Varie correzioni, completata revisione capitolo sull'I/O su file

[gapil.git] / sources / tee.c

diff --git a/sources/tee.c b/sources/tee.c
index 4c4a872c0d5b8252f751b226fa2a93f09a52282a..8c09ae35bae08e4ee7118a6be8a9f25ca7621e26 100644 (file)
--- a/sources/tee.c
+++ b/sources/tee.c
@@ -1,28 +1,68 @@
+/* tee.c
+ * 
+ * Copyright (C) 2007 Simone Piccardi
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/****************************************************************
+ *
+ * Program tee.c: 
+ * A sample program that duolicete stdin to stdout and a file
+ *
+ * Author: Simone Piccardi
+ * Aug. 2007
+ *
+ ****************************************************************/
+/* 
+ * Include needed headers
+ */
 #define _GNU_SOURCE
-#include <fcntl.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <assert.h>
-#include <errno.h>
-#include <limits.h>
-
+#include <fcntl.h>       /* file control functions */
+#include <unistd.h>      /* unix standard library */
+#include <stdlib.h>      /* C standard library */
+#include <errno.h>       /* error definitions and routines */
+#include <stdio.h>       /* standard I/O library */
+#include <string.h>      /* C strings library */
+#include <sys/stat.h>    /* file characteristics constants and functions */
+#include <sys/types.h>   /* primitive system data types */
+#include <limits.h>      /* system limits constants, types and functions */
 
+#include "macros.h"
+/* 
+ * Function and globals definitions
+ */
+void usage(void);  /* Help printing routine */
+/*
+ * Main program
+ */
 int main(int argc, char *argv[])
 {
    /*
     * Variables definition
     */
     int i;
-    int size = 4096;
+    size_t size = 4096;
     int fd;
     int len, nwrite;
+    struct stat fdata;
     /*
      * Input section: decode command line parameters 
      * Use getopt function
      */
     opterr = 0;  /* don't want writing to stderr */
-    while ( (i = getopt(argc, argv, "h")) != -1) {
+    while ( (i = getopt(argc, argv, "hs:")) != -1) {
         switch (i) {
         /* 
          * Handling options 
@@ -32,7 +72,7 @@ int main(int argc, char *argv[])
             usage();
             return -1;
             break;
-        case 's':      /* take wait time for childen */
+        case 's':      /* buffer size */
             size = strtol(optarg, NULL, 10);    /* convert input */
             break;
        case '?':      /* unrecognized options */
@@ -45,21 +85,39 @@ int main(int argc, char *argv[])
    /*
     * Main body
     */
-    if ((argc - optind) != 1) { /* There must two argument */
+    if ((argc - optind) != 1) { /* There must be one argument */
         printf("Wrong number of arguments %d\n", argc - optind);
         usage();
     }
-    /* open destination file */
+    /* open destination file and check stdin and stdout */
     fd = open(argv[1], O_WRONLY|O_CREAT|O_TRUNC, 0644);
     if (fd == -1) {
         printf("cannot open destination file %s, %s", argv[1], 
               strerror(errno));
         exit(EXIT_FAILURE);
     }
+    if (fstat(STDIN_FILENO, &fdata) < 0) {
+       perror("stat");
+       exit(EXIT_FAILURE);
+    }
+    if (!S_ISFIFO(fdata.st_mode)) {
+       fprintf(stderr, "stdin must be a pipe\n");
+       exit(EXIT_FAILURE);
+    }
+    if (fstat(STDOUT_FILENO, &fdata) < 0) {
+       perror("stat");
+       exit(EXIT_FAILURE);
+    }
+    if (!S_ISFIFO(fdata.st_mode)) {
+       fprintf(stderr, "stdout must be a pipe\n");
+       exit(EXIT_FAILURE);
+    }
     /* tee loop */
     while (1) {
         /* copy stdin to stdout */
-        len = tee(STDIN_FILENO, STDOUT_FILENO, size, SPLICE_F_NONBLOCK);
+        len = tee(STDIN_FILENO, STDOUT_FILENO, size, 0);
+       fprintf(stderr, "Copied %d byte\n", len); /* debug (use stderr!) */
+       if (len == 0) break;
         if (len < 0) {
             if (errno == EAGAIN) {
                continue;
@@ -67,9 +125,7 @@ int main(int argc, char *argv[])
                perror("error on tee stdin to stdout");
                exit(EXIT_FAILURE);
            }
-        } else {
-            if (len == 0) break;
-       }
+        }
         /* write data to the file using splice */
         while (len > 0) {
             nwrite = splice(STDIN_FILENO, NULL, fd, NULL, len, SPLICE_F_MOVE);
@@ -83,3 +139,16 @@ int main(int argc, char *argv[])
     close(fd);
     exit(EXIT_SUCCESS);
 }
+
+/*
+ * routine to print usage info and exit 
+ */
+void usage(void) {
+    printf("Program tee: duplicate stdin to stdout and a file\n");
+    printf("Usage:\n");
+    printf("  tee [-h] [-s N] filename\n");
+    printf("  -h           print this help\n");
+    printf("  -s N         set a buffer size of N bytes \n");
+    exit(1);
+}
+