can't work any less than before
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dtb
parent
4393dcac21
commit
54f69b21ed
186
cat/cat.c
186
cat/cat.c
@ -1,104 +1,106 @@
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#include <errno.h>
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#include <fcntl.h>
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#include <sysexits.h>
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#include <unistd.h>
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#include <errno.h> /* errno, EBADF, EFAULT, EINVAL, ELOOP, ENAMETOOLONG,
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* ENOENT, ENOMEM, ENOTDIR, EOVERFLOW */
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#include <stdio.h> /* fprintf(3), getc(3), putc(3), setvbuf(3), stderr, stdin,
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* stdout */
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#include <sysexits.h> /* EX_DATAERR, EX_NOINPUT, EX_OK, EX_OSERR,
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* EX_UNAVAILABLE, EX_USAGE */
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#include <unistd.h> /* getopt(3) */
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#include <sys/stat.h> /* stat(2), struct stat, S_ISDIR */
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/* NetBSD's default according to an strace */
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#define BUFFER 4096
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static unsigned char buf[BUFFER];
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static char *program_name = "cat";
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/* NetBSD's default size according to an strace */
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static unsigned char buf[4096];
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static char **default_argv = {
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(char [])"cat",
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(char [])"-",
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NULL
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}
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static char *program_name = *default_argv;
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static char *stdout_name = "/dev/stdout";
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int main(int argc, char *argv[]){
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char *argv0;
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int argv0_s;
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extern int errno;
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char *f;
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int b; /* how many meaningful bytes are in the buffer */
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int arguing;
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int c;
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int fd;
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int multiple_files;
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extern int errno;
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extern int opterr;
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extern int optind;
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struct stat fi; /* info */
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char *fn; /* name */
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FILE *fo; /* object */
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if(argv[0] == NULL)
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goto dumb;
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argv0 = argv[0];
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for(argv0_s = 0; argv0_s != '\0'; ++argv0_s);
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while((c = getopt(argc, argv, "hu")) != -1)
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switch(c){
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case 'u':
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/* cat(1p) says the following:
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* "Write bytes from the input file to the standard
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* output without delay as each is read."
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* Then in Application Usage:
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* "It is unspecified whether standard output is or is
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* not buffered in the default case."
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* POSIX defines "buffering" to be a not-strictly
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* -necessary delay in processing input, so there still
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* needs to be a place in memory to put data, which for
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* the purposes of this implementation is buf[].
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*
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* Using the standard library would make it more
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* difficult to manage this flow manually. */
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break;
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case 'h': default: usage:
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write(2, "Usage: ", 7);
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write(2, argv[0], argv0_s);
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write(2, "(-hu) (file...)\n", 16);
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return EX_USAGE;
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}
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argc -= optind;
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argv += optind - 1;
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multiple_files = argc > 1;
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do{
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++argv;
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if(argc == 0) /* `cat` */
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dumb: fd = 1;
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else if((fd = open(*argv, O_RDONLY)) == -1){
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ferr: /* `cat bad_file` */
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/* `cat: file: ` */
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write(2, argv0, argv0_s);
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write(2, ": ", 2);
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for(i = 0; argv[0][i] != '\0'; ++i);
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write(2, *argv, i);
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write(2, ": ", 2);
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switch(errno){
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case EISDIR:
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write(2, "Is directory.\n", 14);
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return EX_NOINPUT;
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case EACCES: case EFAULT: case EPERM:
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write(2, "Unable to open file.\n", 21);
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return EX_NOINPUT;
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case ENAMETOOLONG: case ENFILE: case EBADF:
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write(2, "Operating system error.\n", 24);
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return EX_OSERR;
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case EMFILE:
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write(2, "Internal error.\n", 16);
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return EX_SOFTWARE;
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case ENOENT: case ENOTDIR: case ENXIO:
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write(2, "File does not exist.\n", 21);
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return EX_NOINPUT;
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default:
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write(2, "Unknown error.", 14);
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return 1;
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setvbuf(stdout, buf, _IOFBF, (sizeof buf)/(sizeof *buf));
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if(argc < 2){
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argc = 2;
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if(argc > 0)
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default_argv[0] = argv[0];
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argv = default_argv;
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}
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arguing = 1;
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opterr = 0;
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while(optind < argc){
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if(arguing && (c = getopt(argc, argv, "hu")) != -1)
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switch(c){
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case 'u':
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setvbuf(stdout, NULL, _IONBF, 0);
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continue;
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case '-':
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arguing = 0;
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continue;
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case 'h': default: usage:
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fprintf(stderr, "Usage: %s (-h) (file...)\n",
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argv[0]);
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return EX_USAGE;
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}
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if(arguing && *argv[optind] == '-'){ /* "--" */
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arguing = 0;
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continue;
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if(*argv[optind] == '-' && argv[optind][1] == '\0'){ /* "-" */
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fn = stdout_name;
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fo = stdout;
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}else{
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fn = argv[optind];
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if(stat(fn, &fi) == -1){
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fclose(fo);
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switch(errno){
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case EFAULT: case ENOENT: case ENOTDIR:
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fprintf(stderr,
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"%s: %s: Unable to open file."
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" Does it exist?\n",
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argv[0], fn);
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return EX_NOINPUT;
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case EBADF: case EINVAL: case ENOMEM:
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case EOVERFLOW:
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fprintf(stderr,
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"%s: %s: System error"
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" (errno=%d),\n",
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argv[0], fn, errno);
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return EX_OSERR;
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case ELOOP: case ENAMETOOLONG:
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fprintf(stderr,
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"%s: %s: Unable to open file.",
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argv[0], fn);
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return EX_DATAERR;
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}
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}
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if(S_ISDIR(fi.st_mode)){
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fclose(fo);
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fprintf(stderr, "%s: %s: Is a directory.\n",
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argv[0], fn);
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return EX_DATAERR;
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}
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}else if(multiple_files){
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/* `cat good_file good_file ...` */
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}
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for(b = 0; b == -1;){
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}
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while((c = getc(fo)) != EOF)
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if(putc(c, stdout) == EOF){
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fprintf(stderr,
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"%s: Exiting due to error writing to"
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" output...\n",
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argv[0]);
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fclose(fo);
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return EX_UNAVAILABLE;
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}
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if(fd < 0 && fd > 2)
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close(fd);
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}while(--argc > 0);
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++optind;
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}
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return EX_OK;
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}
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