cpio: add functions to create cpio images

Signed-off-by: Sven Peter <sven@svenpeter.dev>
This commit is contained in:
Sven Peter 2021-07-01 20:17:22 +02:00 committed by Hector Martin
parent e74b79dc2a
commit cd4b563a31
3 changed files with 166 additions and 0 deletions

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@ -39,6 +39,7 @@ OBJECTS := \
adt.o \ adt.o \
bootlogo_128.o bootlogo_256.o \ bootlogo_128.o bootlogo_256.o \
chickens.o \ chickens.o \
cpio.o \
dart.o \ dart.o \
exception.o exception_asm.o \ exception.o exception_asm.o \
fb.o font.o font_retina.o \ fb.o font.o font_retina.o \

147
src/cpio.c Normal file
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@ -0,0 +1,147 @@
/* SPDX-License-Identifier: MIT */
#include <string.h>
#include "cpio.h"
#include "malloc.h"
#include "types.h"
#include "utils.h"
#define CPIO_MAX_FILES 20
#define CPIO_MODE_DIR 0040755
#define CPIO_MODE_FILE 0100644
#define CPIO_HEADER_MAGIC "070701"
struct cpio_header {
char magic[6];
char inode[8];
char mode[8];
char uid[8];
char gid[8];
char nlink[8];
char mtime[8];
char filesize[8];
char devmajor[8];
char devminor[8];
char rdevmajor[8];
char rdevminor[8];
char namesize[8];
char checksum[8];
} PACKED;
struct cpio {
u32 n_files;
struct {
const u8 *ptr;
size_t sz;
const char *name;
size_t name_sz;
struct cpio_header hdr;
} files[CPIO_MAX_FILES];
};
static char hex(u8 c)
{
if (c <= 9)
return '0' + c;
return 'a' + c - 10;
}
static void write_hex32(char *p, u32 val)
{
for (unsigned int i = 0; i < 8; ++i) {
u32 shift = 28 - (4 * i);
p[i] = hex((val >> shift) & 0xf);
}
}
struct cpio *cpio_init(void)
{
struct cpio *c = malloc(sizeof(*c));
if (!c)
return NULL;
c->n_files = 0;
return c;
}
int cpio_add(struct cpio *c, const char *name, u64 mode, const u8 *bfr, size_t sz)
{
struct cpio_header *hdr;
if (c->n_files >= CPIO_MAX_FILES) {
printf("cpio: cannot add more than %d files.\n", CPIO_MAX_FILES);
return -1;
}
c->files[c->n_files].ptr = bfr;
c->files[c->n_files].sz = sz;
c->files[c->n_files].name = name;
c->files[c->n_files].name_sz = strlen(name) + 1;
hdr = &c->files[c->n_files].hdr;
memcpy(hdr->magic, CPIO_HEADER_MAGIC, 6);
write_hex32(hdr->mode, mode);
write_hex32(hdr->nlink, 1);
write_hex32(hdr->filesize, sz);
write_hex32(hdr->namesize, strlen(name) + 1);
c->n_files++;
return 0;
}
int cpio_add_file(struct cpio *c, const char *name, const u8 *bfr, size_t sz)
{
return cpio_add(c, name, CPIO_MODE_FILE, bfr, sz);
}
int cpio_add_dir(struct cpio *c, const char *name)
{
return cpio_add(c, name, CPIO_MODE_DIR, NULL, 0);
}
size_t cpio_get_size(struct cpio *c)
{
size_t sz = 0;
for (u32 i = 0; i < c->n_files; ++i) {
sz += sizeof(struct cpio_header);
sz += c->files[i].name_sz;
sz = ALIGN_UP(sz, 4);
sz += c->files[i].sz;
sz = ALIGN_UP(sz, 4);
}
return sz;
}
size_t cpio_finalize(struct cpio *c, u8 *bfr, size_t bfr_size)
{
size_t off = 0;
if (cpio_get_size(c) > bfr_size)
return 0;
for (u32 i = 0; i < c->n_files; ++i) {
memcpy(bfr + off, &c->files[i].hdr, sizeof(struct cpio_header));
off += sizeof(struct cpio_header);
memcpy(bfr + off, c->files[i].name, c->files[i].name_sz);
off += c->files[i].name_sz;
off = ALIGN_UP(off, 4);
memcpy(bfr + off, c->files[i].ptr, c->files[i].sz);
off += c->files[i].sz;
off = ALIGN_UP(off, 4);
}
return off;
}
void cpio_free(struct cpio *c)
{
free(c);
}

18
src/cpio.h Normal file
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@ -0,0 +1,18 @@
/* SPDX-License-Identifier: MIT */
#ifndef CPIO_H
#define CPIO_H
#include "types.h"
#include "utils.h"
struct cpio;
struct cpio *cpio_init(void);
int cpio_add_file(struct cpio *c, const char *name, const u8 *bfr, size_t sz);
int cpio_add_dir(struct cpio *c, const char *name);
size_t cpio_get_size(struct cpio *c);
size_t cpio_finalize(struct cpio *c, u8 *bfr, size_t bfr_size);
void cpio_free(struct cpio *c);
#endif