cc-wrapper.c

#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <ctype.h>

void unescape(char *buf)
{
	char *ptr = buf;
	while (*buf != 0) {
		if (buf[0] == '\\' && buf[1] != 0) {
			buf++;
		}
		*ptr++ = *buf++;
	}
	*ptr = 0;
}

bool check_arg(const char *const arg);

bool check_args_file(const char *const filename)
{
	struct stat st;
	int fd = open(filename, O_RDONLY);
	if (fd == 0) {
		return false;
	}
	if (fstat(fd, &st)) {
		close(fd);
		return false;
	}
	char *buf = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	close(fd);
	if (buf == MAP_FAILED) {
		return false;
	}

	for (size_t i = 0; i < st.st_size; i++) {
		if (isspace(buf[i])) {
			continue;
		}

		char *arg = NULL;
		size_t len = 0;
		if (buf[i] == '"') {
			i++;
			while (i + len < st.st_size && buf[i + len] != '"') {
				if (buf[i + len] == '\\') {
					len++;
				} 
				len++;
			}
			arg = strndup(buf + i, len);
			if (arg == NULL) {
				exit(EXIT_FAILURE);
			}
			unescape(arg);
		} else if (buf[i] == '\'') {
			i++;
			while (i + len < st.st_size && buf[i + len] != '\'') {
				if (buf[i + len] == '\\') {
					len++;
				} 
				len++;
			}
			arg = strndup(buf + i, len);
			if (arg == NULL) {
				exit(EXIT_FAILURE);
			}
			unescape(arg);
		} else {
			while (i + len < st.st_size && !isspace(buf[i + len])) {
				len++;
			}
			arg = strndup(buf + i, len);
			if (arg == NULL) {
				exit(EXIT_FAILURE);
			}
		}

		if (check_arg(arg)) {
			free(arg);
			return true;
		}

		free(arg);
		i += len;
	}
	return false;
}

bool check_arg(const char *const arg)
{
	if (arg[0] == '@' && check_args_file(arg + 1)) {
		return true;
	}
	if (!strcmp(arg, "-E")) {
		return true;
	}
	if (!strcmp(arg, "-Xpreprocessor")) {
		return true;
	}
	return false;
}

int main(int argc, char **argv)
{
	for (int i = 1; i < argc; i++) {
		if (check_arg(argv[i])) {
			if (strlen(argv[0]) >= strlen("clang")) {
				strcpy(argv[0], "clang");
			}
			return execvp("clang", argv);
		}
	}

	if (strlen(argv[0]) >= strlen("lcc")) {
		strcpy(argv[0], "lcc");
	}
	return execvp("lcc", argv);
}