From 849efe7683e163ede9240b27d675977c71c76ce8 Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Fri, 22 Nov 2002 16:25:53 +0000 Subject: [PATCH] Orthogonal approach to read()/write() that handles EINTR and counts > 2^31 correctly. --- lib/ChangeLog | 15 ++++++++++ lib/full-read.c | 65 ++++++++++++++++++++++++++++++++++++++++++++ lib/full-read.h | 24 ++++++++++++++++ lib/full-write.c | 55 ++++++++++++++++++------------------- lib/full-write.h | 33 ++++++++++++++++------ lib/safe-read.c | 68 +++++++++++++++++++++++++++++++--------------- lib/safe-read.h | 33 +++++++++++++++------- lib/safe-write.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/safe-write.h | 23 ++++++++++++++++ 9 files changed, 330 insertions(+), 69 deletions(-) create mode 100644 lib/full-read.c create mode 100644 lib/full-read.h create mode 100644 lib/safe-write.c create mode 100644 lib/safe-write.h diff --git a/lib/ChangeLog b/lib/ChangeLog index 90bd01850..f85e7176c 100644 --- a/lib/ChangeLog +++ b/lib/ChangeLog @@ -1,3 +1,18 @@ +2002-11-22 Bruno Haible + + * safe-read.h: Assume C89. Add comments. + (safe_read): Change return type to size_t. + * safe-read.c (safe_read): Change return type to size_t. Handle byte + counts > SSIZE_MAX correctly. + * safe-write.h: New file. + * safe-write.c: New file. + * full-read.h: New file. + * full-read.c: New file. + * full-write.h: Assume C89. Add comments. + * full-write.c: Include safe-write.h. + (full_write): Rewritten to use safe_write. + Suggested by Jim Meyering and Paul Eggert. + 2002-11-21 Bruno Haible Remove case insensitive option matching. diff --git a/lib/full-read.c b/lib/full-read.c new file mode 100644 index 000000000..a328588ca --- /dev/null +++ b/lib/full-read.c @@ -0,0 +1,65 @@ +/* An interface to read() that reads all it is asked to read. + + Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002 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 + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, read to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#if HAVE_CONFIG_H +# include +#endif + +/* Specification. */ +#include "full-read.h" + +#include +#ifndef errno +extern int errno; +#endif + +#include "safe-read.h" + +/* Read COUNT bytes at BUF to descriptor FD, retrying if interrupted + or if partial reads occur. Return the number of bytes successfully + read, setting errno if that is less than COUNT. errno = 0 means EOF. */ +size_t +full_read (int fd, void *buf, size_t count) +{ + size_t total_read = 0; + + if (count > 0) + { + char *ptr = buf; + + do + { + size_t nread = safe_read (fd, ptr, count); + if (nread == (size_t)-1) + break; + if (nread == 0) + { + /* EOF. */ + errno = 0; + break; + } + total_read += nread; + ptr += nread; + count -= nread; + } + while (count > 0); + } + + return total_read; +} diff --git a/lib/full-read.h b/lib/full-read.h new file mode 100644 index 000000000..71f19a3bd --- /dev/null +++ b/lib/full-read.h @@ -0,0 +1,24 @@ +/* An interface to read() that reads all it is asked to read. + + Copyright (C) 2002 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 + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, read to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include + +/* Read COUNT bytes at BUF to descriptor FD, retrying if interrupted + or if partial reads occur. Return the number of bytes successfully + read, setting errno if that is less than COUNT. errno = 0 means EOF. */ +extern size_t full_read (int fd, void *buf, size_t count); diff --git a/lib/full-write.c b/lib/full-write.c index 4e566f6e2..f21e4791a 100644 --- a/lib/full-write.c +++ b/lib/full-write.c @@ -1,6 +1,6 @@ -/* full-write.c -- an interface to write that retries after interrupts +/* An interface to write() that writes all it is asked to write. - Copyright 1993, 1994, 1997, 1998, 1999, 2000, 2001 Free Software + Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify @@ -15,53 +15,52 @@ You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, - Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - - Written by Paul Eggert. */ + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #if HAVE_CONFIG_H # include #endif -#include - +/* Specification. */ #include "full-write.h" -#if HAVE_UNISTD_H -# include -#endif - #include #ifndef errno extern int errno; #endif -/* Write LEN bytes at PTR to descriptor DESC, retrying if interrupted - or if partial writes occur. Return the number of bytes successfully - written, setting errno if that is less than LEN. */ +#include "safe-write.h" +/* 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. */ size_t -full_write (int desc, const char *ptr, size_t len) +full_write (int fd, const void *buf, size_t count) { size_t total_written = 0; - while (len > 0) + if (count > 0) { - ssize_t written = write (desc, ptr, len); - if (written <= 0) + const char *ptr = buf; + + do { - /* Some buggy drivers return 0 when you fall off a device's end. */ + size_t written = safe_write (fd, ptr, count); + if (written == (size_t)-1) + break; if (written == 0) - errno = ENOSPC; -#ifdef EINTR - if (errno == EINTR) - continue; -#endif - break; + { + /* Some buggy drivers return 0 when you fall off a device's + end. (Example: Linux 1.2.13 on /dev/fd0.) */ + errno = ENOSPC; + break; + } + total_written += written; + ptr += written; + count -= written; } - total_written += written; - ptr += written; - len -= written; + while (count > 0); } + return total_written; } diff --git a/lib/full-write.h b/lib/full-write.h index f23bccb5a..8cd2e8157 100644 --- a/lib/full-write.h +++ b/lib/full-write.h @@ -1,9 +1,24 @@ -#ifndef PARAMS -# if defined PROTOTYPES || (defined __STDC__ && __STDC__) -# define PARAMS(Args) Args -# else -# define PARAMS(Args) () -# endif -#endif - -size_t full_write PARAMS ((int, const char *, size_t)); +/* An interface to write() that writes all it is asked to write. + + Copyright (C) 2002 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 + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include + +/* 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. */ +extern size_t full_write (int fd, const void *buf, size_t count); diff --git a/lib/safe-read.c b/lib/safe-read.c index e404586c7..79d85417d 100644 --- a/lib/safe-read.c +++ b/lib/safe-read.c @@ -1,5 +1,5 @@ -/* safe-read.c -- an interface to read that retries after interrupts - Copyright (C) 1993, 1994, 1998 Free Software Foundation, Inc. +/* 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 it under the terms of the GNU General Public License as published by @@ -13,15 +13,17 @@ You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, - Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - */ + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #if HAVE_CONFIG_H # include #endif -#include +/* Specification. */ +#include "safe-read.h" +/* Get ssize_t. */ +#include #if HAVE_UNISTD_H # include #endif @@ -31,29 +33,51 @@ extern int errno; #endif -#include "safe-read.h" +#include -/* Read LEN bytes at PTR from descriptor DESC, retrying if interrupted. - Return the actual number of bytes read, zero for EOF, or negative - for an error. */ +/* 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 + Tru64 5.1. */ +#define MAX_BYTES_TO_READ INT_MAX -ssize_t -safe_read (int desc, void *ptr, size_t len) +/* 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. */ +size_t +safe_read (int fd, void *buf, size_t count) { - ssize_t n_chars; + size_t total_read = 0; - if (len <= 0) - return len; + if (count > 0) + { + char *ptr = (char *) buf; + do + { + 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; + result = read (fd, ptr, nbytes_to_read); + if (result < 0) + { #ifdef EINTR - do - { - n_chars = read (desc, ptr, len); - } - while (n_chars < 0 && errno == EINTR); -#else - n_chars = read (desc, ptr, len); + if (errno == EINTR) + continue; #endif + return result; + } + total_read += result; + ptr += result; + count -= result; + } + while (count > 0); + } - return n_chars; + return total_read; } diff --git a/lib/safe-read.h b/lib/safe-read.h index 8e4b165cb..c4445ac1b 100644 --- a/lib/safe-read.h +++ b/lib/safe-read.h @@ -1,10 +1,23 @@ -#ifndef PARAMS -# if defined PROTOTYPES || (defined __STDC__ && __STDC__) -# define PARAMS(Args) Args -# else -# define PARAMS(Args) () -# endif -#endif - -ssize_t -safe_read PARAMS ((int desc, void *ptr, size_t len)); +/* An interface to read() that retries after interrupts. + Copyright (C) 2002 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 + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include + +/* 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. */ +extern size_t safe_read (int fd, void *buf, size_t count); diff --git a/lib/safe-write.c b/lib/safe-write.c new file mode 100644 index 000000000..55962039e --- /dev/null +++ b/lib/safe-write.c @@ -0,0 +1,83 @@ +/* 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 + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#if HAVE_CONFIG_H +# include +#endif + +/* Specification. */ +#include "safe-write.h" + +/* Get ssize_t. */ +#include +#if HAVE_UNISTD_H +# include +#endif + +#include +#ifndef errno +extern int errno; +#endif + +#include + +/* 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 + +/* 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. */ +size_t +safe_write (int fd, const void *buf, size_t count) +{ + size_t total_written = 0; + + if (count > 0) + { + 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); + } + + return total_written; +} diff --git a/lib/safe-write.h b/lib/safe-write.h new file mode 100644 index 000000000..25d1a4d48 --- /dev/null +++ b/lib/safe-write.h @@ -0,0 +1,23 @@ +/* An interface to write() that retries after interrupts. + Copyright (C) 2002 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 + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include + +/* 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. */ +extern size_t safe_write (int fd, const void *buf, size_t count); -- 2.11.0