[clang] 1fae591 - [clang-format] Fix an off-by-1 bug with -length option (#143302)

[via cfe-commits]

Author: Owen Pan
Date: 2025-06-13T00:45:52-07:00
New Revision: 1fae5918b3d6fbed8ce6d8a2edf31bdf304ca8db

URL: https://github.com/llvm/llvm-project/commit/1fae5918b3d6fbed8ce6d8a2edf31bdf304ca8db
DIFF: https://github.com/llvm/llvm-project/commit/1fae5918b3d6fbed8ce6d8a2edf31bdf304ca8db.diff

LOG: [clang-format] Fix an off-by-1 bug with -length option (#143302)

Also validate the argument value.

Fixes #56245

Added: 
    

Modified: 
    clang/test/Format/multiple-inputs-error.cpp
    clang/test/Format/ranges.cpp
    clang/tools/clang-format/ClangFormat.cpp

Removed: 
    


################################################################################
diff  --git a/clang/test/Format/multiple-inputs-error.cpp b/clang/test/Format/multiple-inputs-error.cpp
index 1aa9c9f3e2fad..7cb835d39f23e 100644
--- a/clang/test/Format/multiple-inputs-error.cpp
+++ b/clang/test/Format/multiple-inputs-error.cpp
@@ -1,6 +1,6 @@
 // RUN: cp %s %t-1.cpp
 // RUN: cp %s %t-2.cpp
-// RUN: not clang-format 2>&1 >/dev/null -offset=1 -length=0 %t-1.cpp %t-2.cpp |FileCheck %s
+// RUN: not clang-format 2>&1 >/dev/null -offset=1 -length=1 %t-1.cpp %t-2.cpp |FileCheck %s
 // RUN: not clang-format 2>&1 >/dev/null -lines=1:1 %t-1.cpp %t-2.cpp |FileCheck %s -check-prefix=CHECK-LINE
 // CHECK: error: -offset, -length and -lines can only be used for single file.
 // CHECK-LINE: error: -offset, -length and -lines can only be used for single file.

diff  --git a/clang/test/Format/ranges.cpp b/clang/test/Format/ranges.cpp
index 66b984e037b3c..f42492e43f84b 100644
--- a/clang/test/Format/ranges.cpp
+++ b/clang/test/Format/ranges.cpp
@@ -1,5 +1,5 @@
 // RUN: grep -Ev "// *[A-Z-]+:" %s \
-// RUN:   | clang-format -style=LLVM -offset=2 -length=0 -offset=28 -length=0 \
+// RUN:   | clang-format -style=LLVM -offset=2 -length=1 -offset=28 -length=1 -offset=35 -length=8 \
 // RUN:   | FileCheck -strict-whitespace %s
 // CHECK: {{^int\ \*i;$}}
 int*i;
@@ -9,3 +9,12 @@ int  *  i;
 
 // CHECK: {{^int\ \*i;$}}
 int   *   i;
+
+// CHECK: int I;
+// CHECK-NEXT: int J ;
+int I ;
+int J ;
+
+// RUN: not clang-format -length=0 %s 2>&1 \
+// RUN:   | FileCheck -strict-whitespace -check-prefix=CHECK0 %s
+// CHECK0: error: length should be at least 1

diff  --git a/clang/tools/clang-format/ClangFormat.cpp b/clang/tools/clang-format/ClangFormat.cpp
index 24ad3cb42254d..c0efbb7588ccb 100644
--- a/clang/tools/clang-format/ClangFormat.cpp
+++ b/clang/tools/clang-format/ClangFormat.cpp
@@ -284,7 +284,7 @@ static bool fillRanges(MemoryBuffer *Code,
   if (Offsets.size() == 1 && EmptyLengths) {
     Length = Sources.getFileOffset(Sources.getLocForEndOfFile(ID)) - Offsets[0];
   } else if (Offsets.size() != Lengths.size()) {
-    errs() << "error: number of -offset and -length arguments must match.\n";
+    errs() << "error: number of -offset and -length arguments must match\n";
     return true;
   }
   for (unsigned I = 0, E = Offsets.size(), CodeSize = Code->getBufferSize();
@@ -296,12 +296,16 @@ static bool fillRanges(MemoryBuffer *Code,
     }
     if (!EmptyLengths)
       Length = Lengths[I];
+    if (Length == 0) {
+      errs() << "error: length should be at least 1\n";
+      return true;
+    }
     if (Offset + Length > CodeSize) {
       errs() << "error: invalid length " << Length << ", offset + length ("
-             << Offset + Length << ") is outside the file.\n";
+             << Offset + Length << ") is outside the file\n";
       return true;
     }
-    Ranges.push_back(tooling::Range(Offset, Length));
+    Ranges.push_back(tooling::Range(Offset, Length - 1));
   }
   return false;
 }