453 lines
13 KiB
C
453 lines
13 KiB
C
/*
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* Copyright (c) 2024 DTB <trinity@trinity.moe>
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU Affero General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see https://www.gnu.org/licenses/.
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*/
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#include <ctype.h> /* isupper(3), tolower(3) */
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#include <errno.h> /* errno */
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#include <fcntl.h> /* open(2) */
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#include <stdio.h> /* fprintf(3), stderr */
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#include <stdlib.h> /* free(3), malloc(3), strtol(3), size_t */
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#include <string.h> /* memcpy(3), memmove(3), memset(3) */
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#include <sysexits.h> /* EX_OK, EX_USAGE */
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#include <unistd.h> /* close(2), getopt(3), lseek(2), read(2), write(2),
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* optarg, optind, STDIN_FILENO, STDOUT_FILENO */
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extern int errno;
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/* dj uses two structures that respectively correspond to the reading and
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* writing ends of its jockeyed "pipe". User-configurable members are noted
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* with their relevant options. */
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struct Io{
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int bs; /* buffer size (-bB) */
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size_t bufuse; /* buffer usage */
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char *buf; /* buffer */
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int bytes; /* bytes processed */
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int fd; /* file descriptor */
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int fl; /* file opening flags */
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char *fn; /* file name (may be stdin_name or stdout_name) (-io) */
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int prec; /* partial records processed */
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int rec; /* records processed */
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long seek; /* bytes to seek/skip (will be 0 after skippage) (-sS) */
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} ep[2]; /* "engineered pipe"; also "extended play", for the deejay */
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/* Additionally, the following global variables are used to store user options.
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*/
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/* (-a) */ static int align; /* Only the lower 8b are used but align is
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* negative if no alignment is being done. */
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/* (-c) */ static int count; /* 0 if dj(1) runs until no more reads are
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* possible. */
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/* ASCII field separator delimited statistics */
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static char *fmt_asv = "%d\037%d\036%d\037%d\035%d\036%d\034";
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/* human-readable statistics */
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static char *fmt_human = "%d+%d > %d+%d; %d > %d\n";
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/* pointer to chosen formatting */
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/* (-H) */ static char *fmt_output; /* fmt_asv (default) or fmt_human (-H) */
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/* (-dq) */ static char debug; /*
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* -d increments dj -qq | 0 - no diagnostic output whatsoever
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* -q decrements dj -q | 1 - typical output without
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* | notifications on partial reads or
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* | writes
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* dj | 2 - typical output (default)
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* dj -d | 3 - verbose status messages */
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/* (-n) */ static char noerror; /* 0 - exits on partial reads or writes
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* (default)
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* 1 - retries on partial reads/writes
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* (-n) */
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/* Non-configurable defaults. */
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#define bs_default 1024 /* GNU dd(1) default; twice POSIX but a neat 2^10 */
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static char *program_name = "<no argv[0]>";
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static char *stdin_name = "<stdin>";
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static char *stdout_name = "<stdout>";
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static int read_flags = O_RDONLY; /* These flags are consistent with Busybox */
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static int write_flags = O_WRONLY | O_CREAT; /* dd(1). */
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/* Macro to set defaults for user-configurable options. */
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#define setdefaults do{ \
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align = -1; \
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count = 0; \
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debug = 2; \
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fmt_output = fmt_asv; \
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noerror = 0; \
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ep[0].fl = read_flags; \
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Io_setdefaults(&ep[0]); \
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ep[1].fl = write_flags; \
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Io_setdefaults(&ep[1]); }while(0)
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#define MIN(a, b) (((a) < (b)) ? (a) : (b))
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/* Macro to check if fd is a std* file, e.g. stdin. */
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#define fdisstd(fd) \
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((fd) == STDIN_FILENO \
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|| (fd) == STDOUT_FILENO \
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|| (fd) == STDERR_FILENO)
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/* Macro to call the cleanup functions that operate on struct io on the
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* particular io[2] used in main. Error conditions are not checked because this
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* is only used when the program is about to terminate (hence its name). */
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#define terminate(io) do{ \
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Io_buffree(&(io)[0]); \
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Io_buffree(&(io)[1]); \
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Io_fdclose(&(io)[0]); \
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Io_fdclose(&(io)[1]); }while(0)
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/* Allocates *io's buffer. Returns NULL if unsuccessful. */
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static void *
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Io_bufalloc(struct Io *io){
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return (io->buf = malloc(io->bs * (sizeof *io->buf)));
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}
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/* Frees *io's buffer. Returns io. */
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static struct Io *
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Io_buffree(struct Io *io){
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free(io->buf);
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return io;
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}
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/* Fills the unused portion of io's buffer with padding, updating io->bufuse.
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* Returns io. */
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static struct Io *
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Io_bufrpad(struct Io *io, int padding){
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memset(io->buf + io->bufuse, padding, io->bs - io->bufuse);
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io->bufuse = io->bs;
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return io;
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}
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/* Copies from the buffer in src as much as possible to the free space in the
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* dest buffer, removing the copied units from src and permuting the remaining
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* units in the src buffer to the start of the buffer, modifying both the src
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* and dest bufuse and returning dest. */
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static struct Io*
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Io_bufxapp(struct Io *dest, struct Io *src){
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int n;
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n = MIN(src->bufuse, dest->bs - dest->bufuse);
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memcpy(dest->buf + dest->bufuse, src->buf, n);
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dest->bufuse += n;
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memmove(src->buf, src->buf + n, src->bs - n);
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src->bufuse -= n;
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return dest;
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}
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/* Copies from the buffer in src to the buffer in dest no more than n units,
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* removing the copied units from src and permuting the remaining units in the
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* src buffer to the start of the buffer, modifying both the src and dest
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* bufuse and returning dest. */
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static struct Io*
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Io_bufxfer(struct Io *dest, struct Io *src, int n){
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memcpy(dest->buf, src->buf, (dest->bufuse = n));
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memmove(src->buf, src->buf + n, (src->bufuse -= n));
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return dest;
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}
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/* Closes io->fn and returns -1 on error, otherwise io->fd. */
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static int
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Io_fdclose(struct Io *io){
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return fdisstd(io->fd)
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? 0
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: close(io->fd);
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}
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/* Opens io->fn and saves the file descriptor into io->fd. Returns io->fd,
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* which will be -1 if an error occured. */
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static int
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Io_fdopen(struct Io *io, char *fn){
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int fd;
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if((fd = open(fn, io->fl,
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/* these are the flags used by touch(1p) */
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S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH))
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!= -1
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&& Io_fdclose(io) == 0){
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io->fd = fd;
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io->fn = fn;
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}
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return fd;
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}
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/* Seeks io->seek bytes through *io's file descriptor, (counter-intuitively)
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* returning -1 if successful and a sysexits.h exit code if an unrecoverable
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* error occurred. io->buf will be cleared of useful bytes and io->seek will
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* be set to zero to indicate the seek occurred. */
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static int
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Io_fdseek(struct Io *io){
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int (*op)(int, void *, size_t);
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if(!fdisstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) != -1)
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return -1;
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/* repeated code to get the condition out of the loop */
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if(io->fl == write_flags){
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memset(io->buf, '\0', io->bs);
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/* We're going to cheat and use bufuse as the retval for write(2),
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* which is fine because it'll be zeroed as this function returns
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* anyway. */
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do{
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if((io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek)))
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== 0)
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/* second chance */
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io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek));
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}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
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}else if(io->fl == read_flags){
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do{
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if((io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek)))
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== 0)
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/* second chance */
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io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek));
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}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
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}else
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return EX_SOFTWARE;
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io->bufuse = 0;
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return -1;
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}
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/* Reads io->bs bytes from *io's file descriptor into io->buf, storing the
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* number of read bytes in io->bufuse and updating io->bytes. If io->bufuse is
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* 0, errno will probably be set. Returns io. */
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static struct Io *
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Io_read(struct Io *io){
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io->bytes += (io->bufuse = read(io->fd, io->buf, io->bs));
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return io;
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}
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/* Sets the variables in a struct *io to the defaults. Identifies the read/
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* write ends of the "pipe" by checking io->fl. Returns io. */
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static struct Io *
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Io_setdefaults(struct Io *io){
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io->bs = bs_default;
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io->buf = NULL;
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io->bytes = 0;
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io->fd = (io->fl == read_flags) ? STDIN_FILENO : STDOUT_FILENO;
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io->fn = (io->fl == read_flags) ? stdin_name : stdout_name;
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io->prec = 0;
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io->rec = 0;
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io->seek = 0;
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return io;
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}
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/* Writes io->bufuse units from io->buf to io->fd, permuting any unwritten
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* bytes to the start of io->buf and updating io->bufuse. If io->bufuse doesn't
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* change, errno will probably be set. Returns io. */
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static struct Io *
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Io_write(struct Io *io){
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int t;
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if((t = write(io->fd, io->buf, io->bufuse)) > 0)
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memmove(io->buf, io->buf + t, (io->bufuse -= t));
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io->bytes += t;
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return io;
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}
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/* Prints an error message suitable for the event of an operating system error,
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* with the error itself to be described in the string s. */
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static int
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oserr(char *s){
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fprintf(stderr, "%s: %s: %s\n", program_name, s, strerror(errno));
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return EX_OSERR;
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}
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/* Prints statistics regarding the use of dj, particularly partially and
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* completely read and written records, accessing debug, ep, and fmt_output. */
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static void
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output(void){
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if(debug >= 1)
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fprintf(stderr, fmt_output,
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ep[0].rec, ep[0].prec, ep[1].rec, ep[1].prec,
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ep[0].bytes, ep[1].bytes);
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return;
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}
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/* Parses the string s to an integer, returning either the integer or in the
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* case of an error a negative integer. This is used for argument parsing
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* (e.g. -B [int]) in dj and no negative integer would be valid anyway. */
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static long
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parse(char *s){
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long r;
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errno = 0;
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r = strtol(s, &s, 0);
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return (*s == '\0' /* no chars left unparsed */ && errno == 0)
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? r
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: -1;
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}
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static int
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usage(void){
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fprintf(stderr, "Usage: %s (-AdfHqQ) (-a [byte]) (-c [count])\n"
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"\t(-i [input file]) (-b [input block size]) (-s [input offset])\n"
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"\t(-o [output file]) (-B [output block size]) (-S [output offset])\n",
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program_name);
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return EX_USAGE;
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}
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int main(int argc, char *argv[]){
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int c;
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int i;
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setdefaults;
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if(argc > 0){
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program_name = argv[0];
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while((c = getopt(argc, argv, "a:Ab:B:c:di:hHnqs:S:o:")) != -1)
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switch(c){
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case 'i': case 'o':
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i = (c == 'o');
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if(optarg[0] == '-' && optarg[1] == '\0'){ /* optarg == "-" */
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ep[i].fd = (i == 0) ? STDIN_FILENO : STDOUT_FILENO;
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ep[i].fn = (i == 0) ? stdin_name : stdout_name;
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break;
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}else if(Io_fdopen(&ep[i], optarg) != -1)
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break;
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terminate(ep);
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return oserr(optarg);
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case 'A': align = '\0'; break;
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case 'd': ++debug; break;
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case 'n': noerror = 1; break;
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case 'H': fmt_output = fmt_human; break;
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case 'q': --debug; break;
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case 'a':
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if(optarg[0] != '\0' && optarg[1] == '\0'){
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align = optarg[0];
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break;
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}
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/* FALLTHROUGH */
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case 'c': case 'b': case 's': case 'B': case 'S':
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if(c == 'c' && (count = parse(optarg)) >= 0)
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break;
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i = isupper(c);
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c = tolower(c);
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if((c == 'b' && (ep[i].bs = parse(optarg)) > 0)
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|| (c == 's' && (ep[i].seek = parse(optarg)) >= 0))
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break;
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/* FALLTHROUGH */
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default:
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terminate(ep);
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return usage();
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}
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}
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if(debug >= 3)
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fprintf(stderr,
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"argv0=%s\n"
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"in=%s\tibs=%d\tskip=%ld\talign=%hhx\tcount=%d\n"
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"out=%s\tobs=%d\tseek=%ld\tdebug=%2d\tnoerror=%d\n",
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program_name,
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ep[0].fn, ep[0].bs, ep[0].seek, align, count,
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ep[1].fn, ep[1].bs, ep[1].seek, debug, noerror);
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if(argc > optind){
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terminate(ep);
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return usage();
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}
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for(i = 0; i <= 1; ++i){
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if(Io_bufalloc(&ep[i]) == NULL){
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fprintf(stderr, "%s: Failed to allocate %d bytes\n",
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program_name, ep[i].bs);
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terminate(ep);
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return EX_OSERR;
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}else if(ep[i].seek > 0)
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switch(Io_fdseek(&ep[i])){
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case EX_OK:
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output();
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terminate(ep);
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return EX_OK;
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}
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}
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do{ /* read */
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Io_read(&ep[0]);
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if(!noerror && ep[0].bufuse == 0)
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Io_read(&ep[0]); /* second chance */
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if(ep[0].bufuse == 0) /* that's all she wrote */
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break;
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else if(ep[0].bufuse < ep[0].bs){
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++ep[0].prec;
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if(debug >= 2){
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fprintf(stderr, "%s: Partial read:\n\t", program_name);
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output();
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}
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if(!noerror)
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count = 1;
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if(align >= 0)
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Io_bufrpad(&ep[0], align);
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}else
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++ep[0].rec;
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/* write */
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do{ if(ep[1].bs > ep[0].bs){ /* io[1].bs > io[0].bs */
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Io_bufxapp(&ep[1], &ep[0]);
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if(ep[0].bs + ep[1].bufuse <= ep[1].bs && count != 1)
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continue; /* we could write more */
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}else
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Io_bufxfer(&ep[1], &ep[0], MIN(ep[0].bufuse, ep[1].bs));
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c = ep[1].bufuse;
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Io_write(&ep[1]);
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if(!noerror && ep[1].bufuse == c)
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Io_write(&ep[1]); /* second chance */
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if(c == ep[1].bufuse){ /* no more love */
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count = 1;
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break;
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}else if(c > ep[1].bufuse && ep[1].bufuse > 0){
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ep[1].prec += 1;
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if(debug >= 2){
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fprintf(stderr, "%s: Partial write:\n\t", program_name);
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output();
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}
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if(!noerror)
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count = 1;
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}else if(ep[1].bufuse == 0 && c < ep[1].bs)
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++ep[1].prec;
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else
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++ep[1].rec;
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}while(ep[0].bufuse > 0);
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}while(count == 0 || --count > 0);
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output();
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terminate(ep);
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return EX_OK;
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}
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