boot/mkfile.c

   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 void 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= '0' + (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         static char buf[512];
  76         unsigned long size, mul;
  77         off_t offset;
  78         char *cp;
  79         int fd;
  80         char *file;
  81
  82         if (argc != 3) usage();
  83
  84         cp= argv[1];
  85         size= 0;
  86         while ((unsigned) (*cp - '0') < 10) {
  87                 unsigned d= *cp++ - '0';
  88                 if (size <= (ULONG_MAX-9) / 10) {
  89                         size= size * 10 + d;
  90                 } else {
  91                         size= ULONG_MAX;
  92                 }
  93         }
  94         if (cp == argv[1]) usage();
  95         while (*cp != 0) {
  96                 mul = 1;
  97                 switch (*cp++) {
  98                 case 'G':
  99                 case 'g':       mul *= 1024;
 100                 case 'M':
 101                 case 'm':       mul *= 1024;
 102                 case 'K':
 103                 case 'k':       mul *= 1024;
 104                 case 'B':
 105                 case 'b':       break;
 106                 default:        usage();
 107                 }
 108                 if (size <= ULONG_MAX / mul) {
 109                         size *= mul;
 110                 } else {
 111                         size= ULONG_MAX;
 112                 }
 113         }
 114
 115         if (size > 1024L*1024*1024) {
 116                 printf("mkfile: A file size over 1G is a bit too much\n");
 117                 exit(1);
 118         }
 119
 120         /* Open existing file, or create a new file. */
 121         file= argv[2];
 122         if ((fd= open(file, O_WRONLY)) < 0) {
 123                 if (errno == 2) {
 124                         fd= creat(file, 0666);
 125                 }
 126         }
 127         if (fd < 0) {
 128                 printf("mkfile: Can't open %s: %s\n", file, strerror(errno));
 129                 exit(1);
 130         }
 131
 132         /* How big is the file now? */
 133         if ((offset= lseek(fd, 0, SEEK_END)) == -1) {
 134                 printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
 135                 exit(1);
 136         }
 137
 138         if (offset == 0 && size == 0) exit(0);  /* Huh? */
 139
 140         /* Write the first bit if the file is zero length.  This is necessary
 141          * to circumvent a DOS bug by extending a new file by lseek.  We also
 142          * want to make sure there are zeros in the first sector.
 143          */
 144         if (offset == 0) {
 145                 if (write(fd, buf, sizeof(buf)) == -1) {
 146                         printf("mkfile: Can't write to %s: %s\n",
 147                                 file, strerror(errno));
 148                         exit(1);
 149                 }
 150         }
 151
 152         /* Seek to the required size and write 0 bytes to extend/truncate the
 153          * file to that size.
 154          */
 155         if (lseek(fd, size, SEEK_SET) == -1) {
 156                 printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
 157                 exit(1);
 158         }
 159         if (write(fd, buf, 0) == -1) {
 160                 printf("mkfile: Can't write to %s: %s\n",
 161                         file, strerror(errno));
 162                 exit(1);
 163         }
 164
 165         /* Did the file become the required size? */
 166         if ((offset= lseek(fd, 0, SEEK_END)) == -1) {
 167                 printf("mkfile: Can't seek in %s: %s\n", file, strerror(errno));
 168                 exit(1);
 169         }
 170         if (offset != size) {
 171                 printf("mkfile: Failed to extend %s.  Disk full?\n", file);
 172                 exit(1);
 173         }
 174         return 0;
 175 }
 176
 177 /*
 178  * $PchId: mkfile.c,v 1.4 2000/08/13 22:06:40 philip Exp $
 179  */