216952 - isdigit() used incorrectly throughout codebase (use mozilla::IsAsciiDigit())

Status: RESOLVED FIXED

(Developer Infrastructure :: Source Code Analysis, task)

Description

[Andrew Mann]

User-Agent:       Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 1.0.3705)
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.5b) Gecko/20030820

isdigit() called with incorrect parameter.  isdigit() should be called with 
either an EOF or a value that can be represented as an unsigned char.
It's called with a char in these cases.  Negative values aside from EOF cause 
undefined results from isdigit, and cause an assertion under
MSVC.NET (vc7).
  The following locations contain bad calls to isdigit():
mozilla\gc\boehm\typeinfo.cpp(187):                while (isdigit(*type)) 
++type;
mozilla\htmlparser\tests\outsinks\Convert.cpp(244):        if (isdigit(argv[0]
[2]))
mozilla\htmlparser\tests\outsinks\Convert.cpp(254):        if (isdigit(argv[0]
[2]))
mozilla\mailnews\extensions\bayesian-spam-filter\src\nsBayesianFilter.cpp
(232):        if (!isdigit(c))
mozilla\mailnews\imap\src\nsImapSearchResults.cpp(118):		while (isdigit
(*++fPositionInCurrentLine))
mozilla\mailnews\imap\src\nsImapServerResponseParser.cpp(2755):		if (! 
isdigit(string[i]))

// Unsure?  nsCAutoString line;
mozilla\netwerk\protocol\ftp\src\nsFtpConnectionThread.cpp
(496):                           isdigit(line[0]) &&
mozilla\netwerk\protocol\ftp\src\nsFtpConnectionThread.cpp
(497):                           isdigit(line[1]) &&
mozilla\netwerk\protocol\ftp\src\nsFtpConnectionThread.cpp
(498):                           isdigit(line[2]));

// Numerous occassions in ParseFTPList.cpp
mozilla\netwerk\streamconv\converters\ParseFTPList.cpp(149):            if 
(isdigit(line[pos]))

mozilla\xpinstall\wizard\libxpnet\src\nsFTPConn.cpp(520):    while (!isdigit
((int)(*c)))
mozilla\xpinstall\wizard\libxpnet\src\nsSocket.cpp(512):        else if (!
isdigit(aAddress[i]))
mozilla\xpinstall\wizard\windows\ds32\ds32.cpp
(409):                                if(isdigit(argv[i][2]) == 0)
mozilla\xpinstall\wizard\windows\ds32\ds32.cpp
(417):                                if(isdigit(argv[i][0]) == 0)

Reproducible: Always

Steps to Reproduce:
1. 
2.
3.

Actual Results:  
VC7 causes an assertion.  Man pages under RedHat Linux 7.1 also indicate that 
isdigit() should be called with an int parameter with either EOF or a value in 
the range of an unsigned char.  Other projects seem to indicate that other 
platforms aside from Windows VC7 debug builds have problems with isdigit() 
being passed invalid values as well.
  This causes a debug build of a clean checkout compiled with Vc7 to be hardly 
usable as isdigit() causes asserts like crazy - especially in the mail portion.

Expected Results:  
char c;
isdigit((unsigned char)c)
?

Comment 1

[Jon Henry]

-> Build config

Is this the right place for this bug? I've had problems with MSVC 7 asserting
like crazy as well.

Comment 2

[cls]

This is a general coding bug not a build/config bug.

Comment 3

[cls]

This is a general coding bug not a build/config bug.

Comment 4

[Daniel Veditz [:dveditz] back January 5, 2026]

Not a blocker. Should use NS_IS_DIGIT() instead

Comment 5

[Henri Sivonen (:hsivonen) (away from Bugzilla until 2025-12-29)]

Per https://stackoverflow.com/questions/2898228/can-isdigit-legitimately-be-locale-dependent-in-c isdigit() depends on the locale on Windows in violation of the C standard.

Comment 6

[Sylvestre Ledru [:Sylvestre]]

Closing as I guess it is fixed. Please reopen if I am wrong