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

[gapil.git] / sources / BarCodePage.c

diff --git a/sources/BarCodePage.c b/sources/BarCodePage.c
index ef48ce77bcd4d2d6c2fb43e7e9673d47b935fc08..6895a87896b2fc188b4680493176bd1219c02b4a 100644 (file)
--- a/sources/BarCodePage.c
+++ b/sources/BarCodePage.c
@@ -1,4 +1,4 @@
-/* BarCodeOld.c
+/* BarCodePage.c
  * 
  * Copyright (C) 2002 Simone Piccardi
  * 
@@ -29,28 +29,25 @@
  * http://localhost/cgi-bin/barcode?string
  * where string is the code to be converted
  *
- * $Id: BarCodePage.c,v 1.1 2002/06/30 13:26:17 piccardi Exp $ 
- *
  ****************************************************************/
 /* 
  * Include needed headers
  */
-#include <sys/types.h>   /* predefined types */
-#include <sys/stat.h>    /* stat deinitiions */
-#include <unistd.h>      /* include unix standard library */
-/* */
-#include <stdio.h>      /* include standard I/O library */
-#include <stdlib.h>     /* include standard library */
-#include <string.h>     /* include string library */
-#include <wait.h>       /* include wait call */
-#include <fcntl.h>
-#include <assert.h>
-#include <time.h>
+#include <sys/types.h>   /* primitive system data types */
+#include <sys/stat.h>    /* file characteristics constants and functions */
+#include <unistd.h>      /* unix standard library */
+#include <stdio.h>      /* standard I/O library */
+#include <stdlib.h>     /* C standard library */
+#include <string.h>     /* C strings library */
+#include <wait.h>       /* process termination constants and functions */
+#include <fcntl.h>       /* file control functions */
+#include <assert.h>     /* C assertion functions */
+#include <time.h>        /* date and time constants, types and functions */
+
 
 #include"macros.h"
 void WriteMess(char *mess);
 
-
 /* Program begin */
 int main(int argc, char *argv[], char *envp[])
 {
@@ -66,7 +63,7 @@ int main(int argc, char *argv[], char *envp[])
     /* 
      * Begin
      */
-    /* create two pipes to handle process communication */
+    /* create two pipes, pipein and pipeout, to handle communication */
     if ( (retval = pipe(pipein)) ) {
        WriteMess("input pipe creation error");
        exit(0);        
@@ -75,11 +72,10 @@ int main(int argc, char *argv[], char *envp[])
        WriteMess("output pipe creation error");
        exit(0);        
     }   
-    /* fork child to run barcode program */
-    pid = fork();
-    if (pid == -1) {
+    /* First fork: use child to run barcode program */
+    if ( (pid = fork()) == -1 ) {
        WriteMess("child creation error");
-       exit(0);        
+       exit(0);
     }
     /* if child */
     if (pid == 0) {
@@ -92,7 +88,7 @@ int main(int argc, char *argv[], char *envp[])
        dup2(pipein[0], STDIN_FILENO);   /* remap stdin in pipe input */
        close(pipeout[0]);
        dup2(pipeout[1], STDOUT_FILENO); /* remap stdout in pipe output */
-       execlp("barcode", "barcode", size, NULL); //"-o", "-",  NULL);
+       execlp("barcode", "barcode", size, NULL); 
     } 
     /*
      * Parent write string to pipe input and close it, 
@@ -103,9 +99,8 @@ int main(int argc, char *argv[], char *envp[])
     write(pipein[1], argv[1], strlen(argv[1]));
     close(pipein[1]);
     waitpid(pid, NULL, 0);
-    /* Second fork use child to run ghostscript*/
-    pid = fork();
-    if (pid == -1) {
+    /* Second fork: use child to run ghostscript*/
+    if ( (pid = fork()) == -1) {
        WriteMess("child creation error");
        exit(0);
     }