liminix-fork/pkgs/preinit/preinit.c
Daniel Barlow a8891461aa use devtmpfs in initramfs
static device nodes don't work with virtio
2023-12-07 20:03:03 +00:00

101 lines
2.6 KiB
C

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
#include <asm/setup.h> /* for COMMAND_LINE_SIZE */
void parseopts(char * cmdline, char **root, char **rootfstype);
#define ERR(x) write(2, x, strlen(x))
#define AVER(c) do { if(c < 0) { ERR("failed: " #c ": error=0x" ); pr_u32(errno); ERR("\n"); } } while(0)
char * pr_u32(int32_t input);
static void die() {
/* if init exits, it causes a kernel panic. On the Turris
* Omnia (and maybe other hardware, I don't know), the kernel
* panics _before_ any of the messages from AVER are printed,
* which makes it really hard to tell what went wrong. So
* let's wait a little here to give the console a chance to
* catch up.
*
* Yes, I know that file descriptor IO is supposedly
* non-buffered. Empirical observation suggests that there
* must be a buffer of some kind somewhere though.
*/
sleep(10);
exit(1);
}
static int fork_exec(char * command, char *args[])
{
int fork_pid = fork();
AVER(fork_pid);
if(fork_pid > 0)
return wait(NULL);
else
return execve(command, args, NULL);
}
char banner[] = "Running pre-init...\n";
char buf[COMMAND_LINE_SIZE];
int main(int argc, char *argv[], char *envp[])
{
char *rootdevice = 0;
char *rootfstype = 0;
write(1, banner, strlen(banner));
AVER(mount("none", "/proc", "proc", 0, NULL));
AVER(mount("none", "/dev", "devtmpfs", 0, NULL));
int cmdline = open("/proc/cmdline", O_RDONLY, 0);
if(cmdline>=0) {
int len = read(cmdline, buf, sizeof buf - 1);
buf[len]='\0';
while(buf[len-1]=='\n') {
buf[len-1]='\0';
len--;
}
write(1, "cmdline: \"", 10);
write(1, buf, len);
write(1, "\"\n", 2);
} else {
ERR("failed: open(\"/proc/cmdline\")\n");
die();
}
parseopts(buf, &rootdevice, &rootfstype);
if(rootdevice) {
if(!rootfstype) rootfstype = "jffs2"; /* backward compatibility */
write(1, "rootdevice ", 11);
write(1, rootdevice, strlen(rootdevice));
write(1, " (", 2);
write(1, rootfstype, strlen(rootfstype));
write(1, ")\n", 2);
AVER(mount(rootdevice, "/target/persist", rootfstype, 0, NULL));
AVER(mount("/target/persist/nix", "/target/nix",
"bind", MS_BIND, NULL));
char *exec_args[] = { "activate", "/target", NULL };
AVER(fork_exec("/target/persist/activate", exec_args));
AVER(chdir("/target"));
AVER(mount("/target", "/", "bind", MS_BIND | MS_REC, NULL));
AVER(chroot("."));
argv[0] = "init";
argv[1] = NULL;
AVER(execve("/persist/init", argv, envp));
}
die();
}