Provided a variant of ReadCStringFromMemory that supports null terminators of any character width.
This prevents unbounded reads (i.e. reads of GetMaximumSizeOfStringSummary() bytes)
from causing test failures (i.e. due to ptrace EIO or EFAULT on Linux).
Note that ReadCStringFromMemory is marked as deprecated because the loop that calls
ReadMemory does not continue until the string has been completely read.
The expected behavior is to read until until max_bytes or a null terminator.
Note: As discussed on lldb-dev, further testing will be performed with ReadStringFromMemory
before further changes are made for users of ReadCStringFromMemory.
Thanks to Enrico, Matt and Andy for their review feedback.
git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@179857 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Target/Process.cpp b/source/Target/Process.cpp
index 3fe92a3..b9abee6 100644
--- a/source/Target/Process.cpp
+++ b/source/Target/Process.cpp
@@ -2357,6 +2357,60 @@
size_t
+Process::ReadStringFromMemory (addr_t addr, char *dst, size_t max_bytes, Error &error,
+ size_t type_width)
+{
+ size_t total_bytes_read = 0;
+ if (dst && max_bytes && type_width && max_bytes >= type_width)
+ {
+ // Ensure a null terminator independent of the number of bytes that is read.
+ memset (dst, 0, max_bytes);
+ size_t bytes_left = max_bytes - type_width;
+
+ const char terminator[4] = {'\0', '\0', '\0', '\0'};
+ assert(sizeof(terminator) >= type_width &&
+ "Attempting to validate a string with more than 4 bytes per character!");
+
+ addr_t curr_addr = addr;
+ const size_t cache_line_size = m_memory_cache.GetMemoryCacheLineSize();
+ char *curr_dst = dst;
+
+ error.Clear();
+ while (bytes_left > 0 && error.Success())
+ {
+ addr_t cache_line_bytes_left = cache_line_size - (curr_addr % cache_line_size);
+ addr_t bytes_to_read = std::min<addr_t>(bytes_left, cache_line_bytes_left);
+ size_t bytes_read = ReadMemory (curr_addr, curr_dst, bytes_to_read, error);
+
+ if (bytes_read == 0)
+ break;
+
+ // Search for a null terminator of correct size and alignment in bytes_read
+ size_t aligned_start = total_bytes_read - total_bytes_read % type_width;
+ for (size_t i = aligned_start; i + type_width <= total_bytes_read + bytes_read; i += type_width)
+ if (::strncmp(&dst[i], terminator, type_width) == 0)
+ {
+ error.Clear();
+ return i;
+ }
+
+ total_bytes_read += bytes_read;
+ curr_dst += bytes_read;
+ curr_addr += bytes_read;
+ bytes_left -= bytes_read;
+ }
+ }
+ else
+ {
+ if (max_bytes)
+ error.SetErrorString("invalid arguments");
+ }
+ return total_bytes_read;
+}
+
+// Deprecated in favor of ReadStringFromMemory which has wchar support and correct code to find
+// null terminators.
+size_t
Process::ReadCStringFromMemory (addr_t addr, char *dst, size_t dst_max_len, Error &result_error)
{
size_t total_cstr_len = 0;