I am supposed to write documentation and report for the code below but I am new to operating system concepts I will appreciate if someone can help make a detailed comment on each line of code for better understanding. Thanks
#include <pthread.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#define handle_error_en(en, msg) \
do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
struct thread_info { /* Used as argument to thread_start() */
pthread_t thread_id; /* ID returned by pthread_create() */
int thread_num; /* Application-defined thread # */
char *argv_string; /* From command-line argument */ };
/* Thread start function: display address near top of our stack, and return upper-cased copy of argv_string */
static void * thread_start(void *arg) {
struct thread_info *tinfo = arg;
char *uargv, *p;
printf("Thread %d: top of stack near %p; argv_string=%s\n", tinfo->thread_num, &p, tinfo->argv_string);
uargv = strdup(tinfo->argv_string);
if (uargv == NULL) handle_error("strdup");
for (p = uargv; *p != '\0'; p++)
*p = toupper(*p);
return uargv;
}
int main(int argc, char *argv[]) {
int s, tnum, opt, num_threads;
struct thread_info *tinfo;
pthread_attr_t attr;
int stack_size;
void *res;
/* The "-s" option specifies a stack size for our threads */
stack_size = -1;
while ((opt = getopt(argc, argv, "s:")) != -1) {
switch (opt) {
case 's': stack_size = strtoul(optarg, NULL, 0);
break;
default: fprintf(stderr, "Usage: %s [-s stack-size] arg...\n", argv[0]);
exit(EXIT_FAILURE);
}
}
num_threads = argc - optind;
/* Initialize thread creation attributes */
s = pthread_attr_init(&attr);
if (s != 0)
handle_error_en(s, "pthread_attr_init");
if (stack_size > 0) {
s = pthread_attr_setstacksize(&attr, stack_size);
if (s != 0)
handle_error_en(s, "pthread_attr_setstacksize");
}
/* Allocate memory for pthread_create() arguments */
tinfo = calloc(num_threads, sizeof(struct thread_info));
if (tinfo == NULL)
handle_error("calloc");
/* Create one thread for each command-line argument */
for (tnum = 0; tnum < num_threads; tnum++) {
tinfo[tnum].thread_num = tnum + 1;
tinfo[tnum].argv_string = argv[optind + tnum];
/* The pthread_create() call stores the thread ID into corresponding element of tinfo[] */
s = pthread_create(&tinfo[tnum].thread_id, &attr, &thread_start, &tinfo[tnum]);
if (s != 0)
handle_error_en(s, "pthread_create");
}
/* Destroy the thread attributes object, since it is no longer needed */
s = pthread_attr_destroy(&attr);
if (s != 0)
handle_error_en(s, "pthread_attr_destroy");
/* Now join with each thread, and display its returned value */
for (tnum = 0; tnum < num_threads; tnum++) {
s = pthread_join(tinfo[tnum].thread_id, &res);
if (s != 0)
handle_error_en(s, "pthread_join");
printf("Joined with thread %d; returned value was %s\n", tinfo[tnum].thread_num, (char *) res);
free(res); /* Free memory allocated by thread */
}
free(tinfo);
exit(EXIT_SUCCESS);
}
#include
#include
#include
#include
#include
#include
#include
#define handle_error_en(en, msg) \
do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
struct thread_info { /* Used as argument to thread_start() */
pthread_t thread_id; /* ID returned by pthread_create() */
int thread_num; /* Application-defined thread # */
char *argv_string; /* From command-line argument */ };
/* Thread start function: display address near top of our stack, and return upper-cased copy of argv_string */
static void * thread_start(void *arg) {
struct thread_info *tinfo = arg;
char *uargv, *p;
printf("Thread %d: top of stack near %p; argv_string=%s\n", tinfo->thread_num, &p, tinfo->argv_string);
uargv = strdup(tinfo->argv_string);
if (uargv == NULL) handle_error("strdup");
for (p = uargv; *p != '\0'; p++)
*p = toupper(*p);
return uargv;
}
int main(int argc, char *argv[]) {
int s, tnum, opt, num_threads;
struct thread_info *tinfo;
pthread_attr_t attr;
int stack_size;
void *res;
/* The "-s" option specifies a stack size for our threads */
stack_size = -1;
while ((opt = getopt(argc, argv, "s:")) != -1) {
switch (opt) {
case 's': stack_size = strtoul(optarg, NULL, 0);
break;
default: fprintf(stderr, "Usage: %s [-s stack-size] arg...\n", argv[0]);
exit(EXIT_FAILURE);
}
}
num_threads = argc - optind;
/* Initialize thread creation attributes */
s = pthread_attr_init(&attr);
if (s != 0)
handle_error_en(s, "pthread_attr_init");
if (stack_size > 0) {
s = pthread_attr_setstacksize(&attr, stack_size);
if (s != 0)
handle_error_en(s, "pthread_attr_setstacksize");
}
/* Allocate memory for pthread_create() arguments */
tinfo = calloc(num_threads, sizeof(struct thread_info));
if (tinfo == NULL)
handle_error("calloc");
/* Create one thread for each command-line argument */
for (tnum = 0; tnum < num_threads; tnum++) {
tinfo[tnum].thread_num = tnum + 1;
tinfo[tnum].argv_string = argv[optind + tnum];
/* The pthread_create() call stores the thread ID into corresponding element of tinfo[] */
s = pthread_create(&tinfo[tnum].thread_id, &attr, &thread_start, &tinfo[tnum]);
if (s != 0)
handle_error_en(s, "pthread_create");
}
/* Destroy the thread attributes object, since it is no longer needed */
s = pthread_attr_destroy(&attr);
if (s != 0)
handle_error_en(s, "pthread_attr_destroy");
/* Now join with each thread, and display its returned value */
for (tnum = 0; tnum < num_threads; tnum++) {
s = pthread_join(tinfo[tnum].thread_id, &res);
if (s != 0)
handle_error_en(s, "pthread_join");
printf("Joined with thread %d; returned value was %s\n", tinfo[tnum].thread_num, (char *) res);
free(res); /* Free memory allocated by thread */
}
free(tinfo);
exit(EXIT_SUCCESS);
}
output: Compilation error
I am supposed to write documentation and report for the code below but I am new...
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