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  #1 (permalink)  
Old March 6th, 2008, 12:05 AM
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Default Can someone help me

#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>


int main(int argc, char **argv)
{
    int i;

    struct stat *buf;

    for (i = 1; i < argc; i++)
    {
        if (stat(*(argv + i), buf) == -1)
        {
            fprintf(stderr, "%s: cannot access %s\n", *(argv), *(argv + i));
            continue;
        }
        printf("Hello\n");
    }
}

Hi
Can someone help me whats wrong with my code on line 14 if(stat() == -1)? my code compiles fine on gcc, but when i run my code, i get segmentation fault (core dumped).

my code works fine when i use char *argv[], but not with doube pointer.


Thanks
Regards
Mani

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  #2 (permalink)  
Old March 6th, 2008, 05:26 AM
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Default

You are sure you are not getting any warnings while compiling this piece? Post back with stat's definition, if you are still stuck.

Regards
Ankur
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Old March 6th, 2008, 07:28 PM
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Hi, thanks for reply
On freebsd, no there are no warnings, on linux (UBUNTU) yes and it complains about strlen, strcat, and malloc.

At the beginning, i thought the same thing and i delete everything, except line 14 if(stat() == -1). same error.

Can u please tell me how to get the stat definition?


Thanks
Regards
Mani

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Old March 7th, 2008, 05:08 AM
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Well, stat definition must be there in stat.h. Open stat.h and see how its defined.

Regards
Ankur
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Old March 7th, 2008, 04:52 PM
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Hi Thanks again for your reply.
As i search online, i figured that i cannot use *buf, so i changed:
struct stat * buf -> struct stat buf, and
if (stat(*(argv + i), buf) == -1) -> if (stat(*(argv + i), &buf) == -1) and everything works really good.

Now my question is how can figure that i have to use pointer for struct or variable. because pwd.h need struct passwd *pwd and stat.h need struct stat buf (not *buf).

I found stat.h, can you please tell me how should i figure that out from header file?

stat.h
************************************************** ******
/* Copyright (C) 1991, 1992, 1995-2004, 2005, 2006, 2007
   Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA. */

/*
 * POSIX Standard: 5.6 File Characteristics <sys/stat.h>
 */

#ifndef _SYS_STAT_H
#define _SYS_STAT_H 1

#include <features.h>

#include <bits/types.h> /* For __mode_t and __dev_t. */

#if defined __USE_XOPEN || defined __USE_XOPEN2K || defined __USE_MISC || defined __USE_ATFILE
# if defined __USE_XOPEN || defined __USE_XOPEN2K
# define __need_time_t
# endif
# if defined __USE_MISC || defined __USE_ATFILE
# define __need_timespec
# endif
# include <time.h> /* For time_t resp. timespec. */
#endif

#if defined __USE_XOPEN || defined __USE_XOPEN2K
/* The Single Unix specification says that some more types are
   available here. */
# ifndef __dev_t_defined
typedef __dev_t dev_t;
# define __dev_t_defined
# endif

# ifndef __gid_t_defined
typedef __gid_t gid_t;
# define __gid_t_defined
# endif

# ifndef __ino_t_defined
# ifndef __USE_FILE_OFFSET64
typedef __ino_t ino_t;
# else
typedef __ino64_t ino_t;
# endif
# define __ino_t_defined
# endif

# ifndef __mode_t_defined
typedef __mode_t mode_t;
# define __mode_t_defined
# endif

# ifndef __nlink_t_defined
typedef __nlink_t nlink_t;
# define __nlink_t_defined
# endif

# ifndef __off_t_defined
# ifndef __USE_FILE_OFFSET64
typedef __off_t off_t;
# else
typedef __off64_t off_t;
# endif
# define __off_t_defined
# endif

# ifndef __uid_t_defined
typedef __uid_t uid_t;
# define __uid_t_defined
# endif
#endif /* X/Open */

#ifdef __USE_UNIX98
# ifndef __blkcnt_t_defined
# ifndef __USE_FILE_OFFSET64
typedef __blkcnt_t blkcnt_t;
# else
typedef __blkcnt64_t blkcnt_t;
# endif
# define __blkcnt_t_defined
# endif

# ifndef __blksize_t_defined
typedef __blksize_t blksize_t;
# define __blksize_t_defined
# endif
#endif /* Unix98 */

__BEGIN_DECLS

#include <bits/stat.h>

#if defined __USE_BSD || defined __USE_MISC || defined __USE_XOPEN
# define S_IFMT __S_IFMT
# define S_IFDIR __S_IFDIR
# define S_IFCHR __S_IFCHR
# define S_IFBLK __S_IFBLK
# define S_IFREG __S_IFREG
# ifdef __S_IFIFO
# define S_IFIFO __S_IFIFO
# endif
# ifdef __S_IFLNK
# define S_IFLNK __S_IFLNK
# endif
# if (defined __USE_BSD || defined __USE_MISC || defined __USE_UNIX98) && defined __S_IFSOCK
# define S_IFSOCK __S_IFSOCK
# endif
#endif

/* Test macros for file types. */

#define __S_ISTYPE(mode, mask) (((mode) & __S_IFMT) == (mask))

#define S_ISDIR(mode) __S_ISTYPE((mode), __S_IFDIR)
#define S_ISCHR(mode) __S_ISTYPE((mode), __S_IFCHR)
#define S_ISBLK(mode) __S_ISTYPE((mode), __S_IFBLK)
#define S_ISREG(mode) __S_ISTYPE((mode), __S_IFREG)
#ifdef __S_IFIFO
# define S_ISFIFO(mode) __S_ISTYPE((mode), __S_IFIFO)
#endif
#ifdef __S_IFLNK
# define S_ISLNK(mode) __S_ISTYPE((mode), __S_IFLNK)
#endif

#if defined __USE_BSD && !defined __S_IFLNK
# define S_ISLNK(mode) 0
#endif

#if (defined __USE_BSD || defined __USE_UNIX98) && defined __S_IFSOCK
# define S_ISSOCK(mode) __S_ISTYPE((mode), __S_IFSOCK)
#endif

/* These are from POSIX.1b. If the objects are not implemented using separate
   distinct file types, the macros always will evaluate to zero. Unlike the
   other S_* macros the following three take a pointer to a `struct stat'
   object as the argument. */
#ifdef __USE_POSIX199309
# define S_TYPEISMQ(buf) __S_TYPEISMQ(buf)
# define S_TYPEISSEM(buf) __S_TYPEISSEM(buf)
# define S_TYPEISSHM(buf) __S_TYPEISSHM(buf)
#endif


/* Protection bits. */

#define S_ISUID __S_ISUID /* Set user ID on execution. */
#define S_ISGID __S_ISGID /* Set group ID on execution. */

#if defined __USE_BSD || defined __USE_MISC || defined __USE_XOPEN
/* Save swapped text after use (sticky bit). This is pretty well obsolete. */
# define S_ISVTX __S_ISVTX
#endif

#define S_IRUSR __S_IREAD /* Read by owner. */
#define S_IWUSR __S_IWRITE /* Write by owner. */
#define S_IXUSR __S_IEXEC /* Execute by owner. */
/* Read, write, and execute by owner. */
#define S_IRWXU (__S_IREAD|__S_IWRITE|__S_IEXEC)

#if defined __USE_MISC && defined __USE_BSD
# define S_IREAD S_IRUSR
# define S_IWRITE S_IWUSR
# define S_IEXEC S_IXUSR
#endif

#define S_IRGRP (S_IRUSR >> 3) /* Read by group. */
#define S_IWGRP (S_IWUSR >> 3) /* Write by group. */
#define S_IXGRP (S_IXUSR >> 3) /* Execute by group. */
/* Read, write, and execute by group. */
#define S_IRWXG (S_IRWXU >> 3)

#define S_IROTH (S_IRGRP >> 3) /* Read by others. */
#define S_IWOTH (S_IWGRP >> 3) /* Write by others. */
#define S_IXOTH (S_IXGRP >> 3) /* Execute by others. */
/* Read, write, and execute by others. */
#define S_IRWXO (S_IRWXG >> 3)


#ifdef __USE_BSD
/* Macros for common mode bit masks. */
# define ACCESSPERMS (S_IRWXU|S_IRWXG|S_IRWXO) /* 0777 */
# define ALLPERMS (S_ISUID|S_ISGID|S_ISVTX|S_IRWXU|S_IRWXG|S_IRWXO)/* 07777 */
# define DEFFILEMODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)/* 0666*/

# define S_BLKSIZE 512 /* Block size for `st_blocks'. */
#endif


#ifndef __USE_FILE_OFFSET64
/* Get file attributes for FILE and put them in BUF. */
extern int stat (__const char *__restrict __file,
         struct stat *__restrict __buf) __THROW __nonnull ((1, 2));

/* Get file attributes for the file, device, pipe, or socket
   that file descriptor FD is open on and put them in BUF. */
extern int fstat (int __fd, struct stat *__buf) __THROW __nonnull ((2));
#else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (stat, (__const char *__restrict __file,
                  struct stat *__restrict __buf), stat64)
     __nonnull ((1, 2));
extern int __REDIRECT_NTH (fstat, (int __fd, struct stat *__buf), fstat64)
     __nonnull ((2));
# else
# define stat stat64
# define fstat fstat64
# endif
#endif
#ifdef __USE_LARGEFILE64
extern int stat64 (__const char *__restrict __file,
           struct stat64 *__restrict __buf) __THROW __nonnull ((1, 2));
extern int fstat64 (int __fd, struct stat64 *__buf) __THROW __nonnull ((2));
#endif

#ifdef __USE_ATFILE
/* Similar to stat, get the attributes for FILE and put them in BUF.
   Relative path names are interpreted relative to FD unless FD is
   AT_FDCWD. */
# ifndef __USE_FILE_OFFSET64
extern int fstatat (int __fd, __const char *__restrict __file,
            struct stat *__restrict __buf, int __flag)
     __THROW __nonnull ((2, 3));
# else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (fstatat, (int __fd, __const char *__restrict __file,
                     struct stat *__restrict __buf,
                     int __flag),
               fstatat64) __nonnull ((2, 3));
# else
# define fstatat fstatat64
# endif
# endif

extern int fstatat64 (int __fd, __const char *__restrict __file,
              struct stat64 *__restrict __buf, int __flag)
     __THROW __nonnull ((2, 3));
#endif

#if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
# ifndef __USE_FILE_OFFSET64
/* Get file attributes about FILE and put them in BUF.
   If FILE is a symbolic link, do not follow it. */
extern int lstat (__const char *__restrict __file,
          struct stat *__restrict __buf) __THROW __nonnull ((1, 2));
# else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (lstat,
               (__const char *__restrict __file,
                struct stat *__restrict __buf), lstat64)
     __nonnull ((1, 2));
# else
# define lstat lstat64
# endif
# endif
# ifdef __USE_LARGEFILE64
extern int lstat64 (__const char *__restrict __file,
            struct stat64 *__restrict __buf)
     __THROW __nonnull ((1, 2));
# endif
#endif

/* Set file access permissions for FILE to MODE.
   If FILE is a symbolic link, this affects its target instead. */
extern int chmod (__const char *__file, __mode_t __mode)
     __THROW __nonnull ((1));

#ifdef __USE_BSD
/* Set file access permissions for FILE to MODE.
   If FILE is a symbolic link, this affects the link itself
   rather than its target. */
extern int lchmod (__const char *__file, __mode_t __mode)
     __THROW __nonnull ((1));
#endif

/* Set file access permissions of the file FD is open on to MODE. */
#if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
extern int fchmod (int __fd, __mode_t __mode) __THROW;
#endif

#ifdef __USE_ATFILE
/* Set file access permissions of FILE relative to
   the directory FD is open on. */
extern int fchmodat (int __fd, __const char *__file, __mode_t mode, int __flag)
     __THROW __nonnull ((2)) __wur;
#endif /* Use ATFILE. */



/* Set the file creation mask of the current process to MASK,
   and return the old creation mask. */
extern __mode_t umask (__mode_t __mask) __THROW;

#ifdef __USE_GNU
/* Get the current `umask' value without changing it.
   This function is only available under the GNU Hurd. */
extern __mode_t getumask (void) __THROW;
#endif

/* Create a new directory named PATH, with permission bits MODE. */
extern int mkdir (__const char *__path, __mode_t __mode)
     __THROW __nonnull ((1));

#ifdef __USE_ATFILE
/* Like mkdir, create a new directory with permission bits MODE. But
   interpret relative PATH names relative to the directory associated
   with FD. */
extern int mkdirat (int __fd, __const char *__path, __mode_t __mode)
     __THROW __nonnull ((2));
#endif

/* Create a device file named PATH, with permission and special bits MODE
   and device number DEV (which can be constructed from major and minor
   device numbers with the `makedev' macro above). */
#if defined __USE_MISC || defined __USE_BSD || defined __USE_XOPEN_EXTENDED
extern int mknod (__const char *__path, __mode_t __mode, __dev_t __dev)
     __THROW __nonnull ((1));
#endif

#ifdef __USE_ATFILE
/* Like mknod, create a new device file with permission bits MODE and
   device number DEV. But interpret relative PATH names relative to
   the directory associated with FD. */
extern int mknodat (int __fd, __const char *__path, __mode_t __mode,
            __dev_t __dev) __THROW __nonnull ((2));
#endif


/* Create a new FIFO named PATH, with permission bits MODE. */
extern int mkfifo (__const char *__path, __mode_t __mode)
     __THROW __nonnull ((1));

#ifdef __USE_ATFILE
/* Like mkfifo, create a new FIFO with permission bits MODE. But
   interpret relative PATH names relative to the directory associated
   with FD. */
extern int mkfifoat (int __fd, __const char *__path, __mode_t __mode)
     __THROW __nonnull ((2));
#endif

#ifdef __USE_ATFILE
/* Set file access and modification times relative to directory file
   descriptor. */
extern int utimensat (int __fd, __const char *__path,
              __const struct timespec __times[2],
              int __flags)
     __THROW __nonnull ((2));
#endif

#ifdef __USE_GNU
/* XXX This will change to the macro for the next 2008 POSIX revision. */
/* Set file access and modification times of the file associated with FD. */
extern int futimens (int __fd, __const struct timespec __times[2]) __THROW;
#endif

/* To allow the `struct stat' structure and the file type `mode_t'
   bits to vary without changing shared library major version number,
   the `stat' family of functions and `mknod' are in fact inline
   wrappers around calls to `xstat', `fxstat', `lxstat', and `xmknod',
   which all take a leading version-number argument designating the
   data structure and bits used. <bits/stat.h> defines _STAT_VER with
   the version number corresponding to `struct stat' as defined in
   that file; and _MKNOD_VER with the version number corresponding to
   the S_IF* macros defined therein. It is arranged that when not
   inlined these function are always statically linked; that way a
   dynamically-linked executable always encodes the version number
   corresponding to the data structures it uses, so the `x' functions
   in the shared library can adapt without needing to recompile all
   callers. */

#ifndef _STAT_VER
# define _STAT_VER 0
#endif
#ifndef _MKNOD_VER
# define _MKNOD_VER 0
#endif

/* Wrappers for stat and mknod system calls. */
#ifndef __USE_FILE_OFFSET64
extern int __fxstat (int __ver, int __fildes, struct stat *__stat_buf)
     __THROW __nonnull ((3));
extern int __xstat (int __ver, __const char *__filename,
            struct stat *__stat_buf) __THROW __nonnull ((2, 3));
extern int __lxstat (int __ver, __const char *__filename,
             struct stat *__stat_buf) __THROW __nonnull ((2, 3));
extern int __fxstatat (int __ver, int __fildes, __const char *__filename,
               struct stat *__stat_buf, int __flag)
     __THROW __nonnull ((3, 4));
#else
# ifdef __REDIRECT_NTH
extern int __REDIRECT_NTH (__fxstat, (int __ver, int __fildes,
                      struct stat *__stat_buf), __fxstat64)
     __nonnull ((3));
extern int __REDIRECT_NTH (__xstat, (int __ver, __const char *__filename,
                     struct stat *__stat_buf), __xstat64)
     __nonnull ((2, 3));
extern int __REDIRECT_NTH (__lxstat, (int __ver, __const char *__filename,
                      struct stat *__stat_buf), __lxstat64)
     __nonnull ((2, 3));
extern int __REDIRECT_NTH (__fxstatat, (int __ver, int __fildes,
                    __const char *__filename,
                    struct stat *__stat_buf, int __flag),
               __fxstatat64) __nonnull ((3, 4));

# else
# define __fxstat __fxstat64
# define __xstat __xstat64
# define __lxstat __lxstat64
# endif
#endif

#ifdef __USE_LARGEFILE64
extern int __fxstat64 (int __ver, int __fildes, struct stat64 *__stat_buf)
     __THROW __nonnull ((3));
extern int __xstat64 (int __ver, __const char *__filename,
              struct stat64 *__stat_buf) __THROW __nonnull ((2, 3));
extern int __lxstat64 (int __ver, __const char *__filename,
               struct stat64 *__stat_buf) __THROW __nonnull ((2, 3));
extern int __fxstatat64 (int __ver, int __fildes, __const char *__filename,
             struct stat64 *__stat_buf, int __flag)
     __THROW __nonnull ((3, 4));
#endif
extern int __xmknod (int __ver, __const char *__path, __mode_t __mode,
             __dev_t *__dev) __THROW __nonnull ((2, 4));

extern int __xmknodat (int __ver, int __fd, __const char *__path,
               __mode_t __mode, __dev_t *__dev)
     __THROW __nonnull ((3, 5));

#if defined __GNUC__ && __GNUC__ >= 2
/* Inlined versions of the real stat and mknod functions. */

__extern_inline int
__NTH (stat (__const char *__path, struct stat *__statbuf))
{
  return __xstat (_STAT_VER, __path, __statbuf);
}

# if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
__extern_inline int
__NTH (lstat (__const char *__path, struct stat *__statbuf))
{
  return __lxstat (_STAT_VER, __path, __statbuf);
}
# endif

__extern_inline int
__NTH (fstat (int __fd, struct stat *__statbuf))
{
  return __fxstat (_STAT_VER, __fd, __statbuf);
}

# ifdef __USE_ATFILE
__extern_inline int
__NTH (fstatat (int __fd, __const char *__filename, struct stat *__statbuf,
        int __flag))
{
  return __fxstatat (_STAT_VER, __fd, __filename, __statbuf, __flag);
}
# endif

# if defined __USE_MISC || defined __USE_BSD
__extern_inline int
__NTH (mknod (__const char *__path, __mode_t __mode, __dev_t __dev))
{
  return __xmknod (_MKNOD_VER, __path, __mode, &__dev);
}
# endif

# ifdef __USE_ATFILE
__extern_inline int
__NTH (mknodat (int __fd, __const char *__path, __mode_t __mode,
        __dev_t __dev))
{
  return __xmknodat (_MKNOD_VER, __fd, __path, __mode, &__dev);
}
# endif

# if defined __USE_LARGEFILE64 && (! defined __USE_FILE_OFFSET64 || (defined __REDIRECT_NTH && defined __OPTIMIZE__))
__extern_inline int
__NTH (stat64 (__const char *__path, struct stat64 *__statbuf))
{
  return __xstat64 (_STAT_VER, __path, __statbuf);
}

# if defined __USE_BSD || defined __USE_XOPEN_EXTENDED
__extern_inline int
__NTH (lstat64 (__const char *__path, struct stat64 *__statbuf))
{
  return __lxstat64 (_STAT_VER, __path, __statbuf);
}
# endif

__extern_inline int
__NTH (fstat64 (int __fd, struct stat64 *__statbuf))
{
  return __fxstat64 (_STAT_VER, __fd, __statbuf);
}

# ifdef __USE_GNU
__extern_inline int
__NTH (fstatat64 (int __fd, __const char *__filename, struct stat64 *__statbuf,
          int __flag))
{
  return __fxstatat64 (_STAT_VER, __fd, __filename, __statbuf, __flag);
}
# endif

# endif

#endif

__END_DECLS


#endif /* sys/stat.h */

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