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/* bootlog.c */
/* diet -Os gcc -o bootlog bootlog.c -Wall -W */
#include <unistd.h>
#include <alloca.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h> /* rename */
#include <sys/mman.h>
#include <sys/wait.h>
#include "../ninitfeatures.h"
static int xx_write(int fd, void *buf, size_t len);
static int do_io(void *buf, int len);
static int mk_backup();
struct mem {
struct mem *x;
unsigned int p;
};
static struct mem *last, *root;
static char *flag_rename, *name;
static int flagstderr, flagstdout, m;
int fd = -1;
#include "../pagesize_defs.h"
#define mem_size sizeof(struct mem)
#define alloc_size (page_size - mem_size)
void *mmap_alloc() {
struct mem *m;
m=mmap(0,page_size,PROT_READ|PROT_WRITE,MAP_ANONYMOUS|MAP_PRIVATE,-1,0);
if (m==(struct mem*)-1) return 0;
/* kernel must zeroed m->p and m->x */
if (last) last->x = m;
else root = m;
last = m;
return ((void *)m) + mem_size;
}
static void flush_root() {
if (mk_backup()) return;
if (fd < 0) fd = open(name, O_WRONLY | m, 0644);
if (fd < 0) return;
while (root) {
void *x = root->x;
xx_write(fd, ((void *)root) + mem_size, root->p);
root->p = 0;
if (root == last) break;
munmap(root, page_size);
root = x;
}
}
static void loop(unsigned long len) {
char *buf = 0;
int r;
if (flag_rename) {
char *d, *s = name;
d = flag_rename = alloca(str_len(name) + 5);
while (*s) *d++ = *s++;
d[0] = '~';
d[1] = 0;
}
while (len) {
if (buf == 0 && (buf=mmap_alloc()) == 0) break;
if (last->p >= alloc_size) {
flush_root();
if (last->p) { buf = 0; continue; }
}
r = do_io(buf + last->p, alloc_size - last->p);
if (r==0) break;
if (r<0) continue;
if ((unsigned long)r > len) r = len;
last->p += r;
len -= r;
}
if (buf==0 || len==0) {
char tmp[1024];
while (do_io(tmp,sizeof(tmp)));
}
mk_backup();
flag_rename = 0;
flush_root();
fsync(fd);
close(fd);
}
#include "bootlog.h"
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