0000075: functions that are allowed to overwrite returned static data

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Category

Severity

Type

Date Submitted

Last Update

0000075

[1003.1(2008)/Issue 7] System Interfaces

Objection

Error

2009-06-29 02:32

2013-04-16 13:06

Reporter

geoffclare

View Status

public

Assigned To

ajosey

Priority

normal

Resolution

Accepted

Status

Closed

Name

Geoff Clare

Organization

User Reference

Section

basename

Page Number

614

Line Number

20984

Interp Status

Approved

Final Accepted Text

Note: 0000175

Summary

0000075: functions that are allowed to overwrite returned static data

Description

_____________________________________________________________________________
OBJECTION Enhancement Request Number 12
gwc:xxxxxxxxxxxxx Bug in XSHd5.1 basename (rdvk# 2)
[gwc static data] Tue, 28 Oct 2008 12:12:45 +0000
_____________________________________________________________________________

The issue identified for setlocale() in aardvark XSH ERN 250 against
the 2004 edition of the standard also affects several other functions.
These are functions that are allowed to overwrite returned static data,
but should also be allowed to use an internally reallocated buffer for
the data.

In some cases the statement that returned data may be overwritten is
in APPLICATION USAGE. In these cases the proposed replacement is in
normative text.

Desired Action

[Page and line numbers are for draft 5.1.]

basename: P614 L20984
Change
     "The basename() function may modify the string pointed to by
     path, and may return a pointer to static storage that may then be
     overwritten by a subsequent call to basename()."
to
     "The basename() function may modify the string pointed to by
     path, and may return a pointer to internal storage.
     The returned pointer might be invalidated or the storage
     might be overwritten by a subsequent call to basename()."

ctermid: P713 L24020
Change
     "If s is a null pointer, the string shall be generated in an area

     that may be static (and therefore may be overwritten by each call),
     the address of which shall be returned. Otherwise, ..."
to
     "If s is a null pointer, the string shall be generated in a area
     that may be static, the address of which shall be returned. The
     application shall not modify the string returned. The returned
     pointer might be invalidated or the string content might be
     overwritten by a subsequent call to ctermid(). If s is not a
     null pointer, ..."

dirname: P725 L24385
Change
     "The dirname() function may modify the string pointed to by path,
     and may return a pointer to static storage that may then be
     overwritten by subsequent calls to dirname()."
to
     "The dirname() function may modify the string pointed to by path,
     and may return a pointer to internal storage. The returned
     pointer might be invalidated or the storage might be overwritten
     by a subsequent call to dirname()."

dlerror: P730 L24547
Add a new paragraph to the RETURN VALUE section:
     "The application shall not modify the string returned. The
     returned pointer might be invalidated or the string content might
     be overwritten by a subsequent call to dlerror()."

dlerror: P730 L24560
Delete
     "The messages returned by dlerror() may reside in a static buffer
     that is overwritten on each call to dlerror(). Application code
     should not write to this buffer. Programs wishing to preserve an
     error message should make their own copies of that message."

getgrent: P747 L25066 section endgrent
Change
     "The return value may point to a static area which is overwritten
     by a subsequent call to getgrgid(), getgrnam(), or getgrent()."
to
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getgrgid(),
     getgrnam(), or getgrent()."

gethostent: P749 L25126 section endhostent
Add a new paragraph to the RETURN VALUE section:
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to gethostent()."

gethostent: P749 L25132 section endhostent
Change
     "The gethostent() function may return pointers to static data,
     which may be overwritten by subsequent calls to any of these

     functions."
to
     "None"

getnet*: P751 L25180 section endnetent
Add a new paragraph to the RETURN VALUE section:
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getnetbyaddr(),
     getnetbyname(), or getnetent()."

getnet*: P752 L25186 section endnetent
Change
     "The getnetbyaddr(), getnetbyname(), and getnetent() functions may
     return pointers to static data, which may be overwritten by
     subsequent calls to any of these functions."
to
     "None"

getproto*: P753 L25235 section endprotoent
Add a new paragraph to the RETURN VALUE section:
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getprotobyname(),
     getprotobynumber(), or getprotoent()."

getproto*: P754 L25241 section endprotoent
Change
     "The getprotobyname(), getprotobynumber(), and getprotoent()
     functions may return pointers to static data, which may be
     overwritten by subsequent calls to any of these functions."
to
     "None"

getpwent: P755 L25276 section endpwent
Add a new paragraph to the RETURN VALUE section:
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getpwuid(),
     getpwnam(), or getpwent()."

getpwent: P755 L25283 section endpwent
Delete from the ERRORS section:
     "The return value may point to a static area which is overwritten
     by a subsequent call to getpwuid(), getpwnam(), or getpwent()."

getserv*: P758 L25367 section endservent
Add a new paragraph to the RETURN VALUE section:
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage

     areas might be overwritten by a subsequent call to getservbyname(),
     getservbyport(), or getservent()."

getserv*: P759 L25375 section endservent
Delete
     "The getservbyname(), getservbyport(), and getservent() functions
     may return pointers to static data, which may be overwritten by
     subsequent calls to any of these functions."

getenv: P1008 L33858
Change
     "The string pointed to may be overwritten by a subsequent call to
     getenv(), [CX]setenv(), unsetenv(),[/CX] [XSI]or putenv()[/XSI]
     but shall not be overwritten by a call to any other function in
     this volume of POSIX.1-200x."
to
     "[CX]The returned string pointer might be invalidated or[/CX] the
     string content might be overwritten by a subsequent call to
     getenv(), [CX]setenv(), unsetenv(),[/CX] [XSI]or putenv()[/XSI]
     but they shall not be affected by a call to any other function in
     this volume of POSIX.1-200x."

getgrgid: P1014 L34026
Change
     "The return value may point to a static area which is overwritten
     by a subsequent call to getgrent(), getgrgid(), or getgrnam()."
to
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getgrent(),
     getgrgid(), or getgrnam()."

getgrnam: P1018 L34154
Change
     "The return value may point to a static area which is overwritten
     by a subsequent call to getgrent(), getgrgid(), or getgrnam()."
to
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getgrent(),
     getgrgid(), or getgrnam()."

getlogin: P1029 L34474
Change
     "The return value from getlogin() may point to static data whose
     content is overwritten by each call."
to
     "The application shall not modify the string returned.
     The returned pointer might be invalidated or the string content
     might be overwritten by a subsequent call to getlogin()."

getpwnam: P1058 L35324
Change
     "The return value may point to a static area which is overwritten

     by a subsequent call to getpwent(), getpwnam(), or getpwuid()."
to
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getpwent(),
     getpwnam(), or getpwuid()."

getpwuid: P1061 L35457
Change
     "The return value may point to a static area which is overwritten
     by a subsequent call to getpwent(), getpwnam(), or getpwuid()."
to
     "The application shall not modify the structure to which the
     return value points, nor any storage areas pointed to by pointers
     within the structure. The returned pointer, and pointers within
     the structure, might be invalidated or the structure or the storage
     areas might be overwritten by a subsequent call to getpwent(),
     getpwnam(), or getpwuid()."

localeconv: P1235 L40722
Change
     "The application shall not modify the structure pointed to
     by the return value which may be overwritten by a subsequent call
     to localeconv(). In addition, calls to setlocale() with the
     categories LC_ALL, LC_MONETARY, or LC_NUMERIC or calls to uselocale()
     which change the categories LC_MONETARY or LC_NUMERIC may overwrite
     the contents of the structure."
to
     "The application shall not modify the structure to which the
     return value points, [CX]nor any storage areas pointed to by
     pointers within the structure. The returned pointer, and pointers
     within the structure, might be invalidated or[/CX] the structure
     [CX]or the storage areas[/CX] might be overwritten by a subsequent
     call to localeconv(). In addition, [CX]the returned pointer, and
     pointers within the structure, might be invalidated or[/CX] the
     structure [CX]or the storage areas[/CX] might be overwritten by
     subsequent calls to setlocale() with the categories LC_ALL,
     LC_MONETARY, or LC_NUMERIC, [CX]or by calls to uselocale() which
     change the categories LC_MONETARY or LC_NUMERIC[/CX]."

nl_langinfo: P1375 L45104
Delete
     "Calls to setlocale() with a category corresponding to the
     category of item (see <langinfo.h>), or to the category LC_ALL,
     may overwrite the array pointed to by the return value. Calls to
     uselocale() which change the category corresponding to the
     category of item may overwrite the array pointed to by the return
     value."

nl_langinfo: P1375 L45113
Change
     "This pointer may point to static data that may be overwritten on
     the next call to either function."
to
     "The application shall not modify the string returned.
     The returned pointer might be invalidated or the string content

     might be overwritten by a subsequent call to either function, by
     subsequent calls to setlocale() with a category corresponding to
     the category of item (see <langinfo.h>) or the category LC_ALL, or
     by subsequent calls to uselocale() which change the category
     corresponding to the category of item."

ptsname: P1712 L54754
Add a new paragraph to the RETURN VALUE section:
     "The application shall not modify the string returned.
     The returned pointer might be invalidated or the string content
     might be overwritten by a subsequent call to ptsname()."

ptsname: P1712 L54760
Change
     "The value returned may point to a static data area that is
     overwritten by each call to ptsname()."
to
     "None"

readdir: P1744 L55685
Change
     "The pointer returned by readdir() points to data which may be
     overwritten by another call to readdir() on the same directory
     stream. This data is not overwritten by another call to readdir()
     on a different directory stream."
to
     "The application shall not modify the structure to which the
     return value of readdir() points, nor any storage areas pointed to
     by pointers within the structure. The returned pointer, and
     pointers within the structure, might be invalidated or the
     structure or the storage areas might be overwritten by a
     subsequent call to readdir() on the same directory stream.
     They shall not be affected by a call to readdir() on a different
     directory stream."

strerror: P1999 L63238
Change
     "The string pointed to shall not be modified by the application.
     The string may be overwritten by a subsequent call to strerror().
     [CX]The string may be overwritten by a subsequent call to
     strerror_l() in the same thread.[/CX]"
to
     "The application shall not modify the string returned.
     [CX]The returned string pointer might be invalidated or[/CX] the
     string content might be overwritten by a subsequent call to
     strerror(), [CX]or by a subsequent call to strerror_l() in the
     same thread[/CX]."

strsignal: P2032 L64345
Change
     "The string pointed to shall not be modified by the application,
     but may be overwritten by a subsequent call to strsignal() or
     setlocale()."
to
     "The application shall not modify the string returned.
     The returned pointer might be invalidated or the string content
     might be overwritten by a subsequent call to strsignal() or
     setlocale()."

ttyname: P2140 L67655
Change
     "The return value may point to static data whose content is
     overwritten by each call."
to
     "The application shall not modify the string returned.
     The returned pointer might be invalidated or the string content
     might be overwritten by a subsequent call to ttyname()."

Notes
(0000175) ajosey (manager) 2009-08-06 15:33 edited on: 2009-10-09 16:40	Interpretation response ------------------------ The standard states the requirements for functions overwriting static data, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor. Rationale: ------------- None. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- Make the change suggested by the submitter

(0000728) ajosey (manager) 2011-03-30 09:50	When applying the change for dlerror() in the draft TC1-2008, bug 97 was also taken into account when updating the RETURN VALUE section. "The application shall not modify the string returned. The returned pointer might be invalidated or the string content might be overwritten by a subsequent call to dlerror() in the same thread (if dlerror() is thread-safe) or in any thread (if dlerror() is not thread-safe)."

Issue History
Date Modified	Username	Field	Change
2009-06-29 02:32	msbrown	New Issue
2009-06-29 02:32	msbrown	Status	New => Under Review
2009-06-29 02:32	msbrown	Assigned To	=> ajosey
2009-06-29 02:32	msbrown	Name	=> Mark Brown
2009-06-29 02:32	msbrown	Organization	=> IBM
2009-06-29 02:32	msbrown	Section	=> basename
2009-06-29 02:32	msbrown	Page Number	=> 614
2009-06-29 02:32	msbrown	Line Number	=> 20984
2009-06-29 02:33	msbrown	Status	Under Review => Resolved
2009-06-29 02:33	msbrown	Resolution	Open => Accepted
2009-07-01 14:03	msbrown	Name	Mark Brown => Geoff Clare
2009-07-01 14:03	msbrown	Organization	IBM =>
2009-07-01 14:03	msbrown	Reporter	msbrown => geoffclare
2009-08-06 15:33	ajosey	Note Added: 0000175
2009-08-06 15:33	ajosey	Status	Resolved => Interpretation Required
2009-08-11 16:31	Don Cragun	Interp Status	=> Pending
2009-09-17 15:41	nick	Interp Status	Pending => Proposed
2009-10-09 16:40	ajosey	Note Edited: 0000175
2009-10-09 16:41	ajosey	Interp Status	Proposed => Approved
2009-10-09 16:41	ajosey	Final Accepted Text	=> Note: 0000175
2010-09-07 10:53	geoffclare	Relationship added	related to 0000288
2010-09-20 09:16	geoffclare	Tag Attached: tc1-2008
2011-03-24 15:07	eblake	Relationship added	related to 0000097
2011-03-30 09:50	ajosey	Note Added: 0000728
2011-04-04 14:27	geoffclare	Relationship added	related to 0000402
2011-11-10 21:28	eblake	Relationship added	related to 0000508
2013-02-21 17:00	eblake	Relationship added	related to 0000656
2013-04-16 13:06	ajosey	Status	Interpretation Required => Closed