diff options
author | H. Peter Anvin <hpa@linux.intel.com> | 2012-10-01 00:23:52 +0200 |
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committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-30 18:02:20 -0700 |
commit | e6459606b04e6385ccd3c2060fc10f78a92c7700 (patch) | |
tree | d89592d1a11147c46fa72795e99ca2bc8726f58a /lib/earlycpio.c | |
parent | 979570e02981d4a8fc20b3cc8fd651856c98ee9d (diff) | |
download | linux-e6459606b04e6385ccd3c2060fc10f78a92c7700.tar.bz2 |
lib: Add early cpio decoder
Add a simple cpio decoder without library dependencies for the purpose
of extracting components from the initramfs blob for early kernel
uses. Intended consumers so far are microcode and ACPI override.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1349043837-22659-2-git-send-email-trenn@suse.de
Cc: Len Brown <lenb@kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'lib/earlycpio.c')
-rw-r--r-- | lib/earlycpio.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/lib/earlycpio.c b/lib/earlycpio.c new file mode 100644 index 000000000000..8078ef49cb79 --- /dev/null +++ b/lib/earlycpio.c @@ -0,0 +1,145 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2012 Intel Corporation; author H. Peter Anvin + * + * This file is part of the Linux kernel, and is made available + * under the terms of the GNU General Public License version 2, as + * published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * ----------------------------------------------------------------------- */ + +/* + * earlycpio.c + * + * Find a specific cpio member; must precede any compressed content. + * This is used to locate data items in the initramfs used by the + * kernel itself during early boot (before the main initramfs is + * decompressed.) It is the responsibility of the initramfs creator + * to ensure that these items are uncompressed at the head of the + * blob. Depending on the boot loader or package tool that may be a + * separate file or part of the same file. + */ + +#include <linux/earlycpio.h> +#include <linux/kernel.h> +#include <linux/string.h> + +enum cpio_fields { + C_MAGIC, + C_INO, + C_MODE, + C_UID, + C_GID, + C_NLINK, + C_MTIME, + C_FILESIZE, + C_MAJ, + C_MIN, + C_RMAJ, + C_RMIN, + C_NAMESIZE, + C_CHKSUM, + C_NFIELDS +}; + +/** + * cpio_data find_cpio_data - Search for files in an uncompressed cpio + * @path: The directory to search for, including a slash at the end + * @data: Pointer to the the cpio archive or a header inside + * @len: Remaining length of the cpio based on data pointer + * @offset: When a matching file is found, this is the offset to the + * beginning of the cpio. It can be used to iterate through + * the cpio to find all files inside of a directory path + * + * @return: struct cpio_data containing the address, length and + * filename (with the directory path cut off) of the found file. + * If you search for a filename and not for files in a directory, + * pass the absolute path of the filename in the cpio and make sure + * the match returned an empty filename string. + */ + +struct cpio_data __cpuinit find_cpio_data(const char *path, void *data, + size_t len, long *offset) +{ + const size_t cpio_header_len = 8*C_NFIELDS - 2; + struct cpio_data cd = { NULL, 0, "" }; + const char *p, *dptr, *nptr; + unsigned int ch[C_NFIELDS], *chp, v; + unsigned char c, x; + size_t mypathsize = strlen(path); + int i, j; + + p = data; + + while (len > cpio_header_len) { + if (!*p) { + /* All cpio headers need to be 4-byte aligned */ + p += 4; + len -= 4; + continue; + } + + j = 6; /* The magic field is only 6 characters */ + chp = ch; + for (i = C_NFIELDS; i; i--) { + v = 0; + while (j--) { + v <<= 4; + c = *p++; + + x = c - '0'; + if (x < 10) { + v += x; + continue; + } + + x = (c | 0x20) - 'a'; + if (x < 6) { + v += x + 10; + continue; + } + + goto quit; /* Invalid hexadecimal */ + } + *chp++ = v; + j = 8; /* All other fields are 8 characters */ + } + + if ((ch[C_MAGIC] - 0x070701) > 1) + goto quit; /* Invalid magic */ + + len -= cpio_header_len; + + dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4); + nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4); + + if (nptr > p + len || dptr < p || nptr < dptr) + goto quit; /* Buffer overrun */ + + if ((ch[C_MODE] & 0170000) == 0100000 && + ch[C_NAMESIZE] >= mypathsize && + !memcmp(p, path, mypathsize)) { + *offset = (long)nptr - (long)data; + if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) { + pr_warn( + "File %s exceeding MAX_CPIO_FILE_NAME [%d]\n", + p, MAX_CPIO_FILE_NAME); + } + strlcpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME); + + cd.data = (void *)dptr; + cd.size = ch[C_FILESIZE]; + return cd; /* Found it! */ + } + len -= (nptr - p); + p = nptr; + } + +quit: + return cd; +} |