sanitizer_common: bump default file max size to 256MB

[dvyukov]

Summary

I am hitting some cases where /proc/self/maps does not fit into 64MB.
256MB is lots of memory, but it's not radically more than the current 64MB.
Ideally we should read/parse these huge files incrementally,
but that's lots of work for a debugging/introspection interface.
So for now just bump the limit.

Depends on D112793.

[melver]

compiler-rt/lib/sanitizer_common/sanitizer_common.h

724

Is 64MB more likely to be exceeded on 64-bit systems?

If so, maybe make the size conditional on bit-ness of the system? Because 64 vs 256 MB might be a lot for some 32-bit system.

[dvyukov]

use smaller limit for 32-bit arches

compiler-rt/lib/sanitizer_common/sanitizer_common.h

if (comp(v[last], v[i])) {
         v[last] = v[i];
     } else {
       CHECK(!comp(v[i], v[last]));
     }
   }
   v.resize(last + 1);
 }
 
+constexpr uptr kDefaultFileMaxSize = FIRST_32_SECOND_64(1 << 26, 1 << 28);
+
 // Opens the file 'file_name" and reads up to 'max_len' bytes.
 // The resulting buffer is mmaped and stored in '*buff'.
 // Returns true if file was successfully opened and read.
 bool ReadFileToVector(const char *file_name,
                       InternalMmapVectorNoCtor<char> *buff,
-                      uptr max_len = 1 << 26, error_t *errno_p = nullptr);
+                      uptr max_len = kDefaultFileMaxSize,
+                      error_t *errno_p = nullptr);
 
 // Opens the file 'file_name" and reads up to 'max_len' bytes.
 // This function is less I/O efficient than ReadFileToVector as it may reread
 // file multiple times to avoid mmap during read attempts. It's used to read
 // procmap, so short reads with mmap in between can produce inconsistent result.
 // The resulting buffer is mmaped and stored in '*buff'.
 // The size of the mmaped region is stored in '*buff_size'.
 // The total number of read bytes is stored in '*read_len'.
 // Returns true if file was successfully opened and read.
 bool ReadFileToBuffer(const char *file_name, char **buff, uptr *buff_size,
-                      uptr *read_len, uptr max_len = 1 << 26,
+                      uptr *read_len, uptr max_len = kDefaultFileMaxSize,
                       error_t *errno_p = nullptr);
 
 // When adding a new architecture, don't forget to also update
 // script/asan_symbolize.py and sanitizer_symbolizer_libcdep.cpp.
 inline const char *ModuleArchToString(ModuleArch arch) {
   switch (arch) {
     case kModuleArchUnknown:
       return "";