2024-01-04 work
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Wip/dj/dj.c
221
Wip/dj/dj.c
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@ -2,17 +2,36 @@
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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> /* memset(3) */
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#include <string.h> /* memcpy(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), read(2), write(2), optarg, optind,
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STDIN_FILENO, STDOUT_FILENO */
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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 (argv[0] == NULL ? "<no argv[0]>" : argv[0])
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#define MIN(a, b) (((a) < (b)) ? (a) : (b))
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/* Macro to ensure fd is not a std* file, e.g. stdin. */
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#define fdisnotstd(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. */
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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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static int read_flags = O_RDONLY;
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static int write_flags = O_WRONLY | O_CREAT;
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static char *stdin_name = "<stdin>";
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static char *stdout_name = "<stdout>";
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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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@ -21,29 +40,28 @@ struct Io{
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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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size_t index; /* index in io[] array */
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int prec; /* partial records processed */
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int rec; /* records processed */
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int seek; /* bytes to seek/skip (will be 0 after skippage) */
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};
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static char *stdin_name = "<stdin>";
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static char *stdout_name = "<stdout>";
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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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static void
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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;
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return io;
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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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@ -52,6 +70,8 @@ Io_fdclose(struct Io *io){
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: 0;
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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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@ -65,81 +85,79 @@ Io_fdopen(struct Io *io, char *fn){
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return fd;
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}
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static int _read(int fd, void *b, size_t bs);
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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. If io->bufuse is 0, errno will probably
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* be set. Returns io. */
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static struct Io *
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Io_read(struct Io *io){
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/* counter-intuitively, returns negative if successful and a sysexits.h exit
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* code if an unrecoverable error occurred */
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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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if(fdisnotstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) == -1)
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return -1;
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else if(io->fl == O_RDONLY){
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do if((io->bufuse = _read(io->fd, io->buf,
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(io->bs < io->seek) ? io->bs : io->seek)) != 0)
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io->seek -= io->bufuse;
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else /* not enough to skip */
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return EX_OK;
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while(io->seek > 0);
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}else{
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memset(io->buf, '\0', io->bs);
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/* cheat and use bufuse as the retval for write
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* (the buffer is zeroed, it doesn't matter) */
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do if((io->bufuse = write(io->fd, io->buf,
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(io->bs < io->seek) ? io->bs : io->seek)) != 0)
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io->seek -= io->bufuse;
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else
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return EX_OK;
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while(io->seek > 0);
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}
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memset(io->buf, '\0', io->bs);
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do{ if( (io->fl == read_flags
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&& (((io->bufuse = read(io->fd, io->buf,
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MIN(io->bs, io->seek))) != 0)
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/* second chance if 0 */
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|| ((io->bufuse = read(io->fd, io->buf,
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MIN(io->bs, io->seek))) != 0)))
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/* cheat and use bufuse as the retval for write
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* (the buffer is zeroed, it doesn't matter) */
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|| (io->fl == write_flags
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&& ((io->bufuse = write(io->fd, io->buf,
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MIN(io->bs, io->seek))) != 0)))
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io->seek -= io->bufuse;
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else
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return EX_OK;
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}while(io->seek > 0);
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return -1;
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}
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static void
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Io_setdefaults(struct Io io[2]){
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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[0].bs = io[1].bs = 1024;
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io[0].buf = io[1].buf = NULL;
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io[0].fd = STDIN_FILENO;
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io[1].fd = STDOUT_FILENO;
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io[0].fl = O_RDONLY;
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io[1].fl = O_WRONLY | O_CREAT;
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io[0].fn = stdin_name;
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io[1].fn = stdout_name;
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io[0].index = 0;
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io[1].index = 1;
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io[0].prec = io[1].prec = 0;
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io[0].rec = io[1].rec = 0;
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io[0].seek = io[1].seek = 0;
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io->bs = 1024;
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io->buf = NULL;
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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;
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return io;
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}
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/* read(2) but with a second chance if it returns zero */
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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 int
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_read(int fd, void *b, size_t bs){
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int retval;
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return ((retval = read(fd, buf, bs)) == 0)
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? read(fd, buf, bs)
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: retval;
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}
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static int /* on error returns -1, else returns non-negative */
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parse(char *s){
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int r;
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errno = 0;
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return (*s == '\0' /* empty string */
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|| *(s = (int)strtol(s, &s, 0)) != '\0' /* not fully processed */
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|| errno != 0)
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r = (int)strtol(s, &s, 0);
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return (*s == '\0' /* empty string */ || errno != 0)
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? -1
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: r;
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}
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/* s is the component (e.g. filename) that failed */
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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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@ -148,7 +166,8 @@ oserr(char *argv0, char *s){
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return EX_OSERR;
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}
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/* diagnostic output */
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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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@ -158,21 +177,10 @@ output(struct Io io[2]){
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return io;
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}
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static int
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terminate(struct Io io[2]){
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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]);
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return EX_OK;
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}
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static int
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usage(char **argv){
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fprintf(stderr, "Usage: %s (-af) (-c [count]\n"
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fprintf(stderr, "Usage: %s (-fA) (-a [byte]) (-c [count]\n"
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"\t(-i [input file]) (-b [input block size])"
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" (-s [input offset])\n"
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"\t(-o [output file]) (-B [output block size])"
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@ -191,23 +199,29 @@ int main(int argc, char *argv[]){
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struct Io io[2]; /* { read, write } same as pipe(2) */
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/* defaults */
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align = 0;
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align = -1;
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count = 0;
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noerror = 0;
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Io_setdefaults(io);
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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, "ac:i:b:fs:o:B:S:")) != -1)
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while((c = getopt(argc, argv, "aAc:i:b:fs:o:B:S:")) != -1)
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if((c == 'i' || c == 'o')
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&& Io_fdopen(&io[c == 'o'], optarg) != 0){ /* file args */
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terminate(io);
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return oserr(argv[0], optarg);
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/* boolean arguments */
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}else if(c == 'a')
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align = 1;
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else if(c == 'f')
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/* boolean/flag arguments */
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}else if(c == 'f')
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noerror = 1;
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/* numeric arguments */
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else if(c == 'A')
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align = '\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 as a double negative to catch uncaught stuff */
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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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@ -228,34 +242,37 @@ int main(int argc, char *argv[]){
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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: return terminate(output(io));
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case EX_OK: terminate(output(io)); return EX_OK;
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}
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}
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do{ /* read */ if((io[0].bufuse
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= read(io[0].fd, io[0].buf, io[0].bs))
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< io[0].bs){
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if(io[0].bufuse == 0 && (!noerror
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|| ((io[0].bufuse = read(io[0].fd, io[0].buf, io[0].bs))
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== 0)))
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break; /* that's all she wrote */
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else{
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io[0].prec += 1;
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if(noerror){
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}else
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count = 1;
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if(align){
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memset(io[0].buf + io[0].bufuse, '\0',
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io[0].bs - io[0].bufuse);
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io[0].bufuse = io[0].bs;
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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 += 1;
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if(noerror){
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output(io);
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}else
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count = 1;
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if(align >= 0){
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memset(io[0].buf + io[0].bufuse, align,
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io[0].bs - io[0].bufuse);
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io[0].bufuse = io[0].bs;
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}
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}
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/* write */ while(io[0].bufuse > 0){
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memcpy(io[1].buf, io[0].buf, io[1].bs);
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memmove(io[0].buf, io[0].buf + io[1].bs, io[0].bs - io[1].bs);
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}
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}while(count == 0 || --count > 0);
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return terminate(output(io));
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terminate(output(io));
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return EX_OK;
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}
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