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#define _XOPEN_SOURCE 700
#include <errno.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
enum {
FLAG_c = 1 << 0,
FLAG_l = 1 << 1,
FLAG_n = 1 << 2,
FLAG_v = 1 << 3,
};
int
match(const char *string, regex_t *re) {
int status = regexec(re, string, 0, NULL, 0);
if (status != 0)
return 0;
return 1;
}
int
grep(FILE *f, regex_t *re, int flags, char *fname) {
size_t len = LINE_MAX;
ssize_t bytes;
char *buf = malloc(len);
if (buf == NULL) {
fprintf(stderr, "grep: %s\n", strerror(errno));
return 1;
}
int num_matches = 0;
int lineno = 0;
while ((bytes = getline(&buf, &len, f)) != -1) {
lineno++;
int matches = match(buf, re);
if ((matches && ! (flags & FLAG_v)) || (! matches && (flags & FLAG_v))) {
num_matches++;
if (! (flags & FLAG_c) && ! (flags & FLAG_l)) {
if (fname)
printf("%s:", fname);
if (flags & FLAG_n)
printf("%d:", lineno);
printf("%s", buf);
}
}
}
if (flags & FLAG_l) {
printf("%s\n", fname);
} else if (flags & FLAG_c) {
if (fname)
printf("%s:", fname);
printf("%d\n", num_matches);
}
if (ferror(f)) {
fprintf(stderr, "grep: %s\n", strerror(errno));
return 1;
}
free(buf);
if (num_matches == 0)
return 1;
return 0;
}
void
print_usage(void) {
fprintf(stderr, "usage: grep [-E|-F] [-cilnv] regexp [file...]\n");
}
int
main(int argc, char **argv) {
int ret = 1;
int c;
int REGFLAGS = REG_NOSUB;
int flags = 0;
while ((c = getopt(argc, argv, "EFcilnv")) != -1) {
switch (c) {
case 'E':
REGFLAGS |= REG_EXTENDED;
break;
case 'F':
REGFLAGS &= ~REG_EXTENDED;
break;
case 'c':
flags |= FLAG_c;
flags &= ~FLAG_l;
break;
case 'i':
REGFLAGS |= REG_ICASE;
break;
case 'l':
flags |= FLAG_l;
flags &= ~FLAG_c;
break;
case 'n':
flags |= FLAG_n;
break;
case 'v':
flags |= FLAG_v;
break;
case '?':
print_usage();
return 1;
}
}
argc -= optind;
argv += optind - 1;
if (argc == 0) {
print_usage();
return 1;
}
/* TODO: allow '--' after pattern_list
* make a list of regex_ts to do for the -e and -f options
*/
char *regexp = *++argv;
regex_t re;
int regerr = regcomp(&re, regexp, REGFLAGS);
if (regerr != 0) {
char errbuf[100] = {'\0'};
regerror(regerr, &re, errbuf, 100);
fprintf(stderr, "grep: bad regex: %s\n", errbuf);
regfree(&re);
return 1;
}
if (argc == 1) {
ret = grep(stdin, &re, flags, "(standardinput)");
} else {
FILE *f;
while (*++argv) {
char *fname = NULL;
if (**argv == '-' && *(*argv + 1) == '\0') {
f = stdin;
fname = "(standardinput)";
} else {
f = fopen(*argv, "r");
if (f == NULL) {
fprintf(stderr, "grep: %s: %s\n", *argv, strerror(errno));
ret = 1;
continue;
}
fname = *argv;
}
if (argc == 2)
fname = NULL;
/* grep only returns 1 or 0. */
ret *= grep(f, &re, flags, fname);
if (f != stdin && fclose(f) == EOF) {
fprintf(stderr, "grep: %s: %s\n", *argv, strerror(errno));
ret = 1;
continue;
}
}
}
regfree(&re);
return ret;
}
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