From: Scott Gifford (sgiffordsuspectclass.com)
Date: Fri Apr 15 2005 - 00:33:12 CDT

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"Mark Senior" <Mark.Seniorgov.ab.ca> writes:

>
>
>> From: Derek Martin [mailto:codepizzashack.org]
>> Sent: April 13, 2005 08:50
>>
>>
>> The open() call is at fault here. If instead of being called
>> with a mode of RW_USER, it is called with the final intended
>> access mode, there is no need to later call chmod(), and the
>> problem is averted.
>
> One wrinkle - if the file is not intended to have user write permission
> on it, and gzip (unzip/cpio/pax...) initially created it with the
> intended permissions, there would be no way to then write the file.

In a quick test, this seems not to be true, at least on my Linux
system. It may be true over NFS.
    
    [giffordgifford tmp]$ ls -ld testfile
    ls: testfile: No such file or directory
    [giffordgifford tmp]$ cat t.c
    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <fcntl.h>
     
    void die(char *msg)
    {
      perror(msg);
      exit(1);
    }
     
    int main()
    {
      int fd;
     
      if ((fd = open("testfile",O_CREAT|O_WRONLY,0)) < 0)
        die("open failed");
      if (write(fd,"output\n",7) < 0)
        die("write failed");
      if (close(fd) < 0)
        die("close failed");
     
      return 0;
    }
    [giffordgifford tmp]$ gcc -Wall t.c
    [giffordgifford tmp]$ ./a.out
    [giffordgifford tmp]$ ls -ld testfile
    ---------- 1 gifford gifford 7 Apr 15 01:28 testfile
    [giffordgifford tmp]$ chmod +r testfile
    [giffordgifford tmp]$ cat testfile
    output
    [giffordgifford tmp]$

----ScottG.

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