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make_initrd.c
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make_initrd.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define HEADER_MAGIC 0xBF;
struct initrd_header
{
unsigned char magic;
char name[64];
unsigned int offset;
unsigned int length;
};
/* There is no sub-directory
* First 4 byte stores number of file
* Then there are 64 headers having name, offset and size of file
* Then the actual data follows */
int main(char argc, char **argv)
{
int nheaders = (argc - 1) / 2;
struct initrd_header headers[64];
unsigned int off = sizeof(struct initrd_header) * 64 + sizeof(int);
for (int i = 0; i < nheaders; i++)
{
printf("Writing file %s->%s at 0x%0x\n", argv[i * 2 + 1], argv[i * 2 + 2], off);
strcpy(headers[i].name, argv[i * 2 + 2]);
headers[i].offset = off;
FILE *stream = fopen(argv[i * 2 + 1], "r");
if (stream == 0)
{
printf("Error: file not found: %s\n", argv[i * 2 + 1]);
return 1;
}
fseek(stream, 0, SEEK_END);
headers[i].length = ftell(stream);
off += headers[i].length;
headers[i].magic = HEADER_MAGIC;
fclose(stream);
}
FILE *wstream = fopen("./initrd.img", "w");
unsigned char *data = (unsigned char *)malloc(off);
fwrite(&nheaders, sizeof(int), 1, wstream);
fwrite(headers, sizeof(struct initrd_header), 64, wstream);
for (int i = 0; i < nheaders; i++)
{
FILE *stream = fopen(argv[i * 2 + 1], "r");
unsigned char *buff = (unsigned char*) malloc(headers[i].length);
fread(buff, 1, headers[i].length, stream);
fwrite(buff, 1, headers[i].length, stream);
fclose(stream);
free(buff);
}
fclose(wstream);
free(data);
return 0;
}