user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/sysdeps/ironclad/generic/mntent.cpp

@@ -0,0 +1,82 @@
+#include <errno.h>
+#include <mntent.h>
+#include <stdio.h>
+#include <limits.h>
+#include <string.h>
+#include <bits/ensure.h>
+
+namespace {
+
+char *internal_buf;
+size_t internal_bufsize;
+
+}
+
+#define SENTINEL (char *)&internal_buf
+
+FILE *setmntent(const char *name, const char *mode) {
+	return fopen(name, mode);
+}
+
+struct mntent *getmntent(FILE *f) {
+	static struct mntent mnt;
+	return getmntent_r(f, &mnt, SENTINEL, 0);
+}
+
+int addmntent(FILE *f, const struct mntent *mnt) {
+	if(fseek(f, 0, SEEK_END)) {
+		return 1;
+	}
+	return fprintf(f, "%s\t%s\t%s\t%s\t%d\t%d\n",
+		mnt->mnt_fsname, mnt->mnt_dir, mnt->mnt_type, mnt->mnt_opts,
+		mnt->mnt_freq, mnt->mnt_passno) < 0;
+}
+
+int endmntent(FILE *f) {
+	if(f) {
+		fclose(f);
+	}
+	return 1;
+}
+
+char *hasmntopt(const struct mntent *mnt, const char *opt) {
+	return strstr(mnt->mnt_opts, opt);
+}
+
+/* Adapted from musl */
+struct mntent *getmntent_r(FILE *f, struct mntent *mnt, char *linebuf, int buflen) {
+	bool use_internal = (linebuf == SENTINEL);
+
+	char source[60];
+	char target[30];
+	char fs[30];
+	char options[30];
+	int dump;
+	int pass;
+
+	do {
+		if (use_internal) {
+			getline(&internal_buf, &internal_bufsize, f);
+			linebuf = internal_buf;
+		} else {
+			fgets(linebuf, buflen, f);
+		}
+
+		if (feof(f) || ferror(f)) {
+			return 0;
+		}
+
+		if (sscanf(linebuf, "%s %s %s %s %d %d\n", source, target, fs, options,
+		           &dump, &pass) != 6) {
+			continue;
+		}
+	} while(linebuf[0] == '#');
+
+	mnt->mnt_fsname = strdup(source);
+	mnt->mnt_dir    = strdup(target);
+	mnt->mnt_type   = strdup(fs);
+	mnt->mnt_opts   = strdup(options);
+	mnt->mnt_freq   = dump;
+	mnt->mnt_passno = pass;
+	return mnt;
+}