2 files changed, 87 insertions, 0 deletions
diff --git a/lib/libc/pwd/getgrgid.c b/lib/libc/pwd/getgrgid.c
new file mode 100644
index 00000000..5e825c12
--- /dev/null
+++ b/lib/libc/pwd/getgrgid.c
@@ -0,0 +1,15 @@
+#include <pwd.h>
+#include <stddef.h>
+#include <limits.h>
+
+struct passwd *getpwuid(uid_t uid)
+{
+	static struct passwd pwd;
+	static char buf[LINE_MAX * 4];
+	struct passwd *res;
+
+	if (getpwuid_r(uid, &pwd, buf, sizeof(buf), &res) != 0)
+		return NULL;
+
+	return res;
+}
diff --git a/lib/libc/pwd/getgrgid_r.c b/lib/libc/pwd/getgrgid_r.c
new file mode 100644
index 00000000..33705fdf
--- /dev/null
+++ b/lib/libc/pwd/getgrgid_r.c
@@ -0,0 +1,72 @@
+#include <pwd.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+
+static char *copy_str(const char *src, char **buf, size_t *buflen)
+{
+	size_t len = strlen(src) + 1;
+	if (len > *buflen)
+		return NULL;
+	char *dst = *buf;
+	memcpy(dst, src, len);
+	*buf += len;
+	*buflen -= len;
+	return dst;
+}
+
+int getpwuid_r(uid_t uid, struct passwd *pwd, char *buf, size_t buflen,
+	       struct passwd **result)
+{
+	FILE *stream = fopen("/etc/passwd", "r");
+	if (stream == NULL) {
+		*result = NULL;
+		return errno;
+	}
+
+	char line[LINE_MAX];
+
+	while (fgets(line, sizeof(line), stream)) {
+		char *name = strtok(line, ":");
+		char *passwd = strtok(NULL, ":");
+		char *uid_str = strtok(NULL, ":");
+		char *gid_str = strtok(NULL, ":");
+		strtok(NULL, ":");
+		char *dir = strtok(NULL, ":");
+		char *shell = strtok(NULL, "\n");
+
+		if (name == NULL || passwd == NULL || uid_str == NULL ||
+		    gid_str == NULL)
+			continue;
+
+		uid_t file_uid = (uid_t)strtoul(uid_str, NULL, 10);
+		if (file_uid != uid)
+			continue;
+
+		size_t rem = buflen;
+
+		pwd->pw_name = copy_str(name, &buf, &rem);
+		pwd->pw_dir = copy_str(dir ? dir : "", &buf, &rem);
+		pwd->pw_shell = copy_str(shell ? shell : "", &buf, &rem);
+		pwd->pw_uid = file_uid;
+		pwd->pw_gid = (gid_t)strtoul(gid_str, NULL, 10);
+		pwd->pw_uid = file_uid;
+		pwd->pw_gid = (gid_t)strtoul(gid_str, NULL, 10);
+
+		if (pwd->pw_name == NULL || pwd->pw_dir == NULL ||
+		    pwd->pw_shell == NULL) {
+			fclose(stream);
+			return ERANGE;
+		}
+
+		fclose(stream);
+		*result = pwd;
+		return 0;
+	}
+
+	fclose(stream);
+	*result = NULL;
+	return 0;
+}