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This commit is contained in:
Jim Meyering
2002-12-03 12:03:55 +00:00
parent 01d5814091
commit b3e08a0a69
1 changed files with 37 additions and 37 deletions
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lib/safe-write.c
+37 -37
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@@ -1,4 +1,4 @@
/* An interface to write() that retries after interrupts.
/* An interface to write 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
@@ -33,51 +33,51 @@
extern int errno;
#endif
#ifdef EINTR
# define IS_EINTR(x) ((x) == EINTR)
#else
# define IS_EINTR(x) 0
#endif
#include <limits.h>
/* We don't pass an nbytes count > SSIZE_MAX to write() - POSIX says the
effect would be implementation-defined. Also we don't pass an nbytes
count > INT_MAX but <= SSIZE_MAX to write() - this triggers a bug in
Tru64 5.1. */
#define MAX_BYTES_TO_READ INT_MAX
#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
/* Write up to COUNT bytes at BUF to descriptor FD, retrying if interrupted.
Return the actual number of bytes written, zero for EOF, or (size_t) -1
for an error. */
Return the actual number of bytes written, zero for EOF, or SAFE_WRITE_ERROR
upon error. */
size_t
safe_write (int fd, const void *buf, size_t count)
{
size_t total_written = 0;
ssize_t result;
if (count > 0)
/* POSIX limits COUNT to SSIZE_MAX, but we limit it further, requiring
that COUNT <= INT_MAX, to avoid triggering a bug in Tru64 5.1.
When decreasing COUNT, keep the file pointer block-aligned.
Note that in any case, write may succeed, yet write fewer than COUNT
bytes, so the caller must be prepared to handle partial results. */
if (count > INT_MAX)
count = INT_MAX & ~8191;
do
{
const char *ptr = (const char *) buf;
do
{
size_t nbytes_to_write = count;
ssize_t result;
/* Limit the number of bytes to write in one round, to avoid running
into unspecified behaviour. But keep the file pointer block
aligned when doing so. */
if (nbytes_to_write > MAX_BYTES_TO_READ)
nbytes_to_write = MAX_BYTES_TO_READ & ~8191;
result = write (fd, ptr, nbytes_to_write);
if (result < 0)
{
#ifdef EINTR
if (errno == EINTR)
continue;
#endif
return result;
}
total_written += result;
ptr += result;
count -= result;
}
while (count > 0);
result = write (fd, buf, count);
}
while (result < 0 && IS_EINTR (errno));
return total_written;
return (size_t) result;
}