git.scottworley.com Git - tl-append/blob - tl-append.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3
   4 const char *FILENAME = "tl.log";
   5 const size_t BUF_SIZE = 1024;
   6
   7 static void die(const char *message) {
   8   fputs(message, stderr);
   9   fputc('\n', stderr);
  10   exit(1);
  11 }
  12
  13 static void die_err(const char *message) {
  14   perror(message);
  15   exit(1);
  16 }
  17
  18 static void read_line(char *buf) {
  19   if (fgets(buf, BUF_SIZE, stdin) == NULL) {
  20     if (ferror(stdin))
  21       die("I/O error reading line");
  22     if (feof(stdin)) {
  23       buf[0] = '\0'; /* Unclear if fgets does this already */
  24       return;
  25     }
  26     die("Unexpected error reading line");
  27   }
  28 }
  29
  30 static void write_line(const char *line) {
  31   FILE *f = fopen(FILENAME, "a");
  32   if (f == NULL)
  33     die_err("Error opening output file");
  34   if (fputs(line, f) == EOF)
  35     die("Error writing to output file");
  36   if (fclose(f) != 0)
  37     die_err("Error closing output file");
  38 }
  39
  40 int main() {
  41   char buf[BUF_SIZE];
  42   for (read_line(buf); buf[0]; read_line(buf)) {
  43     write_line(buf);
  44   }
  45   return 0;
  46 }