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problem of readdir on IA64 suse

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Operating Systems Linux SuSE problem of readdir on IA64 suse
# 8  
Old 08-28-2009
man 3 readdir gives me this:
Code:
       On Linux, the dirent structure is defined as follows:

           struct dirent {
               ino_t          d_ino;       /* inode number */
               off_t          d_off;       /* offset to the next dirent */
               unsigned short d_reclen;    /* length of this record */
               unsigned char  d_type;      /* type of file; not supported
                                              by all file system types */
               char           d_name[256]; /* filename */
           };

So it may not be the architecture per se, but the filesystem. Not something to be depended on in any case.
# 9  
Old 09-22-2009
can anybody tell me what is the exact difference between readdirand readdir_r i have written a small program using readdir which is working fine#include #include int main(){ DIR *dirp; struct dirent *direntp; if (( dirp = opendir ("."))== NULL) printf("Failed to open current directory"); while (( direntp = readdir (dirp))!= NULL ) printf( "%s\n", direntp->d_name );closedir( dirp );}its generating all the files and directory in the current directorynow i want to know how readdir_r works and how is it different from readdirplease show with some example thanks in advance,haris
# 10  
Old 09-23-2009
Quote:
Originally Posted by haris
Can anybody tell me what is the exact difference between readdirand readdir_r? I have written a small program using readdir which is working fine:
Code:
int main()
{
        DIR *dirp;
        struct dirent *direntp;
        if  (( dirp = opendir ("."))== NULL)
                printf("Failed to open current directory")

        while (( direntp = readdir (dirp))!= NULL )
                printf( "%s\n", direntp->d_name );

        closedir( dirp );
}

It's generating all the files and directory in the current directory. Now I want to know how readdir_r works, and how is it different from readdir. Please show with some example. Thanks in advance, haris
  1. Please use linebreaks and punctuation. I'm not a grammar nazi, but your post was very difficult to understand at all without them.
  2. Please use code tags for code, [ code ] stuff [ /code] without the extra spaces. It makes it easier to read, and stops the forum from eating your #include tags.
  3. Please make new threads for new topics instead of dumping new questions into tangentially related threads.

readdir() is not context-safe. The data in the pointer it returns gets overwritten every time you call it. If you opened two directories at the same time like this:
Code:
struct dirent *p1, *p2;
DIR *d1, *d2;
d1=popen("/bin");
d2=popen("/dev");
p1=readdir(d1);
p2=readdir(d2);

...both p1 and p2 would point to the same data: Whatever the last readdir() found.

readdir_r() avoids this by writing data to wherever you tell it instead of giving you a pointer to its own memory.
Code:
struct dirent p1, p2;
DIR *d1, *d2;
d1=popen("/bin");
d2=popen("/dev");
readdir_r(d1, &p1);
readdir(d2, &p2);

This way, p1 and p2 both contain the expected data, instead of just containing whatever the last value read by readdir() was.
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