[1003.1(2008)/Issue 7 0001153]: fread/fwrite to/from buffer underlying the memory stream
The following issue has been UPDATED. == http://austingroupbugs.net/view.php?id=1153 == Reported By:Villemoes Assigned To:ajosey == Project:1003.1(2008)/Issue 7 Issue ID: 1153 Category: System Interfaces Type: Clarification Requested Severity: Editorial Priority: normal Status: Resolved Name: Rasmus Villemoes Organization: User Reference: Section:fmemopen Page Number: Line Number: Interp Status: --- Final Accepted Text:See http://austingroupbugs.net/view.php?id=1153#c4186 Resolution: Accepted As Marked Fixed in Version: == Date Submitted: 2017-06-22 08:02 UTC Last Modified: 2018-12-13 17:00 UTC == Summary:fread/fwrite to/from buffer underlying the memory stream == Issue History Date ModifiedUsername FieldChange == 2017-06-22 08:02 Villemoes New Issue 2017-06-22 08:02 Villemoes Status New => Under Review 2017-06-22 08:02 Villemoes Assigned To => ajosey 2017-06-22 08:02 Villemoes Name => Rasmus Villemoes 2017-06-22 08:02 Villemoes Section => fmemopen 2018-12-13 16:59 nick Note Added: 0004186 2018-12-13 17:00 nick Interp Status => --- 2018-12-13 17:00 nick Status Under Review => Resolved 2018-12-13 17:00 nick Resolution Open => Accepted As Marked 2018-12-13 17:00 nick Final Accepted Text => See http://austingroupbugs.net/view.php?id=1153#c4186 ==
[1003.1(2008)/Issue 7 0001153]: fread/fwrite to/from buffer underlying the memory stream
The following issue has been RESOLVED. == http://austingroupbugs.net/view.php?id=1153 == Reported By:Villemoes Assigned To:ajosey == Project:1003.1(2008)/Issue 7 Issue ID: 1153 Category: System Interfaces Type: Clarification Requested Severity: Editorial Priority: normal Status: Resolved Name: Rasmus Villemoes Organization: User Reference: Section:fmemopen Page Number: Line Number: Interp Status: --- Final Accepted Text: Resolution: Accepted As Marked Fixed in Version: == Date Submitted: 2017-06-22 08:02 UTC Last Modified: 2018-12-13 17:00 UTC == Summary:fread/fwrite to/from buffer underlying the memory stream == Issue History Date ModifiedUsername FieldChange == 2017-06-22 08:02 Villemoes New Issue 2017-06-22 08:02 Villemoes Status New => Under Review 2017-06-22 08:02 Villemoes Assigned To => ajosey 2017-06-22 08:02 Villemoes Name => Rasmus Villemoes 2017-06-22 08:02 Villemoes Section => fmemopen 2018-12-13 16:59 nick Note Added: 0004186 2018-12-13 17:00 nick Interp Status => --- 2018-12-13 17:00 nick Status Under Review => Resolved 2018-12-13 17:00 nick Resolution Open => Accepted As Marked ==
[1003.1(2008)/Issue 7 0001153]: fread/fwrite to/from buffer underlying the memory stream
A NOTE has been added to this issue. == http://austingroupbugs.net/view.php?id=1153 == Reported By:Villemoes Assigned To:ajosey == Project:1003.1(2008)/Issue 7 Issue ID: 1153 Category: System Interfaces Type: Clarification Requested Severity: Editorial Priority: normal Status: Under Review Name: Rasmus Villemoes Organization: User Reference: Section:fmemopen Page Number: Line Number: Interp Status: --- Final Accepted Text: == Date Submitted: 2017-06-22 08:02 UTC Last Modified: 2018-12-13 16:59 UTC == Summary:fread/fwrite to/from buffer underlying the memory stream == -- (0004186) nick (manager) - 2018-12-13 16:59 http://austingroupbugs.net/view.php?id=1153#c4186 -- Add a new paragraph (CX shaded) to page 496 line 17237 section 2.5: When a standard I/O stream has an associated memory buffer (whether allocated internally, supplied to setvbuf(), or supplied to fmemopen()), the behavior is undefined if that buffer overlaps with the destination buffer passed to a call that reads from the stream or with the source buffer passed to a call that writes to the stream. Issue History Date ModifiedUsername FieldChange == 2017-06-22 08:02 Villemoes New Issue 2017-06-22 08:02 Villemoes Status New => Under Review 2017-06-22 08:02 Villemoes Assigned To => ajosey 2017-06-22 08:02 Villemoes Name => Rasmus Villemoes 2017-06-22 08:02 Villemoes Section => fmemopen 2018-12-13 16:59 nick Note Added: 0004186 ==
[1003.1(2008)/Issue 7 0001153]: fread/fwrite to/from buffer underlying the memory stream
The following issue has been SUBMITTED.
==
http://austingroupbugs.net/view.php?id=1153
==
Reported By:Villemoes
Assigned To:ajosey
==
Project:1003.1(2008)/Issue 7
Issue ID: 1153
Category: System Interfaces
Type: Clarification Requested
Severity: Editorial
Priority: normal
Status: Under Review
Name: Rasmus Villemoes
Organization:
User Reference:
Section:fmemopen
Page Number:
Line Number:
Interp Status: ---
Final Accepted Text:
==
Date Submitted: 2017-06-22 08:02 UTC
Last Modified: 2017-06-22 08:02 UTC
==
Summary:fread/fwrite to/from buffer underlying the memory
stream
Description:
In glibc, running the code below under valgrind gives a
Source and destination overlap in memcpy
Without the setvbuf calls, this doesn't trigger because the reads and
writes happen via an internal buffer.
I cannot find anything that says the application cannot do fread/fwrite
calls on a memory stream, using part of the stream's underlying buffer as
destination/source.
#include
int main(int argc, char *argv[])
{
char x[4] = "123";
char y[4] = "abc";
FILE *f = fmemopen(x, 3, "r");
FILE *g = fmemopen(y, 3, "w");
setvbuf(f, NULL, _IONBF, 0);
setvbuf(g, NULL, _IONBF, 0);
fread([1], 1, 2, f);
fwrite([1], 1, 2, g);
printf("x = %s\n", x);
printf("y = %s\n", y);
fclose(f);
fclose(g);
printf("x = %s\n", x);
printf("y = %s\n", y);
return 0;
}
Desired Action:
Clarify whether the implementation must behave as if it was using memmove
internally, or alternatively, that it is up to the application to avoid
fread/fwrite calls on memory streams that will trigger such copies. The
latter seems hard to do in general.
==
Issue History
Date ModifiedUsername FieldChange
==
2017-06-22 08:02 Villemoes New Issue
2017-06-22 08:02 Villemoes Status New => Under Review
2017-06-22 08:02 Villemoes Assigned To => ajosey
2017-06-22 08:02 Villemoes Name => Rasmus Villemoes
2017-06-22 08:02 Villemoes Section => fmemopen
==
