simplify and comment
This commit is contained in:
parent
8ae20904b6
commit
0624c3561b
271
mm/mm.c
271
mm/mm.c
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@ -1,3 +1,21 @@
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/*
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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 <errno.h> /* errno */
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#include <signal.h> /* signal(2), SIG_ERR, SIG_IGN, SIGINT */
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#include <stdio.h> /* fclose(3), fopen(3), fprintf(3), getc(3), putc(3),
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@ -5,11 +23,29 @@
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#include <stdlib.h> /* free(3), realloc(3) */
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#include <string.h> /* strerror(3) */
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#include <unistd.h> /* getopt(3) */
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#if !defined EX_OK || !defined EX_USAGE
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#if !defined EX_OSERR || !defined EX_USAGE
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# include <sysexits.h>
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#endif
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extern int errno;
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/* mm(1) works similarly to dj(1) in that, fundamentally, they both take bytes
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* from input and write them to output, but whereas dj(1)'s utility is in
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* controlling the reads and writes themselves across an individual input file
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* and individual output file - with regards to quantity of bytes read/written,
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* buffering of reads and writes, and where in the input to read and where in
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* the output to write - mm(1)'s utility is in handling arbitrary quantities of
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* input files and writing to arbitrary quantities of output files, without
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* the fine-grained control dj(1) offers. There are design decisions in mm(1)
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* that are repeated from dj(1) (the same author wrote each utility's initial
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* implementation) but, while dj(1)'s design is modeled around juggling text
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* within buffers, mm(1)'s design is modeled around juggling open files. */
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/* mm(1) can take arbitrary files but for the sake of resiliency it has a
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* 10-file (for input and output independently) pre-allocated array and
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* additional dynamically allocated lists of FILE pointers for when those
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* arrays are full, with Io_ functions handling necessary operations on both
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* the Io struct and its nested Io_ex struct. */
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struct Io_ex{
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size_t s;
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FILE **files;
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@ -24,30 +60,26 @@ struct Io{
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struct Io_ex *ex;
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};
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/* pre-allocated strings */
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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 char *stderr_name = "<stderr>";
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static char *amode = "ab";
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static char *rmode = "rb";
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static char *wmode = "rb+";
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static char *(fmode[]) = { (char []){"rb"}, (char []){"rb+"} };
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static char *wharsh = "wb";
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/* Opens the file at the path s and puts it in the io struct, returning NULL if
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* either the opening or the placement of the open FILE pointer fail. */
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#define Io_fopen(io, s) Io_fappend((io), fopen((s), (io)->fmode), (s))
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/* Destructs the io[2] used by main. */
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#define terminate(io) do{ \
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Io_destruct(&(io)[0]); \
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Io_destruct(&(io)[1]); }while(0)
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static struct Io *
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Io_construct(struct Io *io){
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io->s = 0;
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io->ex->s = 0;
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io->ex->files = NULL;
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io->ex->names = NULL;
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return io;
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}
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static struct Io *Io_initialize(struct Io *io, struct Io_ex *io_ex);
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/* Destructs an io struct by closing its handled files and freeing its extended
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* file and name arrays. Returns the destructed io. */
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static struct Io *
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Io_destruct(struct Io *io){
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size_t i;
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@ -55,36 +87,46 @@ Io_destruct(struct Io *io){
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if(io->s == -1)
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io->s = 0;
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for(i = 0; i < io->s; ++i)
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fclose(io->files[i]);
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for(i = 0; i < io->ex->s; ++i)
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fclose(io->ex->files[i]);
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for(i = 0; i < io->s; fclose(io->files[i++]));
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for(i = 0; i < io->ex->s; fclose(io->ex->files[i++]));
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free(io->ex->files);
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free(io->ex->names);
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return Io_construct(io); /* counter-intuitive but NULLs and 0s */
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return Io_initialize(io, io->ex);
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}
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/* Adds the open FILE pointer for the file at the path s to the io struct,
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* returning the FILE if successful and NULL if not. */
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static FILE *
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Io_fappend(struct Io *io, FILE *f, char *s){
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if(f == NULL)
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return NULL;
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if(io->s == -1)
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io->s = 0;
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if(io->s < (sizeof (io->files)) / (sizeof *(io->files))){
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io->names[io->s] = s;
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return io->files[io->s++] = f;
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}else{
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io->ex->files = realloc(io->ex->files,
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(sizeof *(io->ex->files)) * ++io->ex->s);
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io->ex->names = realloc(io->ex->names,
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(sizeof *(io->ex->names)) * io->ex->s);
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if(io->s >= (sizeof io->files) / (sizeof *io->files)){
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if((io->ex->files = realloc(io->ex->files,
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(sizeof *(io->ex->files))
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* ++io->ex->s))
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== NULL
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|| (io->ex->names = realloc(io->ex->names,
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(sizeof *(io->ex->names))
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* io->ex->s))
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== NULL)
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return NULL;
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io->ex->names[io->ex->s] = s;
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return io->ex->files[io->ex->s++] = f;
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}
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io->names[io->s] = s;
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return io->files[io->s++] = f;
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}
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/* Returns the first index within io->files of the given FILE pointer f. If f
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* isn't within io->files but is within io->ex->files, returns the sum of io->s
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* and the index of the FILE pointer in io->ex->files. If f is within neither
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* io->files or io->ex->files, returns -1. */
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static int
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Io_fileindex(struct Io *io, FILE *f){
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size_t i;
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return -1;
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}
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/* Returns the corresponding file name in the io struct to the FILE pointer f,
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* or NULL if f isn't in io->files or io->ex->files. */
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static char *
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Io_filename(struct Io *io, FILE *f){
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int i;
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return io->ex->names[i - io->s];
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}
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static FILE *
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Io_fopen(struct Io *io, char *s){
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FILE *f;
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if((f = fopen(s, io->fmode)) == NULL)
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return NULL;
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else
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return Io_fappend(io, f, s);
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}
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static struct Io *Io_fremove(struct Io *io, FILE *f);
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static FILE *Io_nextfile(struct Io *io, FILE *f);
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/* Prints c to all io->files, returning c. If a stream can't be written, a
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* message is printed to standard error and the stream is closed and removed
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* from io. If no stream can be written, returns EOF. */
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static int
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Io_fputc(struct Io *io, int c){
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FILE *f;
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@ -133,25 +169,24 @@ Io_fputc(struct Io *io, int c){
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f = NULL;
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lf = NULL;
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while((f = Io_nextfile(io, f)) != NULL){
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for(f = NULL; (f = Io_nextfile(io, f)) != NULL;){
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if(lf != NULL){
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if(fclose(lf) == EOF)
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fprintf(stderr, "%s: %s: %s\n",
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program_name, ln, strerror(errno));
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Io_fremove(io, lf);
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if(io->s == 0)
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if(Io_fremove(io, lf)->s == 0)
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return EOF;
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lf = NULL;
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}
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if(putc(c, f) == EOF){
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lf = f;
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ln = Io_filename(io, lf);
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}
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if(putc(c, f) == EOF)
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ln = Io_filename(io, lf = f);
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}
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return c;
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}
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/* Removes a given file pointer from the given io struct, returning NULL if the
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* file was already absent from io and otherwise io. */
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static struct Io *
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Io_fremove(struct Io *io, FILE *f){
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size_t i;
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return io;
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}
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static FILE *
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Io_nextfile(struct Io *io, FILE *f){
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size_t i;
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/* Initializes the members of the given io and io_ex structs (including setting
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* io->ex to io_ex) and returns io. */
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static struct Io *
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Io_initialize(struct Io *io, struct Io_ex *io_ex){
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if(f == NULL)
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return io->files[0];
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io->s = 0;
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io->ex = io_ex;
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io->ex->s = 0;
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io->ex->files = NULL;
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io->ex->names = NULL;
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for(i = 0; i < io->s; ++i)
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if(io->files[i] == f){
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if(i == io->s - 1 && io->ex->s == 0)
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return NULL;
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else if(i == io->s - 1)
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return io->ex->files[0];
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else
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return io->files[i + 1];
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}
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for(i = 0; i < io->ex->s; ++i)
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if(io->ex->files[i] == f){
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if(i == io->ex->s - 1)
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break;
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else
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return io->ex->files[i + 1];
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}
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return NULL;
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return io;
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}
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/* Returns the first file in io if f is NULL, NULL if the file is the last in
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* or absent from io, or the file after f in io. */
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static FILE *
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Io_nextfile(struct Io *io, FILE *f){
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int i;
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return (f == NULL)
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? io->files[0]
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: ((i = Io_fileindex(io, f)) == -1
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|| i == io->s + io->ex->s - 1)
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? NULL
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: (i < io->s - 1)
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? io->files[i + 1]
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: io->ex->files[i - io->s + 1];
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}
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/* Stops stdio from buffering io. Returns io. */
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static struct Io *
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Io_unbuffer(struct Io *io){
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size_t i;
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for(i = 0; i < io->s; ++i)
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setvbuf(io->files[i], NULL, _IONBF, 0);
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for(i = 0; i < io->ex->s; ++i)
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setvbuf(io->ex->files[i], NULL, _IONBF, 0);
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for(i = 0; i < io->s; setvbuf(io->files[i++], NULL, _IONBF, 0));
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for(i = 0; i < io->ex->s; setvbuf(io->ex->files[i++], NULL,_IONBF, 0));
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return io;
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}
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/* Prints a diagnostic message based on errno and returns an exit status
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* appropriate for an OS error. */
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static int
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oserr(char *s, char *r){
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@ -233,6 +271,8 @@ oserr(char *s, char *r){
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return EX_OSERR;
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}
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/* Prints a diagnostic message synopsizing usage and returns an exit status
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* appropriate for a usage error. */
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static int
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usage(char *s){
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@ -245,47 +285,59 @@ usage(char *s){
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int main(int argc, char *argv[]){
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int c;
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size_t i;
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struct Io io[2]; /* {read, write, error} */
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struct Io io[2]; /* {read, write} */
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struct Io_ex io_ex[2];
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int o;
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char unbuffered;
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int s; /* scratch variable */
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/* The simple invocation (without given arguments) requires no memory
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* allocations or use of the io structs and is therefore treated as a
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* special case. To do the same with all bells and whistles call
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* $ mm -i - -o - */
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if(argc < 2){ /* simple invocation */
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while((c = getc(stdin)) != EOF)
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if(putc(c, stdout) == EOF)
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break;
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return EX_OK;
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return 1;
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return 0;
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}
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io[0].ex = &io_ex[0];
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io[1].ex = &io_ex[1];
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Io_construct(&io[0]);
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Io_construct(&io[1]);
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io[0].fmode = rmode;
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io[1].fmode = wmode;
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/* Initializes the io structs with their default values, standard input
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* and standard output. Both io->s are set to -1, a special value
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* indicating that they're at their defaults and that their FILE
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* pointers won't need to be closed. If an input or an output is
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* specified these initial values will be overwritten, so to, say, use
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* mm(1) equivalently to tee(1p), -o - will need to be specified before
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* additional files to ensure standard output is still written. */
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for(i = 0; i < 2; ++i){
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Io_initialize(&io[i], &io_ex[i])->fmode = fmode[i];
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Io_fappend(&io[i], i == 0 ? stdin : stdout,
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i == 0 ? stdin_name : stdout_name);
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io[i].s = -1;
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}
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Io_fappend(&io[0], stdin, stdin_name);
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Io_fappend(&io[1], stdout, stdout_name);
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io[0].s = -1;
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io[1].s = -1;
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unbuffered = 0;
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s = 0; /* Refers to whether or not io will be unbuffered. */
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while((c = getopt(argc, argv, "aehi:no:u")) != -1)
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switch(c){
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case 'a':
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io[1].fmode = amode;
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case 'a': /* "rb+" -> "ab" */
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io[1].fmode[0] = 'a';
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io[1].fmode[2] = '\0';
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break;
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case 'e':
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Io_fappend(&io[1], stderr, stderr_name);
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break;
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if(Io_fappend(&io[1], stderr, stderr_name) != NULL)
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break;
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terminate(io);
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return oserr(argv[0], "-e");
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case 'i': case 'o':
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if(optarg[0] == '-' && optarg[1] == '\0'){
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/* "-" */
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Io_fappend(&io[c == 'o'],
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c == 'i' ? stdin : stdout,
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c == 'i' ? stdin_name : stdout_name);
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break;
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if(Io_fappend(&io[c == 'o'],
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c == 'i' ? stdin : stdout,
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c == 'i'
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? stdin_name
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: stdout_name) != NULL)
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break;
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terminate(io);
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return oserr(argv[0], optarg);
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}else if(Io_fopen(&io[c == 'o'], optarg)
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!= NULL)
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break;
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@ -293,7 +345,7 @@ int main(int argc, char *argv[]){
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if(c == 'o' && errno == ENOENT){
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io[1].fmode = wharsh;
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if(Io_fopen(&io[1], optarg) != NULL){
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io[1].fmode = wmode;
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io[1].fmode = fmode[1];
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break;
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}
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}
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@ -305,14 +357,14 @@ int main(int argc, char *argv[]){
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terminate(io);
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return oserr(argv[0], "-n");
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case 'u':
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unbuffered = 1;
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s = 1;
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break;
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default:
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terminate(io);
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return usage(argv[0]);
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}
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if(unbuffered){
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if(s){
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Io_unbuffer(&io[0]);
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Io_unbuffer(&io[1]);
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}
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@ -321,7 +373,10 @@ int main(int argc, char *argv[]){
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io[0].s = 1;
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if(io[1].s == -1)
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io[1].s = 1;
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o = io[1].s;
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/* Refers to the amount of outputs prior to writing; Io_fputc will
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* remove any to which it can't write. */
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s = io[1].s;
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for(i = 0; i < io[0].s; ++i){
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while((c = getc(io[0].files[i])) != EOF)
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@ -331,8 +386,12 @@ int main(int argc, char *argv[]){
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}
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}
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o = io[1].s != o;
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/* Reflects whether (s==0) or not (s==1) the full length of the inputs
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* could be written to all outputs, which is the return value for main
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* to maintain feature parity with tee(1p). */
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s = io[1].s != s;
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terminate(io);
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return o;
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return s;
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}
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