Files
Compsys-2021-Assignments/A2/fauxgrep.c
Nikolaj 456adc7611 😄
2021-10-26 16:12:26 +02:00

83 lines
1.7 KiB
C

// Setting _DEFAULT_SOURCE is necessary to activate visibility of
// certain header file contents on GNU/Linux systems.
#define _DEFAULT_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fts.h>
// err.h contains various nonstandard BSD extensions, but they are
// very handy.
#include <err.h>
int fauxgrep_file(char const *needle, char const *path) {
FILE *f = fopen(path, "r");
if (f == NULL) {
warn("failed to open %s", path);
return -1;
}
char *line = NULL;
size_t linelen = 0;
int lineno = 1;
while (getline(&line, &linelen, f) != -1) {
if (strstr(line, needle) != NULL) {
printf("%s:%d: %s", path, lineno, line);
}
lineno++;
}
free(line);
fclose(f);
return 0;
}
int main(int argc, char * const *argv) {
if (argc < 2) {
err(1, "usage: STRING paths...");
exit(1);
}
char const *needle = argv[1];
char * const *paths = &argv[2];
// FTS_LOGICAL = follow symbolic links
// FTS_NOCHDIR = do not change the working directory of the process
//
// (These are not particularly important distinctions for our simple
// uses.)
int fts_options = FTS_LOGICAL | FTS_NOCHDIR;
FTS *ftsp;
if ((ftsp = fts_open(paths, fts_options, NULL)) == NULL) {
err(1, "fts_open() failed");
return -1;
}
FTSENT *p;
while ((p = fts_read(ftsp)) != NULL) {
switch (p->fts_info) {
case FTS_D:
break;
case FTS_F:
fauxgrep_file(needle, p->fts_path);
break;
default:
break;
}
}
fts_close(ftsp);
return 0;
}