Initial commit

1 files changed, 109 insertions, 0 deletions

diff --git a/cscript.c b/cscript.c
new file mode 100644
index 0000000..c7dbcf5
--- /dev/null
+++ b/cscript.c
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+
+int main(int argc, char *argv[], char *envp[])
+{
+	int fd, fd2, input = -1, pipes[2] = { 0 }, status;
+	pid_t compiler_pid;
+	char *output_path;
+
+	if (argc > 1 && argv[argc - 1][0] != '-') {
+		input = open(argv[1], O_RDONLY);
+		++argv;
+		--argc;
+		if (input < 0) {
+			perror("Error: unable to open input file");
+			return 1;
+		}
+		if (pipe(pipes) < 0) {
+			perror("Error: unable to open filter pipe");
+			return 1;
+		}
+	}
+
+	fd = open(getenv("HOME") ?: getenv("TMPDIR") ?: "/tmp", O_TMPFILE | O_EXCL | O_RDWR, S_IWUSR | S_IRUSR);
+	if (fd < 0) {
+		perror("Error: unable to create temporary inode");
+		return 1;
+	}
+	if (asprintf(&output_path, "/proc/self/fd/%d", fd) < 0) {
+		perror("Error: unable to allocate memory for fd string");
+		return 1;
+	}
+
+	compiler_pid = fork();
+	if (compiler_pid < 0) {
+		perror("Error: unable to fork for compiler");
+		return 1;
+	}
+
+	if (compiler_pid == 0) {
+		const char *cc = getenv("CC") ?: "gcc";
+		close(input);
+		if (pipes[0] != 0) {
+			close(pipes[1]);
+			if (dup2(pipes[0], 0) < 0) {
+				perror("Error: unable to duplicate pipe fd");
+				_exit(1);
+			}
+			close(pipes[0]);
+		}
+		execlp(cc, cc, "-xc", "-o", output_path, "-", NULL);
+		_exit(1);
+	}
+
+	if (input != -1) {
+		char beginning[2];
+		ssize_t len;
+
+		close(pipes[0]);
+		len = read(input, beginning, 2);
+		if (len < 0) {
+			perror("Error: unable to read from input file");
+			return 1;
+		} else if (len == 2 && beginning[0] == '#' && beginning[1] == '!')
+			len = write(pipes[1], "//", 2);
+		else if (len > 0)
+			len = write(pipes[1], beginning, len);
+		if (len < 0) {
+			perror("Error: unable to write input preamble");
+			return 1;
+		}
+		if (splice(input, NULL, pipes[1], NULL, 0x7fffffff, 0) < 0) {
+			perror("Error: unable to splice input to compiler child");
+			return 1;
+		}
+		close(pipes[1]);
+	}
+
+	if (waitpid(compiler_pid, &status, 0) != compiler_pid || (!WIFEXITED(status) || WEXITSTATUS(status))) {
+		fprintf(stderr, "Error: compiler process did not complete successfully\n");
+		return 1;
+	}
+
+	fd2 = open(output_path, O_RDONLY);
+	if (fd2 < 0) {
+		perror("Error: unable to reopen temporary inode");
+		return 1;
+	}
+	close(fd);
+
+	if (fexecve(fd2, argv, envp) < 0) {
+		perror("Error: could not execute compiled program");
+		return 1;
+	}
+	return 0;
+}