move dj(1) out of Wip
This commit is contained in:
1
dj/Makefile
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1
dj/Makefile
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@@ -0,0 +1 @@
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dj: dj.c
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386
dj/dj.c
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386
dj/dj.c
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@@ -0,0 +1,386 @@
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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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/* Macro to use the appropriate string for argv[0] in the case that
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* argc == 0. */
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#define ARGV0(argv0) ((argv0) == NULL ? program_name : (argv0))
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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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extern int errno;
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static char *fmt_asv = "%d\037%d\036%d\037%d\035%d\036%d\034";
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static char *fmt_human = "%d+%d > %d+%d; %d > %d\n";
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static char *fmt_output;
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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;
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static int write_flags = O_WRONLY | O_CREAT;
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/* information that needs to be kept about each file in the "pipe" */
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struct Io{
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int bs; /* buffer size */
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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) */
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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) */
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};
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/* Allocates *io's buffer. Returns NULL if successful. */
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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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/* 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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/* 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. */
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static int
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Io_seek(struct Io *io){
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ssize_t (*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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else if(io->fl == write_flags){
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/* cheat and use bufuse as the retval for write */
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memset(io->buf, '\0', io->bs);
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/* This is a dirty trick; rather than testing conditions and operating
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* likewise, because the parameters to read or write are going to be
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* the same either way, just use a function pointer to keep track of
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* the intended operation. */
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op = &write; /* Ignore -Wincompatible-pointer-types, it's fine. */
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/* The difference is between const void * and void * which isn't
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* significant enough to affect program behavior. */
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}else
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op = &read;
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do{ if( (io->bufuse = (*op)(io->fd, io->buf, MIN(io->bs, io->seek))) == 0)
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/* second chance */
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io->bufuse = (*op)(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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io->bufuse = 0;
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return -1;
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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 = 1024;
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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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/* 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 = (long)strtol(s, &s, 0);
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if(*s == '\0' /* no chars left unparsed */ && errno == 0)
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return r;
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else
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return -1;
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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 *argv0, char *s){
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fprintf(stderr, "%s: %s: %s\n", argv0, 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. */
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struct Io *
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output(struct Io io[2]){
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fprintf(stderr, fmt_output,
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io[0].rec, io[0].prec, io[1].rec, io[1].prec,
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io[0].bytes, io[1].bytes);
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return io;
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}
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static int
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usage(char *argv0){
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fprintf(stderr, "Usage: %s (-dfAH) (-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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ARGV0(argv0));
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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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char align;
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char debug;
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char noerror;
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int c;
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int count;
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int p; /* pipe side */
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struct Io io[2]; /* { read, write } same as pipe(2) */
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/* defaults */
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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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io[0].fl = read_flags;
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Io_setdefaults(&io[0]);
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io[1].fl = write_flags;
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Io_setdefaults(&io[1]);
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if(argc > 0)
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while((c = getopt(argc, argv, "a:Ab:B:c:i:fHqQs:S:o:")) != -1)
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if(c == 'i' || c == 'o'){
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if(Io_fdopen(&io[c == 'o'], optarg) == -1){
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terminate(io);
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return oserr(argv[0], optarg);
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}
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/* boolean/flag arguments */
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}else if(c == 'A')
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align = '\0';
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else if(c == 'f')
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noerror = 1;
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else if(c == 'H')
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fmt_output = fmt_human;
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else if(c == 'q')
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debug = 1;
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else if(c == 'Q')
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debug = 0;
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/* optarg */
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else if(c == 'a' && optarg[0] != '\0' && optarg[1] == '\0')
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align = optarg[0];
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/* numeric args */
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else if(!((c == 'c' && (count = parse(optarg)) >= 0)
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|| (c == 'b' && (io[0].bs = parse(optarg)) >= 0)
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|| (c == 's' && (io[0].seek = parse(optarg)) >= 0)
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|| (c == 'B' && (io[1].bs = parse(optarg)) >= 0)
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|| (c == 'S' && (io[1].seek = parse(optarg)) >= 0))){
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terminate(io);
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return usage(argv[0]);
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}
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if(argc > optind){
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terminate(io);
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return usage(argv[0]);
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}
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for(p = 0; p <= 1; ++p){
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if(Io_bufalloc(&io[p]) == NULL){
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fprintf(stderr, "%s: Failed to allocate %d bytes\n",
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ARGV0(argv[0]), io[p].bs);
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terminate(io);
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return EX_OSERR;
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}else if(io[p].seek > 0) /* seek */
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switch(Io_seek(&io[p])){
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case EX_OK:
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if(debug >= 1)
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output(io);
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terminate(io);
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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(&io[0]);
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if(!noerror && io[0].bufuse == 0)
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Io_read(&io[0]); /* second chance */
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if(io[0].bufuse == 0) /* that's all she wrote */
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break;
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else if(io[0].bufuse < io[0].bs){
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++io[0].prec;
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if(debug >= 2){
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fprintf(stderr, "%s: Partial write:\n\t", ARGV0(argv[0]));
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output(io);
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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(&io[0], align);
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}else
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++io[0].rec;
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/* write */
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do{ if(io[1].bs > io[0].bs){ /* io[1].bs > io[0].bs */
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Io_bufxapp(&io[1], &io[0]);
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if(io[0].bs + io[1].bufuse <= io[1].bs && count != 1)
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continue; /* we could write more */
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}else
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Io_bufxfer(&io[1], &io[0], MIN(io[0].bufuse, io[1].bs));
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c = io[1].bufuse;
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Io_write(&io[1]);
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if(!noerror && io[1].bufuse == c)
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Io_write(&io[1]); /* second chance */
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if(c == io[1].bufuse) /* no more love */
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count = 1;
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else if(c > io[1].bufuse && io[1].bufuse > 0){
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io[1].prec += 1;
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if(debug >= 2){
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fprintf(stderr, "%s: Partial write:\n\t", ARGV0(argv[0]));
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output(io);
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}
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if(!noerror)
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count = 1;
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}else if(io[1].bufuse == 0 && c < io[1].bs)
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++io[1].prec;
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else
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++io[1].rec;
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}while(io[0].bufuse > 0);
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}while(count == 0 || --count > 0);
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if(debug >= 1)
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output(io);
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terminate(io);
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return EX_OK;
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}
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Block a user