Exactly, I thought that I finished my project until compiling isn't accepted on ubuntu because of mmap(). I'm trying to access(read) files by using fork(). It's okey. But, When I want to count number of read files, entered folder(directories) and child, I powned! How and What can I use or change mmap() because I get error: ‘MAP_ANON’ undeclared (first use in this function)|
. On mac, It's okey but on ubuntu error. Thank you for helps.
#define _XOPEN_SOURCE 700
#define _POSIX_C_SOURCE 200809L
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <dirent.h>
#include <errno.h>
#include <ftw.h>
#include <ctype.h>
#include <sys/mman.h>
#define MAX_PATH_LEN 2048
static int *wordCount = 0;
static int *childCount = 0;
static int *folderCount = 0;
int relatedWord(const char *arr);
int checkWord(const char arr[], int size);
void err_sys(const char *msg);
int disp(const char *filepath, const struct stat *finfo, int flag, struct FTW *ftw);
int main(int argc, char *argv[])
{
//struct stat finfo;
//int count = 0;
wordCount = mmap(NULL, sizeof *wordCount, PROT_READ | PROT_WRITE,MAP_SHARED | MAP_ANON, -1, 0);
childCount = mmap(NULL, sizeof *childCount, PROT_READ | PROT_WRITE,MAP_SHARED | MAP_ANON, -1, 0);
folderCount = mmap(NULL, sizeof *folderCount, PROT_READ | PROT_WRITE,MAP_SHARED | MAP_ANON, -1, 0);
if (argc != 2) {
fprintf(stderr, "Wrong number of arguments!\nUsage: dirwalk6 <path>\n");
exit(EXIT_FAILURE);
}
if (nftw(argv[1], disp, 20, 0) < 0)
err_sys("ntfw");
printf( "\nTotal words = %d\n\n", *wordCount);
printf( "\nTotal folders = %d\n\n", *folderCount);
printf( "\nTotal childs = %d\n\n", *childCount);
return 0;
}
int disp(const char *filepath, const struct stat *finfo, int flag, struct FTW *ftw)
{
int count = 0; /* number of words */
switch (flag) {
case FTW_F: /* determining file */
printf("%*s%s\n", ftw->level * 4, "", filepath);
pid_t pid;
pid=fork();
if(pid < 0)
{
perror("Error corresponding to fork()");
}
else if (pid == 0)
{
count += relatedWord(filepath);
*wordCount += count;
*childCount += 1;
exit(1);
}
else
{
while( pid != wait(0) ) ;
}
// printf( "word = %d, file = %s \n", count,filepath);
break;
case FTW_D: /* determining folder */
printf("%*s%s\n", ftw->level * 4, "", filepath + ftw->base);
*folderCount += 1;
break;
}
return 0;
}
From the man page for mmap(2) (my bold):
Certain flags constants are defined only if either _BSD_SOURCE or _SVID_SOURCE is defined. (Requiring _GNU_SOURCE also suffices, and requiring that macro specifically would have been more logical, since these flags are all Linux specific.) The relevant flags are: MAP_32BIT, MAP_ANONYMOUS (and the synonym MAP_ANON), MAP_DENYWRITE, MAP_EXECUTABLE, MAP_FILE, MAP_GROWSDOWN, MAP_HUGETLB, MAP_LOCKED, MAP_NONBLOCK, MAP_NORESERVE, MAP_POPULATE, and MAP_STACK.
So you will need to define _BSD_SOURCE, _SVID_SOURCE or (if I read that right) _GNU_SOURCE at the top of the file, but in any event prior to
#include <sys/mman.h>
As per #mafso's comment, best to do this prior to any system header include (not least in case an another header itself includes <sys/mman.h>
Related
This question already has answers here:
When using regex in C, \d does not work but [0-9] does
(4 answers)
Closed 3 years ago.
In the following code, I am trying to filter out using regex ONLY, the file called test.jpg, what am I doing wrong as the code below is not filtering this out?
I know there are simpler ways, but eventually I would like to change the regex to ^(image_)\\d{3,6}_201412\\d{2}_\\d{6}\\.(jpg)
and also my folder contains 100,000+ files, so I can only use the c getdents function which is super fast compared to any other way
I get the following output:
**************found*******
image_0179_20141212_060714.jpg
#define _GNU_SOURCE
#include <dirent.h> /* Defines DT_* constants */
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <string.h>
#include <regex.h>
#include <stdio.h>
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
struct linux_dirent {
long d_ino;
off_t d_off;
unsigned short d_reclen;
char d_name[];
};
#define BUF_SIZE 1024*1024*5
int
main(int argc, char *argv[])
{
int fd, nread;
char buf[BUF_SIZE];
struct linux_dirent *d;
int bpos;
char d_type;
regex_t reg;
regmatch_t pmatch[40];
#define NAME "image_0179_20141212_060714.jpg"
const char *pattern = "^(image_)\\d{3,6}_201412\\d{2}_\\d{6}\\.(jpg)";
regcomp(®, pattern, REG_ICASE | REG_EXTENDED);
int retval = 0;
char buffer[1024] = "";
fd = open(argc > 1 ? argv[1] : ".", O_RDONLY | O_DIRECTORY);
if (fd == -1)
handle_error("open");
for ( ; ; )
{
nread = syscall(SYS_getdents, fd, buf, BUF_SIZE);
if (nread == -1)
handle_error("getdents");
if (nread == 0)
break;
for (bpos = 0; bpos < nread;)
{
d = (struct linux_dirent *) (buf + bpos);
d_type = *(buf + bpos + d->d_reclen - 1);
if( d->d_ino != 0 && d_type == DT_REG )
{
//printf("%s\n", (char *)d->d_name );
if (strstr(d->d_name, NAME) != NULL)
{
printf("**************found*******\n");
printf("%s\n", (char *)d->d_name );
};
retval = regexec(®, d->d_name, 2, pmatch, 0);
//printf("%d\n",retval);
if(retval==0)
{
printf("**************found regex*******\n");
printf("%s\n", (char *)d->d_name );
}
}
bpos += d->d_reclen;
}
}
regfree(®);
exit(EXIT_SUCCESS);
}
use the following regex instead
^image_[0-9]{3,6}_201412[0-9]{2}_[0-9]{6}\.jpg$
This code scans for newly created files within a directory, however where "%s" should contain the name of the new file(s) this does not occur.
I can imagine there are unnecessary pieces of code written here, however being quite unfamiliar with C I'm simply happy it compiles at this point (and actually recognizes new files) !
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <sys/inotify.h>
int main (int argc, char *argv[])
{
char target[FILENAME_MAX];
int result;
int fd;
int wd; /* watch descriptor */
const int event_size = sizeof(struct inotify_event);
const int buf_len = 1024 * (event_size + FILENAME_MAX);
fd = inotify_init();
if (fd < 0) {
perror("inotify_init");
}
wd = inotify_add_watch(fd, "/home/joe/Documents", IN_CREATE);
while (1) {
char buff[buf_len];
int no_of_events, count = 0;
no_of_events = read (fd, buff, buf_len);
while (count < no_of_events) {
struct inotify_event *event = (struct inotify_event *)&buff[count];
if (event->len) {
if (event->mask & IN_CREATE)
if(!(event->mask & IN_ISDIR)) {
printf("The file %s has been created\n", target);
fflush(stdout);
}
}
count += event_size + event->len;
}
}
return 0;
}
You're printing out target when you get an event, however target is never modified.
The name of the created file is stored in event->name. That's what you want to print.
printf("The file %s has been created\n", event->name);
While retrieving the broken-out fields of the record in the password database (e.g., the local password file /etc/passwd, NIS, and LDAP) that matches a provided username name, I am using the getpwnam_r (http://linux.die.net/man/3/getpwnam_r) function.
#define __USE_BSD
#define _BSD_SOURCE
#include <pwd.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
int
main(int argc, char *argv[])
{
struct passwd pwd;
struct passwd *result;
char *buf;
size_t bufsize;
int s;
if (argc != 2) {
fprintf(stderr, "Usage: %s username\n", argv[0]);
exit(EXIT_FAILURE);
}
bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
if (bufsize == -1) /* Value was indeterminate */
bufsize = 16384; /* Should be more than enough */
buf = malloc(bufsize);
if (buf == NULL) {
perror("malloc");
exit(EXIT_FAILURE);
}
s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result);
if (result == NULL) {
if (s == 0)
printf("Not found\n");
else {
errno = s;
perror("getpwnam_r");
}
exit(EXIT_FAILURE);
}
printf("Name: %s; UID: %ld\n", pwd.pw_gecos, (long) pwd.pw_uid);
exit(EXIT_SUCCESS);
}
The code works fine, but Eclipse shows me a warning as follows:
warning: implicit declaration of function ‘getpwnam_r’ [-Wimplicit-function-declaration]
How could I fix it?
Note that I'm currently using Ubuntu 14.04 LTS.
To use this function you need two includes :
#include <sys/types.h>
#include <pwd.h>
Add them and it should not complain anymore.
You can see that by running man getpwnam_r.
You also need to define either __USE_MISC or __USE_SVID since it a POSIX only function.
I have problem with creating shared memory between two processes.
I getting this error, and I don't know what to do because I think a have all libraries included.
Log...
g++ exc8.c -o exc8
exc8.c: In function ‘int main(int, char**)’:
exc8.c:29:37: error: ‘ltrunc’ was not declared in this scope
size = ltrunc(fd, B_SIZE, SEEK_SET);
Code...
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>
#include <stdio.h>
#define B_SIZE 4
char* memory = new char[4];
int main(int argc, char *argv[]) {
int size, fd;
char *buf;
char memory[4];
fd = shm_open(memory, O_RDWR|O_CREAT, 0774);
if (fd < -0) {
perror("open");
exit(-1);
}
size = ltrunc(fd, B_SIZE, SEEK_SET);
if(size < 0) {
perror("trunc");
exit(-1);
}
buf = (char *)mmap(0, B_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if(buf == NULL) {
perror("map");
exit(-1);
}
}
I don't know where ltrunc() comes from, but
you can set the size of a shared memory object with ftruncate():
if (ftruncate(fd, B_SIZE) == -1) {
// Handle error
}
(from http://pubs.opengroup.org/onlinepubs/009695299/functions/shm_open.html).
ltrunc is not a standard function. It seems defined in QNX Platform using qcc as the compiler, which truncates a file at given position. Probably POSIX provides the truncate() and ftruncate() functions for the job.
The following C code illustrates a problem I'm seeing on Linux 2.6.30.5-43.fc11.x86_64:
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main() {
char buf[1024];
void *base;
int fd;
size_t pagesz = sysconf(_SC_PAGE_SIZE);
fd = open("<some file, at least 4*pagesz in length>", O_RDONLY);
if (fd < 0) {
perror("open");
return 1;
}
base = mmap(0, 4*pagesz, PROT_READ, MAP_SHARED, fd, 0);
if (base < 0) {
perror("mmap");
close(fd);
return 1;
}
memcpy(buf, (char*)base + 2*pagesz, 1024);
if (remap_file_pages(base, pagesz, 0, 2, 0) < 0) {
perror("remap_file_pages");
munmap(base, 4*pagesz);
close(fd);
return 1;
}
printf("%d\n", memcmp(buf, base, 1024));
munmap(base, 4*pagesz);
close(fd);
return 0;
}
This always fails with remap_file_pages() returning -1 and errno set to EINVAL. Looking at the kernel source I can see all the conditions in remap_file_pages() where it might fail but none of them seem to apply to my example. What's going on?
It's caused by the file being opened O_RDONLY. If you change the open mode to O_RDWR, it works (even if the mmap() still specifies just PROT_READ).
This code in do_mmap_pgoff is the root cause - it only marks the vma as VM_SHARED if the file was opened for writing:
vm_flags |= VM_SHARED | VM_MAYSHARE;
if (!(file->f_mode & FMODE_WRITE))
vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
So in remap_file_pages(), you fail on the first check:
if (!vma || !(vma->vm_flags & VM_SHARED))
goto out;