Avoid guessing vsnprintf() buffer length.

This pattern is widely used in chrome.

Change-Id: I64229b2ce298bf78773fe47c68d19be59411a76a
Reviewed-on: https://pdfium-review.googlesource.com/3293
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

2 files changed, 9 insertions, 208 deletions

diff --git a/core/fxcrt/fx_basic_bstring.cpp b/core/fxcrt/fx_basic_bstring.cpp
index a4e491f4d3..f0052b6968 100644
--- a/core/fxcrt/fx_basic_bstring.cpp
+++ b/core/fxcrt/fx_basic_bstring.cpp
@@ -449,203 +449,16 @@ void CFX_ByteString::FormatV(const char* pFormat, va_list argList) {
 #else
   argListSave = argList;
 #endif
-  int nMaxLen = 0;
-  for (const char* pStr = pFormat; *pStr != 0; pStr++) {
-    if (*pStr != '%' || *(pStr = pStr + 1) == '%') {
-      nMaxLen += FXSYS_strlen(pStr);
-      continue;
+  FX_STRSIZE nMaxLen = vsnprintf(nullptr, 0, pFormat, argList);
+  if (nMaxLen > 0) {
+    GetBuffer(nMaxLen);
+    if (m_pData) {
+      // In the following two calls, there's always space in the buffer for
+      // a terminating NUL that's not included in nMaxLen.
+      memset(m_pData->m_String, 0, nMaxLen + 1);
+      vsnprintf(m_pData->m_String, nMaxLen + 1, pFormat, argListSave);
+      ReleaseBuffer();
     }
-    int nItemLen = 0;
-    int nWidth = 0;
-    for (; *pStr != 0; pStr++) {
-      if (*pStr == '#') {
-        nMaxLen += 2;
-      } else if (*pStr == '*') {
-        nWidth = va_arg(argList, int);
-      } else if (*pStr != '-' && *pStr != '+' && *pStr != '0' && *pStr != ' ') {
-        break;
-      }
-    }
-    if (nWidth == 0) {
-      nWidth = FXSYS_atoi(pStr);
-      while (std::isdigit(*pStr))
-        pStr++;
-    }
-    if (nWidth < 0 || nWidth > 128 * 1024) {
-      pFormat = "Bad width";
-      nMaxLen = 10;
-      break;
-    }
-    int nPrecision = 0;
-    if (*pStr == '.') {
-      pStr++;
-      if (*pStr == '*') {
-        nPrecision = va_arg(argList, int);
-        pStr++;
-      } else {
-        nPrecision = FXSYS_atoi(pStr);
-        while (std::isdigit(*pStr))
-          pStr++;
-      }
-    }
-    if (nPrecision < 0 || nPrecision > 128 * 1024) {
-      pFormat = "Bad precision";
-      nMaxLen = 14;
-      break;
-    }
-    int nModifier = 0;
-    if (FXSYS_strncmp(pStr, "I64", 3) == 0) {
-      pStr += 3;
-      nModifier = FORCE_INT64;
-    } else {
-      switch (*pStr) {
-        case 'h':
-          nModifier = FORCE_ANSI;
-          pStr++;
-          break;
-        case 'l':
-          nModifier = FORCE_UNICODE;
-          pStr++;
-          break;
-        case 'F':
-        case 'N':
-        case 'L':
-          pStr++;
-          break;
-      }
-    }
-    switch (*pStr | nModifier) {
-      case 'c':
-      case 'C':
-        nItemLen = 2;
-        va_arg(argList, int);
-        break;
-      case 'c' | FORCE_ANSI:
-      case 'C' | FORCE_ANSI:
-        nItemLen = 2;
-        va_arg(argList, int);
-        break;
-      case 'c' | FORCE_UNICODE:
-      case 'C' | FORCE_UNICODE:
-        nItemLen = 2;
-        va_arg(argList, int);
-        break;
-      case 's': {
-        const char* pstrNextArg = va_arg(argList, const char*);
-        if (pstrNextArg) {
-          nItemLen = FXSYS_strlen(pstrNextArg);
-          if (nItemLen < 1) {
-            nItemLen = 1;
-          }
-        } else {
-          nItemLen = 6;
-        }
-      } break;
-      case 'S': {
-        wchar_t* pstrNextArg = va_arg(argList, wchar_t*);
-        if (pstrNextArg) {
-          nItemLen = FXSYS_wcslen(pstrNextArg);
-          if (nItemLen < 1) {
-            nItemLen = 1;
-          }
-        } else {
-          nItemLen = 6;
-        }
-      } break;
-      case 's' | FORCE_ANSI:
-      case 'S' | FORCE_ANSI: {
-        const char* pstrNextArg = va_arg(argList, const char*);
-        if (pstrNextArg) {
-          nItemLen = FXSYS_strlen(pstrNextArg);
-          if (nItemLen < 1) {
-            nItemLen = 1;
-          }
-        } else {
-          nItemLen = 6;
-        }
-      } break;
-      case 's' | FORCE_UNICODE:
-      case 'S' | FORCE_UNICODE: {
-        wchar_t* pstrNextArg = va_arg(argList, wchar_t*);
-        if (pstrNextArg) {
-          nItemLen = FXSYS_wcslen(pstrNextArg);
-          if (nItemLen < 1) {
-            nItemLen = 1;
-          }
-        } else {
-          nItemLen = 6;
-        }
-      } break;
-    }
-    if (nItemLen != 0) {
-      if (nPrecision != 0 && nItemLen > nPrecision) {
-        nItemLen = nPrecision;
-      }
-      if (nItemLen < nWidth) {
-        nItemLen = nWidth;
-      }
-    } else {
-      switch (*pStr) {
-        case 'd':
-        case 'i':
-        case 'u':
-        case 'x':
-        case 'X':
-        case 'o':
-          if (nModifier & FORCE_INT64) {
-            va_arg(argList, int64_t);
-          } else {
-            va_arg(argList, int);
-          }
-          nItemLen = 32;
-          if (nItemLen < nWidth + nPrecision) {
-            nItemLen = nWidth + nPrecision;
-          }
-          break;
-        case 'a':
-        case 'A':
-        case 'e':
-        case 'E':
-        case 'g':
-        case 'G':
-          va_arg(argList, double);
-          nItemLen = 128;
-          if (nItemLen < nWidth + nPrecision) {
-            nItemLen = nWidth + nPrecision;
-          }
-          break;
-        case 'f':
-          if (nWidth + nPrecision > 100) {
-            nItemLen = nPrecision + nWidth + 128;
-          } else {
-            char pszTemp[256];
-            double f = va_arg(argList, double);
-            memset(pszTemp, 0, sizeof(pszTemp));
-            FXSYS_snprintf(pszTemp, sizeof(pszTemp) - 1, "%*.*f", nWidth,
-                           nPrecision + 6, f);
-            nItemLen = FXSYS_strlen(pszTemp);
-          }
-          break;
-        case 'p':
-          va_arg(argList, void*);
-          nItemLen = 32;
-          if (nItemLen < nWidth + nPrecision) {
-            nItemLen = nWidth + nPrecision;
-          }
-          break;
-        case 'n':
-          va_arg(argList, int*);
-          break;
-      }
-    }
-    nMaxLen += nItemLen;
-  }
-  nMaxLen += 32;  // Fudge factor.
-  GetBuffer(nMaxLen);
-  if (m_pData) {
-    memset(m_pData->m_String, 0, nMaxLen);
-    FXSYS_vsnprintf(m_pData->m_String, nMaxLen - 1, pFormat, argListSave);
-    ReleaseBuffer();
   }
   va_end(argListSave);
 }
diff --git a/core/fxcrt/fx_basic_bstring_unittest.cpp b/core/fxcrt/fx_basic_bstring_unittest.cpp
index a58169d039..e234989bf0 100644
--- a/core/fxcrt/fx_basic_bstring_unittest.cpp
+++ b/core/fxcrt/fx_basic_bstring_unittest.cpp
@@ -1047,12 +1047,6 @@ TEST(fxcrt, ByteStringFormatWidth) {
     str.Format("%0d", 1);
     EXPECT_EQ("1", str);
   }
-
-  {
-    CFX_ByteString str;
-    str.Format("%1048576d", 1);
-    EXPECT_EQ("Bad width", str);
-  }
 }
 
 TEST(fxcrt, ByteStringFormatPrecision) {
@@ -1085,12 +1079,6 @@ TEST(fxcrt, ByteStringFormatPrecision) {
     str.Format("%0f", 1.12345);
     EXPECT_EQ("1.123450", str);
   }
-
-  {
-    CFX_ByteString str;
-    str.Format("%.1048576f", 1.2);
-    EXPECT_EQ("Bad precision", str);
-  }
 }
 
 TEST(fxcrt, EmptyByteString) {