[PATCH v1 13/30] lib/process: Add process_get_stdout

[Geoff Levand]

Add a new structure 'struct process_stdout' and optional parameter
'stdout' to the process_run_simple functions to allow the caller
to get a buffer filled with the stdout from the child process.

Rename the process_run_simple functions to process_get_stdout
and add wrappers for the old process_run_simple function names.

Signed-off-by: Geoff Levand <geoff at infradead.org>
---
 lib/process/process.c | 54 ++++++++++++++++++++++++++++++++++++++-------------
 lib/process/process.h | 26 ++++++++++++++++++++-----
 2 files changed, 62 insertions(+), 18 deletions(-)

diff --git a/lib/process/process.c b/lib/process/process.c
index bc392dc..5f1f9d3 100644
--- a/lib/process/process.c
+++ b/lib/process/process.c
@@ -452,48 +452,76 @@ void process_stop_async_all(void)
 	}
 }
 
-int process_run_simple_argv(void *ctx, const char *argv[])
+int process_get_stdout_argv(void *ctx, struct process_stdout **stdout,
+	const char *argv[])
 {
-	struct process *process;
+	struct process *p;
 	int rc;
 
-	process = process_create(ctx);
+	p = process_create(NULL);
+	p->path = argv[0];
+	p->argv = argv;
 
-	process->path = argv[0];
-	process->argv = argv;
+	if (stdout) {
+		p->keep_stdout = true;
+		*stdout = NULL;
+	}
 
-	rc = process_run_sync(process);
+	rc = process_run_sync(p);
 
 	if (!rc)
-		rc = process->exit_status;
+		rc = p->exit_status;
+	else {
+		pb_debug("%s: process_run_sync failed: %s.\n", __func__,
+			p->path);
+		if (*stdout)
+			pb_debug("%s: stdout: %s\n\n", __func__, p->stdout_buf);
+		goto exit;
+	}
+
+	if (!stdout)
+		goto exit;
+
+	*stdout = talloc(ctx, struct process_stdout);
+
+	if (!*stdout) {
+		rc = -1;
+		goto exit;
+	}
 
-	process_release(process);
+	(*stdout)->len = p->stdout_len;
+	(*stdout)->buf = talloc_memdup(*stdout, p->stdout_buf,
+		p->stdout_len + 1);
+	(*stdout)->buf[p->stdout_len] = 0;
 
+exit:
+	process_release(p);
 	return rc;
 }
 
-int process_run_simple(void *ctx, const char *name, ...)
+int process_get_stdout(void *ctx, struct process_stdout **stdout,
+	const char *path, ...)
 {
 	int rc, i, n_argv = 1;
 	const char **argv;
 	va_list ap;
 
-	va_start(ap, name);
+	va_start(ap, path);
 	while (va_arg(ap, char *))
 		n_argv++;
 	va_end(ap);
 
 	argv = talloc_array(ctx, const char *, n_argv + 1);
-	argv[0] = name;
+	argv[0] = path;
 
-	va_start(ap, name);
+	va_start(ap, path);
 	for (i = 1; i < n_argv; i++)
 		argv[i] = va_arg(ap, const char *);
 	va_end(ap);
 
 	argv[i] = NULL;
 
-	rc = process_run_simple_argv(ctx, argv);
+	rc = process_get_stdout_argv(ctx, stdout, argv);
 
 	talloc_free(argv);
 
diff --git a/lib/process/process.h b/lib/process/process.h
index 003ff8e..9473a0d 100644
--- a/lib/process/process.h
+++ b/lib/process/process.h
@@ -27,6 +27,11 @@ struct process_info;
 
 typedef void	(*process_exit_cb)(struct process *);
 
+struct process_stdout {
+	size_t len;
+	char *buf;
+};
+
 struct process {
 	/* caller-provided configuration */
 	const char		*path;
@@ -63,13 +68,24 @@ struct process *process_create(void *ctx);
  */
 void process_release(struct process *process);
 
-/* Synchronous interface. These functions will all block while waiting for
- * the process to exit.
+/* Synchronous interface. The process_run_sync, process_run_simple and
+ * process_get_stdout functions will all block while waiting for the child
+ * process to exit.  Calls to the variadic versions must have a NULL terminating
+ * argument.  For the process_get_stdout calls stderr will go to the log.
  */
 int process_run_sync(struct process *process);
-int process_run_simple_argv(void *ctx, const char *argv[]);
-int process_run_simple(void *ctx, const char *name, ...)
-	__attribute__((sentinel(0)));
+int process_get_stdout_argv(void *ctx, struct process_stdout **stdout,
+	const char *argv[]);
+int process_get_stdout(void *ctx, struct process_stdout **stdout,
+	const char *path, ...) __attribute__((sentinel(0)));
+
+static inline int process_run_simple_argv(void *ctx, const char *argv[])
+{
+	return process_get_stdout_argv(ctx, NULL, argv);
+}
+#define process_run_simple(_ctx, _path, args...) \
+	process_get_stdout(_ctx, NULL, _path, args)
+
 
 /* Asynchronous interface. When a process is run with process_run_async, the
  * function returns without wait()ing for the child process to exit. If the
-- 
2.14.1