1 files changed, 134 insertions, 0 deletions
diff --git a/scripts/syscall_compat32.c b/scripts/syscall_compat32.c
new file mode 100644
index 0000000..03a3474
--- /dev/null
+++ b/scripts/syscall_compat32.c
@@ -0,0 +1,134 @@
+#define _GNU_SOURCE
+#define _LARGEFILE64_SOURCE
+
+#include <asm/unistd_32.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <pwd.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if !defined(__i386__)
+#error "Compile this helper with -m32 so it exercises the compat syscall ABI."
+#endif
+
+static void
+die(const char *msg)
+{
+    perror(msg);
+    exit(1);
+}
+
+static void
+must(bool ok, const char *msg)
+{
+    if (!ok)
+        die(msg);
+}
+
+static void
+must_eq(long rc, const char *msg)
+{
+    if (rc == -1)
+        die(msg);
+}
+
+static void
+write_pid_file(const char *path)
+{
+    FILE *fp = fopen(path, "w");
+
+    must(fp != NULL, "fopen pid file");
+    fprintf(fp, "%ld\n", (long)getpid());
+    fclose(fp);
+}
+
+static void
+wait_for_go(const char *path)
+{
+    while (access(path, F_OK) != 0)
+        usleep(10000);
+}
+
+static void
+write_full(int fd, const char *buf, size_t len)
+{
+    while (len > 0) {
+        ssize_t written = write(fd, buf, len);
+
+        must_eq(written, "write");
+        buf += written;
+        len -= (size_t)written;
+    }
+}
+
+int
+main(int argc, char **argv)
+{
+    if (argc != 5) {
+        fprintf(stderr, "usage: %s PID_FILE GO_FILE BASE_DIR USER\n", argv[0]);
+        return 2;
+    }
+
+    const char *pid_file = argv[1];
+    const char *go_file = argv[2];
+    const char *base = argv[3];
+    const char *user = argv[4];
+    struct passwd *pw = getpwnam(user);
+
+    must(pw != NULL, "getpwnam");
+    must(pw->pw_uid <= USHRT_MAX, "uid fits 16-bit compat ABI");
+    must(pw->pw_gid <= USHRT_MAX, "gid fits 16-bit compat ABI");
+
+    write_pid_file(pid_file);
+    wait_for_go(go_file);
+
+    char path_file[1024];
+    char path_link[1024];
+
+    snprintf(path_file, sizeof(path_file), "%s/compat-open.txt", base);
+    snprintf(path_link, sizeof(path_link), "%s/compat-link.txt", base);
+
+    must_eq(mkdir(base, 0777), "mkdir compat base");
+
+    int dirfd = open(base, O_RDONLY | O_DIRECTORY);
+
+    must_eq(dirfd, "open compat base");
+
+    int fd = open(path_file, O_CREAT | O_RDWR | O_TRUNC, 0644);
+
+    must_eq(fd, "open compat-open.txt");
+    write_full(fd, "compat-data", 11);
+    must_eq(lseek(fd, 0, SEEK_SET), "lseek compat-open.txt");
+    must_eq(symlink(path_file, path_link), "symlink compat-link.txt");
+
+    char dir_buf[4096];
+    long long llseek_result = 0;
+    struct statfs64 sfs;
+
+    must_eq(syscall(__NR_readdir, dirfd, dir_buf, sizeof(dir_buf)),
+            "compat readdir");
+    must_eq(syscall(__NR__llseek, fd, 0UL, 0UL, &llseek_result, SEEK_END),
+            "compat _llseek");
+    must_eq(syscall(__NR_statfs64, base, sizeof(sfs), &sfs),
+            "compat statfs64");
+    must_eq(syscall(__NR_fstatfs64, fd, sizeof(sfs), &sfs),
+            "compat fstatfs64");
+    must_eq(syscall(__NR_chown, path_file, pw->pw_uid, pw->pw_gid),
+            "compat chown16");
+    must_eq(syscall(__NR_lchown, path_link, pw->pw_uid, pw->pw_gid),
+            "compat lchown16");
+    must_eq(syscall(__NR_fchown, fd, pw->pw_uid, pw->pw_gid),
+            "compat fchown16");
+
+    must_eq(close(fd), "close compat-open.txt");
+    must_eq(close(dirfd), "close compat base");
+
+    return 0;
+}