mkfile.c

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    1 /*      mkfile 1.0 - create a file under DOS for use as a Minix "disk".
    2  *                                                      Author: Kees J. Bot
    3  *                                                              9 May 1998
    4  */
    5 #define nil 0
    6 #include <sys/types.h>
    7 #include <string.h>
    8 #include <limits.h>
    9 
   10 /* Stuff normally found in <unistd.h>, <errno.h>, etc. */
   11 extern int errno;
   12 int creat(const char *file, int mode);
   13 int open(const char *file, int oflag);
   14 off_t lseek(int fd, off_t offset, int whence);
   15 ssize_t write(int fd, const char *buf, size_t len);
   16 void exit(int status);
   17 int printf(const char *fmt, ...);
   18 
   19 #define O_WRONLY        1
   20 #define SEEK_SET        0
   21 #define SEEK_END        2
   22 
   23 /* Kernel printf requires a putk() function. */
   24 int putk(int c)
   25 {
   26         char ch = c;
   27 
   28         if (c == 0) return;
   29         if (c == '\n') putk('\r');
   30         (void) write(2, &ch, 1);
   31 }
   32 
   33 static void usage(void)
   34 {
   35         printf("Usage: mkfile <size>[gmk] <file>\n"
   36                 "(Example sizes, all 50 meg: 52428800, 51200k, 50m)\n");
   37         exit(1);
   38 }
   39 
   40 char *strerror(int err)
   41 /* Translate some DOS error numbers to text. */
   42 {
   43         static struct errlist {
   44                 int     err;
   45                 char    *what;
   46         } errlist[] = {
   47                 {  0, "No error" },
   48                 {  1, "Function number invalid" },
   49                 {  2, "File not found" },
   50                 {  3, "Path not found" },
   51                 {  4, "Too many open files" },
   52                 {  5, "Access denied" },
   53                 {  6, "Invalid handle" },
   54                 { 12, "Access code invalid" },
   55                 { 39, "Insufficient disk space" },
   56         };
   57         struct errlist *ep;
   58         static char unknown[]= "Error 65535";
   59         unsigned e;
   60         char *p;
   61 
   62         for (ep= errlist; ep < errlist + sizeof(errlist)/sizeof(errlist[0]);
   63                                                                         ep++) {
   64                 if (ep->err == err) return ep->what;
   65         }
   66         p= unknown + sizeof(unknown) - 1;
   67         e= err;
   68         do *--p= '' + (e % 10); while ((e /= 10) > 0);
   69         strcpy(unknown + 6, p);
   70         return unknown;
   71 }
   72 
   73 int main(int argc, char **argv)
   74 {
   75         int i;
   76         static char buf[512];
   77         unsigned long size, mul;
   78         off_t offset;
   79         char *cp;
   80         int fd;
   81         char *file;
   82 
   83         if (argc != 3) usage();
   84 
   85         cp= argv[1];
   86         size= 0;
   87         while ((unsigned) (*cp - '') < 10) {
   88                 unsigned d= *cp++ - '';
   89                 if (size <= (ULONG_MAX-9) / 10) {
   90                         size= size * 10 + d;
   91                 } else {
   92                         size= ULONG_MAX;
   93                 }
   94         }
   95         if (cp == argv[1]) usage();
   96         while (*cp != 0) {
   97                 mul = 1;
   98                 switch (*cp++) {
   99                 case 'G':
  100                 case 'g':       mul *= 1024;
  101                 case 'M':
  102                 case 'm':       mul *= 1024;
  103                 case 'K':
  104                 case 'k':       mul *= 1024;
  105                 case 'B':
  106                 case 'b':       break;
  107                 default:        usage();
  108                 }
  109                 if (size <= ULONG_MAX / mul) {
  110                         size *= mul;
  111                 } else {
  112                         size= ULONG_MAX;
  113                 }
  114         }
  115 
  116         if (size > 1024L*1024*1024) {
  117                 printf("mkfile: A file size over 1G is a bit too much\n");
  118                 exit(1);
  119         }
  120 
  121         /* Open existing file, or create a new file. */
  122         file= argv[2];
  123         if ((fd= open(file, O_WRONLY)) < 0) {
  124                 if (errno == 2) {
  125                         fd= creat(file, 0666);
  126                 }
  127         }
  128         if (fd < 0) {
  129                 printf("mkfile: Can't open %s: %s\n", file, strerror(errno));
  130                 exit(1);
  131         }
  132 
  133         /* How big is the file now? */
  134         if ((offset= lseek(fd, 0, SEEK_END)) == -1) {
  135                 printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
  136                 exit(1);
  137         }
  138 
  139         if (offset == 0 && size == 0) exit(0);  /* Huh? */
  140 
  141         /* Write the first bit if the file is zero length.  This is necessary
  142          * to circumvent a DOS bug by extending a new file by lseek.  We also
  143          * want to make sure there are zeros in the first sector.
  144          */
  145         if (offset == 0) {
  146                 if (write(fd, buf, sizeof(buf)) == -1) {
  147                         printf("mkfile: Can't write to %s: %s\n",
  148                                 file, strerror(errno));
  149                         exit(1);
  150                 }
  151         }
  152 
  153         /* Seek to the required size and write 0 bytes to extend/truncate the
  154          * file to that size.
  155          */
  156         if (lseek(fd, size, SEEK_SET) == -1) {
  157                 printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
  158                 exit(1);
  159         }
  160         if (write(fd, buf, 0) == -1) {
  161                 printf("mkfile: Can't write to %s: %s\n",
  162                         file, strerror(errno));
  163                 exit(1);
  164         }
  165 
  166         /* Did the file become the required size? */
  167         if ((offset= lseek(fd, 0, SEEK_END)) == -1) {
  168                 printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
  169                 exit(1);
  170         }
  171         if (offset != size) {
  172                 printf("mkfile: Failed to extend %s.  Disk full?\n", file);
  173                 exit(1);
  174         }
  175         return 0;
  176 }
  177 
  178 /*
  179  * $PchId: mkfile.c,v 1.4 2000/08/13 22:06:40 philip Exp $
  180  */

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FreeBSD/Linux Kernel Cross Reference sys/boot/mkfile.c

FreeBSD/Linux Kernel Cross Reference
sys/boot/mkfile.c