libifupdown: add lif_execute_fmt()

Makefile

@@ -16,7 +16,8 @@ LIBIFUPDOWN_SRC = \
 	libifupdown/fgetline.c \
 	libifupdown/version.c \
 	libifupdown/state.c \
-	libifupdown/environment.c
+	libifupdown/environment.c \
+	libifupdown/execute.c
 
 LIBIFUPDOWN_OBJ = ${LIBIFUPDOWN_SRC:.c=.o}
 LIBIFUPDOWN_LIB = libifupdown.a

libifupdown/execute.c

@@ -0,0 +1,54 @@
+/*
+ * libifupdown/execute.c
+ * Purpose: execution of individual commands
+ *
+ * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <spawn.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "libifupdown/execute.h"
+
+#define SHELL	"/bin/sh"
+
+bool
+lif_execute_fmt(char *const envp[], const char *fmt, ...)
+{
+	char cmdbuf[4096];
+	va_list va;
+
+	va_start(va, fmt);
+	vsnprintf(cmdbuf, sizeof cmdbuf, fmt, va);
+	va_end(va);
+
+	pid_t child;
+	char *argv[] = { SHELL, "-c", cmdbuf, NULL };
+
+	if (posix_spawn(&child, SHELL, NULL, NULL, argv, envp) != 0)
+	{
+		fprintf(stderr, "execute '%s': %s\n", cmdbuf, strerror(errno));
+		return false;
+	}
+
+	int status;
+	waitpid(child, &status, 0);
+
+	return WIFEXITED(status) && WEXITSTATUS(status) == 0;
+}

libifupdown/execute.h

@@ -0,0 +1,24 @@
+/*
+ * libifupdown/execute.h
+ * Purpose: execution of individual commands
+ *
+ * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#ifndef LIBIFUPDOWN_EXECUTE_H__GUARD
+#define LIBIFUPDOWN_EXECUTE_H__GUARD
+
+#include <stdarg.h>
+#include <stdbool.h>
+
+extern bool lif_execute_fmt(char *const envp[], const char *fmt, ...);
+
+#endif

libifupdown/libifupdown.h

@@ -24,5 +24,6 @@
 #include "libifupdown/version.h"
 #include "libifupdown/state.h"
 #include "libifupdown/environment.h"
+#include "libifupdown/execute.h"
 
 #endif