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#include <cpio.h>
#include <types.h>
#include <common.h>
#include <log.h>
static uint32_t parse_hex(const char *p)
{
uint32_t value = 0;
for (int i = 0; i < 8; i++) {
char c = p[i];
value <<= 4;
if (c >= '0' && c <= '9')
value |= c - '0';
else if (c >= 'A' && c <= 'F')
value |= c - 'A' + 10;
else if (c >= 'a' && c <= 'f')
value |= c - 'a' + 10;
}
return value;
}
static size_t align4(size_t x)
{
return (x + 3) & ~3;
}
void *cpio_get_file(void *archive, size_t size, const char *filename) {
const uint8_t *p = (uint8_t *)archive;
const uint8_t *end = archive + size;
while (p + CPIO_HEADER_LEN <= end) {
const struct cpio_newc_hdr *hdr =
(const struct cpio_newc_hdr *)p;
if (memcmp(hdr->magic, "070701", 6) &&
memcmp(hdr->magic, "070702", 6)) {
printk("Error parsing cpio: bad magic number!\n");
return NULL;
}
uint32_t namesize = parse_hex(hdr->namesize);
uint32_t filesize = parse_hex(hdr->filesize);
p += CPIO_HEADER_LEN;
if (p + namesize > end) {
printk("Error parsing cpio: truncated filename\n");
return NULL;
}
const char *name = (const char *)p;
if (strcmp(name, "TRAILER!!!") == 0)
return 0;
p += align4(namesize);
if (p + filesize > end) {
printk("Error parsing cpio: truncated file\n");
return NULL;
}
if (strcmp(name, filename) == 0) {
return (void*)p;
}
p += align4(filesize);
}
return NULL;
}
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