Messages in this thread Patch in this message | | | Date | Wed, 22 Feb 2006 10:45:25 +1100 | From | Michael Neuling <> | Subject | [PATCH] initramfs: multiple CPIO unpacking fix |
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The following patch unlinks (deletes) files, symlinks, FIFOs, devices etc before writing them when extracting CPIOs. It doesn't delete directories. This stops weird behaviour like: 1) writing through symlinks created in earlier CPIOs. eg foo->bar in the first CPIO. Having foo as a non link in a subsequent CPIO, results in bar being written and foo remaining as a symlink. 2) if the first version of file foo is larger than foo in a subsequent CPIO, we end up with a mix of the two. ie. neither the first or second version of /foo. 3) special files like devices, fifo etc can't be overwritten in subsequent CPIOS.
With this patch, the kernel will more closely replicate for i in *.cpio; do cpio --extract --unconditional < $i ; done
This patch doesn't break hardlinks like my previous attempt.
Signed-off-by: Michael Neuling <mikey@neuling.org> --- initramfs.c | 3 +++ 1 files changed, 3 insertions(+)
Index: linux-2.6.15/init/initramfs.c =================================================================== --- linux-2.6.15.orig/init/initramfs.c +++ linux-2.6.15/init/initramfs.c @@ -249,6 +249,7 @@ static int __init do_name(void) if (dry_run) return 0; if (S_ISREG(mode)) { + sys_unlink(collected); if (maybe_link() >= 0) { wfd = sys_open(collected, O_WRONLY|O_CREAT, mode); if (wfd >= 0) { @@ -263,6 +264,7 @@ static int __init do_name(void) sys_chmod(collected, mode); } else if (S_ISBLK(mode) || S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) { + sys_unlink(collected); if (maybe_link() == 0) { sys_mknod(collected, mode, rdev); sys_chown(collected, uid, gid); @@ -291,6 +293,7 @@ static int __init do_copy(void) static int __init do_symlink(void) { collected[N_ALIGN(name_len) + body_len] = '\0'; + sys_unlink(collected); sys_symlink(collected + N_ALIGN(name_len), collected); sys_lchown(collected, uid, gid); state = SkipIt;
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