/* 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. */

int 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)

{

int i;

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 $

*/