diff options
Diffstat (limited to 'lib')
-rw-r--r-- | lib/full-write.c | 61 |
1 files changed, 40 insertions, 21 deletions
diff --git a/lib/full-write.c b/lib/full-write.c index a952f8c81..5bb90b44d 100644 --- a/lib/full-write.c +++ b/lib/full-write.c @@ -1,7 +1,6 @@ -/* An interface to write() that writes all it is asked to write. +/* An interface to read and write that retries (if necessary) until complete. - Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002 Free Software - Foundation, Inc. + Copyright (C) 1993, 1994, 1997-2003 Free Software Foundation, Inc. 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 @@ -21,41 +20,61 @@ # include <config.h> #endif -/* Specification. */ -#include "full-write.h" +#ifdef FULL_READ +# include "full-read.h" +# include "safe-read.h" +# define safe_rw safe_read +# define full_rw full_read +# undef const +# define const /* empty */ +#else +# include "full-write.h" +# include "safe-write.h" +# define safe_rw safe_write +# define full_rw full_write +#endif #include <errno.h> #ifndef errno extern int errno; #endif -#include "safe-write.h" +#ifdef FULL_READ +/* Set errno to zero upon EOF. */ +# define ZERO_BYTE_TRANSFER_ERRNO 0 +#else +/* Some buggy drivers return 0 when one tries to write beyond + a device's end. (Example: Linux 1.2.13 on /dev/fd0.) + Set errno to ENOSPC so they get a sensible diagnostic. */ +# define ZERO_BYTE_TRANSFER_ERRNO ENOSPC +#endif -/* Write COUNT bytes at BUF to descriptor FD, retrying if interrupted - or if partial writes occur. Return the number of bytes successfully - written, setting errno if that is less than COUNT. */ +/* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if + interrupted or if a partial write(read) occurs. Return the number + of bytes transferred. + When writing, set errno if fewer than COUNT bytes are written. + When reading, if fewer than COUNT bytes are read, you must examine + errno to distinguish failure from EOF (errno == 0). */ size_t -full_write (int fd, const void *buf, size_t count) +full_rw (int fd, const void *buf, size_t count) { - size_t total_written = 0; + size_t total = 0; const char *ptr = buf; while (count > 0) { - size_t written = safe_write (fd, ptr, count); - if (written == (size_t)-1) + size_t n_rw = safe_rw (fd, ptr, count); + if (n_rw == (size_t) -1) break; - if (written == 0) + if (n_rw == 0) { - /* Some buggy drivers return 0 when you fall off a device's - end. (Example: Linux 1.2.13 on /dev/fd0.) */ - errno = ENOSPC; + errno = ZERO_BYTE_TRANSFER_ERRNO; break; } - total_written += written; - ptr += written; - count -= written; + total += n_rw; + ptr += n_rw; + count -= n_rw; } - return total_written; + return total; } |