examples/fatcat.c

   1 //--------------------------------------------------------------------------------------------------
   2 // Copyright (C) 2022 Marcus Geelnard
   3 //
   4 // Redistribution and use in source and binary forms, with or without modification, are permitted
   5 // provided that the following conditions are met:
   6 //
   7 //   1. Redistributions of source code must retain the above copyright notice, this list of
   8 //      conditions and the following disclaimer.
   9 //
  10 //   2. Redistributions in binary form must reproduce the above copyright notice, this list of
  11 //      conditions and the following disclaimer in the documentation and/or other materials provided
  12 //      with the distribution.
  13 //
  14 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
  15 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  16 // FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
  17 // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  19 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  20 // WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
  21 // WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  22 //--------------------------------------------------------------------------------------------------
  23
  24 #include <mfat.h>
  25
  26 #include <fcntl.h>
  27 #include <stdio.h>
  28 #include <sys/types.h>
  29 #include <unistd.h>
  30
  31 static int blkread(char* ptr, unsigned block_no, void* custom) {
  32   int fd = *(int*)custom;
  33   if (lseek(fd, MFAT_BLOCK_SIZE * (size_t)block_no, SEEK_SET) == -1) {
  34     return -1;
  35   }
  36   size_t num_bytes = read(fd, ptr, MFAT_BLOCK_SIZE);
  37   return (num_bytes != MFAT_BLOCK_SIZE) && (num_bytes != 0) ? -1 : 0;
  38 }
  39
  40 static int blkwrite(const char* ptr, unsigned block_no, void* custom) {
  41   int fd = *(int*)custom;
  42   if (lseek(fd, MFAT_BLOCK_SIZE * (size_t)block_no, SEEK_SET) == -1) {
  43     return -1;
  44   }
  45   size_t num_bytes = write(fd, ptr, MFAT_BLOCK_SIZE);
  46   return (num_bytes != MFAT_BLOCK_SIZE) && (num_bytes != 0) ? -1 : 0;
  47 }
  48
  49 int main(int argc, char** argv) {
  50   // Get arguments.
  51   if (argc != 3) {
  52     printf("Usage: %s FATIMAGE FILE\n", argv[0]);
  53     return 1;
  54   }
  55   const char* img_path = argv[1];
  56   const char* file_name = argv[2];
  57
  58   // Open the FAT image file or device.
  59   int img_fd = open(img_path, O_RDONLY);
  60   if (img_fd == -1) {
  61     fprintf(stderr, "*** Failed to open the FAT image\n");
  62     return 1;
  63   }
  64
  65   // Mount the image in MFAT.
  66   if (mfat_mount(blkread, blkwrite, &img_fd) == -1) {
  67     close(img_fd);
  68     fprintf(stderr, "*** Failed to init MFAT\n");
  69     return 1;
  70   }
  71
  72   // Print the contents of the file to stdout.
  73   int fd = mfat_open(file_name, MFAT_O_RDONLY);
  74   if (fd != -1) {
  75     uint8_t buf[100];
  76     while (1) {
  77       ssize_t bytes_read = mfat_read(fd, &buf[0], sizeof(buf));
  78       if (bytes_read > 0) {
  79         ssize_t bytes_written = write(STDOUT_FILENO, &buf[0], bytes_read);
  80         (void)bytes_written;  // Silence compiler warnings.
  81       } else {
  82         // 0 = EOF, -1 = Error
  83         if (bytes_read == -1) {
  84           fprintf(stderr, "*** Failed to read %s\n", file_name);
  85         }
  86         break;
  87       }
  88     }
  89
  90     // Close the file.
  91     mfat_close(fd);
  92   } else {
  93     fprintf(stderr, "*** Failed to open %s\n", file_name);
  94   }
  95
  96   // Unmount and close down.
  97   mfat_unmount();
  98   close(img_fd);
  99
 100   return 0;
 101 }