ohhhhhhhhhhh (exclude linux-extra-rootfs.img build artifact)

CODE/linux/initramfs/bin/utsm_run.c

@@ -0,0 +1,116 @@
+/*
+ * Shebang trampoline: run a script with persist bash + persist glibc.
+ * vdb /usr/bin/bash needs libreadline, and virtio often returns a bad
+ * ext4 inode checksum for that file. persist userland is on vdc.
+ *
+ * Built like utsm_exec_daemon: -static -fcf-protection=none.
+ */
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+extern char **environ;
+
+static void kmsg(const char *s)
+{
+    int fd = open("/dev/kmsg", O_WRONLY | O_CLOEXEC);
+    if (fd < 0)
+        return;
+    (void)write(fd, s, strlen(s));
+    close(fd);
+}
+
+static int exists(const char *p)
+{
+    return p && access(p, X_OK) == 0;
+}
+
+int main(int argc, char **argv)
+{
+    static const char *ld_cands[] = {
+        "/mnt/persist/usr/lib/ld-linux-x86-64.so.2",
+        "/mnt/persist/lib64/ld-linux-x86-64.so.2",
+        "/mnt/persist/lib/ld-linux-x86-64.so.2",
+        0
+    };
+    static const char *bash_cands[] = {
+        "/mnt/persist/usr/bin/bash",
+        "/mnt/persist/bin/bash",
+        0
+    };
+    const char *libpath =
+        "/mnt/persist/usr/lib:/mnt/persist/lib64:/mnt/persist/lib";
+    const char *path =
+        "/mnt/persist/usr/bin:/mnt/persist/bin:/usr/local/bin:/usr/bin:/bin";
+    const char *ld = 0;
+    const char *bash = 0;
+    char *nargv[64];
+    int n = 0;
+    int i;
+    char line[192];
+
+    kmsg("[utsm_run] start\n");
+    if (argc < 2) {
+        kmsg("[utsm_run] usage: utsm_run script [args]\n");
+        return 2;
+    }
+
+    /* Already inside persist chroot: /mnt/persist is gone, bash is local. */
+    if (access("/etc/deshab-kde-root", F_OK) == 0 ||
+        access("/mnt/persist/usr/bin/bash", X_OK) != 0) {
+        kmsg("[utsm_run] inside persist, exec /usr/bin/bash\n");
+        nargv[n++] = "/usr/bin/bash";
+        for (i = 1; i < argc && n < 62; i++)
+            nargv[n++] = argv[i];
+        nargv[n] = 0;
+        execv("/usr/bin/bash", nargv);
+        kmsg("[utsm_run] inside bash execv failed\n");
+        return 127;
+    }
+
+    setenv("PATH", path, 1);
+    setenv("LD_LIBRARY_PATH", libpath, 1);
+    setenv("GLIBC_TUNABLES", "glibc.cpu.hwcaps=-IBT,-SHSTK", 1);
+
+    for (i = 0; ld_cands[i]; i++) {
+        if (exists(ld_cands[i])) {
+            ld = ld_cands[i];
+            break;
+        }
+    }
+    for (i = 0; bash_cands[i]; i++) {
+        if (exists(bash_cands[i])) {
+            bash = bash_cands[i];
+            break;
+        }
+    }
+
+    /* persist ld.so (as program or as PT_INTERP) SIGSEGVs at -40 in
+     * _dl_find_dso_for_object. Use vdb's RAM-backed interpreter with
+     * persist libraries via LD_LIBRARY_PATH. */
+    (void)ld;
+
+    if (bash) {
+        snprintf(line, sizeof(line), "[utsm_run] persist bash %s\n", bash);
+        kmsg(line);
+        nargv[n++] = (char *)bash;
+        for (i = 1; i < argc && n < 62; i++)
+            nargv[n++] = argv[i];
+        nargv[n] = 0;
+        execve(bash, nargv, environ);
+        kmsg("[utsm_run] persist bash execve failed\n");
+    }
+
+    kmsg("[utsm_run] fallback /usr/bin/bash\n");
+    n = 0;
+    nargv[n++] = "/usr/bin/bash";
+    for (i = 1; i < argc && n < 62; i++)
+        nargv[n++] = argv[i];
+    nargv[n] = 0;
+    execv("/usr/bin/bash", nargv);
+    kmsg("[utsm_run] fallback execv failed\n");
+    return 127;
+}