
+/**
+ * A convenience subprocess target which uses TARGET_FD to
+ * STDIN_FILENO.
+ */
+struct subprocess_target subprocess_stdin;
+
+/**
+ * A convenience subprocess target which uses TARGET_FD to
+ * STDOUT_FILENO.
+ */
+struct subprocess_target subprocess_stdout;
+
+/**
+ * A convenience subprocess target which uses TARGET_FD to
+ * STDERR_FILENO.
+ */
+struct subprocess_target subprocess_stderr;
+
+/**
+ * Call a process described by argv and run until completion. Provide
+ * input from the subprocess target input, output to the subprocess
+ * target output, and error to the subprocess target error.
+ *
+ * If either input, output, or error are set to NULL, the will be
+ * &subprocess_stdin, &subprocess_stdout, or &subprocess_stderr
+ * respectively.
+ *
+ * Returns the exit status on success, or negative values on error.
+ */
+int subprocess_run(const char *const argv[],
+		   struct subprocess_target *input,
+		   struct subprocess_target *output,
+		   struct subprocess_target *error);
+
+#endif  /* VBOOT_REFERENCE_SUBPROCESS_H_ */