libbb/all_read.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  */
  21
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <errno.h>
  25 #include "libbb.h"
  26
  27 extern void archive_xread_all(int fd , char *buf, size_t count)
  28 {
  29         ssize_t size;
  30
  31         size = full_read(fd, buf, count);
  32         if (size != count) {
  33                 perror_msg_and_die("Short read");
  34         }
  35         return;
  36 }
  37
  38 /*
  39  * Read all of the supplied buffer from a file.
  40  * This does multiple reads as necessary.
  41  * Returns the amount read, or -1 on an error.
  42  * A short read is returned on an end of file.
  43  */
  44 ssize_t full_read(int fd, char *buf, int len)
  45 {
  46         ssize_t cc;
  47         ssize_t total;
  48
  49         total = 0;
  50
  51         while (len > 0) {
  52                 cc = safe_read(fd, buf, len);
  53
  54                 if (cc < 0)
  55                         return cc;      /* read() returns -1 on failure. */
  56
  57                 if (cc == 0)
  58                         break;
  59
  60                 buf = ((char *)buf) + cc;
  61                 total += cc;
  62                 len -= cc;
  63         }
  64
  65         return total;
  66 }
  67
  68
  69 ssize_t safe_read(int fd, void *buf, size_t count)
  70 {
  71         ssize_t n;
  72
  73         do {
  74                 n = read(fd, buf, count);
  75         } while (n < 0 && errno == EINTR);
  76
  77         return n;
  78 }
  79
  80
  81
  82 /* END CODE */
  83