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[CMD] FOR: Fix a bug when parsing the "delims=" option in FOR loops.

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Suppose the following FOR-loop command, to be run from the command-line
(if using a batch file, double each percent '%' sign):

  FOR %l IN ("a,b,c,d,e" "f,g,h,i,j") DO (
    FOR /F "delims=, tokens=1-3*" %a IN (%l) DO @echo %a-%b-%c-%d
  )

The outermost FOR-loop enumerates the two strings "a,b,c,d,e" and
"f,g,h,i,j" (placed in %l), and parse each of these in turn, splitting
them at each specified delimiter (here only one character) ',' and storing
the results in consecutive tokens %a, %b, %c, %d, with the last token %d
containing all the remaining string (non-split).
The expected result is:

  a-b-c-d,e
  f-g-h-i,j

However, due to the way the delimiters string specified by the "delims="
option is stored (no stack/heap duplication of the FOR-option substring,
but reading from it directly), during the first run of the innermost
FOR-loop, the option string "delims=, tokens=1-3*" was truncated to just
after the ',' due to the erroneous "delims=" parsing, so that when this
FOR-loop ran for a second time (to deal with the second string), the option
string was already erroneously truncated, without the "tokens=..." part,
so that the parsing results were not stored in the tokens and resulting in:

  a-b-c-d,e
  f-%b-%c-%d

instead. The solution is to save where the "delims=" string needs to be
cut, but wait until running the actual FOR-loop to terminate it (and
saving the original character too), run the FOR-loop body, and then
restore the original character where termination took place. This allows
having the FOR-loop option string valid for the next execution of the
FOR-loop.
This commit is contained in:
Hermès Bélusca-Maïto 2020-07-04 22:22:07 +02:00
parent 5cf0517be1
commit 5d5a1a455c
No known key found for this signature in database
GPG key ID: 3B2539C65E7B93D0
1 changed files with 27 additions and 3 deletions
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30
base/shell/cmd/for.c
View file

@ -121,6 +121,8 @@ static LPTSTR ReadFileContents(FILE *InputFile, TCHAR *Buffer)
static INT ForF(PARSED_COMMAND *Cmd, LPTSTR List, TCHAR *Buffer)
{
LPTSTR Delims = _T(" \t");
LPTSTR DelimsEndPtr = NULL;
TCHAR DelimsEndChr = _T('\0');
TCHAR Eol = _T(';');
INT SkipLines = 0;
DWORD Tokens = (1 << 1);
@ -148,8 +150,13 @@ static INT ForF(PARSED_COMMAND *Cmd, LPTSTR List, TCHAR *Buffer)
else if (_tcsnicmp(Param, _T("delims="), 7) == 0)
{
Param += 7;
/* delims=xxx: Specifies the list of characters that separate tokens */
/*
* delims=xxx: Specifies the list of characters that separate tokens.
* This option does not cumulate: only the latest 'delims=' specification
* is taken into account.
*/
Delims = Param;
DelimsEndPtr = NULL;
while (*Param && *Param != Quote)
{
if (*Param == _T(' '))
@ -158,13 +165,19 @@ static INT ForF(PARSED_COMMAND *Cmd, LPTSTR List, TCHAR *Buffer)
Param += _tcsspn(Param, _T(" "));
/* Exclude trailing spaces if this is not the last parameter */
if (*Param && *Param != Quote)
*FirstSpace = _T('\0');
{
/* Save where the delimiters specification string ends */
DelimsEndPtr = FirstSpace;
}
break;
}
Param++;
}
if (*Param == Quote)
*Param++ = _T('\0');
{
/* Save where the delimiters specification string ends */
DelimsEndPtr = Param++;
}
}
else if (_tcsnicmp(Param, _T("eol="), 4) == 0)
{
@ -301,6 +314,13 @@ static INT ForF(PARSED_COMMAND *Cmd, LPTSTR List, TCHAR *Buffer)
return 1;
}
/* Patch the delimiters string */
if (DelimsEndPtr)
{
DelimsEndChr = *DelimsEndPtr;
*DelimsEndPtr = _T('\0');
}
/* Loop over the input line by line */
for (In = FullInput, Skip = SkipLines;
!ExitingOrGoto(Cmd) && (In != NULL);
@ -343,6 +363,10 @@ static INT ForF(PARSED_COMMAND *Cmd, LPTSTR List, TCHAR *Buffer)
Ret = RunInstance(Cmd);
}
/* Restore the delimiters string */
if (DelimsEndPtr)
*DelimsEndPtr = DelimsEndChr;
cmd_free(FullInput);
}