diff options
| -rwxr-xr-x | scripts/make.sh | 2 | ||||
| -rw-r--r-- | toys/other/switch_root.c | 97 |
2 files changed, 98 insertions, 1 deletions
diff --git a/scripts/make.sh b/scripts/make.sh index 713a6b89..af56e6d1 100755 --- a/scripts/make.sh +++ b/scripts/make.sh @@ -124,7 +124,7 @@ TOYFILES="^$(ls toys/*/*.c | sed -n 's@^.*/\(.*\)\.c$@\1@;s/-/_/g;H;${g;s/\n//;s # 5) Remove any config symbol not recognized as a filename from step 1. # 6) Add "toys/*/" prefix and ".c" suffix. -TOYFILES=$(sed -nre 's/^CONFIG_(.*)=y/\1/;t skip;b;:skip;s/_.*//;p' < .config \ +TOYFILES=$(sed -nre 's/^CONFIG_(.*)=y/\1/p' < .config \ | sort -u | tr A-Z a-z | grep -E "$TOYFILES" | sed 's@\(.*\)@toys/\*/\1.c@') echo "Library probe..." diff --git a/toys/other/switch_root.c b/toys/other/switch_root.c new file mode 100644 index 00000000..b4c0b7dd --- /dev/null +++ b/toys/other/switch_root.c @@ -0,0 +1,97 @@ +/* switch_root.c - Switch from rootfs/initramfs to another filesystem + * + * Copyright 2005 Rob Landley <rob@landley.net> + +USE_SWITCH_ROOT(NEWTOY(switch_root, "<2c:h", TOYFLAG_SBIN)) + +config SWITCH_ROOT + bool "switch_root" + default y + help + usage: switch_root [-c /dev/console] NEW_ROOT NEW_INIT... + + Use from PID 1 under initramfs to free initramfs, chroot to NEW_ROOT, + and exec NEW_INIT. + + -c Redirect console to device in NEW_ROOT + -h Hang instead of exiting on failure (avoids kernel panic) +*/ + +#include "toys.h" +#include <sys/vfs.h> + +DEFINE_GLOBALS( + char *console; + + dev_t rootdev; +) + +#define TT this.switch_root + +#define FLAG_h (1<<0) +#define FLAG_c (1<<1) + +static int del_node(struct dirtree *node) +{ + if (node->st.st_dev == TT.rootdev && dirtree_notdotdot(node)) { + int flag = 0; + if (S_ISDIR(node->st.st_mode)) { + if (node->data != -1) return DIRTREE_COMEAGAIN; + flag = AT_REMOVEDIR; + } + unlinkat(dirtree_parentfd(node), node->name, flag); + } + + return 0; +} + +void switch_root_main(void) +{ + char *newroot = *toys.optargs, **cmdline = toys.optargs+1; + struct stat st1, st2; + struct statfs stfs; + int console = console; // gcc's "may be used" warnings are broken. + + if (getpid() != 1) error_exit("not pid 1"); + + // Root filesystem we're leaving must be ramfs or tmpfs + if (statfs("/", &stfs) || + (stfs.f_type != 0x858458f6 && stfs.f_type != 0x01021994)) + { + error_msg("not ramfs"); + goto panic; + } + + // New directory must be different filesystem instance + if (chdir(newroot) || stat(".", &st1) || stat("/", &st2) || + st1.st_dev == st2.st_dev) + { + error_msg("bad newroot '%s'", newroot); + goto panic; + } + TT.rootdev=st2.st_dev; + + // init program must exist and be an executable file + if (stat("init", &st1) || !S_ISREG(st1.st_mode) || !(st1.st_mode&0100)) { + error_msg("bad init"); + goto panic; + } + + if (TT.console && -1 == (console = open(TT.console, O_RDWR))) { + perror_msg("bad console '%s'", TT.console); + goto panic; + } + + // Ok, enough safety checks: wipe root partition. + dirtree_read("/", del_node); + + if (TT.console) { + int i; + for (i=0; i<3; i++) if (console != i) dup2(console, i); + if (console>2) close(console); + } + execv(*cmdline, cmdline); + perror_msg("Failed to exec '%s'", *cmdline); +panic: + if (toys.optflags & FLAG_h) for (;;) wait(NULL); +} |