Materiale su splice, ed esempio non funzionante

[gapil.git] / sources / splicecp.c

diff --git a/sources/splicecp.c b/sources/splicecp.c
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+/* splicecp.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 splicecp.c: 
+ * A sample program that copy a file using splice
+ *
+ * Author: Simone Piccardi
+ * Aug. 2007
+ *
+ ****************************************************************/
+/* 
+ * Include needed headers
+ */
+#define _GNU_SOURCE
+#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>
+#include <sys/types.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;
+    int pipefd[2];
+    int in_fd, out_fd;
+    int nread, nwrite;
+    /*
+     * Input section: decode command line parameters 
+     * Use getopt function
+     */
+    opterr = 0;  /* don't want writing to stderr */
+    while ( (i = getopt(argc, argv, "hs:")) != -1) {
+        switch (i) {
+        /* 
+         * Handling options 
+         */ 
+        case 'h':      /* help option */
+            printf("Wrong -h option use\n");
+            usage();
+            return -1;
+            break;
+        case 's':      /* take wait time for childen */
+            size = strtol(optarg, NULL, 10);    /* convert input */
+            break;
+       case '?':      /* unrecognized options */
+            printf("Unrecognized options -%c\n", optopt);
+            usage();
+        default:       /* should not reached */
+            usage();
+        }
+    }
+   /*
+    * Main body
+    */
+    if ((argc - optind) != 2) { /* There must two argument */
+        printf("Wrong number of arguments %d\n", argc - optind);
+        usage();
+    }
+    /* open pipe, input and output file */
+    if (pipe(pipefd) == -1) { 
+       perror("Cannot create buffer pipe"); 
+       exit(EXIT_FAILURE); 
+    }
+    in_fd = open(argv[optind], O_RDONLY);
+    if (in_fd < 0) {
+       printf("Input error %s on %s\n", strerror(errno), argv[optind]);
+       exit(EXIT_FAILURE); 
+    }
+    out_fd = open(argv[optind+1], O_CREAT|O_RDWR, 0644);
+    if (out_fd < 0) {
+       printf("Cannot open %s, error %s\n", argv[optind+1], strerror(errno));
+       exit(EXIT_FAILURE); 
+    }
+    /* copy loop */
+    printf("Size %d\n", size);
+    while (1) {
+       nread = splice(in_fd, NULL, pipefd[1], NULL, size, 0);
+       printf("read %d bytes\n", nread);
+       if (nread == 0) break;
+       if (nread < 0) {
+           if (errno == EINTR) {
+               continue;
+           } else {
+               perror("read error");
+               exit(EXIT_FAILURE); 
+           } 
+       }
+       do {
+           nwrite = splice(pipefd[0], NULL, out_fd, NULL, nread, 0); 
+           printf("write %d bytes\n", nwrite);
+           if (nwrite == 0) continue;
+           if (nwrite < 0) {
+               if (errno == EINTR)
+                   continue;
+           } else {
+               perror("write error");
+               exit(EXIT_FAILURE); 
+           }
+           nread -= nwrite;
+           printf("left %d bytes", nread);
+       } while (nread);
+    }
+    return EXIT_SUCCESS;
+}
+
+
+
+/*
+ * routine to print usage info and exit 
+ */
+void usage(void) {
+    printf("Program splicecp: copy two file using splice syscall\n");
+    printf("Usage:\n");
+    printf("  splicecp [-h] [-s N] filesrc filedst \n");
+    printf("  -h           print this help\n");
+    printf("  -s N         set a buffer size of N bytes \n");
+    exit(1);
+}