134 lines
3.1 KiB
C
134 lines
3.1 KiB
C
// Setting _DEFAULT_SOURCE is necessary to activate visibility of
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// certain header file contents on GNU/Linux systems.
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#define _DEFAULT_SOURCE
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fts.h>
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// err.h contains various nonstandard BSD extensions, but they are
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// very handy.
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#include <err.h>
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#include <pthread.h>
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#include "job_queue.h"
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struct job_queue q;
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int fauxgrep_file(char const *needle, char const *path) {
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FILE *f = fopen(path, "r");
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if (f == NULL) {
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warn("failed to open %s", path);
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return -1;
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}
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char *line = NULL;
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size_t linelen = 0;
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int lineno = 1;
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while (getline(&line, &linelen, f) != -1) {
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if (strstr(line, needle) != NULL) {
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printf("%s:%d: %s", path, lineno, line);
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}
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lineno++;
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}
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free(line);
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fclose(f);
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return 0;
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}
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void* fauxgrep_thread(void* arg) {
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char* needle = arg;
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char const* path;
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while (job_queue_pop(&q, (void**) &path) == 0) {
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fauxgrep_file(needle, path);
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}
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return NULL;
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}
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int main(int argc, char * const *argv) {
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if (argc < 3 || (argc == 4 && strcmp(argv[1], "-n") == 0)) {
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err(1, "usage: [-n INT] STRING paths...");
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exit(1);
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}
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int num_threads = 1;
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char const *needle = argv[1];
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char * const *paths = &argv[2];
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if (argc > 3 && strcmp(argv[1], "-n") == 0) {
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// Since atoi() simply returns zero on syntax errors, we cannot
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// distinguish between the user entering a zero, or some
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// non-numeric garbage. In fact, we cannot even tell whether the
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// given option is suffixed by garbage, i.e. '123foo' returns
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// '123'. A more robust solution would use strtol(), but its
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// interface is more complicated, so here we are.
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num_threads = atoi(argv[2]);
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if (num_threads < 1) {
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err(1, "invalid thread count: %s", argv[2]);
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}
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needle = argv[3];
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paths = &argv[4];
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} else {
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needle = argv[1];
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paths = &argv[2];
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}
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job_queue_init(&q, 64);
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pthread_t threads[num_threads];
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for (int i = 0 ; i < num_threads ; i++) {
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pthread_create(&threads[i], NULL, fauxgrep_thread, strdup(needle));
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}
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// FTS_LOGICAL = follow symbolic links
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// FTS_NOCHDIR = do not change the working directory of the process
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//
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// (These are not particularly important distinctions for our simple
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// uses.)
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int fts_options = FTS_LOGICAL | FTS_NOCHDIR;
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FTS *ftsp;
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if ((ftsp = fts_open(paths, fts_options, NULL)) == NULL) {
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err(1, "fts_open() failed");
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return -1;
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}
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FTSENT *p;
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while ((p = fts_read(ftsp)) != NULL) {
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switch (p->fts_info) {
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case FTS_D:
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break;
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case FTS_F:
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job_queue_push(&q, strdup(p->fts_path));
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break;
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default:
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break;
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}
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}
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fts_close(ftsp);
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job_queue_destroy(&q);
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for (int i = 0 ; i < num_threads ; i++) {
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pthread_join(threads[i], NULL);
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}
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return 0;
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}
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