src/bin/unchop.c

   1 // ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
   2 //
   3 //  Copyright (c) 2001-2003, OpenBeOS
   4 //
   5 //  This software is part of the OpenBeOS distribution and is covered
   6 //  by the MIT License.
   7 //
   8 //
   9 //  File:        unchop.c
  10 //  Author:      Daniel Reinhold (danielre@users.sf.net)
  11 //  Description: recreates a file previously split with chop
  12 //
  13 // ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
  14
  15 #include <OS.h>
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <unistd.h>
  22 #include <sys/stat.h>
  23
  24
  25 void  append_file (int, int);
  26 void  do_unchop   (char *, char *);
  27 void  replace     (char *, char *);
  28 char *temp_file   (void);
  29 void  usage       (void);
  30 bool  valid_file  (char *);
  31
  32
  33 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  34 // globals
  35
  36 #define BLOCKSIZE 64 * 1024     // file data is read in BLOCKSIZE blocks
  37 static char Block[BLOCKSIZE];   // and stored in the global Block array
  38
  39 static int Errors = 0;
  40
  41
  42
  43 void
  44 usage()
  45 {
  46         printf("Usage: unchop file\n");
  47         printf("Concatenates files named file00, file01... into file\n");
  48 }
  49
  50
  51 int
  52 main(int argc, char *argv[])
  53 {
  54         if (argc != 2) {
  55                 usage();
  56                 return 0;
  57         }
  58         else {
  59                 char *origfile = argv[1];
  60                 char *tmpfile  = origfile;
  61                 bool  needs_replace = false;
  62
  63                 if (valid_file(origfile)) {
  64                         // output file already exists -- write to temp file
  65                         tmpfile = temp_file();
  66                         needs_replace = true;
  67                 }
  68
  69                 do_unchop(tmpfile, origfile);
  70
  71                 if (needs_replace) {
  72                         if (Errors == 0)
  73                                 replace(origfile, tmpfile);
  74                         else
  75                                 remove(tmpfile);
  76                 }
  77         }
  78
  79         return Errors;
  80 }
  81
  82
  83 void
  84 do_unchop(char *outfile, char *basename)
  85 {
  86         int fdout = open(outfile, O_WRONLY|O_CREAT|O_APPEND);
  87         if (fdout < 0)
  88                 fprintf(stderr, "can't open '%s': %s\n", outfile, strerror(errno));
  89
  90         else {
  91                 int  i;
  92                 char fnameN[256];
  93
  94                 for (i = 0; i < 999999; ++i) {
  95                         sprintf(fnameN,  "%s%02d", basename, i);
  96
  97                         if (valid_file(fnameN)) {
  98                                 int fdin = open(fnameN, O_RDONLY);
  99                                 if (fdin < 0) {
 100                                         fprintf(stderr, "can't open '%s': %s\n", fnameN, strerror(errno));
 101                                         ++Errors;
 102                                 } else {
 103                                         append_file(fdin, fdout);
 104                                         close(fdin);
 105                                 }
 106                         } else {
 107                                 if (i == 0)
 108                                         printf("No chunk files present (%s)", fnameN);
 109                                 break;
 110                         }
 111                 }
 112                 close(fdout);
 113         }
 114 }
 115
 116
 117 void
 118 append_file(int fdin, int fdout)
 119 {
 120         // appends the entire contents of the input file
 121         // to the output file
 122
 123         ssize_t got;
 124
 125         for (;;) {
 126                 got = read(fdin, Block, BLOCKSIZE);
 127                 if (got <= 0)
 128                         break;
 129
 130                 write(fdout, Block, got);
 131         }
 132 }
 133
 134
 135 bool
 136 valid_file(char *fname)
 137 {
 138         // for this program, a valid file is one that:
 139         //   a) exists (that always helps)
 140         //   b) is a regular file (not a directory, link, etc.)
 141
 142         struct stat e;
 143
 144         if (stat(fname, &e) == -1) {
 145                 // no such file
 146                 return false;
 147         }
 148
 149         return (S_ISREG(e.st_mode));
 150 }
 151
 152
 153 void
 154 replace(char *origfile, char *newfile)
 155 {
 156         // replace the contents of the original file
 157         // with the contents of the new file
 158
 159         char buf[1000];
 160
 161         // delete the original file
 162         remove(origfile);
 163
 164         // rename the new file to the original file name
 165         sprintf(buf, "mv \"%s\" \"%s\"", newfile, origfile);
 166         system(buf);
 167 }
 168
 169
 170 char *
 171 temp_file(void)
 172 {
 173         // creates a new, temporary file and returns its name
 174
 175         char *tmp = tmpnam(NULL);
 176
 177         FILE *fp = fopen(tmp, "w");
 178         fclose(fp);
 179
 180         return tmp;
 181 }