https://git.reactos.org/?p=reactos.git;a=commitdiff;h=cdc8e45b4828b53039646d4c9f50241cfb5d46ee
commit cdc8e45b4828b53039646d4c9f50241cfb5d46ee Author: Hermès Bélusca-Maïto <[email protected]> AuthorDate: Thu Jun 4 02:56:18 2020 +0200 Commit: Hermès Bélusca-Maïto <[email protected]> CommitDate: Sat Sep 19 19:44:55 2020 +0200 [CMD] Fix delayed expansion of variables. CORE-13682 - Split SubstituteVars() into its main loop and a helper SubstituteVar() that just substitutes only one variable. - Use this new helper as the basis of the proper implementation of the delayed expansion of variables. - Fix a bug introduced in commit 495c82cc, when GetBatchVar() fails. --- base/shell/cmd/cmd.c | 255 ++++++++++++++++++++++++++++++++++++++++----------- base/shell/cmd/cmd.h | 21 ++++- 2 files changed, 220 insertions(+), 56 deletions(-) diff --git a/base/shell/cmd/cmd.c b/base/shell/cmd/cmd.c index c4d41d0f247..774bc4782bc 100644 --- a/base/shell/cmd/cmd.c +++ b/base/shell/cmd/cmd.c @@ -1318,32 +1318,52 @@ GetBatchVar( } BOOL -SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) +SubstituteVar( + IN PCTSTR Src, + OUT size_t* SrcIncLen, // VarNameLen + OUT PTCHAR Dest, + IN PTCHAR DestEnd, + OUT size_t* DestIncLen, + IN TCHAR Delim) { -#define APPEND(From, Length) { \ +#define APPEND(From, Length) \ +do { \ if (Dest + (Length) > DestEnd) \ goto too_long; \ - memcpy(Dest, From, (Length) * sizeof(TCHAR)); \ - Dest += Length; } -#define APPEND1(Char) { \ + memcpy(Dest, (From), (Length) * sizeof(TCHAR)); \ + Dest += (Length); \ +} while (0) + +#define APPEND1(Char) \ +do { \ if (Dest >= DestEnd) \ goto too_long; \ - *Dest++ = Char; } + *Dest++ = (Char); \ +} while (0) - TCHAR *DestEnd = Dest + CMDLINE_LENGTH - 1; - const TCHAR *Var; - int VarLength; - TCHAR *SubstStart; + PCTSTR Var; + PCTSTR Start, End, SubstStart; TCHAR EndChr; - while (*Src) - { - if (*Src != Delim) - { - APPEND1(*Src++) - continue; - } + size_t VarLength; + + Start = Src; + End = Dest; + *SrcIncLen = 0; + *DestIncLen = 0; + + if (!Delim) + return FALSE; + if (*Src != Delim) + return FALSE; - Src++; + ++Src; + + /* If we are already at the end of the string, fail the substitution */ + SubstStart = Src; + if (!*Src || *Src == _T('\r') || *Src == _T('\n')) + goto bad_subst; + + { if (bc && Delim == _T('%')) { UINT NameLen; @@ -1353,15 +1373,15 @@ SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) /* Return the partially-parsed command to be * echoed for error diagnostics purposes. */ APPEND1(Delim); - APPEND(Src, DestEnd-Dest); + APPEND(Src, _tcslen(Src) + 1); return FALSE; } if (Var != NULL) { VarLength = _tcslen(Var); - APPEND(Var, VarLength) + APPEND(Var, VarLength); Src += NameLen; - continue; + goto success; } } @@ -1369,22 +1389,25 @@ SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) * end the name and begin the optional modifier, but not if it * is immediately followed by the delimiter (%VAR:%). */ SubstStart = Src; - while (*Src != Delim && !(*Src == _T(':') && Src[1] != Delim)) + while (*Src && *Src != Delim && !(*Src == _T(':') && Src[1] != Delim)) { - if (!*Src) - goto bad_subst; - Src++; + ++Src; } + /* If we are either at the end of the string, or the delimiter + * has been repeated more than once, fail the substitution. */ + if (!*Src || Src == SubstStart) + goto bad_subst; EndChr = *Src; - *Src = _T('\0'); + *(PTSTR)Src = _T('\0'); // FIXME: HACK! Var = GetEnvVarOrSpecial(SubstStart); - *Src++ = EndChr; + *(PTSTR)Src++ = EndChr; if (Var == NULL) { - /* In a batch file, %NONEXISTENT% "expands" to an empty string */ + /* In a batch context, %NONEXISTENT% "expands" to an + * empty string, otherwise fail the substitution. */ if (bc) - continue; + goto success; goto bad_subst; } VarLength = _tcslen(Var); @@ -1392,21 +1415,22 @@ SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) if (EndChr == Delim) { /* %VAR% - use as-is */ - APPEND(Var, VarLength) + APPEND(Var, VarLength); } else if (*Src == _T('~')) { /* %VAR:~[start][,length]% - substring - * Negative values are offsets from the end */ - int Start = _tcstol(Src + 1, &Src, 0); - int End = VarLength; + * Negative values are offsets from the end. + */ + size_t Start = _tcstol(Src + 1, (PTSTR*)&Src, 0); + size_t End = VarLength; if (Start < 0) Start += VarLength; Start = max(Start, 0); Start = min(Start, VarLength); if (*Src == _T(',')) { - End = _tcstol(Src + 1, &Src, 0); + End = _tcstol(Src + 1, (PTSTR*)&Src, 0); End += (End < 0) ? VarLength : Start; End = max(End, Start); End = min(End, VarLength); @@ -1417,13 +1441,14 @@ SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) } else { - /* %VAR:old=new% - replace all occurrences of old with new - * %VAR:*old=new% - replace first occurrence only, - * and remove everything before it */ - TCHAR *Old, *New; - DWORD OldLength, NewLength; + /* %VAR:old=new% - Replace all occurrences of old with new. + * %VAR:*old=new% - Replace first occurrence only, + * and remove everything before it. + */ + PCTSTR Old, New; + size_t OldLength, NewLength; BOOL Star = FALSE; - int LastMatch = 0, i = 0; + size_t LastMatch = 0, i = 0; if (*Src == _T('*')) { @@ -1431,7 +1456,7 @@ SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) Src++; } - /* the string to replace may contain the delimiter */ + /* The string to replace may contain the delimiter */ Src = _tcschr(Old = Src, _T('=')); if (Src == NULL) goto bad_subst; @@ -1449,8 +1474,8 @@ SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) if (_tcsnicmp(&Var[i], Old, OldLength) == 0) { if (!Star) - APPEND(&Var[LastMatch], i - LastMatch) - APPEND(New, NewLength) + APPEND(&Var[LastMatch], i - LastMatch); + APPEND(New, NewLength); i += OldLength; LastMatch = i; if (Star) @@ -1459,21 +1484,87 @@ SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim) } i++; } - APPEND(&Var[LastMatch], VarLength - LastMatch) + APPEND(&Var[LastMatch], VarLength - LastMatch); } - continue; + + goto success; bad_subst: Src = SubstStart; + /* Only if no batch context active do we echo the delimiter */ if (!bc) - APPEND1(Delim) + APPEND1(Delim); } - *Dest = _T('\0'); + +success: + *SrcIncLen = (Src - Start); + *DestIncLen = (Dest - End); return TRUE; + too_long: ConOutResPrintf(STRING_ALIAS_ERROR); nErrorLevel = 9023; return FALSE; + +#undef APPEND +#undef APPEND1 +} + +BOOL +SubstituteVars( + IN PCTSTR Src, + OUT PTSTR Dest, + IN TCHAR Delim) +{ +#define APPEND(From, Length) \ +do { \ + if (Dest + (Length) > DestEnd) \ + goto too_long; \ + memcpy(Dest, (From), (Length) * sizeof(TCHAR)); \ + Dest += (Length); \ +} while (0) + +#define APPEND1(Char) \ +do { \ + if (Dest >= DestEnd) \ + goto too_long; \ + *Dest++ = (Char); \ +} while (0) + + PTCHAR DestEnd = Dest + CMDLINE_LENGTH - 1; + PCTSTR End; + size_t SrcIncLen, DestIncLen; + + while (*Src /* && (Dest < DestEnd) */) + { + if (*Src != Delim) + { + End = _tcschr(Src, Delim); + if (End == NULL) + End = Src + _tcslen(Src); + APPEND(Src, End - Src); + Src = End; + continue; + } + + if (!SubstituteVar(Src, &SrcIncLen, Dest, DestEnd, &DestIncLen, Delim)) + { + return FALSE; + } + else + { + Src += SrcIncLen; + Dest += DestIncLen; + } + } + APPEND1(_T('\0')); + return TRUE; + +too_long: + ConOutResPrintf(STRING_ALIAS_ERROR); + nErrorLevel = 9023; + return FALSE; + #undef APPEND #undef APPEND1 } @@ -1545,11 +1636,15 @@ SubstituteForVars( return TRUE; } -LPTSTR -DoDelayedExpansion(LPTSTR Line) +PTSTR +DoDelayedExpansion( + IN PCTSTR Line) { TCHAR Buf1[CMDLINE_LENGTH]; TCHAR Buf2[CMDLINE_LENGTH]; + PTCHAR Src, Dst; + PTCHAR DestEnd = Buf2 + CMDLINE_LENGTH - 1; + size_t SrcIncLen, DestIncLen; /* First, substitute FOR variables */ if (!SubstituteForVars(Line, Buf1)) @@ -1558,12 +1653,64 @@ DoDelayedExpansion(LPTSTR Line) if (!bDelayedExpansion || !_tcschr(Buf1, _T('!'))) return cmd_dup(Buf1); - /* FIXME: Delayed substitutions actually aren't quite the same as - * immediate substitutions. In particular, it's possible to escape - * the exclamation point using ^. */ - if (!SubstituteVars(Buf1, Buf2, _T('!'))) - return NULL; + /* + * Delayed substitutions are not actually completely the same as + * immediate substitutions. In particular, it is possible to escape + * the exclamation point using the escape caret. + */ + + /* + * Perform delayed expansion: expand variables around '!', + * and reparse escape carets. + */ + +#define APPEND1(Char) \ +do { \ + if (Dst >= DestEnd) \ + goto too_long; \ + *Dst++ = (Char); \ +} while (0) + + Src = Buf1; + Dst = Buf2; + while (*Src && (Src < &Buf1[CMDLINE_LENGTH])) + { + if (*Src == _T('^')) + { + ++Src; + if (!*Src || !(Src < &Buf1[CMDLINE_LENGTH])) + break; + + APPEND1(*Src++); + } + else if (*Src == _T('!')) + { + if (!SubstituteVar(Src, &SrcIncLen, Dst, DestEnd, &DestIncLen, _T('!'))) + { + return NULL; // Got an error during parsing. + } + else + { + Src += SrcIncLen; + Dst += DestIncLen; + } + } + else + { + APPEND1(*Src++); + } + continue; + } + APPEND1(_T('\0')); + return cmd_dup(Buf2); + +too_long: + ConOutResPrintf(STRING_ALIAS_ERROR); + nErrorLevel = 9023; + return NULL; + +#undef APPEND1 } diff --git a/base/shell/cmd/cmd.h b/base/shell/cmd/cmd.h index ac2d7fddd8c..93fefe4f4c6 100644 --- a/base/shell/cmd/cmd.h +++ b/base/shell/cmd/cmd.h @@ -95,14 +95,31 @@ ExecuteCommandWithEcho( LPCTSTR GetEnvVarOrSpecial ( LPCTSTR varName ); VOID AddBreakHandler (VOID); VOID RemoveBreakHandler (VOID); -BOOL SubstituteVars(TCHAR *Src, TCHAR *Dest, TCHAR Delim); + +BOOL +SubstituteVar( + IN PCTSTR Src, + OUT size_t* SrcIncLen, // VarNameLen + OUT PTCHAR Dest, + IN PTCHAR DestEnd, + OUT size_t* DestIncLen, + IN TCHAR Delim); + +BOOL +SubstituteVars( + IN PCTSTR Src, + OUT PTSTR Dest, + IN TCHAR Delim); BOOL SubstituteForVars( IN PCTSTR Src, OUT PTSTR Dest); -LPTSTR DoDelayedExpansion(LPTSTR Line); +PTSTR +DoDelayedExpansion( + IN PCTSTR Line); + INT DoCommand(LPTSTR first, LPTSTR rest, struct _PARSED_COMMAND *Cmd); BOOL ReadLine(TCHAR *commandline, BOOL bMore);
