Bug 104613

Summary: [WK2] Fix memory sampler for ARM Linux
Product: WebKit Reporter: Laszlo Gombos <laszlo.gombos>
Component: WebKit2Assignee: JungJik Lee <jungjik.lee>
Status: RESOLVED DUPLICATE    
Severity: Normal CC: benjamin, cdumez, hausmann, jungjik.lee, kenneth, ossy
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 108645    
Attachments:
Description Flags
fix
none
2nd try
benjamin: review-
use a explicit c++ type cast and use feof for checking file-end.
none
Patch ossy: review-, ossy: commit-queue-

Laszlo Gombos
Reported 2012-12-10 16:51:21 PST
Building for ARM Linux gives the following error (e.g. on EFL port) /webkit/Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp: In function ‘WTF::String WebKit::nextToken(FILE*)’: /webkit/Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp:69:19: error: comparison is always false due to limited range of data type The type "char" by default is signed on x86 and unsigned on ARM. On platforms where "char" is unsigned the value -1 (EOF) becomes 255 when stored in an unsigned char (variable ch in the code above). This can easily lead to an infinite loop because the end of the file cannot be recognized.
Attachments
fix (1.77 KB, patch)
2012-12-10 17:12 PST, Laszlo Gombos 		no flags
DetailsFormatted DiffDiff
2nd try (1.77 KB, patch)
2012-12-10 19:15 PST, Laszlo Gombos 		benjamin: review-
DetailsFormatted DiffDiff
use a explicit c++ type cast and use feof for checking file-end. (1.78 KB, patch)
2013-02-14 03:26 PST, JungJik Lee 		no flags
DetailsFormatted DiffDiff
Patch (1.99 KB, patch)
2013-02-18 00:13 PST, JungJik Lee 		ossy: review-
ossy: commit-queue-
DetailsFormatted DiffDiff
Show Obsolete (3) View All Add attachment proposed patch, testcase, etc.
Laszlo Gombos
Comment 1 2012-12-10 17:12:10 PST
Created attachment 178671 [details] fix Make sure that the return value for fgetc() is first assigned to a signed variable to check for EOF and avoid the potential for an infinite loop.
Laszlo Gombos
Comment 2 2012-12-10 19:15:06 PST
Created attachment 178689 [details] 2nd try Swap the conditions for the while as it was in the original code.
Kenneth Rohde Christiansen
Comment 3 2012-12-10 23:54:34 PST
Comment on attachment 178689 [details] 2nd try View in context: https://bugs.webkit.org/attachment.cgi?id=178689&action=review > Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp:-69 > - if (ch == EOF || (isASCIISpace(ch) && index)) // Break on non-initial ASCII space. I think you have the same issue in Source/WebKit2/Shared/Plugins/Netscape/x11/NetscapePluginModuleX11.cpp
Laszlo Gombos
Comment 4 2012-12-11 06:59:20 PST
(In reply to comment #3) > (From update of attachment 178689 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=178689&action=review > > > Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp:-69 > > - if (ch == EOF || (isASCIISpace(ch) && index)) // Break on non-initial ASCII space. > > I think you have the same issue in Source/WebKit2/Shared/Plugins/Netscape/x11/NetscapePluginModuleX11.cpp NetscapePluginModuleX11.cpp looks good to me as the return value of fputc is assigned to a signed variable (int is signed). int result; while ((result = fputc(*current, stdout)) == EOF && errno == EINTR) { }
JungJik Lee
Comment 5 2012-12-11 20:50:27 PST
Comment on attachment 178689 [details] 2nd try View in context: https://bugs.webkit.org/attachment.cgi?id=178689&action=review >>> Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp:-69 >>> - if (ch == EOF || (isASCIISpace(ch) && index)) // Break on non-initial ASCII space. >> >> I think you have the same issue in Source/WebKit2/Shared/Plugins/Netscape/x11/NetscapePluginModuleX11.cpp > > NetscapePluginModuleX11.cpp looks good to me as the return value of fputc is assigned to a signed variable (int is signed). > > int result; > while ((result = fputc(*current, stdout)) == EOF && errno == EINTR) { } I didn't think enough. Could we use feof(file) instead of ch == EOF? if (feof(file) || ferror(file) || (isASCIISpace(ch) && index))
Benjamin Poulain
Comment 6 2013-01-08 19:58:12 PST
Comment on attachment 178689 [details] 2nd try View in context: https://bugs.webkit.org/attachment.cgi?id=178689&action=review > Source/WebKit2/ChangeLog:11 > + > + Make sure that the return value for fgetc() is first assigned to a > + signed variable to check for EOF and avoid the potential for an infinite > + loop. This is important for ARM platforms where "char" type is > + unsigned by default. This whole signed-unsigned char is not the problem. The problem is the assignment from fgetc() was a one with loss. It is incorrect, ARM or not. > Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp:70 > + int ch; > + while ((index < maxBuffer) && (ch = fgetc(file) != EOF)) { > + char charCode = ch; > + if (isASCIISpace(charCode) && index) // Break on non-initial ASCII space. This code is harder to read than it should. Please split your condition and assignment to make something nice and clean. You probably also want a c++ cast for int->char to make it explicit.
JungJik Lee
Comment 7 2013-02-14 03:26:55 PST
Created attachment 188299 [details] use a explicit c++ type cast and use feof for checking file-end.
Chris Dumez
Comment 8 2013-02-17 00:29:35 PST
Comment on attachment 188299 [details] use a explicit c++ type cast and use feof for checking file-end. View in context: https://bugs.webkit.org/attachment.cgi?id=188299&action=review The change makes sense. > Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp:70 > + if ((isASCIISpace(charCode) && index) || feof(file) || ferror(file)) // Break on non-initial ASCII space. I think it would be conceptually nicer to check for end of file and error *before* checking for space. I would reverse the conditions: if (feof(file) || ferror(file) || (isASCIISpace(charCode) && index))
JungJik Lee
Comment 9 2013-02-18 00:13:41 PST
Created attachment 188806 [details] Patch
JungJik Lee
Comment 10 2013-02-18 00:17:46 PST
(In reply to comment #8) > (From update of attachment 188299 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=188299&action=review > > The change makes sense. > > > Source/WebKit2/Shared/linux/WebMemorySamplerLinux.cpp:70 > > + if ((isASCIISpace(charCode) && index) || feof(file) || ferror(file)) // Break on non-initial ASCII space. > > I think it would be conceptually nicer to check for end of file and error *before* checking for space. I would reverse the conditions: > if (feof(file) || ferror(file) || (isASCIISpace(charCode) && index)) Taking your advice, I filed new patch. thanks for your opinion.
Csaba Osztrogonác
Comment 11 2015-05-11 02:18:47 PDT
*** This bug has been marked as a duplicate of bug 144439 ***
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