UNIX — универсальная среда программирования

Керниган Брайан Уилсон

 * 0 if the strings are identical

 * 1 if two chars are transposed

 * 2 if one char wrong, added or deleted

 * 3 otherwise

 */

#define EQ(s,t) (strcmp(s,t) == 0)

spdist(s, t)

 char *s, *t;

{

 while (*s++ == *t)

if (*t++ == '\0')

return 0; /* exact match */

 if (*--s) {

if (*t) {

if (s[1] && t[1] && *s == t[1] && *t == s[1] && EQ(s+2, t+2))

return 1; /* transposition */

if (EQ(s+1, t+1))

return 2; /* 1 char mismatch */

}

if (EQ(s+1, t))

return 2; /* extra character */

 }

 if (*t && EQ(s, t+1))

return 2; /* missing character */

 return 3;

}

3.8.50

strindex.c

strindex(s, t) /* return index of t in s, -1 if none */

 char *s, *t;

{

 int i, n;

 n = strlen(t);

 for (i = 0; s[i] != '\0'; i++)

if (strncmp(s+i, t, n) == 0)

return i;

 return -1;

}

3.8.51

sv.c

/* sv: save new files */

#include <stdio.h>

#include <sys/types.h>

#include <sys/dir.h>

#include <sys/stat.h>

char *progname;

main(argc, argv)

 int argc;

 char *argv[];

{

 int i;

 struct stat stbuf;

 char *dir = argv[argc-1];

 progname = argv[0];

 if (argc <= 2)

error ("Usage: %s files... dir", progname);

 if (stat(dir, festbuf) == -1)

error("can't access directory %s", dir);

 if ((stbuf.st_mode & S_IFMT) != S_IFDIR)

error("%s is not a directory", dir);

 for (i = 1; i < argc-1; i++)

sv(argv[i], dir);

 exit(0);

}

sv(file, dir) /* save file in dir */

 char *file, *dir;

{

 struct stat sti, sto;

 int fin, fout, n;

 char target[BUFSIZ], buf[BUFSIZ], *index;

 sprintf(target, "%s/%s", dir, file);

 if (index(file, '/') != NULL) /* strchr in some systems */

error("won't handle '/'s in %s", file);

 if (stat(file, &sti) == -1)

error("can't stat %s", file);

 if (stat(target, &sto) == -1) /* target not present */

sto.st_mtime = 0; /* so make it look old */

 if (sti.st_mtime < sto.st_mtime) /* target is newer */

fprintf(stderr, "%s: %s not copied\n", progname, file);

 else if ((fin = open(file, 0)) == -1)

error("can't open file %s", file);

 else if ((fout = creat(target, sti.st_mode)) == -1)

error("can't create %s", target);

 while ((n = read(fin, buf, sizeof buf)) > 0)

if (write(fout, buf, n) != n)

error("error writing %s", target);

 close(fin);

 close(fout);

}

#include "error.c"

3.8.52

system1.c

#include <signal.h>

system(s) /* run command line s */

 char *s;

{

 int status, pid, w, tty;

 int (*istat), (*qstat);

 ...

 if ((pid = fork) == 0) {

...

execlp("sh", "sh", "-c", s, (char*)0);

exit(127);

 }

 ...

 istat = signal(SIGINT, SIG_IGN);

 qstat = signal(SIGQUIT, SIG_IGN);

 while ((w = wait(&status)) != pid && w != -1)

;

 if (w == -1)

status = -1;

 signal(SIGINT, istat);