minix/boot/mkfile.c
2010-04-07 11:25:51 +00:00

179 lines
3.9 KiB
C

/* mkfile 1.0 - create a file under DOS for use as a Minix "disk".
* Author: Kees J. Bot
* 9 May 1998
*/
#define nil 0
#include <sys/types.h>
#include <string.h>
#include <limits.h>
/* Stuff normally found in <unistd.h>, <errno.h>, etc. */
extern int errno;
int creat(const char *file, int mode);
int open(const char *file, int oflag);
off_t lseek(int fd, off_t offset, int whence);
ssize_t write(int fd, const char *buf, size_t len);
void exit(int status);
int printf(const char *fmt, ...);
#define O_WRONLY 1
#define SEEK_SET 0
#define SEEK_END 2
/* Kernel printf requires a putk() function. */
void putk(int c)
{
char ch = c;
if (c == 0) return;
if (c == '\n') putk('\r');
(void) write(2, &ch, 1);
}
static void usage(void)
{
printf("Usage: mkfile <size>[gmk] <file>\n"
"(Example sizes, all 50 meg: 52428800, 51200k, 50m)\n");
exit(1);
}
char *strerror(int err)
/* Translate some DOS error numbers to text. */
{
static struct errlist {
int err;
char *what;
} errlist[] = {
{ 0, "No error" },
{ 1, "Function number invalid" },
{ 2, "File not found" },
{ 3, "Path not found" },
{ 4, "Too many open files" },
{ 5, "Access denied" },
{ 6, "Invalid handle" },
{ 12, "Access code invalid" },
{ 39, "Insufficient disk space" },
};
struct errlist *ep;
static char unknown[]= "Error 65535";
unsigned e;
char *p;
for (ep= errlist; ep < errlist + sizeof(errlist)/sizeof(errlist[0]);
ep++) {
if (ep->err == err) return ep->what;
}
p= unknown + sizeof(unknown) - 1;
e= err;
do *--p= '0' + (e % 10); while ((e /= 10) > 0);
strcpy(unknown + 6, p);
return unknown;
}
int main(int argc, char **argv)
{
static char buf[512];
unsigned long size, mul;
off_t offset;
char *cp;
int fd;
char *file;
if (argc != 3) usage();
cp= argv[1];
size= 0;
while ((unsigned) (*cp - '0') < 10) {
unsigned d= *cp++ - '0';
if (size <= (ULONG_MAX-9) / 10) {
size= size * 10 + d;
} else {
size= ULONG_MAX;
}
}
if (cp == argv[1]) usage();
while (*cp != 0) {
mul = 1;
switch (*cp++) {
case 'G':
case 'g': mul *= 1024;
case 'M':
case 'm': mul *= 1024;
case 'K':
case 'k': mul *= 1024;
case 'B':
case 'b': break;
default: usage();
}
if (size <= ULONG_MAX / mul) {
size *= mul;
} else {
size= ULONG_MAX;
}
}
if (size > 1024L*1024*1024) {
printf("mkfile: A file size over 1G is a bit too much\n");
exit(1);
}
/* Open existing file, or create a new file. */
file= argv[2];
if ((fd= open(file, O_WRONLY)) < 0) {
if (errno == 2) {
fd= creat(file, 0666);
}
}
if (fd < 0) {
printf("mkfile: Can't open %s: %s\n", file, strerror(errno));
exit(1);
}
/* How big is the file now? */
if ((offset= lseek(fd, 0, SEEK_END)) == -1) {
printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
exit(1);
}
if (offset == 0 && size == 0) exit(0); /* Huh? */
/* Write the first bit if the file is zero length. This is necessary
* to circumvent a DOS bug by extending a new file by lseek. We also
* want to make sure there are zeros in the first sector.
*/
if (offset == 0) {
if (write(fd, buf, sizeof(buf)) == -1) {
printf("mkfile: Can't write to %s: %s\n",
file, strerror(errno));
exit(1);
}
}
/* Seek to the required size and write 0 bytes to extend/truncate the
* file to that size.
*/
if (lseek(fd, size, SEEK_SET) == -1) {
printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
exit(1);
}
if (write(fd, buf, 0) == -1) {
printf("mkfile: Can't write to %s: %s\n",
file, strerror(errno));
exit(1);
}
/* Did the file become the required size? */
if ((offset= lseek(fd, 0, SEEK_END)) == -1) {
printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
exit(1);
}
if (offset != size) {
printf("mkfile: Failed to extend %s. Disk full?\n", file);
exit(1);
}
return 0;
}
/*
* $PchId: mkfile.c,v 1.4 2000/08/13 22:06:40 philip Exp $
*/