Mercurial > hg > octave-lyh > gnulib-hg
changeset 4043:82f73831ca62
(safe_read): Also exit the loop when read returns zero.
(CHAR_BIT, TYPE_SIGNED, TYPE_MINIMUM, TYPE_MAXIMUM, INT_MAX): Define.
author | Jim Meyering <jim@meyering.net> |
---|---|
date | Sun, 01 Dec 2002 21:40:08 +0000 |
parents | 4dde81cd5ec3 |
children | c5aa8e0dbf7b |
files | lib/safe-read.c |
diffstat | 1 files changed, 39 insertions(+), 25 deletions(-) [+] |
line wrap: on
line diff
--- a/lib/safe-read.c +++ b/lib/safe-read.c @@ -1,4 +1,4 @@ -/* An interface to read() that retries after interrupts. +/* An interface to read that retries after interrupts. Copyright (C) 1993, 1994, 1998, 2002 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify @@ -35,6 +35,22 @@ #include <limits.h> +#ifndef CHAR_BIT +# define CHAR_BIT 8 +#endif + +/* The extra casts work around common compiler bugs. */ +#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) +/* The outer cast is needed to work around a bug in Cray C 5.0.3.0. + It is necessary at least when t == time_t. */ +#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \ + ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0)) +#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t))) + +#ifndef INT_MAX +# define INT_MAX TYPE_MAXIMUM (int) +#endif + /* We don't pass an nbytes count > SSIZE_MAX to read() - POSIX says the effect would be implementation-defined. Also we don't pass an nbytes count > INT_MAX but <= SSIZE_MAX to read() - this triggers a bug in @@ -42,41 +58,39 @@ #define MAX_BYTES_TO_READ INT_MAX /* Read up to COUNT bytes at BUF from descriptor FD, retrying if interrupted. - Return the actual number of bytes read, zero for EOF, or (size_t) -1 - for an error. */ + Return the actual number of bytes read, zero for EOF, or SAFE_READ_ERROR + upon error. */ size_t safe_read (int fd, void *buf, size_t count) { size_t total_read = 0; + char *ptr = buf; - if (count > 0) + while (count > 0) { - char *ptr = (char *) buf; - do - { - size_t nbytes_to_read = count; - ssize_t result; + size_t nbytes_to_read = count; + ssize_t result; - /* Limit the number of bytes to read in one round, to avoid running - into unspecified behaviour. But keep the file pointer block - aligned when doing so. */ - if (nbytes_to_read > MAX_BYTES_TO_READ) - nbytes_to_read = MAX_BYTES_TO_READ & ~8191; + /* Limit the number of bytes to read in one round, to avoid running + into unspecified behaviour. But keep the file pointer block + aligned when doing so. */ + if (nbytes_to_read > MAX_BYTES_TO_READ) + nbytes_to_read = MAX_BYTES_TO_READ & ~8191; - result = read (fd, ptr, nbytes_to_read); - if (result < 0) - { + result = read (fd, ptr, nbytes_to_read); + if (result == 0) + break; + if (result < 0) + { #ifdef EINTR - if (errno == EINTR) - continue; + if (errno == EINTR) + continue; #endif - return result; - } - total_read += result; - ptr += result; - count -= result; + return SAFE_READ_ERROR; } - while (count > 0); + total_read += result; + ptr += result; + count -= result; } return total_read;