Bug 5984

Summary:	Enable UCLIBC_HAS_FOPEN_EXCLUSIVE_MODE by default
Product:	uClibc	Reporter:	Jeffrey Walton <noloader>
Component:	stdio	Assignee:	unassigned
Status:	RESOLVED INVALID
Severity:	normal	CC:	uclibc-cvs
Priority:	P5
Version:	0.9.33.3
Target Milestone:	---
Hardware:	PC
OS:	Linux
Host:		Target:
Build:

Description Jeffrey Walton 2013-02-27 23:36:20 UTC

The description is below, but I believe its not quite correct.
C11 adds the "x" mode, so its not a glibc thing anymore. See, for example, https://www.securecoding.cert.org/confluence/display/seccode/FIO03-C.+Do+not+make+assumptions+about+fopen%28%29+and+file+creation.

I understand uClibc may not be C11 compliant (and may not even desire it). But "x" mode has security implications, and claiming its a compat option may not be doing it justice.

   ───── Support an fopen() 'x' flag for exclusive mode (glibc-compat) ─────┐
  │ UCLIBC_HAS_FOPEN_EXCLUSIVE_MODE:                                        │  
  │                                                                         │  
  │ Answer Y to support a glibc extension to allow passing                  │  
  │ additional 'x' flag in the mode string for fopen() to specify that      │  
  │ the file should be open()ed with the O_EXCL flag set.                   │  
  │                                                                         │  
  │ Most people will answer N.                                              │  
  │                                                                         │  
  │ Symbol: UCLIBC_HAS_FOPEN_EXCLUSIVE_MODE [=y]                            │  
  │ Prompt: Support an fopen() 'x' flag for exclusive mode (glibc-compat)   │  
  │   Defined at extra/Configs/Config.in:1728                               │  
  │   Location:                                                             │  
  │     -> String and Stdio Support

Comment 1 Bernhard Reutner-Fischer 2013-02-28 12:12:40 UTC

This library aims to implement SUSv4 (aka POSIX-2008 aka IEEE Std 1003.1-2008).

$ grep "through SUSv4" TODO 
    *) Go through SUSv4

So yes, SUSv4 compliants is on the TODO list. Please do not file bugs about those but send proper and complete patches to handle SUSv4.

Regarding this issue here. There is no 'x' mode in http://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.html
so we rightfully have it as an extension.

You may want to send a patch that adds ...glibc extension (and C11 requirement).. to the help-text, sure.

TIA,