From e597ffa521de978642946160fa5cf05a16d83b7e Mon Sep 17 00:00:00 2001 From: Oleg Ranevskyy Date: Tue, 5 Jan 2016 19:56:12 +0000 Subject: [PATCH] [Clang/Support/Windows/Unix] Command lines created by clang may exceed the command length limit set by the OS Summary: Hi Rafael, Would you be able to review this patch, please? (Clang part of the patch is D15832). When clang runs an external tool, e.g. a linker, it may create a command line that exceeds the length limit. Clang uses the llvm::sys::argumentsFitWithinSystemLimits function to check if command line length fits the OS limitation. There are two problems in this function that may cause exceeding of the limit: 1. It ignores the length of the program path in its calculations. On the other hand, clang adds the program path to the command line when it runs the program. 2. It assumes no space character is inserted after the last argument, which is not true for Windows. The flattenArgs function adds the trailing space for *each* argument. The result of this is that the terminating NULL character is not counted and may be placed beyond the length limit if the command line is exactly 32768 characters long. The WinAPI's CreateProcess does not find the NULL character and fails. Reviewers: rafael, ygao, probinson Subscribers: asl, llvm-commits Differential Revision: http://reviews.llvm.org/D15831 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256866 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/Program.h | 2 +- lib/Support/Unix/Program.inc | 4 ++-- lib/Support/Windows/Program.inc | 9 +++++---- 3 files changed, 8 insertions(+), 7 deletions(-) diff --git a/include/llvm/Support/Program.h b/include/llvm/Support/Program.h index 43302101e3e..727864df272 100644 --- a/include/llvm/Support/Program.h +++ b/include/llvm/Support/Program.h @@ -130,7 +130,7 @@ struct ProcessInfo { /// Return true if the given arguments fit within system-specific /// argument length limits. - bool argumentsFitWithinSystemLimits(ArrayRef Args); + bool commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef Args); /// File encoding options when writing contents that a non-UTF8 tool will /// read (on Windows systems). For UNIX, we always use UTF-8. diff --git a/lib/Support/Unix/Program.inc b/lib/Support/Unix/Program.inc index a8d1fe3c07d..7d3537e2072 100644 --- a/lib/Support/Unix/Program.inc +++ b/lib/Support/Unix/Program.inc @@ -446,7 +446,7 @@ llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents, return EC; } -bool llvm::sys::argumentsFitWithinSystemLimits(ArrayRef Args) { +bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef Args) { static long ArgMax = sysconf(_SC_ARG_MAX); // System says no practical limit. @@ -456,7 +456,7 @@ bool llvm::sys::argumentsFitWithinSystemLimits(ArrayRef Args) { // Conservatively account for space required by environment variables. long HalfArgMax = ArgMax / 2; - size_t ArgLength = 0; + size_t ArgLength = Program.size() + 1; for (ArrayRef::iterator I = Args.begin(), E = Args.end(); I != E; ++I) { ArgLength += strlen(*I) + 1; diff --git a/lib/Support/Windows/Program.inc b/lib/Support/Windows/Program.inc index d4e14ddc651..78fc538bd9b 100644 --- a/lib/Support/Windows/Program.inc +++ b/lib/Support/Windows/Program.inc @@ -535,14 +535,15 @@ llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents, return EC; } -bool llvm::sys::argumentsFitWithinSystemLimits(ArrayRef Args) { +bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef Args) { // The documented max length of the command line passed to CreateProcess. static const size_t MaxCommandStringLength = 32768; - size_t ArgLength = 0; + // Account for the trailing space for the program path and the + // trailing NULL of the last argument. + size_t ArgLength = ArgLenWithQuotes(Program.str().c_str()) + 2; for (ArrayRef::iterator I = Args.begin(), E = Args.end(); I != E; ++I) { - // Account for the trailing space for every arg but the last one and the - // trailing NULL of the last argument. + // Account for the trailing space for every arg ArgLength += ArgLenWithQuotes(*I) + 1; if (ArgLength > MaxCommandStringLength) { return false; -- 2.34.1