Make ReadEntireFileToString return a std::string.

Note: this makes the method unavailable for export from angle_util,
which is probably why it was designed the way it was in the first
place. However, we import the test utils source file as a static
lib into each test executable and test shared module, so it works.

Bug: angleproject:7404
Change-Id: Ia957268882c2b8529643660d7d4f34d142c0dc43
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3708602
Commit-Queue: Roman Lavrov <romanl@google.com>
Reviewed-by: Roman Lavrov <romanl@google.com>

src/tests/test_utils/runner/TestSuite.cpp

@@ -1196,15 +1196,8 @@ TestSuite::TestSuite(int *argc, char **argv, std::function<void()> registerTests
             exit(EXIT_FAILURE);
         }
 
-        uint32_t fileSize = 0;
-        if (!GetFileSize(mFilterFile.c_str(), &fileSize))
-        {
-            printf("Error getting filter file size: %s\n", mFilterFile.c_str());
-            exit(EXIT_FAILURE);
-        }
-
-        std::vector<char> fileContents(fileSize + 1, 0);
-        if (!ReadEntireFileToString(mFilterFile.c_str(), fileContents.data(), fileSize))
+        std::string fileContents;
+        if (!ReadEntireFileToString(mFilterFile.c_str(), &fileContents))
         {
             printf("Error loading filter file: %s\n", mFilterFile.c_str());
             exit(EXIT_FAILURE);

util/shader_utils.cpp

@@ -16,17 +16,6 @@
 
 namespace
 {
-bool ReadEntireFile(const std::string &filePath, std::string *contentsOut)
-{
-    constexpr uint32_t kMaxBufferSize = 2000;
-    char buffer[kMaxBufferSize]       = {};
-    if (!angle::ReadEntireFileToString(filePath.c_str(), buffer, kMaxBufferSize) ||
-        strlen(buffer) == 0)
-        return false;
-    *contentsOut = buffer;
-    return true;
-}
-
 GLuint CompileProgramInternal(const char *vsSource,
                               const char *tcsSource,
                               const char *tesSource,
@@ -200,7 +189,7 @@ GLuint CompileShader(GLenum type, const char *source)
 GLuint CompileShaderFromFile(GLenum type, const std::string &sourcePath)
 {
     std::string source;
-    if (!ReadEntireFile(sourcePath, &source))
+    if (!angle::ReadEntireFileToString(sourcePath.c_str(), &source))
     {
         std::cerr << "Error reading shader file: " << sourcePath << "\n";
         return 0;
@@ -318,14 +307,14 @@ GLuint CompileProgramWithTESS(const char *vsSource,
 GLuint CompileProgramFromFiles(const std::string &vsPath, const std::string &fsPath)
 {
     std::string vsSource;
-    if (!ReadEntireFile(vsPath, &vsSource))
+    if (!angle::ReadEntireFileToString(vsPath.c_str(), &vsSource))
     {
         std::cerr << "Error reading shader: " << vsPath << "\n";
         return 0;
     }
 
     std::string fsSource;
-    if (!ReadEntireFile(fsPath, &fsSource))
+    if (!angle::ReadEntireFileToString(fsPath.c_str(), &fsSource))
     {
         std::cerr << "Error reading shader: " << fsPath << "\n";
         return 0;

util/test_utils.cpp

@@ -37,7 +37,7 @@ bool GetFileSize(const char *filePath, uint32_t *sizeOut)
     return true;
 }
 
-bool ReadEntireFileToString(const char *filePath, char *contentsOut, uint32_t maxLen)
+bool ReadEntireFileToString(const char *filePath, std::string *contentsOut)
 {
     std::ifstream stream(filePath);
     if (!stream)
@@ -45,15 +45,12 @@ bool ReadEntireFileToString(const char *filePath, char *contentsOut, uint32_t ma
         return false;
     }
 
-    std::string contents;
-
     stream.seekg(0, std::ios::end);
-    contents.reserve(static_cast<unsigned int>(stream.tellg()));
+    contentsOut->reserve(static_cast<unsigned int>(stream.tellg()));
     stream.seekg(0, std::ios::beg);
 
-    contents.assign((std::istreambuf_iterator<char>(stream)), std::istreambuf_iterator<char>());
+    contentsOut->assign((std::istreambuf_iterator<char>(stream)), std::istreambuf_iterator<char>());
 
-    strncpy(contentsOut, contents.c_str(), maxLen);
     return true;
 }
 

util/test_utils.h

@@ -51,8 +51,9 @@ bool CreateTemporaryFileInDir(const char *dir, char *tempFileNameOut, uint32_t m
 // Deletes a file or directory.
 bool DeleteSystemFile(const char *path);
 
-// Reads a file contents into a string.
-bool ReadEntireFileToString(const char *filePath, char *contentsOut, uint32_t maxLen);
+// Reads a file contents into a string. Note: this method cannot be exported across a shared module
+// boundary because it does memory allocation.
+bool ReadEntireFileToString(const char *filePath, std::string *contentsOut);
 
 // Compute a file's size.
 bool GetFileSize(const char *filePath, uint32_t *sizeOut);

util/test_utils_unittest.cpp

@@ -93,9 +93,9 @@ TEST(TestUtils, MAYBE_CreateAndDeleteTemporaryFile)
     EXPECT_GE(retval, 0);
 
     // Test ReadEntireFileToString
-    char actualString[kMaxPath];
-    EXPECT_TRUE(ReadEntireFileToString(path, actualString, kMaxPath));
-    EXPECT_EQ(strcmp(actualString, kOutputString), 0);
+    std::string actualString;
+    EXPECT_TRUE(ReadEntireFileToString(path, &actualString));
+    EXPECT_EQ(strcmp(actualString.c_str(), kOutputString), 0);
 
     // Delete the temporary file.
     EXPECT_TRUE(angle::DeleteSystemFile(path));
@@ -121,9 +121,9 @@ TEST(TestUtils, MAYBE_CreateAndDeleteFileInTempDir)
     EXPECT_GE(retval, 0);
 
     // Test ReadEntireFileToString
-    char actualString[kMaxPath];
-    EXPECT_TRUE(ReadEntireFileToString(path, actualString, kMaxPath));
-    EXPECT_EQ(strcmp(actualString, kOutputString), 0);
+    std::string actualString;
+    EXPECT_TRUE(ReadEntireFileToString(path, &actualString));
+    EXPECT_EQ(strcmp(actualString.c_str(), kOutputString), 0);
 
     // Delete the temporary file.
     EXPECT_TRUE(angle::DeleteSystemFile(path));