1 files changed, 89 insertions, 0 deletions
diff --git a/makefile.c b/makefile.c
new file mode 100644
index 0000000..ef280b9
--- /dev/null
+++ b/makefile.c
@@ -0,0 +1,89 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+static const char *const default_makefiles[] = {
+	"makefile",
+	"Makefile"
+};
+
+
+int
+open_default_makefile(const char **pathp)
+{
+	int fd;
+	size_t i;
+
+	/* The specification says that the alternatives “shall be
+	 * tried”, but it uses the phrase “if neither … are found”,
+	 * implying that make(1) shall fail if a file cannot be
+	 * opened and only try the next alternative if it failed
+	 * becomes the file does not exist.
+	 */
+
+	for (i = 0; i < ELEMSOF(default_makefiles); i++) {
+		*pathp = default_makefiles[i];
+		fd = open(*pathp, O_RDONLY);
+		if (fd >= 0) {
+			printinfof(WC_MAKEFILE, "found standard makefile to use: %s", *pathp);
+			goto find_existing_fallbacks;
+		} else if (errno != ENOENT) {
+			eprintf("found standard makefile to use, but failed to open: %s:", *pathp);
+		}
+	}
+
+	printerrorf("couldn't find any makefile to use, portable "
+	            "alternatives are ./makefile and ./Makefile");
+
+find_existing_fallbacks:
+	for (i++; i < ELEMSOF(default_makefiles); i++)
+		if (!access(default_makefiles[i], F_OK))
+			warnf_warning(WC_EXTRA_MAKEFILE, "found additional standard makefile: %s",
+			              default_makefiles[i]);
+
+	return fd;
+}
+
+
+void
+cmdline_opt_f(const char *arg, const char **makefile_pathp)
+{
+	static int warning_emitted = 0;
+
+	if (*makefile_pathp && !warning_emitted) {
+		warning_emitted = 1;
+		warnf_unspecified(WC_CMDLINE, "the -f option has been specified multiple times, "
+		                              "they are processed in order, but the behaviour is "
+	                                      "otherwise unspecified");
+		printinfof(WC_CMDLINE, "this implementation will use the last "
+		                       "option and discard earlier options");
+	}
+
+	*makefile_pathp = arg;
+}
+
+
+struct line *
+load_makefile(const char *path, size_t *nlinesp)
+{
+	struct line *lines;
+	int fd;
+
+	if (!path) {
+		fd = open_default_makefile(&path);
+	} else if (!strcmp(path, "-")) {
+		/* “A pathname of '-' shall denote the standard input” */
+		fd = dup(STDIN_FILENO);
+		if (fd < 0)
+			eprintf("dup <stdin>:");
+		path = "<stdin>";
+	} else {
+		fd = open(path, O_RDONLY);
+		if (fd < 0)
+			eprintf("open %s O_RDONLY:", path);
+	}
+
+	lines = load_text_file(fd, path, 0, nlinesp);
+	close(fd);
+	return lines;
+}