1 files changed, 110 insertions, 0 deletions
diff --git a/vendor/github.com/projectatomic/buildah/unshare/unshare.c b/vendor/github.com/projectatomic/buildah/unshare/unshare.c
new file mode 100644
index 000000000..83864359b
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/unshare/unshare.c
@@ -0,0 +1,110 @@
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+
+static int _buildah_unshare_parse_envint(const char *envname) {
+	char *p, *q;
+	long l;
+
+	p = getenv(envname);
+	if (p == NULL) {
+		return -1;
+	}
+	q = NULL;
+	l = strtol(p, &q, 10);
+	if ((q == NULL) || (*q != '\0')) {
+		fprintf(stderr, "Error parsing \"%s\"=\"%s\"!\n", envname, p);
+		_exit(1);
+	}
+	unsetenv(envname);
+	return l;
+}
+
+void _buildah_unshare(void)
+{
+	int flags, pidfd, continuefd, n, pgrp, sid, ctty, allow_setgroups;
+	char buf[2048];
+
+	flags = _buildah_unshare_parse_envint("_Buildah-unshare");
+	if (flags == -1) {
+		return;
+	}
+	if ((flags & CLONE_NEWUSER) != 0) {
+		if (unshare(CLONE_NEWUSER) == -1) {
+			fprintf(stderr, "Error during unshare(CLONE_NEWUSER): %m\n");
+			_exit(1);
+		}
+	}
+	pidfd = _buildah_unshare_parse_envint("_Buildah-pid-pipe");
+	if (pidfd != -1) {
+		snprintf(buf, sizeof(buf), "%llu", (unsigned long long) getpid());
+		if (write(pidfd, buf, strlen(buf)) != strlen(buf)) {
+			fprintf(stderr, "Error writing PID to pipe on fd %d: %m\n", pidfd);
+			_exit(1);
+		}
+		close(pidfd);
+	}
+	continuefd = _buildah_unshare_parse_envint("_Buildah-continue-pipe");
+	if (continuefd != -1) {
+		n = read(continuefd, buf, sizeof(buf));
+		if (n > 0) {
+			fprintf(stderr, "Error: %.*s\n", n, buf);
+			_exit(1);
+		}
+		close(continuefd);
+	}
+	sid = _buildah_unshare_parse_envint("_Buildah-setsid");
+	if (sid == 1) {
+		if (setsid() == -1) {
+			fprintf(stderr, "Error during setsid: %m\n");
+			_exit(1);
+		}
+	}
+	pgrp = _buildah_unshare_parse_envint("_Buildah-setpgrp");
+	if (pgrp == 1) {
+		if (setpgrp() == -1) {
+			fprintf(stderr, "Error during setpgrp: %m\n");
+			_exit(1);
+		}
+	}
+	ctty = _buildah_unshare_parse_envint("_Buildah-ctty");
+	if (ctty != -1) {
+		if (ioctl(ctty, TIOCSCTTY, 0) == -1) {
+			fprintf(stderr, "Error while setting controlling terminal to %d: %m\n", ctty);
+			_exit(1);
+		}
+	}
+	allow_setgroups = _buildah_unshare_parse_envint("_Buildah-allow-setgroups");
+	if ((flags & CLONE_NEWUSER) != 0) {
+		if (allow_setgroups == 1) {
+			if (setgroups(0, NULL) != 0) {
+				fprintf(stderr, "Error during setgroups(0, NULL): %m\n");
+				_exit(1);
+			}
+		}
+		if (setresgid(0, 0, 0) != 0) {
+			fprintf(stderr, "Error during setresgid(0): %m\n");
+			_exit(1);
+		}
+		if (setresuid(0, 0, 0) != 0) {
+			fprintf(stderr, "Error during setresuid(0): %m\n");
+			_exit(1);
+		}
+	}
+	if ((flags & ~CLONE_NEWUSER) != 0) {
+		if (unshare(flags & ~CLONE_NEWUSER) == -1) {
+			fprintf(stderr, "Error during unshare(...): %m\n");
+			_exit(1);
+		}
+	}
+	return;
+}