Spanify FX_strstr() and FX_wcsstr()
Avoid having to document UNSAFE_BUFFER() usage.
Bug: pdfium:1706
Change-Id: If8de5a5bda22e4e4d5d5572e56861db4b00df9fe
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/116250
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Thomas Sepez <tsepez@google.com>
diff --git a/core/fxcrt/bytestring.cpp b/core/fxcrt/bytestring.cpp
index 534740a..41d46e2 100644
--- a/core/fxcrt/bytestring.cpp
+++ b/core/fxcrt/bytestring.cpp
@@ -19,6 +19,7 @@
#include "core/fxcrt/fx_memcpy_wrappers.h"
#include "core/fxcrt/fx_safe_types.h"
#include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span_util.h"
#include "core/fxcrt/string_pool_template.h"
#include "third_party/base/check.h"
#include "third_party/base/check_op.h"
@@ -33,27 +34,21 @@
constexpr char kTrimChars[] = "\x09\x0a\x0b\x0c\x0d\x20";
-const char* FX_strstr(const char* haystack,
- size_t haystack_len,
- const char* needle,
- size_t needle_len) {
- if (needle_len > haystack_len || needle_len == 0)
- return nullptr;
-
- const char* end_ptr = haystack + haystack_len - needle_len;
- while (haystack <= end_ptr) {
- size_t i = 0;
- while (true) {
- if (haystack[i] != needle[i])
- break;
-
- i++;
- if (i == needle_len)
- return haystack;
- }
- haystack++;
+absl::optional<size_t> FX_strpos(pdfium::span<const char> haystack,
+ pdfium::span<const char> needle) {
+ if (needle.empty() || needle.size() > haystack.size()) {
+ return absl::nullopt;
}
- return nullptr;
+ // After `end_pos`, not enough characters remain in `haystack` for
+ // a full match to occur.
+ size_t end_pos = haystack.size() - needle.size();
+ for (size_t haystack_pos = 0; haystack_pos <= end_pos; ++haystack_pos) {
+ auto candidate = haystack.subspan(haystack_pos, needle.size());
+ if (fxcrt::span_equals(candidate, needle)) {
+ return haystack_pos;
+ }
+ }
+ return absl::nullopt;
}
} // namespace
@@ -558,18 +553,18 @@
absl::optional<size_t> ByteString::Find(ByteStringView subStr,
size_t start) const {
- if (!m_pData)
+ if (!m_pData) {
return absl::nullopt;
-
- if (!IsValidIndex(start))
+ }
+ if (!IsValidIndex(start)) {
return absl::nullopt;
-
- const char* pStr =
- FX_strstr(m_pData->m_String + start, m_pData->m_nDataLength - start,
- subStr.unterminated_c_str(), subStr.GetLength());
- return pStr ? absl::optional<size_t>(
- static_cast<size_t>(pStr - m_pData->m_String))
- : absl::nullopt;
+ }
+ absl::optional<size_t> result =
+ FX_strpos(m_pData->span().subspan(start), subStr.span());
+ if (!result.has_value()) {
+ return absl::nullopt;
+ }
+ return start + result.value();
}
absl::optional<size_t> ByteString::ReverseFind(char ch) const {
@@ -638,25 +633,24 @@
if (!m_pData || pOld.IsEmpty())
return 0;
- size_t nSourceLen = pOld.GetLength();
- size_t nReplacementLen = pNew.GetLength();
size_t nCount = 0;
- const char* pStart = m_pData->m_String;
- char* pEnd = m_pData->m_String + m_pData->m_nDataLength;
- while (true) {
- const char* pTarget = FX_strstr(pStart, static_cast<int>(pEnd - pStart),
- pOld.unterminated_c_str(), nSourceLen);
- if (!pTarget)
- break;
-
- nCount++;
- pStart = pTarget + nSourceLen;
+ {
+ // Limit span lifetime.
+ pdfium::span<char> search_span = m_pData->span();
+ while (true) {
+ absl::optional<size_t> found = FX_strpos(search_span, pOld.span());
+ if (!found.has_value()) {
+ break;
+ }
+ nCount++;
+ search_span = search_span.subspan(found.value() + pOld.GetLength());
+ }
}
if (nCount == 0)
return 0;
size_t nNewLength =
- m_pData->m_nDataLength + (nReplacementLen - nSourceLen) * nCount;
+ m_pData->m_nDataLength + nCount * (pNew.GetLength() - pOld.GetLength());
if (nNewLength == 0) {
clear();
@@ -664,19 +658,20 @@
}
RetainPtr<StringData> pNewData(StringData::Create(nNewLength));
- pStart = m_pData->m_String;
- char* pDest = pNewData->m_String;
- for (size_t i = 0; i < nCount; i++) {
- const char* pTarget = FX_strstr(pStart, static_cast<int>(pEnd - pStart),
- pOld.unterminated_c_str(), nSourceLen);
- FXSYS_memcpy(pDest, pStart, pTarget - pStart);
- pDest += pTarget - pStart;
- FXSYS_memcpy(pDest, pNew.unterminated_c_str(), pNew.GetLength());
- pDest += pNew.GetLength();
- pStart = pTarget + nSourceLen;
+ {
+ // Spans can't outlive the StringData buffers.
+ pdfium::span<const char> search_span = m_pData->span();
+ pdfium::span<char> dest_span = pNewData->span();
+ for (size_t i = 0; i < nCount; i++) {
+ size_t found = FX_strpos(search_span, pOld.span()).value();
+ dest_span = fxcrt::spancpy(dest_span, search_span.first(found));
+ dest_span = fxcrt::spancpy(dest_span, pNew.span());
+ search_span = search_span.subspan(found + pOld.GetLength());
+ }
+ dest_span = fxcrt::spancpy(dest_span, search_span);
+ CHECK(dest_span.empty());
}
- FXSYS_memcpy(pDest, pStart, pEnd - pStart);
- m_pData.Swap(pNewData);
+ m_pData = std::move(pNewData);
return nCount;
}
diff --git a/core/fxcrt/string_data_template.h b/core/fxcrt/string_data_template.h
index bc5cac6..fcbe81c 100644
--- a/core/fxcrt/string_data_template.h
+++ b/core/fxcrt/string_data_template.h
@@ -10,6 +10,8 @@
#include <stddef.h>
#include <stdint.h>
+#include "third_party/base/containers/span.h"
+
namespace fxcrt {
template <typename CharType>
@@ -29,6 +31,13 @@
void CopyContents(const CharType* pStr, size_t nLen);
void CopyContentsAt(size_t offset, const CharType* pStr, size_t nLen);
+ pdfium::span<CharType> span() {
+ return pdfium::make_span(m_String, m_nDataLength);
+ }
+ pdfium::span<const CharType> span() const {
+ return pdfium::make_span(m_String, m_nDataLength);
+ }
+
// To ensure ref counts do not overflow, consider the worst possible case:
// the entire address space contains nothing but pointers to this object.
// Since the count increments with each new pointer, the largest value is
diff --git a/core/fxcrt/widestring.cpp b/core/fxcrt/widestring.cpp
index f346e38..82358ef 100644
--- a/core/fxcrt/widestring.cpp
+++ b/core/fxcrt/widestring.cpp
@@ -17,6 +17,7 @@
#include "core/fxcrt/fx_memcpy_wrappers.h"
#include "core/fxcrt/fx_safe_types.h"
#include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span_util.h"
#include "core/fxcrt/string_pool_template.h"
#include "core/fxcrt/utf16.h"
#include "third_party/base/check.h"
@@ -53,27 +54,21 @@
constexpr wchar_t kWideTrimChars[] = L"\x09\x0a\x0b\x0c\x0d\x20";
-const wchar_t* FX_wcsstr(const wchar_t* haystack,
- size_t haystack_len,
- const wchar_t* needle,
- size_t needle_len) {
- if (needle_len > haystack_len || needle_len == 0)
- return nullptr;
-
- const wchar_t* end_ptr = haystack + haystack_len - needle_len;
- while (haystack <= end_ptr) {
- size_t i = 0;
- while (true) {
- if (haystack[i] != needle[i])
- break;
-
- i++;
- if (i == needle_len)
- return haystack;
- }
- haystack++;
+absl::optional<size_t> FX_wcspos(pdfium::span<const wchar_t> haystack,
+ pdfium::span<const wchar_t> needle) {
+ if (needle.empty() || needle.size() > haystack.size()) {
+ return absl::nullopt;
}
- return nullptr;
+ // After this `end_pos`, not enough characters remain in `haystack` for
+ // a full match to occur.
+ size_t end_pos = haystack.size() - needle.size();
+ for (size_t haystack_pos = 0; haystack_pos <= end_pos; ++haystack_pos) {
+ auto candidate = haystack.subspan(haystack_pos, needle.size());
+ if (fxcrt::span_equals(candidate, needle)) {
+ return haystack_pos;
+ }
+ }
+ return absl::nullopt;
}
absl::optional<size_t> GuessSizeForVSWPrintf(const wchar_t* pFormat,
@@ -871,18 +866,18 @@
absl::optional<size_t> WideString::Find(WideStringView subStr,
size_t start) const {
- if (!m_pData)
+ if (!m_pData) {
return absl::nullopt;
-
- if (!IsValidIndex(start))
+ }
+ if (!IsValidIndex(start)) {
return absl::nullopt;
-
- const wchar_t* pStr =
- FX_wcsstr(m_pData->m_String + start, m_pData->m_nDataLength - start,
- subStr.unterminated_c_str(), subStr.GetLength());
- return pStr ? absl::optional<size_t>(
- static_cast<size_t>(pStr - m_pData->m_String))
- : absl::nullopt;
+ }
+ absl::optional<size_t> result =
+ FX_wcspos(m_pData->span().subspan(start), subStr.span());
+ if (!result.has_value()) {
+ return absl::nullopt;
+ }
+ return start + result.value();
}
absl::optional<size_t> WideString::ReverseFind(wchar_t ch) const {
@@ -951,26 +946,24 @@
if (!m_pData || pOld.IsEmpty())
return 0;
- size_t nSourceLen = pOld.GetLength();
- size_t nReplacementLen = pNew.GetLength();
size_t count = 0;
- const wchar_t* pStart = m_pData->m_String;
- wchar_t* pEnd = m_pData->m_String + m_pData->m_nDataLength;
- while (true) {
- const wchar_t* pTarget =
- FX_wcsstr(pStart, static_cast<size_t>(pEnd - pStart),
- pOld.unterminated_c_str(), nSourceLen);
- if (!pTarget)
- break;
-
- count++;
- pStart = pTarget + nSourceLen;
+ {
+ // Limit span lifetime.
+ pdfium::span<const wchar_t> search_span = m_pData->span();
+ while (true) {
+ absl::optional<size_t> found = FX_wcspos(search_span, pOld.span());
+ if (!found.has_value()) {
+ break;
+ }
+ ++count;
+ search_span = search_span.subspan(found.value() + pOld.GetLength());
+ }
}
if (count == 0)
return 0;
size_t nNewLength =
- m_pData->m_nDataLength + (nReplacementLen - nSourceLen) * count;
+ m_pData->m_nDataLength + count * (pNew.GetLength() - pOld.GetLength());
if (nNewLength == 0) {
clear();
@@ -978,20 +971,20 @@
}
RetainPtr<StringData> pNewData(StringData::Create(nNewLength));
- pStart = m_pData->m_String;
- wchar_t* pDest = pNewData->m_String;
- for (size_t i = 0; i < count; i++) {
- const wchar_t* pTarget =
- FX_wcsstr(pStart, static_cast<size_t>(pEnd - pStart),
- pOld.unterminated_c_str(), nSourceLen);
- FXSYS_wmemcpy(pDest, pStart, pTarget - pStart);
- pDest += pTarget - pStart;
- FXSYS_wmemcpy(pDest, pNew.unterminated_c_str(), pNew.GetLength());
- pDest += pNew.GetLength();
- pStart = pTarget + nSourceLen;
+ {
+ // Spans can't outlive StrinData buffers.
+ pdfium::span<const wchar_t> search_span = m_pData->span();
+ pdfium::span<wchar_t> dest_span = pNewData->span();
+ for (size_t i = 0; i < count; i++) {
+ size_t found = FX_wcspos(search_span, pOld.span()).value();
+ dest_span = fxcrt::spancpy(dest_span, search_span.first(found));
+ dest_span = fxcrt::spancpy(dest_span, pNew.span());
+ search_span = search_span.subspan(found + pOld.GetLength());
+ }
+ dest_span = fxcrt::spancpy(dest_span, search_span);
+ CHECK(dest_span.empty());
}
- FXSYS_wmemcpy(pDest, pStart, pEnd - pStart);
- m_pData.Swap(pNewData);
+ m_pData = std::move(pNewData);
return count;
}
