src/process1.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4
   5 /* open/read/write/close */
   6 #include <fcntl.h>
   7
   8 /** If buffer is too small to hold entire string, it is incremented by this value */
   9 #define BUFFER_STEP 16
  10
  11 /**
  12  * Program reads entire lines of text from the standard input and pass them
  13  * to the process2 using created pipe.
  14  */
  15 int main(void) {
  16         /** Currently fetched from stdin character */
  17         int c;
  18
  19         /** Buffer used to store line of characters */
  20         char * buffer = NULL;
  21
  22         /** Current buffer length*/
  23         int buffer_length = 0;
  24
  25         /** Index of the current character */
  26         int i = 0;
  27
  28         /**
  29          * Temporary buffer used as a proxy between
  30          * checking memory allocation and copying data to real buffer
  31          */
  32         char * tmp = NULL;
  33
  34         /** Named pipe used to communnicate with process2 */
  35         char * write_pipe = "/tmp/process1pipe";
  36
  37         /** File descriptor of pipe */
  38         int file_descriptor;
  39
  40         mkfifo(write_pipe, 0666);
  41
  42         file_descriptor = open(write_pipe, O_WRONLY);
  43
  44         fprintf(stderr, "[%s] Init!\n", "process1");
  45
  46         do {
  47                 c = fgetc(stdin);
  48
  49                 /*
  50                  * Check if current index is bigger than current buffer size.
  51                  * If so increment buffer size. On error release memory, and set
  52                  * appropriate flags.
  53                  */
  54                 if (i >= buffer_length) {
  55                         tmp = NULL;
  56                         buffer_length += BUFFER_STEP;
  57                         tmp = (char*) realloc(buffer, buffer_length);
  58                         if (tmp == NULL) {
  59                                 fprintf(stderr, "[%s] Memory allocation problem on read!\n", "process1");
  60                                 free(buffer);
  61                                 buffer = NULL;
  62                                 c = EOF;
  63                         }
  64                 }
  65
  66                 /*
  67                  * If there were no errors or it was not just an empty newline:
  68                  * parse data.
  69                  */
  70                 if (c != EOF || ((i == 0) && (c == 10))) {
  71                         /* If newline has been found
  72                          * return entire string and release the memory
  73                          */
  74                         if (c == 10 && (i != 0)) {
  75                                 buffer[i] = '\n';
  76                                 write(file_descriptor, buffer, strlen(buffer));
  77                                 fprintf(stderr, "[%s] buffer: %s/%d\n", "process1", buffer, strlen(buffer));
  78
  79                                 buffer_length = 0;
  80                                 i = 0;
  81
  82                                 free(buffer);
  83                                 buffer = NULL;
  84                                 tmp = NULL;
  85                         }
  86                         /*
  87                          * Normal character, add it to the buffer
  88                          */
  89                         else {
  90                                 buffer = tmp;
  91                                 buffer[i] = c;
  92
  93                                 /* Used only for debugging..*/
  94                                 /*
  95                                 printf("c: %c/%d, i: %d, bl: %d\n", c, c, i, buffer_length);
  96                                 */
  97                                 i++;
  98                         }
  99                 }
 100         } while(c != EOF);
 101
 102         close(write_pipe);
 103         unlink(write_pipe);
 104
 105         if (buffer) {
 106                 free(buffer);
 107                 buffer = NULL;
 108         }
 109
 110         return 0;
 111 }