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598bae70c2
The comments of find_cpio_data() says: * @offset: When a matching file is found, this is the offset to the * beginning of the cpio. ...... But according to the code, dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4); nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4); .... *offset = (long)nptr - (long)data; /* data is the cpio file */ @offset is the offset of the next file, not the matching file itself. This is confused and may cause unnecessary waste of time to debug. So fix it. As Tejun Heo suggested, rename @offset to @nextoff which is more clear to users. And also adjust the new comments. Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
147 lines
3.9 KiB
C
147 lines
3.9 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2012 Intel Corporation; author H. Peter Anvin
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*
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* This file is part of the Linux kernel, and is made available
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* under the terms of the GNU General Public License version 2, as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* ----------------------------------------------------------------------- */
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/*
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* earlycpio.c
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*
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* Find a specific cpio member; must precede any compressed content.
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* This is used to locate data items in the initramfs used by the
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* kernel itself during early boot (before the main initramfs is
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* decompressed.) It is the responsibility of the initramfs creator
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* to ensure that these items are uncompressed at the head of the
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* blob. Depending on the boot loader or package tool that may be a
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* separate file or part of the same file.
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*/
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#include <linux/earlycpio.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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enum cpio_fields {
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C_MAGIC,
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C_INO,
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C_MODE,
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C_UID,
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C_GID,
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C_NLINK,
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C_MTIME,
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C_FILESIZE,
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C_MAJ,
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C_MIN,
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C_RMAJ,
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C_RMIN,
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C_NAMESIZE,
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C_CHKSUM,
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C_NFIELDS
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};
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/**
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* cpio_data find_cpio_data - Search for files in an uncompressed cpio
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* @path: The directory to search for, including a slash at the end
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* @data: Pointer to the the cpio archive or a header inside
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* @len: Remaining length of the cpio based on data pointer
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* @nextoff: When a matching file is found, this is the offset from the
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* beginning of the cpio to the beginning of the next file, not the
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* matching file itself. It can be used to iterate through the cpio
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* to find all files inside of a directory path.
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*
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* @return: struct cpio_data containing the address, length and
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* filename (with the directory path cut off) of the found file.
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* If you search for a filename and not for files in a directory,
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* pass the absolute path of the filename in the cpio and make sure
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* the match returned an empty filename string.
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*/
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struct cpio_data find_cpio_data(const char *path, void *data,
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size_t len, long *nextoff)
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{
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const size_t cpio_header_len = 8*C_NFIELDS - 2;
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struct cpio_data cd = { NULL, 0, "" };
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const char *p, *dptr, *nptr;
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unsigned int ch[C_NFIELDS], *chp, v;
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unsigned char c, x;
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size_t mypathsize = strlen(path);
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int i, j;
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p = data;
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while (len > cpio_header_len) {
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if (!*p) {
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/* All cpio headers need to be 4-byte aligned */
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p += 4;
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len -= 4;
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continue;
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}
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j = 6; /* The magic field is only 6 characters */
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chp = ch;
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for (i = C_NFIELDS; i; i--) {
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v = 0;
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while (j--) {
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v <<= 4;
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c = *p++;
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x = c - '0';
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if (x < 10) {
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v += x;
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continue;
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}
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x = (c | 0x20) - 'a';
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if (x < 6) {
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v += x + 10;
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continue;
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}
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goto quit; /* Invalid hexadecimal */
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}
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*chp++ = v;
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j = 8; /* All other fields are 8 characters */
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}
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if ((ch[C_MAGIC] - 0x070701) > 1)
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goto quit; /* Invalid magic */
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len -= cpio_header_len;
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dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);
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nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4);
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if (nptr > p + len || dptr < p || nptr < dptr)
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goto quit; /* Buffer overrun */
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if ((ch[C_MODE] & 0170000) == 0100000 &&
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ch[C_NAMESIZE] >= mypathsize &&
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!memcmp(p, path, mypathsize)) {
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*nextoff = (long)nptr - (long)data;
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if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
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pr_warn(
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"File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",
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p, MAX_CPIO_FILE_NAME);
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}
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strlcpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME);
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cd.data = (void *)dptr;
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cd.size = ch[C_FILESIZE];
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return cd; /* Found it! */
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}
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len -= (nptr - p);
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p = nptr;
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}
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quit:
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return cd;
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}
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