LXR busybox/libbb/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 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9#include "libbb.h"
  10
  11ssize_t FAST_FUNC safe_read(int fd, void *buf, size_t count)
  12{
  13        ssize_t n;
  14
  15        do {
  16                n = read(fd, buf, count);
  17        } while (n < 0 && errno == EINTR);
  18
  19        return n;
  20}
  21
  22/*
  23 * Read all of the supplied buffer from a file.
  24 * This does multiple reads as necessary.
  25 * Returns the amount read, or -1 on an error.
  26 * A short read is returned on an end of file.
  27 */
  28ssize_t FAST_FUNC full_read(int fd, void *buf, size_t len)
  29{
  30        ssize_t cc;
  31        ssize_t total;
  32
  33        total = 0;
  34
  35        while (len) {
  36                cc = safe_read(fd, buf, len);
  37
  38                if (cc < 0) {
  39                        if (total) {
  40                                /* we already have some! */
  41                                /* user can do another read to know the error code */
  42                                return total;
  43                        }
  44                        return cc; /* read() returns -1 on failure. */
  45                }
  46                if (cc == 0)
  47                        break;
  48                buf = ((char *)buf) + cc;
  49                total += cc;
  50                len -= cc;
  51        }
  52
  53        return total;
  54}
  55
  56ssize_t FAST_FUNC read_close(int fd, void *buf, size_t size)
  57{
  58        /*int e;*/
  59        size = full_read(fd, buf, size);
  60        /*e = errno;*/
  61        close(fd);
  62        /*errno = e;*/
  63        return size;
  64}
  65
  66ssize_t FAST_FUNC open_read_close(const char *filename, void *buf, size_t size)
  67{
  68        int fd = open(filename, O_RDONLY);
  69        if (fd < 0)
  70                return fd;
  71        return read_close(fd, buf, size);
  72}
  73